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Nwambaekwe KC, Ramoroka ME, Yussuf ST, Morudu TC, Ndipingwi MM, Iwuoha EI. Tb- and Eu-doped yttrium oxyselenides as novel absorber layers for superstrate thin-film photovoltaics: improved spectral optical absorption and green-red phosphor activation. Nanoscale 2023; 15:17147-17172. [PMID: 37853791 DOI: 10.1039/d3nr01162c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
To generate and deliver alternative sustainable energy in the face of the current energy crisis, new materials that can capture solar energy and transform it into other useful energies are required. Rare-earth (RE) oxychalcogenides are now being used more frequently as up/down-conversion materials in established photovoltaic (PV) devices to boost their PV performance. Here, through an efficient microwave assisted synthesis procedure, novel nanoplate/sheet shaped nanomaterials of yttrium oxyselenide (YOSe) and its analogues doped with Tb and Eu (YOSe:Tb and YOSe:Eu) were successfully synthesized. Analyses of the structure, stability, morphology, light absorption, and electrochemistry were performed. This work showed that the parent YOSe exhibited green (543 nm) and red (615 nm) emission luminescence when doped with Tb and Eu with a luminescence quantum yield (LQY) of 0.56 and 0.53 for YOSe:Tb and YOSe:Eu nanomaterials, respectively. The surface and material conductivity of YOSe improved with the addition of the dopant elements, with the best outcome shown in YOSe:Eu, according to electrokinetic research evidenced by the enhanced current peaks, reduced charge-transfer resistance (Rct) and low impedance magnitude (Zmag) through electrochemical experiments. These improvements were induced by the distinctive properties of the dopant elements. PCEs of 0.25%, 0.67%, and 1.20% were obtained for YOSe, YOSe:Tb, and YOSe:Eu-based PV devices, respectively, using the nanomaterials as novel absorber layers in a superstrate device design. Our results can initiate further exploitation of the doped host structure for effective down-conversion NIR luminescence for applications in PV devices and to boost the PV performance of existing solar cells.
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Affiliation(s)
- Kelechi C Nwambaekwe
- Key Laboratory for NanoElectrochemistry, University of the Western Cape Sensor Laboratories (SensorLab), 4th Floor Chemical Sciences Building, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Morongwa E Ramoroka
- Key Laboratory for NanoElectrochemistry, University of the Western Cape Sensor Laboratories (SensorLab), 4th Floor Chemical Sciences Building, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Sodiq T Yussuf
- Key Laboratory for NanoElectrochemistry, University of the Western Cape Sensor Laboratories (SensorLab), 4th Floor Chemical Sciences Building, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Tshaamano C Morudu
- Key Laboratory for NanoElectrochemistry, University of the Western Cape Sensor Laboratories (SensorLab), 4th Floor Chemical Sciences Building, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Miranda M Ndipingwi
- Key Laboratory for NanoElectrochemistry, University of the Western Cape Sensor Laboratories (SensorLab), 4th Floor Chemical Sciences Building, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Emmanuel I Iwuoha
- Key Laboratory for NanoElectrochemistry, University of the Western Cape Sensor Laboratories (SensorLab), 4th Floor Chemical Sciences Building, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
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Popoola OK, Marnewick JL, Iwuoha EI, Hussein AA. Methoxylated Flavonols and ent-Kaurane Diterpenes from the South African Helichrysum rutilans and Their Cosmetic Potential. Plants (Basel) 2023; 12:2870. [PMID: 37571023 PMCID: PMC10421400 DOI: 10.3390/plants12152870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 07/11/2023] [Accepted: 07/21/2023] [Indexed: 08/13/2023]
Abstract
Chromatographic fractionation of a methanol extract of Helichrysum rutilans afforded seven known compounds. The isolated compounds were identified as 5,7,8-trihydroxy-3,6-dimethoxyflavone-8-O-2-methyl-2-butanoate (C-1), 5,7-dihydroxy-3,6,8-trimethoxyflavone (C-2), 5-hydroxy-3,6,7,8-tetramethoxyflavone (C-3), 5-hydroxy-3,6,7-trimethoxyflavone (C-4), ent-kaurenoic acid (C-5), ent-kauran-18-al (C-6), and 15-α-hydroxy-(-)-ent-kaur-16-en-19-oic acid (C-7). Compounds C-1-C-4 demonstrated high antioxidant capacities on ORAC hydroxyl radical (2.114 ± 4.01; 2.413 ± 6.20; 1.924 ± 16.40; 1.917 ± 3.91) × 106; ORAC peroxyl radical (3.523 ± 3.22; 2.935 ± 0.13; 2.431 ± 8.63; 2.814 ± 5.20) × 103 µMTE/g; and FRAP (1251.45 ± 4.18; 1402.62 ± 5.77) µMAAE/g, respectively. Moderate inhibitory activities against Fe2+-induced lipid peroxidation were observed for C-1-C-4 as IC50 values of 13.123 ± 0.34, 16.421 ± 0.92, 11.64 ± 1.72, 14.90 ± 0.06 µg/mL, respectively, while their respective anti-tyrosinase activities with IC50 values of 25.735 ± 9.62, 24.062 ± 0.61, 39.03 ± 13.12, 37.67 ± 0.98 µg/mL were also observed. All compounds demonstrated TEAC values within the range of 1105-1424 µMTE/g. The result is an indication that a methanol extract of H. rutilans might possibly be a good source of natural antioxidants against ailments caused by cellular oxidative stress and as inhibitors against skin depigmentation, as well as possible raw materials needed for slowing down perishable agricultural products. This is the first report on the phytochemical and biological evaluation of H. rutilans.
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Affiliation(s)
- Olugbenga K. Popoola
- Applied Microbial and Health Biotechnology Institute, Cape Peninsula University of Technology, Bellville 7535, South Africa;
| | - Jeanine L. Marnewick
- Applied Microbial and Health Biotechnology Institute, Cape Peninsula University of Technology, Bellville 7535, South Africa;
| | - Emmanuel I. Iwuoha
- Chemistry Department, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa;
| | - Ahmed A. Hussein
- Chemistry Department, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa;
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Shi G, Peng X, Zeng J, Zhong L, Sun Y, Yang W, Zhong YL, Zhu Y, Zou R, Admassie S, Liu Z, Liu C, Iwuoha EI, Lu J. A Liquid Metal Microdroplets Initialized Hemicellulose Composite for 3D Printing Anode Host in Zn-Ion Battery. Adv Mater 2023:e2300109. [PMID: 37009654 DOI: 10.1002/adma.202300109] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/15/2023] [Indexed: 06/19/2023]
Abstract
Maintaining a steady affinity between gallium-based liquid metals (LM) and polymer binders, particularly under continuous mechanical deformation, such as extrusion-based 3D printing or plating/stripping of Zinc ion (Zn2+ ), is very challenging. Here, an LM-initialized polyacrylamide-hemicellulose/EGaIn microdroplets hydrogel is used as a multifunctional ink to 3D-print self-standing scaffolds and anode hosts for Zn-ion batteries. The LM microdroplets initiate acrylamide polymerization without additional initiators and cross-linkers, forming a double-covalent hydrogen-bonded network. The hydrogel acts as a framework for stress dissipation, enabling recovery from structural damage due to the cyclic plating/stripping of Zn2+ . The LM-microdroplet-initialized polymerization with hemicelluloses can facilitate the production of 3D printable inks for energy storage devices.
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Affiliation(s)
- Ge Shi
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China
| | - Xinwen Peng
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China
| | - Jiaming Zeng
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China
| | - Linxin Zhong
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China
| | - Yuan Sun
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China
| | - Wu Yang
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China
| | - Yu Lin Zhong
- Queensland Micro- and Nanotechnology Centre, School of Environment and Science, Griffith University, Nathan, QLD, 4111, Australia
| | - Yuxuan Zhu
- Queensland Micro- and Nanotechnology Centre, School of Environment and Science, Griffith University, Nathan, QLD, 4111, Australia
| | - Ren Zou
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China
| | - Shimelis Admassie
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China
- Department of Chemistry, Addis Ababa Univeristy, PO BOX 1176, Addis Ababa, Ethiopia
| | - Zhaoqing Liu
- School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials/Guangzhou Key Laboratory for Clean Energy and Materials/Huangpu Hydrogen Innovation Center, Higher Education Mega Center No. 230 Wai Huan Xi Road, Guangzhou, 510006, China
| | - Chuanfu Liu
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China
| | - Emmanuel I Iwuoha
- Department of Chemistry, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville, Cape Town, 7535, South Africa
| | - Jun Lu
- College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, Zhejiang Province, 310027, China
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Jijana AN, Feleni U, Ndangili PM, Bilibana M, Ajayi RF, Iwuoha EI. Quantum Dot-Sensitised Estrogen Receptor-α-Based Biosensor for 17β-Estradiol. Biosensors (Basel) 2023; 13:242. [PMID: 36832008 PMCID: PMC9954354 DOI: 10.3390/bios13020242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/05/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
17β-estradiol (E2) is an important natural female hormone that is also classified as an estrogenic endocrine-disrupting compound (e-EDC). It is, however, known to cause more damaging health effects compared to other e-EDCs. Environmental water systems are commonly contaminated with E2 that originates from domestic effluents. The determination of the level of E2 is thus very crucial in both wastewater treatment and in the aspect of environmental pollution management. In this work, an inherent and strong affinity of the estrogen receptor-α (ER-α) for E2 was used as a basis for the development of a biosensor that was highly selective towards E2 determination. A gold disk electrode (AuE) was functionalised with a 3-mercaptopropionic acid-capped tin selenide (SnSe-3MPA) quantum dot to produce a SnSe-3MPA/AuE electroactive sensor platform. The ER-α-based biosensor (ER-α/SnSe-3MPA/AuE) for E2 was produced by the amide chemistry of carboxyl functional groups of SnSe-3MPA quantum dots and the primary amines of ER-α. The ER-α/SnSe-3MPA/AuE receptor-based biosensor exhibited a formal potential (E0') value of 217 ± 12 mV, assigned as the redox potential for monitoring the E2 response using square-wave voltammetry (SWV). The response parameters of the receptor-based biosensor for E2 include a dynamic linear range (DLR) value of 1.0-8.0 nM (R2 = 0.99), a limit of detection (LOD) value of 1.69 nM (S/N = 3), and a sensitivity of 0.04 µA/nM. The biosensor exhibited high selectivity for E2 and good recoveries for E2 determination in milk samples.
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Affiliation(s)
- Abongile N. Jijana
- Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, Private Bag X3015, Randburg, Johannesburg 2125, South Africa
- SensorLab (University of the Western Cape Sensor Laboratories), 4th Floor Chemical Sciences Building, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa
| | - Usisipho Feleni
- Institute for Nanotechnology and Water Sustainability (iNanoWS), College of Science, Engineering and Technology, University of South Africa, Florida Campus, P/Bag X6, Florida, Roodepoort, Johannesburg 1710, South Africa
| | - Peter M. Ndangili
- School of Chemistry and Material Science, The Technical University of Kenya, Nairobi P.O. Box 52428-00200, Kenya
| | - Mawethu Bilibana
- Department of Chemistry, School of Physical and Chemical Sciences, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Private Bag X2046, Mmabatho 2735, South Africa
| | - Rachel F. Ajayi
- SensorLab (University of the Western Cape Sensor Laboratories), 4th Floor Chemical Sciences Building, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa
| | - Emmanuel I. Iwuoha
- SensorLab (University of the Western Cape Sensor Laboratories), 4th Floor Chemical Sciences Building, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa
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Mabokela TE, Nwanya AC, Ndipingwi MM, Yussuf ST, Ekwere PI, Uhuo OV, Ikpo CO, Modibane KD, Iwuoha EI. Nanostructured Europium-Doped Layered Lithium Manganese Oxide as a Prospective Cathode Material for Aqueous Lithium-Ion Battery. Electrochim Acta 2023. [DOI: 10.1016/j.electacta.2023.141865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Ramaripa PS, Modibane KD, Makgopa K, Seerane OA, Maubane-Nkadimeng MS, Makhado E, Hato MJ, Ramoroka ME, Molapo KM, Balakrishnan D, Iwuoha EI. Fabrication, characterization, and photovoltaic performance of titanium dioxide/metal-organic framework composite. Journal of Photochemistry and Photobiology 2022. [DOI: 10.1016/j.jpap.2022.100142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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Nolly C, Ikpo CO, Ndipingwi MM, Ekwere P, Iwuoha EI. Pseudocapacitive Effects of Multi-Walled Carbon Nanotubes-Functionalised Spinel Copper Manganese Oxide. Nanomaterials (Basel) 2022; 12:3514. [PMID: 36234643 PMCID: PMC9565235 DOI: 10.3390/nano12193514] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 09/26/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Spinel copper manganese oxide nanoparticles combined with acid-treated multi-walled carbon nanotubes (CuMn2O4/MWCNTs) were used in the development of electrodes for pseudocapacitor applications. The CuMn2O4/MWCNTs preparation involved initial synthesis of Mn3O4 and CuMn2O4 precursors followed by an energy efficient reflux growth method for the CuMn2O4/MWCNTs. The CuMn2O4/MWCNTs in a three-electrode cell assembly and in 3 M LiOH aqueous electrolyte exhibited a specific capacitance of 1652.91 F g-1 at 0.5 A g-1 current load. Similar investigation in 3 M KOH aqueous electrolyte delivered a specific capacitance of 653.41 F g-1 at 0.5 A g-1 current load. Stability studies showed that after 6000 cycles, the CuMn2O4/MWCNTs electrode exhibited a higher capacitance retention (88%) in LiOH than in KOH (64%). The higher capacitance retention and cycling stability with a Coulombic efficiency of 99.6% observed in the LiOH is an indication of a better charge storage behaviour in this electrolyte than in the KOH electrolyte with a Coulombic efficiency of 97.3%. This superior performance in the LiOH electrolyte than in the KOH electrolyte is attributed to an intercalation/de-intercalation mechanism which occurs more easily in the LiOH electrolyte than in the KOH electrolyte.
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Leve ZD, Jahed N, Sanga NA, Iwuoha EI, Pokpas K. Determination of Paracetamol on Electrochemically Reduced Graphene Oxide-Antimony Nanocomposite Modified Pencil Graphite Electrode Using Adsorptive Stripping Differential Pulse Voltammetry. Sensors (Basel) 2022; 22:5784. [PMID: 35957341 PMCID: PMC9370859 DOI: 10.3390/s22155784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/15/2022] [Accepted: 07/16/2022] [Indexed: 06/15/2023]
Abstract
A simple, highly sensitive, accurate, and low-cost electrochemical sensor was developed for the determination of over-the-counter painkiller, paracetamol (PC). The enhanced sensing capabilities of the developed sensor were fabricated by the single-step modification of disposable pencil graphite electrodes (PGEs) with the simultaneous electrochemical reduction in graphene oxide and antimony (II) salts. For this purpose, an electrochemically reduced graphene oxide-antimony nanoparticle (ERGO-SbNP) nanocomposite material was prepared by trapping metallic nanoparticles between individual graphene sheets in the modification of PGEs. Structural characterization by FTIR and Raman spectroscopy was employed to confirm the presence of oxygen functional groups and defects in the conjugated carbon-based structure of GO. Morphological differences between the modified PGEs were confirmed by HRTEM and HRSEM for the presence of nanoparticles. The modified electrodes were further electrochemically characterized using CV and EIS. The electrooxidation of PC on an ERGO-SbNPs-PGE was achieved by adsorptive stripping differential pulse voltametric analysis in 0.1 mol·L-1 phosphate buffer solution at pH = 7.0. The optimum current response was used to record a detection limit of 0.057 µmol·L-1 for PC. The electrochemical sensor was further used in real sample analysis for a commercially available pharmaceutical tablet (500 mg PC), for which the percentage recovery was between 99.4% and 100.8%.
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Ndipingwi MM, Ikpo CO, Nwanya AC, Januarie KC, Ramoroka ME, Uhuo OV, Nwambaekwe K, Yussuf ST, Iwuoha EI. Engineering the chemical environment of lithium manganese silicate by Mn ion substitution to boost the charge storage capacity for application in high efficiency supercapattery. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.140180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Oranzie M, Douman SF, Uhuo OV, Mokwebo KV, Sanga N, Iwuoha EI. Chronocoulometric signalling of BNP using a novel quantum dot aptasensor. Analyst 2022; 147:4829-4837. [DOI: 10.1039/d2an01357f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study is a first-time report of the development of a quantum dot based aptasensor for brain natriuretic peptide (BNP) detection using chronocoulometry for real-time analysis.
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Affiliation(s)
- Marlon Oranzie
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building, University of the Western Cape, Bellville 7535, Cape Town, South Africa
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town, 7700, South Africa
| | - Samantha F. Douman
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town, 7700, South Africa
| | - Onyinyechi V. Uhuo
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building, University of the Western Cape, Bellville 7535, Cape Town, South Africa
| | - Kefilwe V. Mokwebo
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building, University of the Western Cape, Bellville 7535, Cape Town, South Africa
| | - Nelia Sanga
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building, University of the Western Cape, Bellville 7535, Cape Town, South Africa
| | - Emmanuel I. Iwuoha
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building, University of the Western Cape, Bellville 7535, Cape Town, South Africa
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Tefera M, Tessema M, Admassie S, Ward M, Phelane L, Iwuoha EI, Baker PG. Electrochemical application of cobalt nanoparticles-polypyrrole composite modified electrode for the determination of phoxim. Anal Chim Acta X 2021; 9:100077. [PMID: 34622198 PMCID: PMC8482437 DOI: 10.1016/j.acax.2021.100077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/17/2021] [Accepted: 09/18/2021] [Indexed: 11/10/2022] Open
Abstract
In this study, cobalt nanoparticles (CoNPs) were synthesized and cobalt nanoparticles modified glassy carbon electrode (CoNPs/GCE) was prepared by drop coating the nanoparticles on glassy carbon electrode. After preparing polypyrrole modified glassy carbon electrode (PPy/GCE) using electropolymerization of pyrrole in LiClO4 solution, cobalt nanoparticles-polypyrrole composite modified glassy carbon electrode (CoNPs/PPy/GCE) was fabricated by drop coating the CoNPs on the PPy/GCE. Different characterization techniques such as scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, FTIR spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry were used to study the morphological structure and electrochemical behavior of the sensors. The results demonstrated that PPy chains interacted with CoNPs through donor-acceptor bonds. Among all the electrodes, CoNPs/PPy/GCE exhibited highest electroactive surface area and lowest electron transfer resistance towards phoxim. Under the optimal conditions, the sensor showed linear relationship between the reduction peak current and the concentration of phoxim in the range of 0.025 μM-12 μM with the detection limit as 4.5 nM. Besides, the composite electrode demonstrated excellent reproducibility, good stability and selectivity towards the possible interfering substances. All of these properties made CoNPs/PPy/GCE a suitable electrochemical sensor for the electrochemical determination of phoxim in water samples using square wave voltammetry.
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Affiliation(s)
- Molla Tefera
- Department of Chemistry, University of Gondar, P. O. Box 196, Gondar, Ethiopia
| | - Merid Tessema
- Department of Chemistry, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
| | - Shimelis Admassie
- Department of Chemistry, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
| | - Meryck Ward
- Sensor Lab, Department of Chemistry, University of the Western Cape, Private Bag X17, Robert Sobukwe Drive, Bellville, 7535, South Africa
| | - Lisebo Phelane
- Sensor Lab, Department of Chemistry, University of the Western Cape, Private Bag X17, Robert Sobukwe Drive, Bellville, 7535, South Africa
| | - Emmanuel I. Iwuoha
- Sensor Lab, Department of Chemistry, University of the Western Cape, Private Bag X17, Robert Sobukwe Drive, Bellville, 7535, South Africa
| | - Priscilla G.L. Baker
- Sensor Lab, Department of Chemistry, University of the Western Cape, Private Bag X17, Robert Sobukwe Drive, Bellville, 7535, South Africa
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Douman SF, De Eguilaz MR, Cumba LR, Beirne S, Wallace GG, Yue Z, Iwuoha EI, Forster RJ. Electrochemiluminescence at 3D Printed Titanium Electrodes. Front Chem 2021; 9:662810. [PMID: 34113601 PMCID: PMC8186460 DOI: 10.3389/fchem.2021.662810] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
The fabrication and electrochemical properties of a 3D printed titanium electrode array are described. The array comprises 25 round cylinders (0.015 cm radius, 0.3 cm high) that are evenly separated on a 0.48 × 0.48 cm square porous base (total geometric area of 1.32 cm2). The electrochemically active surface area consists of fused titanium particles and exhibits a large roughness factor ≈17. In acidic, oxygenated solution, the available potential window is from ~-0.3 to +1.2 V. The voltammetric response of ferrocyanide is quasi-reversible arising from slow heterogeneous electron transfer due to the presence of a native/oxidatively formed oxide. Unlike other metal electrodes, both [Ru(bpy)3]1+ and [Ru(bpy)3]3+ can be created in aqueous solutions which enables electrochemiluminescence to be generated by an annihilation mechanism. Depositing a thin gold layer significantly increases the standard heterogeneous electron transfer rate constant, ko, by a factor of ~80 to a value of 8.0 ± 0.4 × 10−3 cm s−1 and the voltammetry of ferrocyanide becomes reversible. The titanium and gold coated arrays generate electrochemiluminescence using tri-propyl amine as a co-reactant. However, the intensity of the gold-coated array is between 30 (high scan rate) and 100-fold (slow scan rates) higher at the gold coated arrays. Moreover, while the voltammetry of the luminophore is dominated by semi-infinite linear diffusion, the ECL response is significantly influenced by radial diffusion to the individual microcylinders of the array.
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Affiliation(s)
- Samantha F Douman
- National Centre for Sensor Research, Chemistry Department, Dublin City University, Dublin, Ireland.,SensorLab (University of the Western Cape Sensor Laboratories), University of Western Cape, Cape Town, South Africa
| | - Miren Ruiz De Eguilaz
- National Centre for Sensor Research, Chemistry Department, Dublin City University, Dublin, Ireland
| | - Loanda R Cumba
- National Centre for Sensor Research, Chemistry Department, Dublin City University, Dublin, Ireland
| | - Stephen Beirne
- Australian Research Council, Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Gordon G Wallace
- Australian Research Council, Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Zhilian Yue
- Australian Research Council, Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Emmanuel I Iwuoha
- SensorLab (University of the Western Cape Sensor Laboratories), University of Western Cape, Cape Town, South Africa
| | - Robert J Forster
- National Centre for Sensor Research, Chemistry Department, Dublin City University, Dublin, Ireland.,FutureNeuro SFI Research Centre, Dublin, Ireland
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Douman SF, Collins D, Cumba LR, Beirne S, Wallace GG, Yue Z, Iwuoha EI, Melinato F, Pellegrin Y, Forster RJ. Wireless electrochemiluminescence at functionalised gold microparticles using 3D titanium electrode arrays. Chem Commun (Camb) 2021; 57:4642-4645. [PMID: 33876176 DOI: 10.1039/d1cc01010g] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Wireless electrochemiluminescence is generated using interdigitated, 3D printed, titanium arrays as feeder electrodes to shape the electric field. Gold microparticles (45 μm diameter), functionalised with 11-mercaptoundecanoic acid, act as micro-emitters to generate electrochemiluminescence from [Ru(bpy)3]2+, (bpy is 2,2'-bipyridine) where the co-reactant is tripropylamine. The oxide coated titanium allows intense electric fields, whose distribution depends on the geometry of the array, to be created in the absence of deliberately added electrolyte. COMSOL modelling and long exposure ECL imaging have been used to map the electric field distribution. Significantly, we demonstrate that by controlling the surface charge of the gold microparticles through the solution pH, the light intensity can be increased by a factor of more than 10.
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Affiliation(s)
- Samantha F Douman
- National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, FutureNeuro SFI Research Centre, Dublin 9, Ireland. and SensorLab (UWC Sensor Laboratories), Chemical Sciences Building, University of Western Cape Town, Robert Sobukwe Road, Bellville 7535, Cape, South Africa
| | - David Collins
- National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, FutureNeuro SFI Research Centre, Dublin 9, Ireland.
| | - Loanda R Cumba
- National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, FutureNeuro SFI Research Centre, Dublin 9, Ireland.
| | - Stephen Beirne
- Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, NSW 2522, Australia
| | - Gordon G Wallace
- Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, NSW 2522, Australia
| | - Zhilian Yue
- Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, NSW 2522, Australia
| | - Emmanuel I Iwuoha
- SensorLab (UWC Sensor Laboratories), Chemical Sciences Building, University of Western Cape Town, Robert Sobukwe Road, Bellville 7535, Cape, South Africa
| | - Federica Melinato
- Université de Nantes, CEISAM, UMR CNRS 6230 UFR sciences and techniques, Nantes, France
| | - Yann Pellegrin
- Université de Nantes, CEISAM, UMR CNRS 6230 UFR sciences and techniques, Nantes, France
| | - Robert J Forster
- National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, FutureNeuro SFI Research Centre, Dublin 9, Ireland. and SensorLab (UWC Sensor Laboratories), Chemical Sciences Building, University of Western Cape Town, Robert Sobukwe Road, Bellville 7535, Cape, South Africa
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14
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Etsassala NGER, Cupido CN, Iwuoha EI, Hussein AA. Abietane Diterpenes as Potential Candidates for the Management of Type 2 Diabetes. Curr Pharm Des 2021; 26:2885-2891. [PMID: 32228419 DOI: 10.2174/1381612826666200331082917] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 03/03/2020] [Indexed: 02/07/2023]
Abstract
Diabetes mellitus (DM) is considered one of the most common metabolic disorders with an elevated morbidity and mortality rate. It is characterised by a deficiency in insulin secretion or degradation of secreted insulin. Many internal and external factors, such as oxidative stress, obesity and sedentary lifestyle, among others, have been suggested as the major causes of these cell alterations. Diabetes I and II are the most common types of diabetes. Treatment of type I requires insulin injection, while type II can be managed using different synthetic antidiabetic agents. However, their effectiveness is limited as a result of low bioavailability, high cost of drug production, and unfavourable side effects. There is a great need to develop alternative and more active antidiabetic drugs from natural sources. Different forms of natural products have been used since time immemorial as a source of medicine for the purpose of curing numerous human diseases, including diabetes. Secondary metabolites such as polyphenols, flavonoids, terpenoids, alkaloids and several other constituents have direct and indirect roles in controlling such diseases; among them, abietane diterpenes have been reported to display a broad spectrum of promising biological activities including diabetes. This review aimed to summarize existing data from SciFinder (2005-2018) on the biological importance of abietane diterpenes in the prevention and management of type 2 diabetes and closely related diseases.
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Affiliation(s)
- Ninon G E R Etsassala
- Chemistry Department, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
| | - Christopher N Cupido
- Department of Botany, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
| | - Emmanuel I Iwuoha
- Chemistry Department, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
| | - Ahmed A Hussein
- Chemistry Department, Cape Peninsula University of Technology, Symphony Rd. Bellville 7535, South Africa
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15
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Ramoroka ME, Mdluli SB, John-Denk VS, Modibane KD, Arendse CJ, Iwuoha EI. Synthesis and Photovoltaics of Novel 2,3,4,5-Tetrathienylthiophene-co-poly(3-hexylthiophene-2,5-diyl) Donor Polymer for Organic Solar Cell. Polymers (Basel) 2020; 13:E2. [PMID: 33374983 PMCID: PMC7792595 DOI: 10.3390/polym13010002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 12/04/2020] [Accepted: 12/08/2020] [Indexed: 12/27/2022] Open
Abstract
This report focuses on the synthesis of novel 2,3,4,5-tetrathienylthiophene-co-poly(3-hexylthiophene-2,5-diyl) (TTT-co-P3HT) as a donor material for organic solar cells (OSCs). The properties of the synthesized TTT-co-P3HT were compared with those of poly(3-hexylthiophene-2,5-diyl (P3HT). The structure of TTT-co-P3HT was studied using nuclear magnetic resonance spectroscopy (NMR) and Fourier-transform infrared spectroscopy (FTIR). It was seen that TTT-co-P3HT possessed a broader electrochemical and optical band-gap as compared to P3HT. Cyclic voltammetry (CV) was used to determine lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy gaps of TTT-co-P3HT and P3HT were found to be 2.19 and 1.97 eV, respectively. Photoluminescence revealed that TTT-co-P3HT:PC71BM have insufficient electron/hole separation and charge transfer when compared to P3HT:PC71BM. All devices were fabricated outside a glovebox. Power conversion efficiency (PCE) of 1.15% was obtained for P3HT:PC71BM device and 0.14% was obtained for TTT-co-P3HT:PC71BM device. Further studies were done on fabricated OSCs during this work using electrochemical methods. The studies revealed that the presence of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) on the surface of indium tin oxide (ITO) causes a reduction in cyclic voltammogram oxidation/reduction peak current and increases the charge transfer resistance in comparison with a bare ITO. We also examined the ITO/PEDOT:PSS electrode coated with TTT-co-P3HT:PC71BM, TTT-co-P3HT:PC71BM/ZnO, P3HT:PC71BM and P3HT:PC71BM/ZnO. The study revealed that PEDOT:PSS does not completely block electrons from active layer to reach the ITO electrode.
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Affiliation(s)
- Morongwa E. Ramoroka
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa; (M.E.R.); (S.B.M.)
| | - Siyabonga B. Mdluli
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa; (M.E.R.); (S.B.M.)
| | - Vivian S. John-Denk
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa; (M.E.R.); (S.B.M.)
| | - Kwena D. Modibane
- Department of Chemistry, School of Physical and Mineral Science, University of Limpopo, Sovenga, Polokwane 0727, South Africa;
| | - Christopher J. Arendse
- Department of Physics and Astronomy, University of the Western Cape, Bellville, Cape Town 7535, South Africa;
| | - Emmanuel I. Iwuoha
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa; (M.E.R.); (S.B.M.)
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16
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Ramohlola KE, Iwuoha EI, Hato MJ, Modibane KD. Instrumental Techniques for Characterization of Molybdenum Disulphide Nanostructures. J Anal Methods Chem 2020; 2020:8896698. [PMID: 33381353 PMCID: PMC7758135 DOI: 10.1155/2020/8896698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 11/10/2020] [Accepted: 11/27/2020] [Indexed: 06/12/2023]
Abstract
The excellent chemical and physical properties of materials (nanomaterials) with dimensions of less than 100 nm (nanometers) resulted in researchers and industrialists to have great interest in their discovery and applications in various systems/applications. As their sizes are reduced to nanoscale, these nanomaterials tend to possess exceptional properties differing from those of their bulk counterparts; hence, they have found applications in electronics and medicines. In order to apply them in those applications, there is a need to synthesise these nanomaterials and study their structural, optical, and electrochemical properties. Among several nanomaterials, molybdenum disulphide (MoS2) has received a great interest in energy applications due to its exceptional properties such as stability, conductivity, and catalytic activities. Hence, the great challenge lies in finding the state-of-the-art characterization techniques to reveal the different properties of MoS2 nanostructures with great accuracy. In this regard, there is a need to study and employ several techniques to accurately study the surface chemistry and physics of the MoS2 nanostructures. Hence, this review will comprehensively discuss a detailed literature survey on analytical techniques that can be used to study the chemical, physical, and surface properties of MoS2 nanostructures, namely, ultraviolet-visible spectroscopy (UV-vis), photoluminescence spectroscopy (PL), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, time-of-flight secondary ion mass spectroscopy (TOF-SIMS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopies (SEM and TEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS/X), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and electroanalytical methods which include linear sweep (LSV) and cyclic (CV) voltammetry and electrochemical impedance spectroscopy (EIS).
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Affiliation(s)
- Kabelo E. Ramohlola
- Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa
| | - Emmanuel I. Iwuoha
- SensorLab, Chemistry Department, University of the Western Cape, Bellville, 7535 Cape Town, South Africa
| | - Mpitloane J. Hato
- Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa
| | - Kwena D. Modibane
- Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa
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17
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Nwanya AC, Ndipingwi MM, Ezema FI, Iwuoha EI, Maaza M. Bio-synthesized P2-Na0.57CoO2 nanoparticles as cathode for aqueous sodium ion battery. J Electroanal Chem (Lausanne) 2020. [DOI: 10.1016/j.jelechem.2020.114600] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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18
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Etsassala NGER, Badmus JA, Marnewick JL, Iwuoha EI, Nchu F, Hussein AA. Alpha-Glucosidase and Alpha-Amylase Inhibitory Activities, Molecular Docking, and Antioxidant Capacities of Salvia aurita Constituents. Antioxidants (Basel) 2020; 9:E1149. [PMID: 33228164 PMCID: PMC7699461 DOI: 10.3390/antiox9111149] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/02/2020] [Accepted: 10/09/2020] [Indexed: 11/29/2022] Open
Abstract
Diabetes mellitus (DM) is one of the most dangerous metabolic diseases with a high rate of mortality worldwide. It is well known that insulin resistance and deficiency in insulin production from pancreatic β-cells are the main characteristics of DM. Due to the detrimental side effects of the current treatment, there is a considerable need to develop new effective antidiabetic drugs, especially alpha-glucosidase and alpha-amylase inhibitors with lesser adverse effects. These inhibitors are known to be directly involved in the delay of carbohydrate digestion, resulting in a reduction of glucose absorption rate and, consequently, reducing the postprandial rise of plasma glucose, which can reduce the risk of long-term diabetes complications. Furthermore, natural products are well-known sources for the discovery of new bioactive compounds that can serve as scaffolds for drug discovery, including that of new antidiabetic drugs. The phytochemical investigation of Salvia aurita collected from Hogobach Pass, Eastern Cape Province, South Africa (SA), yielded four known abietane diterpenes namely carnosol (1), rosmanol (2), 7-methoxyrosmanol (3), 12-methoxycarnosic acid (4), and one flavonoid named 4,7-dimethylapigenin (5). Structural characterization of these isolated compounds was conducted using 1 and 2D NMR, in comparison with reported spectroscopic data. These compounds are reported for the first time from S. aurita. The biological evaluation of the isolated compound against alpha-glucosidase exhibited strong inhibitory activities for 3 and 2 with the half maximal inhibitory concentration (IC50) values of 4.2 ± 0.7 and 16.4 ± 1.1 µg/mL respectively, while 4 and 1 demonstrated strong alpha-amylase inhibitory activity amongst the isolated compounds with IC50 values of 16.2 ± 0.3 and 19.8 ± 1.4 µg/mL. Molecular docking analysis confirms the strong inhibitory activity of 3 against alpha-glucosidase. Additionally, excellent antioxidant capacities were displayed by 2, 1, and 3, respectively, with oxygen radical absorbance capacity (ORAC) (25.79 ± 0.01; 23.96 ± 0.01; 23.94 ± 0.02) mM Trolox equivalent (TE)/g; 1 and 2 as ferric-ion reducing antioxidant power (FRAP) (3.92 ± 0.002; 1.52 ± 0.002) mM ascorbic acid equivalent (AAE)/g; 5 and 2 as Trolox equivalent absorbance capacity (TEAC) (3.19 ± 0.003; 2.06 ± 0.003) mM TE/g. The methanolic extract of S. aurita is a rich source of abietane diterpenes with excellent antioxidant and antidiabetic activities that can be useful to modulate oxidative stress and might possibly be excellent candidates for the management of diabetes. This is the first scientific report on the phytochemical isolation and biological evaluation of the alpha-glucosidase and alpha-amylase inhibitory activities of Salvia aurita.
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Affiliation(s)
- Ninon G. E. R. Etsassala
- Department of Horticultural Sciences, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa;
| | - Jelili A. Badmus
- Applied Microbial and Health Biotechnology Institute, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa;
| | - Jeanine L. Marnewick
- Applied Microbial and Health Biotechnology Institute, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa;
| | - Emmanuel I. Iwuoha
- Chemistry Department, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa;
| | - Felix Nchu
- Department of Horticultural Sciences, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa;
| | - Ahmed A. Hussein
- Chemistry Department, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa;
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19
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Raleie N, Suru John‐Denk V, Wonderboy Hlongwa N, Douman SF, Iwuoha EI. Photoelectrochemistry of Poly‐3‐hexylthiophene and Stannum Chromium Bimetallic Nanoparticle Heterojunction Blend. ELECTROANAL 2020. [DOI: 10.1002/elan.202060312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Naledi Raleie
- SensorLab (University of the Western Cape Sensor Laboratoeries) Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Vivian Suru John‐Denk
- SensorLab (University of the Western Cape Sensor Laboratoeries) Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Ntuthuko Wonderboy Hlongwa
- SensorLab (University of the Western Cape Sensor Laboratoeries) Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Samantha Fiona Douman
- SensorLab (University of the Western Cape Sensor Laboratoeries) Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Emmanuel I. Iwuoha
- SensorLab (University of the Western Cape Sensor Laboratoeries) Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
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20
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Teffu DM, Makhafola MD, Ndipingwi MM, Makhado E, Hato MJ, Iwuoha EI, Modibane KD, Makgopa K. Interrogation of Electrochemical Performance of Reduced Graphene Oxide/Metal‐organic Framework Hybrid for Asymmetric Supercabattery Application. ELECTROANAL 2020. [DOI: 10.1002/elan.202060303] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Daniel M. Teffu
- Nanotechnology Research Lab Department of Chemistry School of Physical and Mineral Sciences University of Limpopo (Turfloop) Sovenga 0727 Polokwane South Africa
| | - Mogwasha D. Makhafola
- Nanotechnology Research Lab Department of Chemistry School of Physical and Mineral Sciences University of Limpopo (Turfloop) Sovenga 0727 Polokwane South Africa
| | - Miranda M. Ndipingwi
- SensorLab Chemistry Department University of the Western Cape Cape Town South Africa
| | - Edwin Makhado
- Nanotechnology Research Lab Department of Chemistry School of Physical and Mineral Sciences University of Limpopo (Turfloop) Sovenga 0727 Polokwane South Africa
| | - Mpitloane J. Hato
- Nanotechnology Research Lab Department of Chemistry School of Physical and Mineral Sciences University of Limpopo (Turfloop) Sovenga 0727 Polokwane South Africa
| | - Emmanuel I. Iwuoha
- SensorLab Chemistry Department University of the Western Cape Cape Town South Africa
| | - Kwena D. Modibane
- Nanotechnology Research Lab Department of Chemistry School of Physical and Mineral Sciences University of Limpopo (Turfloop) Sovenga 0727 Polokwane South Africa
| | - Katlego Makgopa
- Department of Chemistry Faculty of Science Tshwane University of Technology (Acardia Campus) Pretoria 0001 South Africa
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21
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Hlongwa NW, Ikpo CO, Ndipingwi MM, Nolly C, Raleie N, Dywili N, Iwuoha EI. Graphene‐functionalised Olivine Lithium Manganese Phosphate Derivatives for High Performance Lithium‐ion Capacitors. ELECTROANAL 2020. [DOI: 10.1002/elan.202060316] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ntuthuko W. Hlongwa
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Chinwe O. Ikpo
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Miranda M. Ndipingwi
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Christopher Nolly
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Naledi Raleie
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Nomxolisi Dywili
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
| | - Emmanuel I. Iwuoha
- SensorLab (University of the Western Cape Sensor Laboratories), Chemical Sciences Building Robert Sobukwe Road, Bellville 7535 Cape Town South Africa
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22
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Etsassala NGER, Ndjoubi KO, Mbira TJ, Pearce B, Pearce K, Iwuoha EI, Hussein AA, Benjeddou M. Glucose-Uptake Activity and Cytotoxicity of Diterpenes and Triterpenes Isolated from Lamiaceae Plant Species. Molecules 2020; 25:molecules25184129. [PMID: 32927596 PMCID: PMC7570927 DOI: 10.3390/molecules25184129] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/11/2020] [Accepted: 08/14/2020] [Indexed: 12/01/2022] Open
Abstract
The prevalence of diabetes mellitus (DM), considered one of the most common metabolic disorders, has dramatically increased and resulted in higher rates of morbidity and mortality around the world in the past decade. It is well known that insulin resistance in target tissues and a deficiency in insulin secretion from pancreatic β-cells are the main characteristics of type 2 diabetes. The aim of this study was the bio-evaluation of compounds isolated from three selected plant species: namely, Salvia africana-lutea, Leonotis ocymifolia, and Plectranthus madagascariensis, for their glucose-uptake ability. Methanolic extracts were produced from the aerial parts of each plant. Compounds were identified using different spectroscopic techniques. The glucose-uptake ability of each compound was then evaluated in mammalian cells using 2-deoxyglucose-6-phosphate. The cytotoxicity of each compound was established via the MTT assay. Chromatographic purification of the three plant species yielded sixteen pure terpenoids. Compounds 1 (p = 0.0031), 8 (p = 0.0053), and 6 (p = 0.0086) showed a marked increase in glucose uptake, respectively. Additionally, 1, 4, and 6 exhibited cytotoxicity toward mammalian tissue with a decrease in cell viability of ~70%, ~68%, and ~67%, respectively. The results suggested that several compounds demonstrated a marked increase in glucose uptake, while two of the compounds exhibited signs of cytotoxicity. It may, therefore, be suggested that these compounds be considered as potential candidates for novel plant-derived alternative therapies in the treatment of type 2 diabetes.
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Affiliation(s)
- Ninon G. E. R. Etsassala
- Department of Horticultural Sciences, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa;
| | - Kadidiatou O. Ndjoubi
- Chemistry Department, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa; (K.O.N.); (T.J.M.); (A.A.H.)
| | - Thilly J. Mbira
- Chemistry Department, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa; (K.O.N.); (T.J.M.); (A.A.H.)
| | - Brendon Pearce
- Precision Medicine Laboratory, Department of Biotechnology, 2nd Floor, Life Science Building, University of the Western Cape, Cape Town 7530, South Africa; (B.P.); (K.P.)
| | - Keenau Pearce
- Precision Medicine Laboratory, Department of Biotechnology, 2nd Floor, Life Science Building, University of the Western Cape, Cape Town 7530, South Africa; (B.P.); (K.P.)
| | - Emmanuel I. Iwuoha
- Chemistry Department, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa;
| | - Ahmed A. Hussein
- Chemistry Department, Cape Peninsula University of Technology, Symphony Rd., Bellville 7535, South Africa; (K.O.N.); (T.J.M.); (A.A.H.)
| | - Mongi Benjeddou
- Precision Medicine Laboratory, Department of Biotechnology, 2nd Floor, Life Science Building, University of the Western Cape, Cape Town 7530, South Africa; (B.P.); (K.P.)
- Correspondence: ; Tel.: +27-21-959-2080; Fax: +27-21-959-3505
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23
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Phelane L, Gouveia-Caridade C, Barsan MM, Baker PGL, Brett CMA, Iwuoha EI. Electrochemical Determination of Tyrosine using a Novel Tyrosinase Multi-Walled Carbon Nanotube (MWCNT) Polysulfone Modified Glassy Carbon Electrode (GCE). ANAL LETT 2019. [DOI: 10.1080/00032719.2019.1649417] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Lisebo Phelane
- Department of Chemistry, University of the Western Cape, Bellville, South Africa
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal
| | - Carla Gouveia-Caridade
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal
| | - Madalina M. Barsan
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal
| | | | - Christopher M. A. Brett
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal
| | - Emmanuel I. Iwuoha
- Department of Chemistry, University of the Western Cape, Bellville, South Africa
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24
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Nwanya AC, Razanamahandry LC, Bashir AKH, Ikpo CO, Nwanya SC, Botha S, Ntwampe SKO, Ezema FI, Iwuoha EI, Maaza M. Industrial textile effluent treatment and antibacterial effectiveness of Zea mays L. Dry husk mediated bio-synthesized copper oxide nanoparticles. J Hazard Mater 2019; 375:281-289. [PMID: 31078988 DOI: 10.1016/j.jhazmat.2019.05.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 04/14/2019] [Accepted: 05/02/2019] [Indexed: 05/02/2023]
Abstract
Zea mays L. dry husk extract was used to bio synthesize copper oxide nanoparticles. Red coloured cubic Cu2O nanoparticles were obtained for the first time via this simple, eco- friendly, green synthesis route. The Cu2O nanoparticles were thermally oxidized to pure monoclinic CuO nanoparticles at 600 °C. The phases of the copper oxides were confirmed from the x-ray diffraction (XRD) studies. The nanoparticle sizes as obtained from high resolution transmission electron microscope (HRTEM) analysis range from 10 to 26 nm, 36-73 nm and 30-90 nm for the unannealed Cu2O, 300 °C and 600 °C annealed CuO respectively. The values of the bandgap energies obtained from diffuse reflectance of the nanoparticles are 2.0, 1.30 and 1.42 eV respectively for the unannealed, 300 °C, and 600 °C annealed copper oxide nanoparticles. The 600 °C annealed copper oxide nanoparticles showed 91% and 90% degradation ability for methylene blue dye (BM) and textile effluent (TE) respectively under visible light irradiation. While CuO_300 is more effective to inhibit the growth of Escherichia coli 518,133 and Staphylococcus aureus 9144, Cu2O is better for Pseudomonas aeruginosa and Bacillus licheniformis. The results confirm the photo-catalytic and anti-microbial effectiveness of the copper oxide nanoparticles.
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Affiliation(s)
- Assumpta Chinwe Nwanya
- Department of Physics and Astronomy, University of Nigeria, Nsukka, Nigeria; UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, South Africa; Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West, PO Box 722, 7129, Somerset West, South Africa.
| | - Lovasoa Christine Razanamahandry
- UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, South Africa; Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West, PO Box 722, 7129, Somerset West, South Africa
| | - A K H Bashir
- UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, South Africa; Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West, PO Box 722, 7129, Somerset West, South Africa
| | - Chinwe O Ikpo
- Sensor Lab, Department of Chemistry, University of the Western Cape, Bellville, 7535, Cape Town, South Africa
| | - Stephen C Nwanya
- Department of Mechanical Engineering, University of Nigeria, Nsukka, Nigeria
| | - Subelia Botha
- Electron Microscope Unit, University of the Western Cape, South Africa
| | - S K O Ntwampe
- Bioresource Engineering Research Group (BioERG), Faculty of Applied Science Department of Biotechnology Cape Peninsula University of Technology, P.O. Box 652, Cape Town, 8000, South Africa
| | - Fabian I Ezema
- Department of Physics and Astronomy, University of Nigeria, Nsukka, Nigeria; UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, South Africa; Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West, PO Box 722, 7129, Somerset West, South Africa
| | - Emmanuel I Iwuoha
- Sensor Lab, Department of Chemistry, University of the Western Cape, Bellville, 7535, Cape Town, South Africa
| | - Malik Maaza
- UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, South Africa; Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West, PO Box 722, 7129, Somerset West, South Africa
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Masikini M, Ghica ME, Baker PGL, Iwuoha EI, Brett CMA. Electrochemical Sensor Based on Multi‐walled Carbon Nanotube/Gold Nanoparticle Modified Glassy Carbon Electrode for Detection of Estradiol in Environmental Samples. ELECTROANAL 2019. [DOI: 10.1002/elan.201900190] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Milua Masikini
- SensorLab, Department of ChemistryUniversity of Western Cape Robert Sobukwe Road, Bellville Cape Town 7535 South Africa
| | - Mariana Emilia Ghica
- Department of Chemistry, Faculty of Sciences and TechnologyUniversity of Coimbra 3004-535 Coimbra Portugal
| | - Priscilla G. L. Baker
- SensorLab, Department of ChemistryUniversity of Western Cape Robert Sobukwe Road, Bellville Cape Town 7535 South Africa
| | - Emmanuel I. Iwuoha
- SensorLab, Department of ChemistryUniversity of Western Cape Robert Sobukwe Road, Bellville Cape Town 7535 South Africa
| | - Christopher M. A. Brett
- Department of Chemistry, Faculty of Sciences and TechnologyUniversity of Coimbra 3004-535 Coimbra Portugal
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26
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Nwanya AC, Ndipingwi MM, Mayedwa N, Razanamahandry L, Ikpo CO, Waryo T, Ntwampe S, Malenga E, Fosso-Kankeu E, Ezema FI, Iwuoha EI, Maaza M. Maize (Zea mays L.) fresh husk mediated biosynthesis of copper oxides: Potentials for pseudo capacitive energy storage. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.01.186] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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27
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Sidwaba U, Ntshongontshi N, Feleni U, Wilson L, Waryo T, Iwuoha EI. Manganese Peroxidase-Based Electro-Oxidation of Bisphenol A at Hydrogellic Polyaniline-Titania Nanocomposite-Modified Glassy Carbon Electrode. Electrocatalysis (N Y) 2019. [DOI: 10.1007/s12678-019-0510-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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28
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Ndipingwi MM, Ikpo CO, Hlongwa NW, Dywili N, Djoumessi Yonkeu AL, Iwuoha EI. Crystal chemistry and lithium-ion intercalation properties of lithium manganese silicate cathode for aqueous rechargeable Li-ion batteries. J APPL ELECTROCHEM 2019. [DOI: 10.1007/s10800-019-01296-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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Dywili NR, Ntziouni A, Ikpo C, Ndipingwi M, Hlongwa NW, Yonkeu ALD, Masikini M, Kordatos K, Iwuoha EI. Graphene Oxide Decorated Nanometal-Poly(Anilino-Dodecylbenzene Sulfonic Acid) for Application in High Performance Supercapacitors. Micromachines (Basel) 2019; 10:E115. [PMID: 30754698 PMCID: PMC6412443 DOI: 10.3390/mi10020115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 12/02/2022]
Abstract
Graphene oxide (GO) decorated with silver (Ag), copper (Cu) or platinum (Pt) nanoparticles that are anchored on dodecylbenzene sulfonic acid (DBSA)-doped polyaniline (PANI) were prepared by a simple one-step method and applied as novel materials for high performance supercapacitors. High-resolution transmission electron microscopy (HRTEM) and high-resolution scanning electron microscopy (HRSEM) analyses revealed that a metal-decorated polymer matrix is embedded within the GO sheet. This caused the M/DBSA⁻PANI (M = Ag, Cu or Pt) particles to adsorb on the surface of the GO sheets, appearing as aggregated dark regions in the HRSEM images. The Fourier transform infrared (FTIR) spectroscopy studies revealed that GO was successfully produced and decorated with Ag, Cu or Pt nanoparticles anchored on DBSA⁻PANI. This was confirmed by the appearance of the GO signature epoxy C⁻O vibration band at 1040 cm-1 (which decreased upon the introduction of metal nanoparticle) and the PANI characteristic N⁻H stretching vibration band at 3144 cm-1 present only in the GO/M/DBSA⁻PANI systems. The composites were tested for their suitability as supercapacitor materials; and specific capacitance values of 206.4, 192.8 and 227.2 F·g-1 were determined for GO/Ag/DBSA⁻PANI, GO/Cu/DBSA⁻PANI and GO/Pt/DBSA⁻PANI, respectively. The GO/Pt/DBSA⁻PANI electrode exhibited the best specific capacitance value of the three electrodes and also had twice the specific capacitance value reported for Graphene/MnO₂//ACN (113.5 F·g-1). This makes GO/Pt/DBSA⁻PANI a very promising organic supercapacitor material.
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Affiliation(s)
- Nomxolisi R Dywili
- SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, Cape Town, South Africa.
- School of Chemical Engineering, Section I: Chemical Sciences, Lab of Inorganic and Analytical Chemistry, National Technical University of Athens, 9 Heroon Polytechniou Str., 15773 Athens, Greece.
| | - Afroditi Ntziouni
- School of Chemical Engineering, Section I: Chemical Sciences, Lab of Inorganic and Analytical Chemistry, National Technical University of Athens, 9 Heroon Polytechniou Str., 15773 Athens, Greece.
| | - Chinwe Ikpo
- SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, Cape Town, South Africa.
| | - Miranda Ndipingwi
- SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, Cape Town, South Africa.
| | - Ntuthuko W Hlongwa
- SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, Cape Town, South Africa.
| | - Anne L D Yonkeu
- SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, Cape Town, South Africa.
| | - Milua Masikini
- SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, Cape Town, South Africa.
| | - Konstantinos Kordatos
- School of Chemical Engineering, Section I: Chemical Sciences, Lab of Inorganic and Analytical Chemistry, National Technical University of Athens, 9 Heroon Polytechniou Str., 15773 Athens, Greece.
| | - Emmanuel I Iwuoha
- SensorLab, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, 7535, Cape Town, South Africa.
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30
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da Silva W, Ghica ME, Ajayi RF, Iwuoha EI, Brett CMA. Impedimetric sensor for tyramine based on gold nanoparticle doped-poly(8-anilino-1-naphthalene sulphonic acid) modified gold electrodes. Talanta 2018; 195:604-612. [PMID: 30625590 DOI: 10.1016/j.talanta.2018.11.054] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 11/09/2018] [Accepted: 11/19/2018] [Indexed: 12/16/2022]
Abstract
A novel impedimetric sensor for the determination of tyramine (Tyr), a biogenic amine, on the surface of gold nanoparticle-poly-(8-anilino-1-napthalene sulphonic acid), AuNP-PANSA modified gold electrode (AuE) is presented for the first time. The AuNP were successfully synthesized by a green synthesis method. Their characterization and optimization were conducted using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. Under optimal conditions, the impedimetric sensor revealed a relatively broad linear range from 0.8 to 80 µM similar to more complex architectures found in the literature and the limit of detection of 0.04 µM was the lowest achieved until now. In order to test the reliability of the proposed method, real sample application studies were conducted using dairy products and fermented drinks. It was found that the sensor presented a good selectivity and recovery. Furthermore, the impedimetric sensor shows good reproducibility, stability, selectivity and very small interferences which augur well for its application in food safety control processes.
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Affiliation(s)
- Wanderson da Silva
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Mariana Emilia Ghica
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Rachel F Ajayi
- SensorLab, Department of Chemistry, University of Western Cape, 7535 Bellville, Cape Town, South Africa
| | - Emmanuel I Iwuoha
- SensorLab, Department of Chemistry, University of Western Cape, 7535 Bellville, Cape Town, South Africa
| | - Christopher M A Brett
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal.
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31
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Tekenya R, Pokpas K, Jahed N, Iwuoha EI. Enhanced Specificity and Sensitivity for the Determination of Nickel(II) by Square-wave Adsorptive Cathodic Stripping Voltammetry at Disposable Graphene-modified Pencil Graphite Electrodes. ANAL LETT 2018. [DOI: 10.1080/00032719.2018.1469139] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Ronald Tekenya
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville, Republic of South Africa
| | - Keagan Pokpas
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville, Republic of South Africa
| | - Nazeem Jahed
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville, Republic of South Africa
| | - Emmanuel I. Iwuoha
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville, Republic of South Africa
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32
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Affiliation(s)
- Samantha F. Douman
- School
of Chemical Sciences, National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland
- Sensor
Lab, Chemistry Department, University of the Western Cape, Cape Town, South Africa
| | - Eoin Brennan
- School
of Chemical Sciences, National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland
| | - Emmanuel I. Iwuoha
- Sensor
Lab, Chemistry Department, University of the Western Cape, Cape Town, South Africa
| | - Robert J. Forster
- School
of Chemical Sciences, National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland
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33
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Ndangili PM, Masikini M, Feleni U, Douman S, Tovide O, Williams A, Baker P, Iwuoha EI. Gallium-Induced Perturbation of Zinc Selenide Quantum Dots Electronics. ChemistrySelect 2017. [DOI: 10.1002/slct.201700748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Peter M. Ndangili
- SensorLab, Department of Chemistry; University of Western Cape; Private Bag X17 Bellville 7535 South Africa
- Department of Chemical Science and Technology; Technical University of Kenya; P.O Box 52428 - 00200 Nairobi Kenya
| | - Milua Masikini
- SensorLab, Department of Chemistry; University of Western Cape; Private Bag X17 Bellville 7535 South Africa
| | - Usisipho Feleni
- SensorLab, Department of Chemistry; University of Western Cape; Private Bag X17 Bellville 7535 South Africa
| | - Samantha Douman
- SensorLab, Department of Chemistry; University of Western Cape; Private Bag X17 Bellville 7535 South Africa
| | - Oluwakemi Tovide
- SensorLab, Department of Chemistry; University of Western Cape; Private Bag X17 Bellville 7535 South Africa
| | - Avril Williams
- Department of Biological and Chemical Sciences; University of the West Indies; Cave Hill Campus, P.O. Box 64 Bridgetown BB11000 Barbados
| | - Priscilla Baker
- SensorLab, Department of Chemistry; University of Western Cape; Private Bag X17 Bellville 7535 South Africa
| | - Emmanuel I. Iwuoha
- SensorLab, Department of Chemistry; University of Western Cape; Private Bag X17 Bellville 7535 South Africa
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34
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Pokpas K, Jahed N, Baker PG, Iwuoha EI. Complexation-Based Detection of Nickel(II) at a Graphene-Chelate Probe in the Presence of Cobalt and Zinc by Adsorptive Stripping Voltammetry. Sensors (Basel) 2017; 17:E1711. [PMID: 28757588 PMCID: PMC5580100 DOI: 10.3390/s17081711] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/01/2017] [Accepted: 07/03/2017] [Indexed: 11/17/2022]
Abstract
The adsorptive stripping voltammetric detection of nickel and cobalt in water samples at metal film electrodes has been extensively studied. In this work, a novel, environmentally friendly, metal-free electrochemical probe was constructed for the ultra-trace determination of Ni2+ in water samples by Adsorptive Cathodic Stripping Voltammetry (AdCSV). The electrochemical platform is based on the adsorptive accumulation of Ni2+ ions directly onto a glassy carbon electrode (GCE) modified with dimethylglyoxime (DMG) as chelating agent and a Nafion-graphene (NGr) nanocomposite to enhance electrode sensitivity. The nafion-graphene dimethylglyoxime modified glassy carbon electrode (NGr-DMG-GCE) shows superior detection capabilities as a result of the improved surface-area-to-volume ratio and enhanced electron transfer kinetics following the incorporation of single layer graphene, while limiting the toxic effects of the sensor by removal of the more common mercury, bismuth and lead films. Furthermore, for the first time the NGr-DMG-GCE, in the presence of common interfering metal ions of Co2+ and Zn2+ demonstrates good selectivity and preferential binding towards the detection of Ni2+ in water samples. Structural and morphological characterisation of the synthesised single layer graphene sheets was conducted by Raman spectrometry, HRTEM and HRSEM analysis. The instrumental parameters associated with the electrochemical response, including accumulation potential and accumulation time were investigated and optimised in addition to the influence of DMG and graphene concentrations. The NGr-DMG-GCE demonstrated well resolved, reproducible peaks, with RSD (%) below 5% and a detection limit of 1.5 µg L-1 for Ni2+ reduction at an accumulation time of 120 s., the prepared electrochemical sensor exhibited good detection and quantitation towards Ni2+ detection in tap water samples, well below 0.1 mg L-1 set by the WHO and EPA standards. This comparable to the South African drinking water guidelines of 0.15 mg L-1.
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Affiliation(s)
- Keagan Pokpas
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535, South Africa.
| | - Nazeem Jahed
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535, South Africa.
| | - Priscilla G Baker
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535, South Africa.
| | - Emmanuel I Iwuoha
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535, South Africa.
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35
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Capoferri D, Del Carlo M, Ntshongontshi N, Iwuoha EI, Sergi M, Di Ottavio F, Compagnone D. MIP-MEPS based sensing strategy for the selective assay of dimethoate. Application to wheat flour samples. Talanta 2017; 174:599-604. [PMID: 28738628 DOI: 10.1016/j.talanta.2017.06.062] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/19/2017] [Accepted: 06/22/2017] [Indexed: 11/17/2022]
Abstract
The aim of this work was to demonstrate the potentialities of the use of a molecularly imprinted (MIP) sensor coupled to a microextraction by packed sorbent (MEPS) strategy for the selective and sensitive detection of dimethoate in real samples. A dimethoate-polypyrrole MIP film was realised by cyclic voltammetry (CV) on the surface of a glassy carbon electrode (GCE). Being dimethoate electro-inactive, K3[Fe(CN)6] was used as probe for the indirect quantification of the analyte via the decrease of redox peaks observed upon binding of the target analyte. Detection of dimethoate at low nanomolar range was achieved with linearity in the 0.1-1nM range. Relative standard deviation calculated for different electrodes at 0.5nM of dimethoate was < 3% and selectivity was very satisfactory being the response for omethoate only 23% of dimethoate. A MEPS strategy for the extraction of dimethoate from a challenging matrix as wheat flour was then used in conjunction with the MIP electrochemical sensor. The procedure applied to flour samples spiked with dimethoate at 0.5 MRL, MRL, and 1.5 MRL gave very favourable comparison with a validated UHPLC-MS/MS method with deviations in the -21% /+17% range, demonstrating the feasibility of the approach as screening assay. This work clearly shows that the sequential use of a microextraction based procedure and electrochemical sensing system is low cost, easy to realise and use and can open new perspectives for the development of selective sensing system to be used in field or decentralised lab testing for the selective screening of target analytes.
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Affiliation(s)
- D Capoferri
- Faculty of Biosciences and Technologies for Food, Agriculture and Environment, University of Teramo, via R. Balzarini 1, 64100 Teramo, Italy
| | - M Del Carlo
- Faculty of Biosciences and Technologies for Food, Agriculture and Environment, University of Teramo, via R. Balzarini 1, 64100 Teramo, Italy
| | - N Ntshongontshi
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535, South Africa
| | - E I Iwuoha
- SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535, South Africa
| | - M Sergi
- Faculty of Biosciences and Technologies for Food, Agriculture and Environment, University of Teramo, via R. Balzarini 1, 64100 Teramo, Italy
| | - F Di Ottavio
- Faculty of Biosciences and Technologies for Food, Agriculture and Environment, University of Teramo, via R. Balzarini 1, 64100 Teramo, Italy
| | - D Compagnone
- Faculty of Biosciences and Technologies for Food, Agriculture and Environment, University of Teramo, via R. Balzarini 1, 64100 Teramo, Italy.
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Bilibana MP, Williams AR, Rassie C, Sunday CE, Makelane H, Wilson L, Ntshongontshi N, Jijana AN, Masikini M, Baker PGL, Iwuoha EI. Electrochemical Aptatoxisensor Responses on Nanocomposites Containing Electro-Deposited Silver Nanoparticles on Poly(Propyleneimine) Dendrimer for the Detection of Microcystin-LR in Freshwater. Sensors (Basel) 2016; 16:E1901. [PMID: 27845719 PMCID: PMC5134560 DOI: 10.3390/s16111901] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 10/19/2016] [Accepted: 10/20/2016] [Indexed: 02/07/2023]
Abstract
A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II) salicylaldiimine metallodendrimer (SDD-Co(II)) doped with electro-synthesized silver nanoparticles (AgNPs) for microcystin-LR (L, l-leucine; R, l-arginine), or MC-LR, detection in the nanomolar range. The GCE|SDD-Co(II)|AgNPs aptatoxisensor was fabricated with 5' thiolated aptamer through self-assembly on the modified surface of the glassy carbon electrode (GCE) and the electronic response was measured using cyclic voltammetry (CV). Specific binding of MC-LR with the aptamer on GCE|SDD-Co(II)|AgNPs aptatoxisensor caused the formation of a complex that resulted in steric hindrance and electrostatic repulsion culminating in variation of the corresponding peak current of the electrochemical probe. The aptatoxisensor showed a linear response for MC-LR between 0.1 and 1.1 µg·L-1 and the calculated limit of detection (LOD) was 0.04 µg·L-1. In the detection of MC-LR in water samples, the aptatoxisensor proved to be highly sensitive and stable, performed well in the presence of interfering analog and was comparable to the conventional analytical techniques. The results demonstrate that the constructed MC-LR aptatoxisensor is a suitable device for routine quantification of MC-LR in freshwater and environmental samples.
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Affiliation(s)
- Mawethu P Bilibana
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
| | - Avril R Williams
- Department of Biological and Chemical Sciences, The University of the West Indies, Cave Hill, St. Michael BB11000, Barbados.
| | - Candice Rassie
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
| | - Christopher E Sunday
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
| | - Hlamulo Makelane
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
| | - Lindsay Wilson
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
| | - Nomaphelo Ntshongontshi
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
| | - Abongile N Jijana
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
| | - Milua Masikini
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
| | - Priscilla G L Baker
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
| | - Emmanuel I Iwuoha
- SensorLab, Department of Chemistry, University of Western Cape, Robert Sobukwe Road, Bellville, Cape Town 7535, South Africa.
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Masikini M, Williams AR, Sunday CE, Waryo TT, Nxusani E, Wilson L, Qakala S, Bilibana M, Douman S, Jonnas A, Baker PGL, Iwuoha EI. Label Free Poly(2,5-dimethoxyaniline)-Multi-Walled Carbon Nanotubes Impedimetric Immunosensor for Fumonisin B₁ Detection. Materials (Basel) 2016; 9:ma9040273. [PMID: 28773401 PMCID: PMC5502966 DOI: 10.3390/ma9040273] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 03/12/2016] [Accepted: 03/24/2016] [Indexed: 11/26/2022]
Abstract
An impedimetric immunosensor for fumonisin B1 (FB1) was developed from a poly(2,5-dimethoxyaniline)-multi-walled carbon nanotube (PDMA-MWCNT) composite on the surface of glassy carbon electrode (GCE). The composite was prepared electrochemically and characterized using cyclic voltammetry. The preparation of the FB1 immunosensor involved the drop-coating of a bovine serum albumin mixture of the anti-fumonisin antibody (anti-Fms) onto the composite polymer-modified GCE. The electrochemical impedance spectroscopy (EIS) responses of the FB1 immunosensor (GCE/PDMA-MWCNT/anti-Fms) have a linear range of 7 to 49 ng·L−1, and the corresponding sensitivity and detection limits are 0.272 kΩ L·ng−1 and 3.8 pg·L−1, respectively. The limit of detection of the immunosensor for certified corn sample (i.e., certified reference material) is 0.014 ppm FB1, which is in excellent agreement with the value published by the vendors and significantly more accurate than that obtained with enzyme-linked immunosorbent assay (ELISA).
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Affiliation(s)
- Milua Masikini
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Avril R Williams
- Department of Biological and Chemical Sciences, The University of the West Indies, Cave Hill Campus, Bridgetown BB11000, Barbados.
| | - Christopher E Sunday
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Tesfaye T Waryo
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Ezo Nxusani
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Lindsay Wilson
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Sinazo Qakala
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Mawethu Bilibana
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Samantha Douman
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Anovuyo Jonnas
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Priscilla G L Baker
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Emmanuel I Iwuoha
- SensorLab, Department of Chemistry, University of the Western Cape Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
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Popoola OK, Marnewick JL, Rautenbach F, Iwuoha EI, Hussein AA. Acylphloroglucinol Derivatives from the South African Helichrysum niveum and Their Biological Activities. Molecules 2015; 20:17309-24. [PMID: 26393563 PMCID: PMC6332446 DOI: 10.3390/molecules200917309] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 09/08/2015] [Accepted: 09/10/2015] [Indexed: 12/26/2022] Open
Abstract
Phytochemical investigation of aerial parts of Helichrysum niveum (H. niveum) using different chromatographic methods including semi-preparative HPLC afforded three new (1–3) and six known (4–10) acylphloroglucinols alongside a known dialcohol triterpene (11). The structures of the isolated compounds were characterized accordingly as 1-benzoyl-3 (3-methylbut-2-enylacetate)-phloroglucinol (helinivene A, 1), 1-benzoyl-3 (2S-hydroxyl-3-methylbut-3-enyl)-phloroglucinol (helinivene B, 2), 8-(2-methylpropanone)-3S,5,7-trihydroxyl-2,2-dimethoxychromane (helinivene C, 3), 1-(2-methylbutanone)-4-O-prenyl-phloroglucinol (4), 1-(2-methylpropanone)-4-O-prennyl-phloroglucinol (5), 1-(butanone)-3-prenyl-phloroglucinol (6), 1-(2-methylbutanone)-3-prenyl-phloroglucinol (7), 1-butanone-3-(3-methylbut-2-enylacetate)-phloroglucinol (8), 1-(2-methylpropanone)-3-prenylphloroglucinol (9), caespitate (10), and 3β-24-dihydroxyterexer-14-ene (11). Excellent total antioxidant capacities were demonstrated by helinivenes A and B (1 and 2) when measured as oxygen radicals absorbance capacity (ORAC), ferric-ion reducing antioxidant power (FRAP), trolox equivalent absorbance capacity (TEAC) and including the inhibition of Fe2+-induced lipid peroxidation (IC50 = 5.12 ± 0.90; 3.55 ± 1.92) µg/mL, while anti-tyrosinase activity at IC50 = 35.63 ± 4.67 and 26.72 ± 5.05 µg/mL were also observed for 1 and 2, respectively. This is the first chemical and in vitro biological study on H. niveum. These findings underpin new perspectives for the exploitation of these natural phenolic compounds in applications such as in the natural cosmeceutical and pharmaceutical sectors.
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Affiliation(s)
- Olugbenga K Popoola
- Chemistry Department, University of Western Cape, Private Bag X17, Bellville 7535, South Africa.
| | - Jeanine L Marnewick
- Oxidative Stress Research Centre, Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, P. O. BOX 1906, Bellville 7535, South Africa.
| | - Fanie Rautenbach
- Oxidative Stress Research Centre, Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, P. O. BOX 1906, Bellville 7535, South Africa.
| | - Emmanuel I Iwuoha
- Chemistry Department, University of Western Cape, Private Bag X17, Bellville 7535, South Africa.
| | - Ahmed A Hussein
- Chemistry Department, University of Western Cape, Private Bag X17, Bellville 7535, South Africa.
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Popoola OK, Marnewick JL, Rautenbach F, Ameer F, Iwuoha EI, Hussein AA. Inhibition of Oxidative Stress and Skin Aging-Related Enzymes by Prenylated Chalcones and Other Flavonoids from Helichrysum teretifolium. Molecules 2015; 20:7143-55. [PMID: 25903365 PMCID: PMC6272301 DOI: 10.3390/molecules20047143] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Revised: 04/09/2015] [Accepted: 04/14/2015] [Indexed: 11/17/2022] Open
Abstract
Ten flavonoid-related structures viz. heliteretifolin (1), isoxanthohumol (2), 2',4',6'-trihydroxy-3'-prenylchalcone (3), isoglabranin (4), glabranin (5), 7-methoxy-isoglabranin (6), quercetin (7), 4'-methoxyquercetin (8), 4'-methoxykaempferol (9) and mosloflavone (10) were isolated from a H. teretifolium methanolic extract and identified. One of them (compound 1) is reported for the first time from a natural source, while compounds 6, 8-10 were isolated for the first time from the genus Helichrysum. The total extract of H. teretifolium showed potent antioxidant activity. When tested for total antioxidant capacity compound 3 possesses moderate biological activity compared to 2, which displayed some of the highest TEAC values (4529.01 ± 2.44; 4170.66 ± 6.72) µM TE/g, respectively. Compounds 7 and 8 demonstrated the highest inhibitory activities on Fe2+-induced lipid peroxidation (IC50 = 2.931; 6.449 µg/mL); tyrosinase (8.092; 27.573) and elastase (43.342; 86.548). Additionally, the total antioxidant capacities measured as FRAP (4816.31 ± 7.42; 3584.17 ± 0.54) µM AAE/g, and ORAC for hydroxyl radical (7.265 ± 0.71; 6.779 ± 3.40) × 106 and peroxyl radical (17.836 ± 2.90; 12.545 ± 5.07) × 103 µM TE/g were also observed for compounds 7 and 8, respectively. In conclusion, H. teretifolium total extract represents a rich source of bioactive constituents with potent antioxidant and moderate anti-tyrosinase and anti-elastase activities that can help to avert accumulation of free radicals in the body, and could therefore be good candidates for the prevention and/or treatment of skin-related conditions, such as aging. This is the first scientific report on the chemical and biological profile of H. teretifolium.
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Affiliation(s)
- Olugbenga K Popoola
- Chemistry Department, University of Western Cape, Private Bag X17, Bellville 7535, South Africa.
| | - Jeanine L Marnewick
- Oxidative Stress Research Centre, Institute of Biomedical and Microbial Biotechnology, Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, P O BOX 1906, Bellville 7535, South Africa.
| | - Fanie Rautenbach
- Oxidative Stress Research Centre, Institute of Biomedical and Microbial Biotechnology, Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, P O BOX 1906, Bellville 7535, South Africa.
| | - Farouk Ameer
- Chemistry Department, University of Western Cape, Private Bag X17, Bellville 7535, South Africa.
| | - Emmanuel I Iwuoha
- Chemistry Department, University of Western Cape, Private Bag X17, Bellville 7535, South Africa.
| | - Ahmed A Hussein
- Chemistry Department, University of Western Cape, Private Bag X17, Bellville 7535, South Africa.
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Sunday CE, Masikini M, Wilson L, Rassie C, Waryo T, Baker PGL, Iwuoha EI. Application on gold nanoparticles-dotted 4-nitrophenylazo graphene in a label-free impedimetric deoxynivalenol immunosensor. Sensors (Basel) 2015; 15:3854-71. [PMID: 25668213 PMCID: PMC4367389 DOI: 10.3390/s150203854] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 11/17/2014] [Accepted: 12/07/2014] [Indexed: 01/01/2023]
Abstract
In this paper, we report a new concept to construct a label-free electrochemical inhibition-based immunosensor for the detection of the mycotoxin deoxynivalenol (DON) in cereal samples. The electrochemical impedance spectroscopy of tris(bipyridine) ruthenium (II) chloride was used as a marker enhanced with gold nanoparticles-dotted 4-nitrophenylazo functionalized graphene (AuNp/G/PhNO2) nanocatalyst mediated in Nafion on a glassy carbon electrode. Under the optimized conditions, the formation of immunocomplexes inhibited electron flow and increased the charge transfer resistance of the sensing interface linearly. The change in impedance was proportional to DON concentrations in the range of 6–30 ng/mL with a sensitivity and detection limit of 32.14 ΩL/ng and 0.3 μg/mL, respectively, which compares favorably with the ELISA result. The proposed sensor had a stability of 80.3%, good precision and selectivity in DON standard solution containing different interfering agents, indicating promising application prospect for this strategy in designing impedimetric, electrochemiluminescent, voltammetric or amperometric sensors.
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Affiliation(s)
- Christopher Edozie Sunday
- Sensor Laboratory, Chemistry Department, University of the Western Cape, Private Bag X 17, Bellville 7535, South Africa.
| | - Milua Masikini
- Sensor Laboratory, Chemistry Department, University of the Western Cape, Private Bag X 17, Bellville 7535, South Africa.
| | - Lindsay Wilson
- Sensor Laboratory, Chemistry Department, University of the Western Cape, Private Bag X 17, Bellville 7535, South Africa.
| | - Candice Rassie
- Sensor Laboratory, Chemistry Department, University of the Western Cape, Private Bag X 17, Bellville 7535, South Africa.
| | - Tesfaye Waryo
- Sensor Laboratory, Chemistry Department, University of the Western Cape, Private Bag X 17, Bellville 7535, South Africa.
| | - Pricilla G L Baker
- Sensor Laboratory, Chemistry Department, University of the Western Cape, Private Bag X 17, Bellville 7535, South Africa.
| | - Emmanuel I Iwuoha
- Sensor Laboratory, Chemistry Department, University of the Western Cape, Private Bag X 17, Bellville 7535, South Africa.
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Masikini M, Mailu SN, Tsegaye A, Njomo N, Molapo KM, Ikpo CO, Sunday CE, Rassie C, Wilson L, Baker PGL, Iwuoha EI. A fumonisins immunosensor based on polyanilino-carbon nanotubes doped with palladium telluride quantum dots. Sensors (Basel) 2014; 15:529-46. [PMID: 25558993 PMCID: PMC4327034 DOI: 10.3390/s150100529] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 12/22/2014] [Indexed: 11/16/2022]
Abstract
An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs) and poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes (PDMA-MWCNT). Preparation of the electrochemical immunosensor for fumonisins involved drop-coating of fumonisins antibody onto the composite modified glassy carbon electrode. The electrochemical impedance spectroscopy response of the FB1 immunosensor (GCE/PT-PDMA-MWCNT/anti-Fms-BSA) gave a linear range of 7 to 49 ng L-1 and the corresponding sensitivity and detection limits were 0.0162 kΩ L ng-1 and 0.46 pg L-1, respectively, hence the limit of detection of the GCE/PT-PDMA-MWCNT immunosensor for fumonisins in corn certified material was calculated to be 0.014 and 0.011 ppm for FB1, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI) for fumonisins (the sum of FB1, FB2, and FB3) established by the Joint FAO/WHO expert committee on food additives and contaminants of 2 μg kg-1 and the maximum level recommended by the U.S. Food and Drug Administration (FDA) for protection of human consumption (2-4 mg L-1).
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Affiliation(s)
- Milua Masikini
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Stephen N Mailu
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Abebaw Tsegaye
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Njagi Njomo
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Kerileng M Molapo
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Chinwe O Ikpo
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Christopher Edozie Sunday
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Candice Rassie
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Lindsay Wilson
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Priscilla G L Baker
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
| | - Emmanuel I Iwuoha
- SensorLab, Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, Cape Town, South Africa.
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Molapo KM, Venkatanarayanan A, Dolan CM, Prendergast U, Baker PG, Iwuoha EI, Keyes TE, Forster RJ. High efficiency electrochemiluminescence from polyaniline:ruthenium metal complex films. Electrochem commun 2014. [DOI: 10.1016/j.elecom.2014.08.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Ross N, Iwuoha EI, Ikpo CO, Baker P, Njomo N, Mailu SN, Masikini M, Matinise N, Tsegaye A, Mayedwa N, Waryo T, Ozoemena KI, Williams A. Amplification of the discharge current density of lithium-ion batteries with spinel phase Li(PtAu)0.02Mn1.98O4 nano-materials. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.12.148] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Hess EH, Waryo T, Sadik OA, Iwuoha EI, Baker PG. Constitution of novel polyamic acid/polypyrrole composite films by in-situ electropolymerization. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2014.01.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Tovide O, Jaheed N, Mohamed N, Nxusani E, Sunday CE, Tsegaye A, Ajayi RF, Njomo N, Makelane H, Bilibana M, Baker PG, Williams A, Vilakazi S, Tshikhudo R, Iwuoha EI. Graphenated polyaniline-doped tungsten oxide nanocomposite sensor for real time determination of phenanthrene. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.12.134] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Ajayi RF, Sidwaba U, Feleni U, Douman SF, Tovide O, Botha S, Baker P, Fuku XG, Hamid S, Waryo TT, Vilakazi S, Tshihkudo R, Iwuoha EI. Chemically amplified cytochrome P450-2E1 drug metabolism nanobiosensor for rifampicin anti-tuberculosis drug. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.12.147] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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West N, Ozoemena KI, Ikpo CO, Baker PG, Iwuoha EI. Transition metal alloy-modulated lithium manganese oxide nanosystem for energy storage in lithium-ion battery cathodes. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2012.11.085] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Venkatanarayanan A, Martin A, Molapo KM, Iwuoha EI, Keyes TE, Forster RJ. Tuning the electrochemiluminescence potential from immobilised BODIPY by co-reactant selection. Electrochem commun 2013. [DOI: 10.1016/j.elecom.2013.03.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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West N, Baker P, Waryo T, Ngece FR, Iwuoha EI, O’Sullivan C, Katakis I. Highly sensitive gold-overoxidized polypyrrole nanocomposite immunosensor for antitransglutaminase antibody. J BIOACT COMPAT POL 2013. [DOI: 10.1177/0883911512472277] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Patients with coeliac disease, a gluten intolerance autoimmune disorder, have elevated levels of antitransglutaminase antibody in their human sera. In this study, an immunosensor for the electrochemical determination of antitransglutaminase antibody was constructed. The immunosensor architecture was based on the electrostatic deposition of transglutaminase antigen on a glassy carbon electrode modified with electrosynthetic overoxidized polypyrrole and gold nanoparticles and capped the transglutaminase layer with bovine serum albumin. As a result, good surface coverage of the gold nanoparticles (~100 nm) was achieved across the overoxidized polypyrrole film. Electrochemical impedance spectroscopy parameters of the gold nanoparticle–overoxidized polypyrrole electrode include time constant, exchange current density, and heterogeneous rate constant. The impedimetric immunosensor exhibited a charge transfer resistance-dependent linear range with a correlation coefficient value of 0.98 and a dynamic linear range of 10−6–10−4 mg mL−1. The synergistic effect of the gold nanoparticles on the overoxidized polypyrrole formed the electronic insulator platform as a selective accumulator for the analytes surrounding the nanoelectrode. This biosensor characteristic enabled detection of antitransglutaminase antibodies at very low concentrations without the aid of a secondary label.
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Affiliation(s)
- Natasha West
- SensorLab, Department of Chemistry, University of Western Cape, Bellville, Cape Town, South Africa
| | - Priscilla Baker
- SensorLab, Department of Chemistry, University of Western Cape, Bellville, Cape Town, South Africa
| | - Tesfaye Waryo
- SensorLab, Department of Chemistry, University of Western Cape, Bellville, Cape Town, South Africa
| | - Fanelwa R Ngece
- SensorLab, Department of Chemistry, University of Western Cape, Bellville, Cape Town, South Africa
| | - Emmanuel I Iwuoha
- SensorLab, Department of Chemistry, University of Western Cape, Bellville, Cape Town, South Africa
| | - Ciara O’Sullivan
- Nanobiotechnology and Bioanalysis Group, Department of Chemical Engineering, Universitat Rovira i Virgili, Taragona, Spain
| | - Ioanis Katakis
- Nanobiotechnology and Bioanalysis Group, Department of Chemical Engineering, Universitat Rovira i Virgili, Taragona, Spain
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