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Pratap R, Niveria K, Srivastava SK, Chaudhary S, Sharma P, Verma AK, Parmar AS. Biogenic synthesis of gold nanoparticles using dual extract of tulsi- Vinca for breast cancer tumor regression in mice. Nanomedicine (Lond) 2023; 18:1941-1959. [PMID: 37991203 DOI: 10.2217/nnm-2023-0208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2023] Open
Abstract
Aim: This work aims to synthesize the gold nanoparticles (GNPs) using a dual extract of tulsi and Vinca (T+V-Gold) for breast cancer tumor regression. Methods: The GNPs were synthesized and characterized for their microscopic, spectroscopic and crystalline properties. Further, the GNPs were investigated for in vitro and in vivo studies for the treatment of the 4T1-induced triple-negative breast cancer murine model. Results: The GNPs for 4T1 tumor-challenged mice resulted in delayed tumor development and lower tumor burden, with T+V-Gold demonstrating the highest prevention of tumor spread. The antitumor effect of T+V-Gold is highly significant in the glutathione family antioxidants glutathione S-transferase and glutathione in tumor tissue samples. Conclusion: The bioefficacy and anticancer outcomes of T+V-Gold nanoformulation can be used as therapeutic agents and drug-delivery vehicles.
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Affiliation(s)
- Ravi Pratap
- Department of Physics, Indian Institute of Technology (BHU), Varanasi, 221005, India
| | - Karishma Niveria
- Nanobiotech Lab Kirori Mal College University of Delhi, Delhi, 110007, India
| | | | - Shilpi Chaudhary
- Department of Physics, Punjab Engineering College (Deemed to be University), Chandigarh, 160012, India
| | - Poonam Sharma
- Department of Dravyagun, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221005, India
| | - Anita K Verma
- Nanobiotech Lab Kirori Mal College University of Delhi, Delhi, 110007, India
- Institution of Eminence Fellow, Delhi School of Public Health, Institution of Eminence, University of Delhi, Delhi, 110007, India
| | - Avanish Singh Parmar
- Department of Physics, Indian Institute of Technology (BHU), Varanasi, 221005, India
- Centre for Biomaterials and Tissue Engineering, Indian Institute of Technology (BHU), Varanasi, 221006, India
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2
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Kim DM, Yoo SM. Colorimetric Systems for the Detection of Bacterial Contamination: Strategy and Applications. BIOSENSORS 2022; 12:bios12070532. [PMID: 35884335 PMCID: PMC9313054 DOI: 10.3390/bios12070532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/10/2022] [Accepted: 07/13/2022] [Indexed: 12/19/2022]
Abstract
Bacterial contamination is a public health concern worldwide causing enormous social and economic losses. For early diagnosis and adequate management to prevent or treat pathogen-related illnesses, extensive effort has been put into the development of pathogenic bacterial detection systems. Colorimetric sensing systems have attracted increasing attention due to their simple and single-site operation, rapid signal readout with the naked eye, ability to operate without external instruments, portability, compact design, and low cost. In this article, recent trends and advances in colorimetric systems for the detection and monitoring of bacterial contamination are reviewed. This article focuses on pathogen detection strategies and technologies based on reaction factors that affect the color change for visual readout. Reactions used in each strategy are introduced by dividing them into the following five categories: external pH change-induced pH indicator reactions, intracellular enzyme-catalyzed chromogenic reactions, enzyme-like nanoparticle (NP)-catalyzed substrate reactions, NP aggregation-based reactions, and NP accumulation-based reactions. Some recently developed colorimetric systems are introduced, and their challenges and strategies to improve the sensing performance are discussed.
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Affiliation(s)
- Dong-Min Kim
- Center for Applied Life Science, Hanbat National University, Daejeon 34158, Korea;
| | - Seung-Min Yoo
- School of Integrative Engineering, Chung-Ang University, Seoul 06974, Korea
- Correspondence:
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3
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Chien YH, Su CH, Hu CC, Yeh KH, Lin WC. Localized Surface Plasmon Resonance-Based Colorimetric Assay Featuring Thiol-Capped Au Nanoparticles Combined with a Mobile Application for On-Site Parathion Organophosphate Pesticide Detection. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:838-848. [PMID: 34989582 DOI: 10.1021/acs.langmuir.1c02901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this study, we employed a dual strategy for parathion organophosphate pesticide (parathion) detection; first, we used a localized surface plasmon resonance (LSPR)-based colorimetric sensor featuring thiol-capped Au NPs, namely cysteine (Cys)@Au NPs, 11-mercaptoundecanoic acid (11-MUA)@Au NPs, and glutathione (GSH)@Au NPs, via acetylcholinesterase (ACHE) and acetylthiocholine (ATCH) enzyme-mediated hydrolysis reactions; second, we developed a color analysis toxicity-sensing app (Toxin APP). Positively charged thiocholine (TCH) molecules, which were continuously generated via hydrolysis, subsequently conjugated with thiol-capped Au NPs, causing Au NP aggregation through electrostatic attractions. The degree of aggregation of the thiol-capped Au NPs was influenced by parathion concentrations in the range 0 to 108 ppt, because parathion acted as an ACHE inhibitor by controlling the amount of TCH generated. Based on the values of LSPR absorbance ratio, the limits of detection (LODs) of three types thiol-capped Au NPs were determined to be 100 ppt using ultraviolet-visible spectroscopy measurements. However, the aggregation efficiency of GSH@Au NPs was lower than that of the others regarding gradual changes in their color and LSPR absorbance band. Furthermore, we designed Toxin APP for color analysis which consists of three modules: processing, database collection, and communication. Toxin APP could on-site and precisely detect the color changes of GSH@Au NPs at parathion concentrations in the ranges of 100 ppt to 1, 10, and 100 ppm and could distinguish between OP and non-OP pesticides (e.g., fipronil) in tap water samples with high sensitivity and selectivity. Moreover, the concentration of residual parathion in real samples (tomato and strawberry) was quantified based on the color changes of GSH@Au NPs detected using Toxin APP. Therefore, the combination of an LSPR-based colorimetric assay and Toxin APP can be a reliable method for the facile and rapid detection of parathion in food and water samples.
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Affiliation(s)
- Yi-Hsin Chien
- Department of Materials Science and Engineering, Feng Chia University, Taichung 40724, Taiwan
| | - Cheng-Hao Su
- Department of Materials Science and Engineering, Feng Chia University, Taichung 40724, Taiwan
| | - Chih-Chun Hu
- Department of Materials Science and Engineering, Feng Chia University, Taichung 40724, Taiwan
| | - Kuan-Hsiang Yeh
- Department of Materials Science and Engineering, Feng Chia University, Taichung 40724, Taiwan
| | - Wei-Chen Lin
- Department of Materials Science and Engineering, Feng Chia University, Taichung 40724, Taiwan
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4
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Gibson JS, Mendes PM. Elucidating the Influence of Electrical Potentials on the Formation of Charged Oligopeptide Self-Assembled Monolayers on Gold. Chemphyschem 2021; 22:684-692. [PMID: 33534936 PMCID: PMC8048453 DOI: 10.1002/cphc.202000988] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/02/2021] [Indexed: 11/09/2022]
Abstract
Self-assembled monolayers (SAMs) based on oligopeptides have garnered immense interest for a wide variety of innovative biomedical and electronic applications. However, to exploit their full potential, it is necessary to understand and control the surface chemistry of oligopeptides. Herein, we report on how different electrical potentials affect the adsorption kinetics, stability and surface coverage of charged oligopeptide SAMs on gold surfaces. Kinetic analysis using electrochemical surface plasmon resonance (e-SPR) reveals a slower oligopeptide adsorption rate at more positive or negative electrical potentials. Additional analysis of the potential-assisted formed SAMs by X-ray photoelectron spectroscopy demonstrates that an applied electrical potential has minimal effect on the packing density. These findings not only reveal that charged oligopeptides exhibit a distinct potential-assisted assembly behaviour but that an electrical potential offers another degree of freedom in controlling their adsorption rate.
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Affiliation(s)
- Joshua S Gibson
- School of Chemical Engineering, University of Birmingham Edgbaston, Birmingham, B15 2TT, UK
| | - Paula M Mendes
- School of Chemical Engineering, University of Birmingham Edgbaston, Birmingham, B15 2TT, UK
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5
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Rosenberg RA, Rozhkova EA, Novosad V. Investigations into Spin- and Unpolarized Secondary Electron-Induced Reactions in Self-Assembled Monolayers of Cysteine. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:2985-2992. [PMID: 33621100 DOI: 10.1021/acs.langmuir.1c00068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Cysteine is the simplest thiolated, chiral amino acid and is often used as the anchor for studies of self-assembled monolayers (SAMs) of complex biomolecules such as peptides. Understanding the interaction of SAMs of cysteine with low-energy secondary electrons (SEs) produced by X-rays can further our understanding of radiation damage in biomolecules. In particular, if the electrons are polarized, chiral-selective chemistry could have bearing on the origin of homochirality in nature. In the present paper, we use synchrotron radiation-based X-ray photoelectron spectroscopy to determine the changes that occur in the bonding of self-assembled layers of cysteine on gold as a result of soft X-ray irradiation. To investigate the possibility of chiral selectivity resulting from the interaction of low-energy, spin-polarized SEs (SPSEs), measurements were conducted on cysteine adsorbed on a 3 nm-thick gold layer deposited on a CoPt thin-film multilayer with perpendicular magnetic anisotropy. Time-dependent measurements of the C 1s, N 1s, O 1s, S 2p, and Au 4f core levels are used to follow the changes in surface chemistry and determine reaction cross-sections as a function of SE exposure. Analysis of the data results in cross-sections in the range of 5-7 Mb and suggests possible reaction pathways. Changing the magnetization direction of the CoPt multilayer produces SPSEs with opposite polarity. Some evidence of spin-dependent reactions is indicated but is inconclusive. Possible reasons for the discrepancy are posited.
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Affiliation(s)
- R A Rosenberg
- Advanced Photon Source, Argonne National Laboratory, Lemont Illinois 60439, United States
| | - E A Rozhkova
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont Illinois 60439, United States
| | - V Novosad
- Material Science Division, Argonne National Laboratory, Lemont Illinois 60439, United States
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6
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Oh H, Hwang H, Song H. Structural complexity induced by {110} blocking of cysteine in electrochemical copper deposition on silver nanocubes. NANOSCALE 2021; 13:1777-1783. [PMID: 33433556 DOI: 10.1039/d0nr07470e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Morphology evolution into intricate structures at the nanoscale is hard to understand, but we can get critical information from the combination of ex situ and in situ spectroelectrochemical techniques. In this study, we investigated the structural complexity generated during electrochemical Cu deposition on individual Ag nanocubes, which was driven by surface regulating cysteine molecules. During the deposition process, selective nucleation occurred on the Ag nanocubes by underpotential deposition, and then sequential structural evolution to a windmill morphology was observed. By adjusting the cysteine coverage, diverse structures were yielded, including face-overgrown, four-leaf clover, and octapod-like structures. Structural analysis along the crystallographic directions demonstrated that cysteine molecules exclusively blocked the growth along 110 and relatively promoted the growth along 100 and 111, respectively. Interestingly, all morphologies maintained a highly symmetric nature from the pristine cube, despite being diverse and sophisticated. These findings would be essential to design complex morphologies and achieve desirable optical and catalytic properties.
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Affiliation(s)
- Hyuncheol Oh
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
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Thuy Nguyen TT, Han OA, Lim EB, Haam S, Park JS, Lee SW. The effect of pH and transition metal ions on cysteine-assisted gold aggregation for a distinct colorimetric response. RSC Adv 2021; 11:9664-9674. [PMID: 35423462 PMCID: PMC8695409 DOI: 10.1039/d1ra00013f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 03/17/2021] [Accepted: 02/10/2021] [Indexed: 01/13/2023] Open
Abstract
Colorimetric detection is a promising sensing strategy that is applicable to qualitative and quantitative determination of an analyte by monitoring visually detectable color changes with the naked eye. This study explored the cysteine (Cys)-induced aggregation of gold nanoparticles (AuNPs) in order to develop a sensitive colorimetric detection method for Cys. For this purpose, we systematically investigated the colorimetric response of AuNPs to Cys with varying particle sizes and concentrations. The AuNPs with various diameters ranging from 26.5 nm to 58.2 nm were synthesized by the citrate reduction method. When dispersed in water to have the same surface area per unit volume, the smaller AuNPs (26.5 nm) exhibited a more sensitive response to Cys compared to a larger counterpart (46.3 nm). We also examined the effect of divalent first-row transition metal ions (Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) on the Cys-induced aggregation of AuNPs. Among the tested metal ions, the addition of Cu2+ provided the highest enhancement in sensitivity to Cys regardless of pH between 3.5 and 7. The significant increase in the sensitivity caused by Cu2+ could be attributed to the capability of Cu2+ to form a highly stable chelate complex with surface-immobilized Cys, facilitating the aggregation of AuNPs. For the AuNPs–Cu2+ system at pH 7, the detection limit for Cys was determined to be 5 nM using UV-vis spectroscopy. The reported strategy showed the potential to be used for a rapid and sensitive detection of Cys and also metal ions that can facilitate Cys-mediated aggregation of AuNPs. Divalent transition metal ions facilitated the aggregation of gold nanoparticles: Fe2+ < Ni2+ < Zn2+ < Co2+ ≪ Mn2+ < Cu2+ at pH 7. The optimized AuNPs-Cu2+ system produced the progressive color change upon the addition of cysteine (0.2–2.0 μM).![]()
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Affiliation(s)
- Trang Thi Thuy Nguyen
- Department of Chemical and Biological Engineering
- Gachon University
- Seongnam-si
- Republic of Korea
| | - Olivia A. Han
- Department of Chemistry
- Eastern University
- St. Davids
- USA
| | - Eun Bi Lim
- Department of Chemical and Biological Engineering
- Gachon University
- Seongnam-si
- Republic of Korea
| | - Seungjoo Haam
- Department of Chemical and Biomolecular Engineering
- Yonsei University
- Seoul 03722
- Republic of Korea
| | - Joon-Seo Park
- Department of Chemistry
- Eastern University
- St. Davids
- USA
| | - Sang-Wha Lee
- Department of Chemical and Biological Engineering
- Gachon University
- Seongnam-si
- Republic of Korea
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8
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Cheng PK, Liu S, Ahmed S, Qu J, Qiao J, Wen Q, Tsang YH. Ultrafast Yb-Doped Fiber Laser Using Few Layers of PdS 2 Saturable Absorber. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2441. [PMID: 33291350 PMCID: PMC7762252 DOI: 10.3390/nano10122441] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 11/30/2020] [Accepted: 12/04/2020] [Indexed: 01/27/2023]
Abstract
Two-dimensional (2D) transition metal dichalcogenide (TMD) materials have exceptional optoelectronic and structural properties, which allow them to be utilized in several significant applications in energy, catalyst, and high-performance optoelectronic devices. Among other properties, the nonlinear optical properties are gaining much attention in the research field. In this work, a unique pentagonal TMD material, palladium disulfide (PdS2), is employed as a saturable absorber (SA) in an ytterbium-doped fiber (YDF) laser cavity and mode-locked laser pulse is generated. At first, liquid phase exfoliation is performed to prepare PdS2 nanoflakes. Afterward, the PdS2-nanoflakes solution was incorporated in the side-polished fiber (SPF) to form SPF-based PdS2-SA. By utilizing this SA, a highly stable mode-locked laser pulse is realized at pump power of 160 mW, which has a center wavelength of 1033 nm and a 3-dB spectral bandwidth of 3.7 nm. Moreover, the pulse duration, maximum power output and corresponding single-pulse energy were determined as 375 ps, 15.7 mW and 0.64 nJ, respectively. During the experiment, the mode-locked pulse remained stable till the pump power reached a value of 400 mW and, for the regulation of power, the slope efficiency is calculated at about 4.99%. These results indicate that PdS2 material is a promising nonlinear optical material for ultrafast optical applications in the near-infrared (NIR) region.
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Affiliation(s)
- Ping Kwong Cheng
- Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; (P.K.C.); (S.A.); (J.Q.)
| | - Shunxiang Liu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; (S.L.); (J.Q.)
| | - Safayet Ahmed
- Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; (P.K.C.); (S.A.); (J.Q.)
| | - Junle Qu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; (S.L.); (J.Q.)
| | - Junpeng Qiao
- Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; (P.K.C.); (S.A.); (J.Q.)
| | - Qiao Wen
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; (S.L.); (J.Q.)
| | - Yuen Hong Tsang
- Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; (P.K.C.); (S.A.); (J.Q.)
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Chang L, Duan W, Chen A, Li J, Huang S, Tang H, Pan G, Deng Y, Zhao L, Li D, Zhao L. Preparation of polyacrylonitrile-based fibres with chelated Ag ions for antibacterial applications. ROYAL SOCIETY OPEN SCIENCE 2020; 7:200324. [PMID: 32874631 PMCID: PMC7428276 DOI: 10.1098/rsos.200324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 06/04/2020] [Indexed: 06/01/2023]
Abstract
The need for an excellent antibacterial material that is sufficiently powerful to never develop bacterial resistance is urgent. In this study, a series of novel polyacrylonitrile-based fibres with chelated Ag ions (referred to as Ag-SH-PANF) were prepared by a two-step chemical modification process: grafting and chelating. The properties of the as-prepared Ag-SH-PANF were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The antibacterial activities of Ag-SH-PANF were examined against pathogenic bacteria, and an antibacterial mechanism was explicated based on the release of Ag ions from the fibres' surfaces. The results showed that, although chelation occurred between the Ag ions and the grafted amino, sulfhydryl and disulfide groups, Ag-SH-PANF retained its fine microstructure and thermal stability. Moreover, Ag-SH-PANF displayed excellent antibacterial ability against pathogenic bacteria as well as good washing durability. In terms of the antibacterial mechanism, Ag ions are the main bactericidal agents in the role of catalysts and are not consumed in the antibacterial process. Nonetheless, a relatively higher concentration of Ag ions can accelerate the bactericidal process.
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Affiliation(s)
- Li Chang
- Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China
| | - Wenjie Duan
- Institute of Chemistry, Henan Academy of Sciences, 450003 Zhengzhou, Henan, People's Republic of China
- School of Materials Science and Engineering, Zhengzhou University, 450000 Zhengzhou, Henan, People's Republic of China
| | - Anguo Chen
- Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China
| | - Jianjun Li
- Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China
| | - Siqi Huang
- Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China
| | - Huijuan Tang
- Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China
| | - Gen Pan
- Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China
| | - Yong Deng
- Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China
| | - Lining Zhao
- Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China
| | - Defang Li
- Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China
| | - Liang Zhao
- Institute of Chemistry, Henan Academy of Sciences, 450003 Zhengzhou, Henan, People's Republic of China
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10
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Borgohain X, Yomcha J, Khan A, Rashid MH. Generation of Anisotropic Au Nanostructures in Aqueous Carboxymethyl Cellulose Matrix for Potential Catalytic Application. ChemistrySelect 2019. [DOI: 10.1002/slct.201902912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Xavy Borgohain
- Department of ChemistryRajiv Gandhi University, Rono Hills Doimukh 791112, Arunachal Pradesh India
| | - Jarpum Yomcha
- Department of ChemistryRajiv Gandhi University, Rono Hills Doimukh 791112, Arunachal Pradesh India
| | - Aslam Khan
- King Abdullah Institute for NanotechnologyKing Saud University Riyadh 11451 Saudi Arabia
| | - Md. Harunar Rashid
- Department of ChemistryRajiv Gandhi University, Rono Hills Doimukh 791112, Arunachal Pradesh India
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11
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Farkhondeh H, Rahsepar FR, Zhang L, Leung KT. Structural and Chemical Evolution of l-Cysteine Nanofilm on Si(111)-√3×√3-Ag: From Preferential Growth at Step Edges and Antiphase Boundaries at Room Temperature to Adsorbate-Mediated Metal Cluster Formation at Elevated Temperature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16185-16200. [PMID: 31661626 DOI: 10.1021/acs.langmuir.9b02852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The interaction of cysteine molecules with the Si(111)-√3×√3-Ag surface has been investigated over the submonolayer to multilayer regime using X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory calculations. With both upper step and lower step terraces, step edges, and antiphase boundaries, the √3×√3-Ag overlayer supported on Si(111) provides a rich two-dimensional template for studying site-specific biomolecular interactions. As an amino acid with three functional groups, cysteine is found to chemisorb through S-H bond cleavage and S-Ag bond linkage first at step edges and antiphase boundaries followed by island formation and expanded growth onto terraces. Intermolecular interactions are dominated by zwitterionic hydrogen bonding at higher coverages, producing a porous unordered interfacial layer composed of cysteine agglomerates at room temperature. Upon annealing, cysteine adsorbates induce structural transformation of the uniform √3×√3-Ag reconstructed surface lattice into metallic Ag clusters with a narrow size distribution and short-range ordering. Preferential nanoaggregate formation of cysteine at defect sites and cysteine-induced metal cluster formation promise a new approach to fabricating nanoclusters for potential applications in chemical sensing and catalysis.
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Affiliation(s)
- Hanieh Farkhondeh
- WATLab and Department of Chemistry , University of Waterloo , Waterloo , Ontario N2L3G1 , Canada
| | - Fatemeh R Rahsepar
- WATLab and Department of Chemistry , University of Waterloo , Waterloo , Ontario N2L3G1 , Canada
| | - Lei Zhang
- WATLab and Department of Chemistry , University of Waterloo , Waterloo , Ontario N2L3G1 , Canada
| | - Kam Tong Leung
- WATLab and Department of Chemistry , University of Waterloo , Waterloo , Ontario N2L3G1 , Canada
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12
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Mendoza-Diaz MI, Garcia-Gutierrez DF, Sepulveda-Guzman S, Moreno-Cortez IE, Garcia-Gutierrez DI. Tuning the optoelectronic properties of PEDOT:PSS-PVP core-shell electrospun nanofibers by solvent-quantum dot doping and phase inversion. NANOTECHNOLOGY 2019; 30:395601. [PMID: 31234156 DOI: 10.1088/1361-6528/ab2c0b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In the present study core-shell PEDOT:PSS-polyvinylpirrolidone nanofibers were synthesized by coaxial electrospinning. These fibers were doped with different solvents (dimethylsulphoxide, dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA), and ethylene glycol), and PbS nanoparticles at different concentrations; additionally, the coaxial electrospinning setup process was inverted in order to exchange the phases comprising the core-shell morphology. Experimental results showed that DMSO and IPA solvents produced a change in the PEDOT:PSS phase from its benzoid structure to a more conjugated (quinoid) one. The synthesized samples displayed an increment in the conductance of the composite nanofibers, based on a more conjugated structure of the PEDOT:PSS phase, and a better dispersion of the PbS nanoparticles within the nanofibers; this increment was, under certain synthesis conditions, up to three orders of magnitude higher than in the case of the nanofibers with no solvent, nor nanoparticles, added. Photoresponse also showed a clear increment in the value of the photogenerated current as the concentration of the nanoparticles increased. Inverting the arrangement of the core-shell phases in the nanofibers increased the conductance and the photogenerated current in the cases analyzed. These results show novel evidence on the capability of tuning the conductance and photoresponse of composite core-shell nanofibers, based on the doping of the PEDOT:PSS phase with different solvents and PbS nanoparticles, and the arrangement of the core-shell phases. Tailoring the optoelectronic properties of conductive, flexible nanofibers is a desirable competence in technological areas such as transparent flexible conductors, biosensors and tissue engineering.
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Affiliation(s)
- M I Mendoza-Diaz
- Universidad Autónoma de Nuevo León, UANL, Facultad de Ingeniería Mecánica y Eléctrica, FIME, Av. Universidad S/N, Cd. Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66450, México. Universidad Autónoma de Nuevo León, UANL, Centro de Innovación, Investigación y Desarrollo en Ingeniería y Tecnología CIIDIT, Apodaca, Nuevo León, México
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Engelbrekt C, Nazmutdinov RR, Zinkicheva TT, Glukhov DV, Yan J, Mao B, Ulstrup J, Zhang J. Chemistry of cysteine assembly on Au(100): electrochemistry, in situ STM and molecular modeling. NANOSCALE 2019; 11:17235-17251. [PMID: 31418761 DOI: 10.1039/c9nr02477h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cysteine (Cys) is an essential amino acid with a carboxylic acid, an amine and a thiol group. We have studied the surface structure and adsorption dynamics of l-cysteine adlayers on Au(100) from aqueous solution using electrochemistry, high-resolution electrochemical scanning tunnelling microscopy (in situ STM), and molecular modelling. Cys adsorption on this low-index Au-surface has been much less studied than Cys adsorption on Au(111)- and Au(110)-electrode surfaces. Chronopotentiometry was employed to monitor the adsorption dynamics at sub-second resolution and showed that adsorption is completed in 30 minutes at Cys concentrations above 100 μM. Two consecutive steps could be fitted to these data. Two separate reductive desorption peaks of Cys adlayers on Au(100) with a total coverage of 2.52 (±0.15) × 10-10 mol cm-2 were observed. In situ STM showed that the adsorbed Cys is organized in stripes with "fork-like" features which co-exist in (11 × 2)-2Cys and (7 × 2)-2Cys lattices, quite differently from Cys adsorption on Au(111)-electrode surfaces. Stripe structures with bright STM contrast in the center suggest that a second Cys adlayer on top of a first adlayer is formed, supporting the dual-peak reductive desorption of Cys adlayers. In addition, monolayers of both pure l-Cys and pure d-Cys and a 1 : 1 racemic mixture of l- and d-Cys on Au(100) were studied. Virtually identical macroscopic electrochemical features were found, but in situ STM discloses many more defects for the racemic mixture than for the pure enantiomers due to structural mismatch of l- and d-Cys. Density functional theory (DFT) calculations combined with a cluster model for the Au(100) surface were carried out to investigate the adsorption energy and geometry of the adsorbed monomer and dimer Cys species in different orientations, with detailed attention to the chirality effects. Optimized DFT geometries were used to construct model STM images, and kinetic Monte Carlo simulations undertaken to illuminate the growth of adsorbate rows and the mechanism of the adlayer formation as well as the Cys adsorption patterns specific to the Au(100)-electrode surface.
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Affiliation(s)
- Christian Engelbrekt
- Department of Chemistry, Building 207, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
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14
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Yin Z, Xu L, He J, Wu H, Fang S, Khoso SA, Hu Y, Sun W. Evaluation of l-cysteine as an eco-friendly depressant for the selective separation of MoS2 from PbS by flotation. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.03.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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15
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Wang X, Qarony W, Cheng PK, Ismail M, Tsang YH. Photoluminescence of PdS2 and PdSe2 quantum dots. RSC Adv 2019; 9:38077-38084. [PMID: 35541785 PMCID: PMC9075810 DOI: 10.1039/c9ra07445g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 11/03/2019] [Indexed: 01/06/2023] Open
Abstract
PdS2 and PdSe2 QDs are fabricated via liquid exfoliation using NMP solvent. The PL behaviors of these QD solutions are studied. The obtained results suggest promising optoelectronic applications with group-10 TMD QDs in the future.
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Affiliation(s)
- Xinyu Wang
- The Hong Kong Polytechnic University Shenzhen Research Institute
- Shenzhen
- China
- Department of Applied Physics and Materials Research Centre
- The Hong Kong Polytechnic University
| | - Wayesh Qarony
- The Hong Kong Polytechnic University Shenzhen Research Institute
- Shenzhen
- China
- Department of Applied Physics and Materials Research Centre
- The Hong Kong Polytechnic University
| | - Ping Kwong Cheng
- The Hong Kong Polytechnic University Shenzhen Research Institute
- Shenzhen
- China
- Department of Applied Physics and Materials Research Centre
- The Hong Kong Polytechnic University
| | - Mohammad Ismail
- The Hong Kong Polytechnic University Shenzhen Research Institute
- Shenzhen
- China
- Department of Applied Physics and Materials Research Centre
- The Hong Kong Polytechnic University
| | - Yuen Hong Tsang
- The Hong Kong Polytechnic University Shenzhen Research Institute
- Shenzhen
- China
- Department of Applied Physics and Materials Research Centre
- The Hong Kong Polytechnic University
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16
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Duan W, Wang J, Chang L, Zhao L, Tian Z, Huang Z, Huang W. Adsorption of mercury(ii) from water by a novel sPAN fiber containing sulfhydryl, carboxyl and amino groups. RSC Adv 2018; 8:38259-38269. [PMID: 35559058 PMCID: PMC9089860 DOI: 10.1039/c8ra06998k] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/08/2018] [Indexed: 12/02/2022] Open
Abstract
A novel fiber containing sulfhydryl, carboxyl and amino groups (sPAN) with high adsorption capacity for mercury was facilely prepared by chemically grafting cysteine onto a commercial polyacrylonitrile (PAN) fiber in a one-step reaction. The as-prepared sPAN was characterized for its chemical structure, thermal stability, tensile strength, surface morphology and surface binding species. The adsorption and desorption performances for mercury were investigated by both batch and dynamic experiments. The results showed that sPAN was effective for mercury removal over pH 4–7, and ionic strength produced no obvious interference with the adsorption. The equilibrium adsorption capacity of mercury could be as high as 459.3 (±16.0) mg g−1, much higher than for most previously reported materials due to the strong interaction between mercury ions and sulfhydryl, carboxyl, amino groups. More than 99% adsorbed mercury could be eluted by the mixture of hydrochloric acid and thiourea, and the regenerated sPAN could be reused for mercury removal with no significant loss of adsorption capacity even after 10 cycles. The dynamic adsorption results indicated that at initial mercury concentrations of 0.1 and 1.0 mg L−1, the residual mercury concentration was less than 1 μg L−1, which could meet the criterion for drinking water. Moreover, at an initial mercury concentration of 10 mg L−1, the residual mercury concentration was less than 50 μg L−1, which could satisfy the Chinese national industry water discharge standard. A novel fiber containing sulfhydryl, carboxyl and amino groups (sPAN) with high adsorption capacity for mercury was facilely prepared by chemically grafting cysteine onto a commercial polyacrylonitrile (PAN) fiber in a one-step reaction.![]()
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Affiliation(s)
- Wenjie Duan
- Institute of Chemistry Henan Academy of Sciences
- Zhengzhou
- China
| | - Jing Wang
- Institute of Chemistry Henan Academy of Sciences
- Zhengzhou
- China
| | - Li Chang
- Institute of Bast Fiber Crops
- Chinese Academy of Agricultural Sciences
- Changsha
- China
| | - Liang Zhao
- Institute of Chemistry Henan Academy of Sciences
- Zhengzhou
- China
| | - Zhenbang Tian
- Institute of Chemistry Henan Academy of Sciences
- Zhengzhou
- China
| | - Zuohua Huang
- Institute of Chemistry Henan Academy of Sciences
- Zhengzhou
- China
| | - Weiqing Huang
- Institute of Chemistry Henan Academy of Sciences
- Zhengzhou
- China
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17
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Li Y, Bao L, Zhou Q, Ou E, Xu W. Functionalized Graphene Obtained via Thiol-Ene Click Reactions as an Efficient Electrochemical Sensor. ChemistrySelect 2017. [DOI: 10.1002/slct.201700659] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Yali Li
- State Key Laboratory for Chemo/Biosensing and Chemometrics; College of Chemistry and Chemical Engineering; Hunan University; Changsha 410082, Hunan Province P.R. China
| | - Lin Bao
- Key Laboratory of Electroanalytical Chemistry of Shaanxi Province; Institute of Analytical Science; Northwest University; Xi'an 710069, Shaanxi Province P. R. China
| | - Qiulan Zhou
- State Key Laboratory for Chemo/Biosensing and Chemometrics; College of Chemistry and Chemical Engineering; Hunan University; Changsha 410082, Hunan Province P.R. China
| | - Encai Ou
- State Key Laboratory for Chemo/Biosensing and Chemometrics; College of Chemistry and Chemical Engineering; Hunan University; Changsha 410082, Hunan Province P.R. China
| | - Weijian Xu
- State Key Laboratory for Chemo/Biosensing and Chemometrics; College of Chemistry and Chemical Engineering; Hunan University; Changsha 410082, Hunan Province P.R. China
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18
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Hau NY, Yang P, Liu C, Wang J, Lee PH, Feng SP. Aminosilane-Assisted Electrodeposition of Gold Nanodendrites and Their Catalytic Properties. Sci Rep 2017; 7:39839. [PMID: 28045064 PMCID: PMC5206629 DOI: 10.1038/srep39839] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 11/29/2016] [Indexed: 12/04/2022] Open
Abstract
A promising alternative route for the synthesis of three-dimensional Au dendrites was developed by direct electrodeposition from a solution of HAuCl4 containing 3-aminopropyltriethoxysilane (APTS). Ultraviolet-visible spectroscopy, fourier transform infrared spectroscopy and isothermal titration calorimetry were used to study the interaction of APTS in electrolyte. The effect of APTS on the formation of the hierarchical structure of Au dendrites was investigated by cyclic voltammetry, rotating disk electrode, electrochemical impedance spectroscopy and quartz crystal microbalance. The growth directions of the trunks and branches of the Au dendrites can be controlled by sweep-potential electrodeposition to obtain more regular structures. The efficacy of as-synthesised Au dendrites was demonstrated in the enhanced electro-catalytic activity to methanol electro-oxidation and the high sensitivity of glucose detection, which have potential applications in direct-methanol fuel cells and non-enzymatic electrochemical glucose biosensors, respectively.
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Affiliation(s)
- Nga Yu Hau
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong
| | - Peixian Yang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong
| | - Chang Liu
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong
| | - Jian Wang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong
| | - Po-Heng Lee
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong
| | - Shien-Ping Feng
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong
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19
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Łuczak T. Highly selective voltammetric sensing of paracetamol on nanogold modified electrode in the presence of interfering compounds. NEW J CHEM 2017. [DOI: 10.1039/c7nj01191a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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New self-assembled layers composed with gold nanoparticles, cysteamine and dihydrolipoic acid deposited on bare gold template for highly sensitive and selective simultaneous sensing of dopamine in the presence of interfering ascorbic and uric acids. J Solid State Electrochem 2016. [DOI: 10.1007/s10008-016-3416-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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21
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Juarez MF, Toader AM, Negrila C, Santos E, Lazarescu V. Combined ab initio and XPS Investigations of the Electronic Interactions of L-Cysteine Adsorbed on GaAs(1 0 0). ChemistrySelect 2016. [DOI: 10.1002/slct.201600589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- María F. Juarez
- Institute of Theoretical Chemistry; Ulm University; 89081 Ulm Germany
| | - Ana M. Toader
- Institute of Physical Chemistry Ilie Murgulescu; Splaiul Independentei; Bucharest Romania
| | | | - Elizabeth Santos
- Institute of Theoretical Chemistry; Ulm University; 89081 Ulm Germany
- Instituto de Física Enrique Gaviola (IFEG-CONICET-FaMAF); Universidad de Córdoba; Argentina
| | - Valentina Lazarescu
- Institute of Physical Chemistry Ilie Murgulescu; Splaiul Independentei; Bucharest Romania
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22
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Łuczak T, Bułat K. Gold Surface Functionalization with S-containing Organic Compounds and Gold Nanoparticles for Ethylene Glycol Electrooxidation. ELECTROANAL 2016. [DOI: 10.1002/elan.201500536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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23
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Gorczyński A, Kubicki M, Szymkowiak K, Łuczak T, Patroniak V. Utilization of a new gold/Schiff-base iron( iii) complex composite as a highly sensitive voltammetric sensor for determination of epinephrine in the presence of ascorbic acid. RSC Adv 2016. [DOI: 10.1039/c6ra22028b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A new voltammetric sensor based on an iron(iii) Schiff-base complex/Au composite is synthesized and applied for the in vitro detection of epinephrine.
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Affiliation(s)
- Adam Gorczyński
- Faculty of Chemistry
- Adam Mickiewicz University
- 61614 Poznań
- Poland
| | - Maciej Kubicki
- Faculty of Chemistry
- Adam Mickiewicz University
- 61614 Poznań
- Poland
| | | | - Teresa Łuczak
- Faculty of Chemistry
- Adam Mickiewicz University
- 61614 Poznań
- Poland
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24
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Bürgi T. Properties of the gold-sulphur interface: from self-assembled monolayers to clusters. NANOSCALE 2015; 7:15553-67. [PMID: 26360607 DOI: 10.1039/c5nr03497c] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The gold-sulphur interface of self-assembled monolayers (SAMs) was extensively studied some time ago. More recently tremendous progress has been made in the preparation and characterization of thiolate-protected gold clusters. In this feature article we address different properties of the two systems such as their structure, the mobility of the thiolates on the surface and other dynamical aspects, the chirality of the structures and characteristics related to it and their vibrational properties. SAMs and clusters are in the focus of different communities that typically use different experimental approaches to study the respective systems. However, it seems that the nature of the Au-S interfaces in the two cases is quite similar. Recent single crystal X-ray structures of thiolate-protected gold clusters reveal staple motifs characterized by gold ad-atoms sandwiched between two sulphur atoms. This finding contradicts older work on SAMs. However, newer studies on SAMs also reveal ad-atoms. Whether this finding can be generalized remains to be shown. In any case, more and more studies highlight the dynamic nature of the Au-S interface, both on flat surfaces and in clusters. At temperatures slightly above ambient thiolates migrate on the gold surface and on clusters. Evidence for desorption of thiolates at room temperature, at least under certain conditions, has been demonstrated for both systems. The adsorbed thiolate can lead to chirality at different lengths scales, which has been shown both on surfaces and for clusters. Chirality emerges from the organization of the thiolates as well as locally at the molecular level. Chirality can also be transferred from a chiral surface to an adsorbate, as evidenced by vibrational spectroscopy.
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Affiliation(s)
- Thomas Bürgi
- Department of Physical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland.
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25
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Sola-Rabada A, Liang MK, Roe MJ, Perry CC. Peptide-directed crystal growth modification in the formation of ZnO. J Mater Chem B 2015; 3:3777-3788. [DOI: 10.1039/c5tb00253b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
ZnO-binding peptides, differing only by Met or Cys at position 5 modify the mechanism of ZnO crystal growth.
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Affiliation(s)
- Anna Sola-Rabada
- Biomolecular and Materials Interface Research Group
- Interdisciplinary Biomedical Research Centre
- School of Science and Technology
- Nottingham Trent University
- Nottingham
| | - Mei-Keat Liang
- Biomolecular and Materials Interface Research Group
- Interdisciplinary Biomedical Research Centre
- School of Science and Technology
- Nottingham Trent University
- Nottingham
| | - Martin J. Roe
- Advanced Materials Research Group
- X-ray Photoelectron Spectroscopy
- Faculty of Engineering
- The University of Nottingham
- Nottingham
| | - Carole C. Perry
- Biomolecular and Materials Interface Research Group
- Interdisciplinary Biomedical Research Centre
- School of Science and Technology
- Nottingham Trent University
- Nottingham
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26
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Interface Electronic Structures of the L-Cysteine on Noble Metal Surfaces Studied by Ultraviolet Photoelectron Spectroscopy. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2015. [DOI: 10.1380/ejssnt.2015.373] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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27
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Geethalakshmi KR, Yang X, Sun Q, Ng TY, Wang D. The nature of interfacial binding of imidazole and carbene ligands with M20 nanoclusters (M = Au, Ag and Cu) – a theoretical study. RSC Adv 2015. [DOI: 10.1039/c5ra14578c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
To inspire more exciting developments in the design and advances of self-assembled monolayers (SAMs), the fundamental understanding of the nature of interaction between metal nanoparticles and certain functional groups is very crucial.
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Affiliation(s)
- K. R. Geethalakshmi
- Centro de Física de Materiales (CSIC-UPV/EHU) and Donostia International Physics Center (DIPC)
- P. Manuel de Lardizabal 5
- 20018 Donostia
- Spain
- School of Mechanical and Aerospace Engineering
| | - Xia Yang
- Institute of High Energy Physics
- Chinese Academy of Science
- Beijing
- China
| | - Qiao Sun
- Institute of Quantitative Biology and Medicine
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions
- School of Radiation Medicine and Protection
- Medical College of Soochow University
- Soochow University
| | - T. Y. Ng
- School of Mechanical and Aerospace Engineering
- Nanyang Technological University Singapore
- Singapore-639798
| | - D. Wang
- Institute of High Energy Physics
- Chinese Academy of Science
- Beijing
- China
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28
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Lin P, Ding L, Lin CW, Gu F. Nonfouling property of zwitterionic cysteine surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:6497-6507. [PMID: 24841849 DOI: 10.1021/la500243s] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Applications of implantable bioelectronics for analytical and curative purposes are currently limited by their poor long-term biofunctionality in physiological media and nonspecific interactions with biomolecules. In an attempt to prolong in vivo functionality, recent advances in surface modifications have demonstrated that zwitterionic coatings can rival the performance of conventional poly(ethylene glycol) polymers in reducing nonspecific protein fouling. Herein, we report the fabrication of a very thin layer of nonfouling zwitterionic cysteine surface capable of protecting implantable bioelectronics from nonspecific adsorption of plasma proteins. This work is the first of its kind to fabricate, through solution chemistry, a cysteine surface exhibiting zwitterionic state as high as 88% and to demonstrate antibiofouling under the exposure of bovine serum albumin (BSA) and human serum. The fabricated surface utilized a minimal amount of gold substrate, approximately 10 nm, and an extremely thin antifouling layer at 1.14 nm verified by ellipsometry. X-ray photoelectron spectroscopy assessment of the nitrogen (N1s) and carbon (C1s) spectra conclude that 87.8% of the fabricated cysteine surface is zwitterionic, 2.5% is positively charged, and 9.6% is noncharged. Antibiofouling performance of the cysteine surface is quantitatively determined by bicinchoninic acid (BCA) protein assay as well as qualitatively confirmed using scanning electron spectroscopy. Cysteine surfaces demonstrated a BSA fouling of 3.9 ± 4.84% μg/cm(2), which is 93.6% and 98.5% lower than stainless steel and gold surfaces, respectively. Surface plasmon resonance imaging analysis returned similar results and suggest that a thinner cysteine coating will enhance performance. Scanning electron microscopy confirmed the results of BCA assay and suggested that the cysteine surface demonstrated a 69% reduction to serum fouling. The results reported in this paper demonstrate that it is possible to achieve a highly zwitterionic surface through solution chemistry on a macroscopic level that is capable of improving biocompatibility of long-term implantable bioelectronics.
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Affiliation(s)
- Peter Lin
- Department of Chemical Engineering, Waterloo Institute for Nanotechnology, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
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29
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Natural zwitterionic organosulfurs as surface ligands for antifouling and responsive properties. Biointerphases 2014; 9:029010. [DOI: 10.1116/1.4869300] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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30
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Wang M, Wu H, Chi Y, Chen G. Synthesis of Au13(glutathionato)8@β-cyclodextrin nanoclusters and their use as a fluorescent probe for silver ions. Mikrochim Acta 2014. [DOI: 10.1007/s00604-014-1253-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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31
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Łuczak T, Bełtowska-Brzezinska M, Holze R. Electrocatalytic activity of gold modified with gold nanoparticles and self-assembled layers of meso-2,3-dimercaptosuccinic acid for oxidation of epinephrine in the presence of ascorbic and uric acids. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.12.173] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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32
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Gong X, Bi Y, Zhao Y, Liu G, Teoh WY. Graphene oxide-based electrochemical sensor: a platform for ultrasensitive detection of heavy metal ions. RSC Adv 2014. [DOI: 10.1039/c4ra02247e] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Facile functionalization of graphene oxide sheets on gold surface results in complexation-enhanced electrochemical detection of heavy metal ions, shown here for Pb2+, Cu2+ and Hg2+, with improved detection limits by two orders of magnitude relative to the control electrode.
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Affiliation(s)
- Xuezhong Gong
- Clean Energy and Nanotechnology (CLEAN) Laboratory
- School of Energy and Environment
- City University of Hong Kong
- Kowloon, Hong Kong S.A.R
| | - Yunlong Bi
- Clean Energy and Nanotechnology (CLEAN) Laboratory
- School of Energy and Environment
- City University of Hong Kong
- Kowloon, Hong Kong S.A.R
| | - Yihua Zhao
- Clean Energy and Nanotechnology (CLEAN) Laboratory
- School of Energy and Environment
- City University of Hong Kong
- Kowloon, Hong Kong S.A.R
| | - Guozhen Liu
- Key Laboratory of Pesticide and Chemical Biology of Ministry of Education
- College of Chemistry
- Central China Normal University
- Wuhan, P. R. China
| | - Wey Yang Teoh
- Clean Energy and Nanotechnology (CLEAN) Laboratory
- School of Energy and Environment
- City University of Hong Kong
- Kowloon, Hong Kong S.A.R
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33
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Caprile L, Cossaro A, Falletta E, Della Pina C, Cavalleri O, Rolandi R, Terreni S, Ferrando R, Rossi M, Floreano L, Canepa M. Interaction of L-cysteine with naked gold nanoparticles supported on HOPG: a high resolution XPS investigation. NANOSCALE 2012; 4:7727-7734. [PMID: 23135640 DOI: 10.1039/c2nr32741d] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report the results of a synchrotron-based high-resolution XPS study of the interaction of L-cysteine (Cys) with well-characterized colloidal gold nanoparticles (NPs, typical size 3-4 nm), which were pre-deposited on highly oriented pyrolytic graphite and then brought into contact with the aqueous solution of Cys by drop-casting. By comparison with data previously obtained for Cys deposition on flat Au substrates (single crystals and high quality films), we demonstrate the formation of a strong Cys/NP thiolate bond. The analysis of the line shape and adsorbate-induced Au 4f core level shift, backed by simulations of the NP structure, reveals the interaction of Cys with low-coordinated Au atoms belonging to the NP edge and corners. The analysis of the N 1s core-level indicates that neutral molecules are the most abundant species. The small facet size limits the formation of extended networks of zwitterionic molecules, typical of single crystal surfaces. This study provides a spectroscopic insight into the intense poisoning effect caused by a limited amount of Cys on Au catalysts described in previous reports.
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Affiliation(s)
- Laura Caprile
- CNISM and Dipartimento di Fisica, Universitá di Genova, via Dodecaneso 33, Genova, Italy
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Abraham A, Ilott AJ, Miller J, Gullion T. 1H MAS NMR Study of Cysteine-Coated Gold Nanoparticles. J Phys Chem B 2012; 116:7771-5. [PMID: 22708845 DOI: 10.1021/jp3011298] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anuji Abraham
- Department of Chemistry, West Virginia University, Morgantown,
West Virginia 26506, United States
| | - Andrew J. Ilott
- Department of Chemistry, SUNY Stony Brook, Stony Brook, New York
11794, United States
| | - Joel Miller
- Chemistry Division, Naval Research Laboratory, Code 6122,
Washington, DC 20375, United States
| | - Terry Gullion
- Department of Chemistry, West Virginia University, Morgantown,
West Virginia 26506, United States
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35
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Filimon AD, Jacob P, Hergenröder R, Jürgensen A. Study on the reversible changes of the surface properties of an L-cysteine self-assembled monolayer on gold as a function of pH. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:8692-8699. [PMID: 22663764 DOI: 10.1021/la3013574] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A stimuli-response biological surface of L-cysteine was prepared on a polycrystalline gold surface from aqueous solution. The effect of the pH value of the rinsing solution on the surface composition was studied with X-ray photoelectron spectroscopy (XPS). Qualitative and quantitative analysis of the amino, carboxyl, and thiol functional groups of these self-assembled monolayers indicate that L-cysteine molecules exist in the neutral and zwitterionic forms and that they are sensitive to the pH of the rinsing solution. In addition, the wetting properties of the functionalized surface were studied by contact angle (CA) analysis: they were also dependent on the pH of the rinsing solution. Furthermore, it was shown that this functionalization process was reversible.
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Affiliation(s)
- Andrei-Daniel Filimon
- Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany
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Di J, Hu Y, Song Y, Tu Y. Formation of hydrous gold(I) oxide in the process of self-assembled cysteine on gold nanoparticles and its electrocatalytic application. J Electroanal Chem (Lausanne) 2012. [DOI: 10.1016/j.jelechem.2012.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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37
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Begonja S, Rodenas LG, Borghi E, Morando P. Adsorption of cysteine on TiO2 at different pH values: Surface complexes characterization by FTIR-ATR and Langmuir isotherms analysis. Colloids Surf A Physicochem Eng Asp 2012. [DOI: 10.1016/j.colsurfa.2012.03.064] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Galal A, Atta NF, El-Ads EH. Probing cysteine self-assembled monolayers over gold nanoparticles – Towards selective electrochemical sensors. Talanta 2012; 93:264-73. [DOI: 10.1016/j.talanta.2012.02.032] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 02/11/2012] [Accepted: 02/15/2012] [Indexed: 11/28/2022]
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39
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Das T, Ghosh P, Shanavas MS, Maity A, Mondal S, Purkayastha P. Cyclodextrin cavity size induced formation of superstructures with embedded gold nanoclusters. RSC Adv 2012. [DOI: 10.1039/c2ra21896h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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40
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Atta NF, Galal A, El-Ads EH. A novel sensor of cysteine self-assembled monolayers over gold nanoparticles for the selective determination of epinephrine in presence of sodium dodecyl sulfate. Analyst 2012; 137:2658-68. [DOI: 10.1039/c2an16210e] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Li Y, Cheng P, Gong J, Fang L, Deng J, Liang W, Zheng J. Amperometric immunosensor for the detection of Escherichia coli O157:H7 in food specimens. Anal Biochem 2011; 421:227-33. [PMID: 22119072 DOI: 10.1016/j.ab.2011.10.049] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 10/25/2011] [Accepted: 10/27/2011] [Indexed: 11/24/2022]
Abstract
A novel, label-free amperometric immunosensor has been developed for the rapid detection of heat-killed Escherichia coli O157:H7 (E. coli O157:H7). This immunosensor was prepared as follows. First, the long-chain, amine-terminated alkanethiol 11-amino-1-undecanethiol hydrochloride (AUT) was self-assembled onto a gold electrode surface to form an ordered, oriented, compact, and stable monolayer possessing -NH(2) functional groups that could immobilize massive gold nanoparticles (GNPs). Next, chitosan-multiwalled carbon nanotubes-SiO(2)/thionine (CHIT-MWNTs-SiO(2)@THI) nanocomposites and GNPs multilayer films were prepared via layer-by-layer (LBL) assembly. The surface area enhancement from the LBL assembly of the multilayer films improves the stability of the immobilized CHIT-MWNTs-SiO(2)@THI. More important, the sensitivity and stability of the immunosensor can be enhanced proportionally to the quantity of the THI mediator immobilized on the electrode surface. Finally, the E. coli O157:H7 antibody (anti-E. coli O157:H7) was covalently bound to the GNP monolayer and its bioactivity was measured by enzyme-linked immunosorbent assay (ELISA). Transmission electron microscopy (TEM) was employed to characterize the morphology of the MWNTs, CHIT-MWNTs, and CHIT-MWNTs-SiO(2)@THI. Under optimal conditions, the calibration curve for heat-killed E. coli O157:H7 has a working range of 4.12×10(2)-4.12×10(5) colony-forming units (CFU)/ml, and the total assay time was less than 45 min.
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Affiliation(s)
- Yan Li
- Department of Clinical Laboratory Science, College of Medical Laboratory, Third Military Medical University, Chongqing 400038, People's Republic of China
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42
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Han JW, James JN, Sholl DS. Chemical speciation of adsorbed glycine on metal surfaces. J Chem Phys 2011; 135:034703. [DOI: 10.1063/1.3610420] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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43
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Xu Z, Yuan SL, Yan H, Liu CB. Adsorption of histidine and histidine-containing peptides on Au(111): A molecular dynamics study. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2011.02.046] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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44
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Singh A, Myerson AS. Chiral Self Assembled Monolayers as Resolving Auxiliaries in the Crystallization of Valine. J Pharm Sci 2010; 99:3931-40. [DOI: 10.1002/jps.22237] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Feyer V, Plekan O, Tsud N, Cháb V, Matolín V, Prince KC. Adsorption of histidine and histidine-containing peptides on Au(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8606-8613. [PMID: 20337409 DOI: 10.1021/la904684e] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The adsorption of histidine (His) and three His-derived peptides on Au(111) has been studied by soft X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS) at the nitrogen and oxygen K edges. The peptides were glycyl-histidine (Gly-His), glycyl-histidine-glycine (Gly-His-Gly), and glycyl-glycyl-histidine (Gly-Gly-His) and were adsorbed at saturated coverage on the Au(111) surface from aqueous solution. Coverages of 1 and 0.5 monolayers (ML) of His were adsorbed by evaporation in vacuum and compared with 1 ML deposited from solution. There were no significant chemical differences between the monolayers deposited in vacuum or from solution. The Au 4f core level shift indicates that a chemisorption rather than a physisorption bond is formed. In both deposited phases, His bonds to the gold surface in anionic form via the imino nitrogen atom of the imidazole ring and the oxygen atoms of the carboxylate group. N and O K-edge NEXAFS indicate that the ring and carboxylate triangle of adsorbed His are tilted at approximately 35 degrees and approximately 27 degrees, respectively, with respect to the Au(111) surface. The peptides bond to the gold surface in a mode similar to the single His molecule, via the imino and carboxylate groups, while the peptide group is at a steep angle to the surface. However, the peptides adsorb with a higher atomic density, consistent with the peptide groups being above the surface. There are also differences between Gly-His-Gly and Gly-Gly-His, implying that the sequence within the peptide has a significant influence on the bonding geometry.
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Affiliation(s)
- Vitaliy Feyer
- Sincrotrone Trieste S.C.p.A., in Area Science Park, Strada Statale 14, km 163.5, I-34012 Basovizza, Trieste, Italy.
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Zhang H, Li Y, Xu X, Sun T, Fuchs H, Chi L. Ion strength and pH sensitive phase transition of N-isobutyryl-L-(D)-cysteine monolayers on Au(111) surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:7343-7348. [PMID: 20355723 DOI: 10.1021/la904237d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Self-assembled monolayers (SAMs) of N-isobutyryl-L-(D)-cysteine (NIBC) on Au(111) surfaces were successfully prepared by immersing the Au(111) surfaces in the preheated pure NIBC aqueous solutions for a certain time and characterized by means of scanning tunneling microscopy. Close-packed lamellar structures with a rectangular (4 x radical3) lattice were found both in the SAMs of L-NIBC and D-NIBC. The pH value of the aqueous solutions was found to be sensitive to adjust the SAM structures during the assembly. Changing the pH value from 5 to 7 may completely shift the SAM structures from close-packed lamellar phase to loose-packed perpendicular phase. Combined with density functional theory calculations, such kind of phase transition was explained by the breaking of hydrogen bonds between carboxylic groups and the formation of extra interactions between COO(-) and Au.
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Affiliation(s)
- Haiming Zhang
- Physicalisches Institut, Muenster University, D-48149 Muenster, Germany
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Velamakanni A, Magnuson CW, Ganesh KJ, Zhu Y, An J, Ferreira PJ, Ruoff RS. Site-specific deposition of Au nanoparticles in CNT films by chemical bonding. ACS NANO 2010; 4:540-546. [PMID: 20055476 DOI: 10.1021/nn901278t] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
There has been no attempt to date to specifically modify the nodes in carbon nanotube (CNT) networks. If the nodes can be modified in favorable ways, the electrical and/or thermal and/or mechanical properties of the CNT networks could be improved. In an attempt to influence the performance as a transparent conductive film, gold nanoparticles capped with the amino acid cysteine (Au-CysNP) have been selectively attached at the nodes of multiwalled carbon nanotubes (MWCNTs) networks. These nanoparticles have an average diameter of 5 nm as observed by TEM. FTIR and XPS were used to characterize each step of the MWCNT chemical functionalization process. The chemical process was designed to favor selective attachment at the nodes and not the segments in the CNT networks. The chemical processing was designed to direct formation of nodes where the gold nanoparticles are. The nanoparticles which were loosely held in the CNT network could be easily washed away by solvents, while those bound chemically remained. TEM results show that the Cys-AuNPs are preferentially located at the nodes of the CNT networks when compared to the segments. These nanoparticles at the nodes were also characterized by a novel technique called diffraction scanning transmission electron microscopy (D-STEM) confirming their identity. Four-probe measurements found that the sheet resistance of the modified CNT networks was half that of similarly transparent pristine multiwalled CNT networks.
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Affiliation(s)
- Aruna Velamakanni
- Department of Mechanical Engineering and The Texas Materials Institute, The University of Texas at Austin, 1 University Station, C2200, Austin, Texas 78712-0292, USA
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Zhou JC, Wang X, Xue M, Xu Z, Hamasaki T, Yang Y, Wang K, Dunn B. Characterization of gold nanoparticle binding to microtubule filaments. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2010. [DOI: 10.1016/j.msec.2009.08.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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50
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Canepa M, Lavagnino L, Pasquali L, Moroni R, Bisio F, De Renzi V, Terreni S, Mattera L. Growth dynamics of L-cysteine SAMs on single-crystal gold surfaces: a metastable deexcitation spectroscopy study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:264005. [PMID: 21828453 DOI: 10.1088/0953-8984/21/26/264005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We report on a metastable deexcitation spectroscopy investigation of the growth of L-cysteine layers deposited under UHV conditions on well-defined Au(110)- (1 × 2) and Au(111) surfaces. The interaction of He(*) with molecular orbitals gave rise to well-defined UPS-like Penning spectra which provided information on the SAM assembly dynamics and adsorption configurations. Penning spectra have been interpreted through comparison with molecular orbital DFT calculations of the free molecule and have been compared with XPS results of previous works. Regarding adsorption of first-layer molecules at room temperature (RT), two different growth regimes were observed. On Au(110), the absence of spectral features related to orbitals associated with SH groups indicated the formation of a compact SAM of thiolate molecules. On Au(111), the data demonstrated the simultaneous presence, since the early stages of growth, of strongly and weakly bound molecules, the latter showing intact SH groups. The different growth mode was tentatively assigned to the added rows of the reconstructed Au(110) surface which behave as extended defects effectively promoting the formation of the S-Au bond. The growth of the second molecular layer was instead observed to proceed similarly for both substrates. Second-layer molecules preferably adopt an adsorption configuration in which the SH group protrudes into the vacuum side.
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Affiliation(s)
- M Canepa
- CNISM and Department of Physics, University of Genova, via Dodecaneso 33, I-16145 Genova, Italy
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