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Abbasi Majd S, Kashanian S, Shekarbeygi Z, Babaei M. Simultaneous sensing of carbidopa and levodopa by a novel strategy based on dual-emission ratiometric assay of modified carbon dots. Biotechnol Appl Biochem 2024. [PMID: 38728602 DOI: 10.1002/bab.2595] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 04/20/2024] [Indexed: 05/12/2024]
Abstract
Rapid control of the content of Parkinson's drugs in biological fluids and pharmaceutical formulations is of great importance because changes in the concentration of these drugs affect their bioavailability and biopharmaceutical properties. Therefore, we presented a simple and convenient method for the ratiometric detection of carbidopa and levodopa for carbon dots (CDs) dual-fluorescent emission. Dual-emission CDs were prepared from chitosan using a microwave method, following which the surface was chemically modified with terephthalaldehyde. CDs had two strong well-separated peaks at 445 and 510 nm. The relative measurement of carbidopa and levodopa was based on the static extinction of CDs at 445 nm and increase at 510 nm, respectively. The linear range for carbidopa measurement was 2.5-300 nM, with a limit of detection (LOD) of 2.1 nM, and a relative standard deviation (RSD) of 1.68%. Further, the linear range for levodopa measurement was equal to 3.0-400 nM, with LOD and RSD% of 2.8 nM and 3.5%, respectively. Also, selectivity of ratiometric sensor in the presence of interferences was investigated, which showed that the recovery of carbidopa and levodopa in serum and urine samples has changed between 96.80% and 116.24% with RSD% 0.11-0.77. CDs also provided good results for the determination of carbidopa and levodopa in real samples, and had high selectivity in the presence of possible interferences.
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Affiliation(s)
- Sasan Abbasi Majd
- Department of Applied Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran
| | - Soheila Kashanian
- Faculty of Chemistry, Sensor and Biosensor Research Center (SBRC), Razi University, Kermanshah, Iran
- Nanobiotechnology Department, Faculty of Innovative Science and Technology, Razi University, Kermanshah, Iran
| | - Zahra Shekarbeygi
- Nano Drug Delivery Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Mahsa Babaei
- Department of Biology, Faculty of Science, Razi University, Kermanshah, Iran
- Department of Biology, Faculty of Sciences, Arak University, Arak, Iran
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2
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Guo Y, Wang J, Zhang L, Wang J. Rapid chemical reduction synthesis of copper nanoclusters with blue fluorescence for highly sensitive detection of furazolidone. LUMINESCENCE 2024; 39:e4702. [PMID: 38418861 DOI: 10.1002/bio.4702] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 01/29/2024] [Accepted: 02/05/2024] [Indexed: 03/02/2024]
Abstract
Tannic acid (TA), as a stabilizing agent, was successfully utilized to establish blue-emitting copper nanoclusters (TA-Cu NCs) on the basis of a facile chemical reduction preparation method. Characterization results proved successful synthesis of TA-Cu NCs with uniform size and excellent stability. TA-Cu NCs exhibited a blue emission wavelength at 431 nm when excited at 364 nm. Interestingly, the as-prepared TA-Cu NCs were selectively quenched by furazolidone based on static quenching. In addition, this analysis platform for furazolidone detection had an excellent linear range from 0.5 to 120 μM with a detection limit of 0.074 μM (S/N = 3). Furthermore, the accuracy of this sensing method was successfully confirmed by detecting furazolidone in bovine serum samples, indicating that TA-Cu NCs had bright application prospects.
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Affiliation(s)
- Yuyu Guo
- College of Arts, Taiyuan University of Technology, Jinzhong, Shanxi, China
| | - Jiancheng Wang
- College of Environmental Science and Engineering, Taiyuan University of Technology, Jinzhong, Shanxi, China
| | - Lili Zhang
- Technical Division, Shanxi iGreen Environmental Protection Technology Co. Ltd., Taiyuan, Shanxi, China
| | - Junkai Wang
- Technical Division, Shanxi iGreen Environmental Protection Technology Co. Ltd., Taiyuan, Shanxi, China
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3
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Zhang S, Ma J, Wu Y, Lu J, Guo Y. Histidine-capped copper nanoclusters for in situ amplified fluorescence monitoring of doxycycline through inner filter effect. LUMINESCENCE 2024; 39:e4677. [PMID: 38286601 DOI: 10.1002/bio.4677] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 12/09/2023] [Accepted: 12/25/2023] [Indexed: 01/31/2024]
Abstract
There is a significant need to accurately measure doxycycline concentrations in view of the adverse effects of an overdose on human health. A fluorescence (FL) detection method was adopted and copper nanoclusters (CuNCs) were synthesized using chemical reduction technology. Based on FL quenching with doxycycline, the prepared CuNCs were used to explore a fluorescent nanoprobe for doxycycline detection. In an optimal sensing environment, this FL nanosensor was sensitive and selective in doxycycline sensing and displayed a linear relationship in the range 0.5-200 μM with a detection limit of 0.092 μΜ. A characterization test demonstrated that CuNCs offered active functional groups for identifying doxycycline using electrostatic interaction and hydrogen bonds. Static quenching and the inner filter effect (IFE) resulted in weakness in the FL of His@CuNCs with doxycycline with great efficiency. This suggested nanosensor was revealed to be a functional model for simple and rapid detection of doxycycline in real samples with very pleasing accuracy.
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Affiliation(s)
- Shen Zhang
- College of Chemistry and Materials, Taiyuan Normal University, Jinzhong, Shanxi, China
| | - Jinlong Ma
- College of Chemistry and Materials, Taiyuan Normal University, Jinzhong, Shanxi, China
| | - Yangfan Wu
- College of Chemistry and Materials, Taiyuan Normal University, Jinzhong, Shanxi, China
| | - Jingwen Lu
- College of Chemistry and Materials, Taiyuan Normal University, Jinzhong, Shanxi, China
| | - Yuyu Guo
- College of Arts, Taiyuan University of Technology, Jinzhong, Shanxi, China
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Santos FDS, Ramasamy E, da Luz LC, Ramamurthy V, Rodembusch FS. Spectroscopic Insights of an Emissive Complex between 4'- N, N-Diethylaminoflavonol in Octa-Acid Deep-Cavity Cavitand and Rhodamine 6G. Molecules 2023; 28:molecules28114260. [PMID: 37298739 DOI: 10.3390/molecules28114260] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/08/2023] [Accepted: 05/20/2023] [Indexed: 06/12/2023] Open
Abstract
Excited-state chemistry relies on the communication between molecules, making it a crucial aspect of the field. One important question that arises is whether intermolecular communication and its rate can be modified when a molecule is confined. To explore the interaction in such systems, we investigated the ground and excited states of 4'-N,N-diethylaminoflavonol (DEA3HF) in an octa acid-based (OA) confined medium and in ethanolic solution, both in the presence of Rhodamine 6G (R6G). Despite the observed spectral overlap between the flavonol emission and the R6G absorption, as well as the fluorescence quenching of the flavonol in the presence of R6G, the almost constant fluorescence lifetime at different amounts of R6G discards the presence of FRET in the studied systems. Steady-state and time-resolved fluorescence indicate the formation of an emissive complex between the proton transfer dye encapsulated within water-soluble supramolecular host octa acid (DEA3HF@(OA)2) and R6G. A similar result was observed between DEA3HF:R6G in ethanolic solution. The respective Stern-Volmer plots corroborate with these observations, suggesting a static quenching mechanism for both systems.
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Affiliation(s)
- Fabiano da Silveira Santos
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada, Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Bairro Agronomia, Porto Alegre CEP 91501-970, Brazil
| | - Elamparuthi Ramasamy
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA
| | - Lilian Camargo da Luz
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada, Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Bairro Agronomia, Porto Alegre CEP 91501-970, Brazil
| | | | - Fabiano Severo Rodembusch
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada, Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Bairro Agronomia, Porto Alegre CEP 91501-970, Brazil
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Mu X, Xu J, Zeng F. A Novel and Sensitive Fluorescent Probe for Glyphosate Detection Based on Cu 2+ Modulated Polydihydroxyphenylalanine Nanoparticles. Biosensors (Basel) 2023; 13:bios13050510. [PMID: 37232871 DOI: 10.3390/bios13050510] [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: 04/03/2023] [Revised: 04/25/2023] [Accepted: 04/25/2023] [Indexed: 05/27/2023]
Abstract
A novel and sensitive fluorescent probe based on Cu2+-modulated polydihydroxyphenylalanine nanoparticles (PDOAs) has been developed for the detection of glyphosate pesticides. Compared to conventional instrumental analysis techniques, fluorometric methods have obtained good results in the field of agricultural residue detection. However, most of the fluorescent chemosensors reported still have some limitations, such as long response times, the high limit of detection, and complex synthetic procedures. In this paper, a novel and sensitive fluorescent probe based on Cu2+ modulated polydihydroxyphenylalanine nanoparticles (PDOAs) has been developed for the detection of glyphosate pesticides. The fluorescence of PDOAs can be effectively quenched by Cu2+ through the dynamic quenching process, which was confirmed by the time-resolved fluorescence lifetime analysis. In the presence of glyphosate, the fluorescence of the PDOAs-Cu2+ system can be effectively recovered due to the higher affinity of glyphosate for Cu2+, and thus released the individual PDOAs. Due to the admirable properties such as high selectivity to glyphosate pesticide, "turn on" fluorescence response, and ultralow detection limit of 1.8 nM, the proposed method has been successfully applied for the determination of glyphosate in environmental water samples.
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Affiliation(s)
- Xiqiong Mu
- Research & Development Center for Eco-Material and Eco-Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- College of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730101, China
| | - Jian Xu
- Research & Development Center for Eco-Material and Eco-Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Fankui Zeng
- Research & Development Center for Eco-Material and Eco-Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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6
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Guo Y, Chu Y, Sun X, Cao S, Li X, Li X. Selective detection of nitrofurantoin by histidine-capped silver nanoclusters with blue luminescence. LUMINESCENCE 2023. [PMID: 37078128 DOI: 10.1002/bio.4508] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 04/12/2023] [Accepted: 04/17/2023] [Indexed: 04/21/2023]
Abstract
In view of the significance of nitrofurantoin, efficient analytical method for accurate nitrofurantoin detection is in urgent demand. Considering the superior fluorescence performance of silver nanoclusters (Ag NCs) and rare report of nitrofurantoin detection by fluorescent Ag NCs, Ag NCs with good stability and uniform size were synthesised through one simple method by protection of histidine (His) and reduction of ascorbic acid (AA). Based on the quenching by nitrofurantoin, Ag NCs were successful applied in nitrofurantoin detection with high sensitivity. In the range of 0.5-150 μM, linear relationship between ln(F0 /F) and nitrofurantoin amounts was found. Static quenching and inner filter effect (IFE) was proved to be the main quenching mechanism. Significantly, the superior selectivity and satisfactory recovery results in bovine serum stated that Ag NCs provided better choice for nitrofurantoin detection.
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Affiliation(s)
- Yuyu Guo
- College of Arts, Taiyuan University of Technology, Jinzhong, Shanxi, China
| | - Yiqing Chu
- College of Arts, Taiyuan University of Technology, Jinzhong, Shanxi, China
| | - Xiaojuan Sun
- College of Arts, Taiyuan University of Technology, Jinzhong, Shanxi, China
| | - Songhao Cao
- College of Arts, Taiyuan University of Technology, Jinzhong, Shanxi, China
| | - Xin Li
- College of Arts, Taiyuan University of Technology, Jinzhong, Shanxi, China
| | - Xinyue Li
- College of Arts, Taiyuan University of Technology, Jinzhong, Shanxi, China
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7
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Chen F, Zhang B, Ding Z, Zhong M, Hou Y, Zhang F, Hu G, Fang J. Hemin as a General Static Dark Quencher for Constructing Heme Oxygenase-1 Fluorescent Probe. Angew Chem Int Ed Engl 2023; 62:e202301598. [PMID: 36939218 DOI: 10.1002/anie.202301598] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/19/2023] [Accepted: 03/20/2023] [Indexed: 03/21/2023]
Abstract
The development of small-molecule probes suitable for live-cell applications remains challenging yet highly desirable. We report the first fluorescent probe, RBH, for imaging the heme oxygenase-1 (HO-1) activity in live cells after discovering hemin as a universal dark quencher. Hemin works via a static quenching mechanism and shows high quenching efficiency (>97%) with fluorophores across a broad spectrum (λex=400-700 nm). The favorable properties of RBH (e.g. long excitation/emission wavelengths, fast response rate and high magnitude of signal increase) enable its use for determining HO-1 activity in complex biological samples. As HO-1 is involved in regulating antioxidant defence, iron homeostasis and gasotransmitter carbon monoxide production, we expect RBH to be a powerful tool for dissecting its functions. Also, the discovery of hemin as a general static dark quencher provides a straightforward strategy for constructing novel fluorescent probes for diverse biological species.
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Affiliation(s)
- Fan Chen
- Lanzhou University, Chemistry, CHINA
| | | | | | | | - Yanan Hou
- Lanzhou University, Chemistry, CHINA
| | | | | | - Jianguo Fang
- Lanzhou University, State key lab of applied organic chemistry, 222 South Tianshui Road, 730000, Lanzhou, CHINA
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8
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Qian H, Guo F, Xiong H, Zhang H, Jiang L, Sun Y. The Interactional Characterization of Lentil Protein Isolate (LPI) with Cyanidin-3-O-Glucoside (C3G) and Their Effect on the Stability and Antioxidant Activity of C3G. Foods 2022; 12. [PMID: 36613320 DOI: 10.3390/foods12010104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/17/2022] [Accepted: 12/22/2022] [Indexed: 12/28/2022] Open
Abstract
The interaction between lentil protein isolate (LPI) and cyanidin-3-O-glucoside (C3G) was investigated via with UV−vis spectroscopy, circular dichroism, and fluorescence spectroscopy and the stability of anthocyanin was also evaluated. After LPI mixed with C3G, the turbidity and foaming capacity increased and the particle size and surface charge did not change significantly, while the surface hydrophobicity decreased significantly (p < 0.05). The fluorescence results indicated that C3G quenched the intrinsic of LPI by static quenching and LPI bound with C3G via hydrophobic effects with Ka of 3.24 × 106 M−1 at 298 K. The addition of LPI significantly (p < 0.05) slightly decreased the thermal and oxidation degradation of C3G by up to 90.23% and 54.20%, respectively, while their antioxidant activity was inhibited upon mixing. These alterations of physicochemical properties might be attributed to their structural changes during the interaction. The obtained results would be of help in stabilizing bioactive compounds and the development of functional foods.
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9
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Zheng L, Yan Y, Wang N, Li M, Shuang S, Bian W, Choi MMF. Sulfur-doped graphitic carbon nitride nanosheets as a sensitive fluorescent probe for detecting environmental and intracellular Ag. Methods Appl Fluoresc 2022; 10. [PMID: 35850115 DOI: 10.1088/2050-6120/ac8223] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 07/18/2022] [Indexed: 11/11/2022]
Abstract
Silver is widely used in medical materials, photography, electronics and other industries as a precious metal. The large-scale industrial production of silver-containing products and liquid waste emissions aggravate the environmental pollution. Silver ion is one of the most toxic metal ions, causing pollution to the environment and damage to public health. Therefore, the efficient and sensitive detection of Ag+ in the water environment is extremely important. Sulfur-doped carbon nitride nanosheets (SCN Ns) were prepared by melamine and thiourea via high-temperature calcination. The morphology, chemical composition and surface functional groups of the SCN Ns were characterized by SEM, TEM, XRD, XPS, and FT-IR. The fluorescence of SCN Ns was gradually quenched as the Ag+ concentration increased. The detection limit for Ag+ was as low as 0.28 nM. The quenching mechanism mainly is attributed to static quenching. In this paper, SCN Ns were used as the fluorescent probe for detecting Ag+. SCN Ns have successfully detected Ag+ in different environmental aqueous samples and cells. Finally, SCN Ns were further applied to the visual quantitative detection of intracellular Ag+.
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Affiliation(s)
- Lingling Zheng
- Shanxi Medical University, Shanxi Medical University, Taiyuan, Shanxi Province, China, Taiyuan, Shanxi , 030001, CHINA
| | - Yangyang Yan
- Shanxi Medical University, Shanxi Medical University, Taiyuan, Shanxi Province, China, Taiyuan, Shanxi , 030001, CHINA
| | - Ning Wang
- Shanxi Medical University, Shanxi Medical University, Taiyuan, Shanxi Province, China, Taiyuan, Shanxi , 030001, CHINA
| | - Mingli Li
- Lvliang People's Hospital, Lvliang People's Hospital, Lvliang, China, Lvliang, 033000, CHINA
| | - Shaomin Shuang
- Shanxi University, Xiaodian District, Taiyuan City, Shanxi Province, Taiyuan, Shanxi , 030006, CHINA
| | - Wei Bian
- Shanxi Medical University, Shanxi Medical University, Taiyuan, Shanxi Province, China, Taiyuan, 030001, CHINA
| | - Martin M F Choi
- c/o Tyndale Baptist Church, Bristol Chinese Christian Church, 137-139 Whiteladies Road, Bristol, BS8 2QG, United Kingdom, Clifton, Bristol, BS8 2QG, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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10
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Sarkar A, Kumbhakar M. Inter-molecular Interaction Kinetics: Tale of Photon Anti-bunching and Bunching in Fluorescence Correlation Spectroscopy (FCS). Methods Appl Fluoresc 2022; 10. [PMID: 35817064 DOI: 10.1088/2050-6120/ac804b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 03/31/2022] [Accepted: 07/11/2022] [Indexed: 11/12/2022]
Abstract
Molecular interactions are fundamental to any chemical or biological processes, and their rates define the operational sequence and control for any desirable product. Here, we deliberate on a recently developed novel fluorescence spectroscopic method, which combines fluorescence photon anti-bunching, photon bunching, time-correlated single-photon counting (TCSPC), and steady-state fluorescence spectroscopy, to study composite chemical reactions with single molecule sensitivity. The proposed method captures the full picture of the multifaceted quenching kinetics, which involves static quenching by ground state complexation and collisional quenching in the excited state under dynamic exchange of fluorophore in a heterogeneous media, and which cannot be seen by steady-state or lifetime measurements alone. Photon correlation in fluorescence correlation spectroscopy (FCS) provides access to interrogate interaction dynamics from picosecond to seconds, stitching all possible stages of dye-quencher interaction in a micellar media. This is not possible with the limited time window available to conventional ensemble techniques like TCSPC, flash photolysis, transient absorption, stop-flow, etc. The basic premises of such unified global analysis and sanctity of extracted parameters critically depends on the minimum but precise description of reaction scheme, for which careful inspection of ensemble spectroscopy data for photo-physical behaviour is very important. Though in this contribution we discussed and demonstrated the merits of photon antibunching and bunching spectroscopy for dye-quencher interaction in cationic cetyltrimethylammonium bromide (CTAB) micellar solution by photo-induced electron transfer mechanism and the influence of micellar charge and microenvironment on the interaction kinetics, but in principal similar arguments are equally applicable to any other interaction mechanisms which alter fluorescence photon correlations, like Förster resonance energy transfer (FRET), proton transfer, isomerisation, etc.
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Affiliation(s)
- Aranyak Sarkar
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, CFB, C-139, Mumbai, Maharashtra, 400085, INDIA
| | - Manoj Kumbhakar
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, CFB, C-139, Mumbai, 400085, INDIA
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11
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Li X, Yang L, Wang Y, Du Z, Mao X, Sun D, Liu J, Zhou Y, Xu X. Studies on binding of single-stranded DNA with reduced graphene oxide-silver nanocomposites. IET Nanobiotechnol 2020; 14:308-313. [PMID: 32463021 PMCID: PMC8676041 DOI: 10.1049/iet-nbt.2019.0377] [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] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 02/21/2020] [Indexed: 11/20/2022] Open
Abstract
The binding reaction of reduced graphene oxide-silver nanocomposites (rGO-AgNCs) with calf thymus single-stranded DNA (ssDNA) was studied by ultraviolet-visible absorption, fluorescence spectroscopy and circular dichroism (CD), using berberine hemisulphate (BR) dye as a fluorescence probe. The absorbance of ssDNA increases, but the fluorescence intensity is quenched with the addition of rGO-AgNCs. The binding of rGO-AgNCs with ssDNA was able to increase the quenching effects of BR and ssDNA, and induce the changes in CD spectra. All of the evidence indicated that there was a relatively strong interaction between ssDNA and rGO-AgNCs. The data obtained from fluorescence experiments revealed that the quenching process of ssDNA caused by rGO-AgNCs is primarily due to complex formation, i.e. static quenching. The increasing trend of the binding equilibrium constant (Ka) with rising temperature indicated that the binding process was an endothermic reaction. The calculated thermodynamic parameters showed that the binding process was thermodynamically spontaneous, and hydrophobic association played predominant roles in the binding of ssDNA to the surface of rGO-AgNCs.
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Affiliation(s)
- Xi Li
- Department of Clinical Laboratory, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510006, Guangdong Province, People's Republic of China
| | - Linqing Yang
- Program for Scientific Research Innovation Team in Precision Medicine of Gynecologic Oncology, Affiliated Hospital of Jining Medical University, Jining 272067, Shandong Province, People's Republic of China
| | - Yunfei Wang
- Program for Scientific Research Innovation Team in Precision Medicine of Gynecologic Oncology, Affiliated Hospital of Jining Medical University, Jining 272067, Shandong Province, People's Republic of China
| | - Zhongyu Du
- College of Basic Medical, Jining Medical University, Jining 272067, Shandong Province, People's Republic of China
| | - Xuyan Mao
- College of Basic Medical, Jining Medical University, Jining 272067, Shandong Province, People's Republic of China
| | - Dezhi Sun
- College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, Shandong Province, People's Republic of China
| | - Jun Liu
- College of Basic Medical, Jining Medical University, Jining 272067, Shandong Province, People's Republic of China
| | - Yu Zhou
- School of Public Health, Jining Medical College, Jining 272067, Shandong Province, People's Republic of China
| | - Xiangyu Xu
- College of Basic Medical, Jining Medical University, Jining 272067, Shandong Province, People's Republic of China.
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12
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Kadian S, Manik G. A highly sensitive and selective detection of picric acid using fluorescent sulfur-doped graphene quantum dots. LUMINESCENCE 2020; 35:763-772. [PMID: 31984670 DOI: 10.1002/bio.3782] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [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: 11/15/2019] [Revised: 12/18/2019] [Accepted: 01/12/2020] [Indexed: 02/06/2023]
Abstract
The development of an analytical probe to monitor highly mutagenic picric acid (PA) carries enormous significance for the environment and for health. A novel, simple and rapid fluorescence analytical assay using sulfur-doped graphene quantum dots (SGQDs) was designed for the highly sensitive and selective detection of PA. SGQDs were synthesized via simple pyrolysis of 3-mercaptopropionic acid and citric acid and characterized using advanced analytical techniques. Fluorescence intensity (FI) of SGQDs was markedly quenched by addition of PA, attributed to the inner filter effect and dominating static quenching mechanism between the two, in addition to a significant colour change. The calibration curve of the proposed assay exhibited a favourable linearity between quenched FI and PA concentration over the 0.1-100 μΜ range with a lowest detection limit of 0.093 μΜ and a correlation coefficient of 0.9967. The analytical assay was investigated for detection of trace amounts of PA in pond and rain water samples and showed great potential for practical applications with both acceptable recovery (98.0-100.8%) and relative standard deviation (1.24-4.67%). Analytical performance of the assay in terms of its detection limit, linearity range, and recovery exhibited reasonable superiority over previously reported methods, thereby holding enormous promise as a simple, sensitive, and selective method for detection of PA.
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Affiliation(s)
- Sachin Kadian
- Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Gaurav Manik
- Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
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13
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Sivasankaran U, Radecki J, Radecka H, Girish Kumar K. Copper nanoclusters: an efficient fluorescence sensing platform for quinoline yellow. LUMINESCENCE 2019; 34:243-248. [PMID: 30746849 DOI: 10.1002/bio.3601] [Citation(s) in RCA: 15] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 12/21/2018] [Accepted: 12/31/2018] [Indexed: 01/31/2023]
Abstract
Fluorescence quenching behavior of artificial food colorant quinoline yellow (QY), on interaction with l-cysteine stabilized copper nanoclusters (l-Cys-CuNCs) is investigated in this work. For this purpose, l-cysteine stabilized CuNCs were synthesized and characterized using various analytical techniques. Results demonstrated that the synthesized probe (size ~2 nm) had very promising optical features such as bright blue fluorescence, significant quantum yield and excellent photostability. l-Cys-CuNCs can function as a fluorescence sensor by selectively sensing QY among other yellow colorants, giving a detection limit as low as 0.11 μM. The developed sensor exhibited a linear concentration range from 5.50 to 0.20 μM. The developed fluorescence assay was successfully applied for testing commercial samples, thereby making this sensing strategy significant for quality control of food stuffs.
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Affiliation(s)
- Unni Sivasankaran
- Department of Applied Chemistry, Cochin University of Science and Technology, Kochi-22, Kerala, India
| | - Jerzy Radecki
- Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, Tuwima 10, Olsztyn, Poland
| | - Hanna Radecka
- Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, Tuwima 10, Olsztyn, Poland
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14
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Zhang HQ, Jia YY, Fang HT, Yin LW, Lü H. [Adsorption Mechanisms of Ciprofloxacin by Extracellular Polymeric Substances of Sulfate-reducing Bacteria Sludge]. Huan Jing Ke Xue 2018; 39:4653-4660. [PMID: 30229614 DOI: 10.13227/j.hjkx.201802132] [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] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Extracellular polymeric substances (EPS) in microbial sludge, fulfils a key role in removal of micro-organic pollutants during biological wastewater treatment. In this study, the authors evaluated the removal of ciprofloxacin (CIP) by sulfate-reducing bacteria (SRB) sludge in a sulfate-reducing up-flow sludge bed (SRUSB) reactor, and examined the role of EPS on CIP removal in an SRB sludge system. The results indicated that CIP was removed efficiently through adsorption and biodegradation by SRB sludge, with adsorption the major removal pathway. EPS also played an important role in CIP adsorption by SRB sludge, and the adsorption mechanisms of CIP by EPS were investigated using the three-dimensional excitation-emission matrix fluorescence spectroscopy technologies combined with parallel factor analysis. The functional groups binding CIP onto EPS were identified through Fourier transform infrared (FTIR) spectra analysis. The results suggested that the static quenching of EPS following CIP adsorption led to formation of an EPS-CIP complex, and that the CIP was mainly bound with tryptophan and tyrosine-like protein substances in EPS with the binding constants of 1.43×104 L·mol-1 and 1.02×104 L·mol-1, respectively. The FTIR results suggested that hydroxyl, amino and carboxyl functional groups were mainly responsible for binding of CIP onto EPS. The results revealed the adsorption mechanisms of CIP by EPS in SRB sludge, and enhanced understanding of the role of EPS in sulfur-mediated biological processes for the removal of CIP and other organic micro-pollutants.
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Affiliation(s)
- Hui-Qun Zhang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510006, China
| | - Yan-Yan Jia
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510006, China
| | - He-Ting Fang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510006, China
| | - Lin-Wan Yin
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510006, China
| | - Hui Lü
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510006, China
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15
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Abstract
Fluorescence quenching was used to investigate the interaction of six fluoroquinolones with humic acid. Static quenching was observed for the binding of ciprofloxacin, enoxacin, fleroxacin, levofloxacin, norfloxacin, and ofloxacin to humic acid. The equilibrium binding constants were found from Stern-Volmer plots of the data. The quenching experiments were repeated over a temperature range of 25-45 ℃ and van't Hoff plots were generated. From these linear plots, thermodynamic values were calculated for Δ H, Δ G, and Δ S for each of the fluoroquinolones. The equilibrium binding constants were found to be <1 for all the antibiotics studied. The calculated ΔH values were all negative and ranged from -9.5 to -27.6 kJ/mol. The high water solubility of the antibiotics and low ΔH of binding suggests that the antibiotics will be transported easily through the environment. Finally, whether the fluoroquinolones are in a protonated, deprotonated, or partially protonated state is found to correlate to the strength of binding to humic acid.
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Affiliation(s)
- Ryan P Ferrie
- Muhlenberg College, Department of Chemistry, Allentown, PA, USA
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16
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Reynard JM, Van Gorder NS, Bright FV. Origin of Analyte-Induced Porous Silicon Photoluminescence Quenching. Appl Spectrosc 2017; 71:2136-2145. [PMID: 28862036 DOI: 10.1177/0003702817696092] [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] [Indexed: 06/07/2023]
Abstract
We report on gaseous analyte-induced photoluminescence (PL) quenching of porous silicon, as-prepared (ap-pSi) and oxidized (ox-pSi). By using steady-state and emission wavelength-dependent time-resolved intensity luminescence measurements in concert with a global analysis scheme, we find that the analyte-induced quenching is best described by a three-component static quenching model. In the model, there are blue, green, and red emitters (associated with the nanocrystallite core and surface trap states) that each exhibit unique analyte-emitter association constants and these association constants are a consequence of differences in the pSi surface chemistries.
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Affiliation(s)
- Justin M Reynard
- 1 Department of Chemistry, Erie Community College, Williamsville, NY, USA
| | - Nathan S Van Gorder
- 2 Department of Chemistry, Natural Sciences Complex, SUNY-Buffalo, Buffalo, NY, USA
| | - Frank V Bright
- 2 Department of Chemistry, Natural Sciences Complex, SUNY-Buffalo, Buffalo, NY, USA
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17
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Zhao L, Wang T, Wu Q, Liu Y, Chen Z, Li X. Fluorescent Strips of Electrospun Fibers for Ratiometric Sensing of Serum Heparin and Urine Trypsin. ACS Appl Mater Interfaces 2017; 9:3400-3410. [PMID: 28067489 DOI: 10.1021/acsami.6b14118] [Citation(s) in RCA: 32] [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] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
"Turn-on" or "turn-off" probes remain challenges in the establishment of sensitive, easily operated, and reliable methods for in situ monitoring bioactive substances. In the current study, electrospun fibrous strips are designed to provide straightforward observations of ratiometric color changes with the naked eye in the presence of serum heparin or urine trypsin. A tetraphenylethene (TPE) derivative is constructed and along with phloxine B is grafted on fibers, followed by protamine adsorption to induce static quenching of phloxine B and aggregation-induced emission of the TPE derivative. The presence of heparin or trypsin removes protamine to restore the fluorescence of phloxine B at 574 nm (I574) and relieve the emission of the TPE derivative at 472 nm (I472). The grafting densities of phloxine B and the TPE derivative are essential to achieve the optimal fluorescence-intensity ratio of I574/I472 for the ratiometric detection of heparin and trypsin. Under illumination by an ultraviolet lamp, the fibrous mats turn from cyan to green in the presence of heparin at 0.4 U/mL and to a bright yellow at 0.8 U/mL, which is feasible in sensing serum heparin levels during postoperative and long-term care of patients after cardiovascular surgery. The protamine digestion results in similar color transitions with increasing trypsin levels up to 8 μg/mL, indicating the potential for monitoring urine trypsin levels of pancreas transplant patients. The color strips based on the ratiometric fluorescent response indicate advantages in lowering the detection limit and improving the accuracy and reproducibility, bearing great potential for a real-time and naked-eye detection of bioactive substances as self-test devices.
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Affiliation(s)
- Long Zhao
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University , Chengdu 610031, PR China
| | - Tao Wang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University , Chengdu 610031, PR China
| | - Qiang Wu
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University , Chengdu 610031, PR China
| | - Yuan Liu
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University , Chengdu 610031, PR China
| | - Zhoujiang Chen
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University , Chengdu 610031, PR China
| | - Xiaohong Li
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University , Chengdu 610031, PR China
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18
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Chen YC, Wang HM, Niu QX, Ye DY, Liang GW. Binding between Saikosaponin C and Human Serum Albumin by Fluorescence Spectroscopy and Molecular Docking. Molecules 2016; 21:153. [PMID: 26828474 PMCID: PMC6273137 DOI: 10.3390/molecules21020153] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [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: 11/11/2015] [Revised: 01/18/2016] [Accepted: 01/21/2016] [Indexed: 02/05/2023] Open
Abstract
Saikosaponin C (SSC) is one of the major active constituents of dried Radix bupleuri root (Chaihu in Chinese) that has been widely used in China to treat a variety of conditions, such as liver disease, for many centuries. The binding of SSC to human serum albumin (HSA) was explored by fluorescence, circular dichroism (CD), UV-vis spectrophotometry, and molecular docking to understand both the pharmacology and the basis of the clinical use of SSC/Chaihu. SSC produced a concentration-dependent quenching effect on the intrinsic fluorescence of HSA, accompanied by a blue shift in the fluorescence spectra. The Stern-Volmer equation showed that this quenching was dominated by static quenching. The binding constant of SSC with HSA was 3.72 × 10³ and 2.99 × 10³ L·mol(-1) at 26 °C and 36 °C, respectively, with a single binding site on each SSC and HSA molecule. Site competitive experiments demonstrated that SSC bound to site I (subdomain IIA) and site II (subdomain IIIA) in HSA. Analysis of thermodynamic parameters indicated that hydrogen bonding and van der Waals forces were mostly responsible for SSC-HSA association. The energy transfer efficiency and binding distance between SSC and HSA was calculated to be 0.23 J and 2.61 nm at 26 °C, respectively. Synchronous fluorescence and CD measurements indicated that SSC affected HSA conformation in the SSC-HSA complex. Molecular docking supported the experimental findings in conformational changes, binding sites and binding forces, and revealed binding of SSC at the interface between subdomains IIA-IIB.
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Affiliation(s)
- Yi-Cun Chen
- Key Immunopharmacology Laboratory of Guangdong Province, Department of Pathophysiology, Institute of Inflammation and Immune Diseases, Shantou University Medical College, Guangdong 515041, China.
- Department of Pharmacology, Traditional Chinese Medicine Laboratory, Shantou University Medical College, Guangdong 515041, China.
| | - Hong-Mei Wang
- Key Immunopharmacology Laboratory of Guangdong Province, Department of Pathophysiology, Institute of Inflammation and Immune Diseases, Shantou University Medical College, Guangdong 515041, China.
| | - Qing-Xia Niu
- Key Immunopharmacology Laboratory of Guangdong Province, Department of Pathophysiology, Institute of Inflammation and Immune Diseases, Shantou University Medical College, Guangdong 515041, China.
| | - Dan-Yan Ye
- Department of Pharmacology, Traditional Chinese Medicine Laboratory, Shantou University Medical College, Guangdong 515041, China.
| | - Guo-Wu Liang
- Key Immunopharmacology Laboratory of Guangdong Province, Department of Pathophysiology, Institute of Inflammation and Immune Diseases, Shantou University Medical College, Guangdong 515041, China.
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19
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Li X, Slyker LW, Nichols VM, Pau GSH, Bardeen CJ, Tang ML. Ligand Binding to Distinct Sites on Nanocrystals Affecting Energy and Charge Transfer. J Phys Chem Lett 2015; 6:1709-1713. [PMID: 26263338 DOI: 10.1021/acs.jpclett.5b00574] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Hybrid optoelectronic devices are attractive because they offer the promise of low-cost, roll-to-roll fabrication. Despite this, energy transfer between organic and inorganic interfaces is not well understood. Device engineering on this class of solution-processed materials generally focuses on replacing the long insulating ligands with short ones. Here, we show that energy and charge transfer between an inorganic nanocrystal (NC) donor and organic molecular acceptor is acutely sensitive to the chemical moiety linking the two species. Our results reveal that the CdS NCs have distinct binding sites for different chemical species because only resonance energy transfer (RET) is observed for the carboxylic-acid-functionalized ligand, while both RET and charge transfer are observed for the amine-functionalized ligand. We observe that the equilibrium constant for this static quenching term increases with decreasing particle size. This finding offers a new approach in the design of hybrid thin films for devices and NC probes based on RET used for imaging, sensing, signal transduction, and photon management.
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Affiliation(s)
- Xin Li
- †Department of Chemistry, University of California, Riverside, Riverside, California 92521, United States
| | - Lydia W Slyker
- †Department of Chemistry, University of California, Riverside, Riverside, California 92521, United States
| | - Valerie M Nichols
- †Department of Chemistry, University of California, Riverside, Riverside, California 92521, United States
| | - George Shu Heng Pau
- ‡Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Christopher J Bardeen
- †Department of Chemistry, University of California, Riverside, Riverside, California 92521, United States
| | - Ming L Tang
- †Department of Chemistry, University of California, Riverside, Riverside, California 92521, United States
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20
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Thomsson D, Camacho R, Tian Y, Yadav D, Sforazzini G, Anderson HL, Scheblykin IG. Cyclodextrin insulation prevents static quenching of conjugated polymer fluorescence at the single molecule level. Small 2013; 9:2619-2627. [PMID: 23463732 DOI: 10.1002/smll.201203272] [Citation(s) in RCA: 16] [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] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Indexed: 06/01/2023]
Abstract
Conjugated polymers (CPs) are promising materials for fluorescence imaging application. However, a significant problem in this field is the unexplained abnormally low fluorescence brightness (or number of fluorescence photons detected per one excitation photon) exhibited by most of CP single chains in solid polymer hosts. Here it is shown that this detrimental effect can be fully avoided for short chains of polyfluorene-bis-vinylphenylene (PFBV) embedded in a host polymer matrix of PMMA, if the conjugated backbone is insulated by cyclodextrin rings to form a polyrotaxane (PFBV-Rtx). Fluorescence kinetics and quantum yields are measured for the polymers in liquid solutions, pristine films, and solid PMMA blends. The fluorescence brightness of PFBV-Rtx single chains dispersed in a solid PMMA is very close to that expected for a chain with 100% fluorescence quantum yield, while the unprotected PFBV chains of the same length possess 4 times lower brightness. Despite this, the fluorescence decay kinetics are the same for both polymers, suggesting the presence of static or ultrafast fluorescence quenching in the unprotected polymer. About 80% of an unprotected PFBV chain is estimated to be completely quenched. The hypothesis is that the cyclodextrin rings prevent the quenching by working as 'bumpers' reducing the mechanical forces applied by the host polymer to the conjugated backbone and help retaining its conformational freedom. While providing a recipe for making CP fluorescence bright at the single-molecule level, these results identify a lack of fundamental understanding in the community of the influence of the environment on excited states in conjugated materials.
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Affiliation(s)
- Daniel Thomsson
- Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden
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21
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Morgounova E, Shao Q, Hackel BJ, Thomas DD, Ashkenazi S. Photoacoustic lifetime contrast between methylene blue monomers and self-quenched dimers as a model for dual-labeled activatable probes. J Biomed Opt 2013; 18:56004. [PMID: 23640075 PMCID: PMC4023645 DOI: 10.1117/1.jbo.18.5.056004] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 03/19/2013] [Accepted: 03/26/2013] [Indexed: 05/23/2023]
Abstract
Activatable photoacoustic probes efficiently combine the high spatial resolution and penetration depth of ultrasound with the high optical contrast and versatility of molecular imaging agents. Our approach is based on photoacoustic probing of the excited-state lifetime of methylene blue (MB), a fluorophore widely used in clinical therapeutic and diagnostic applications. Upon aggregation, static quenching between the bound molecules dramatically shortens their lifetime by three orders of magnitude. We present preliminary results demonstrating the ability of photoacoustic imaging to probe the lifetime contrast between monomers and dimers with high sensitivity in cylindrical phantoms. Gradual dimerization enhancement, driven by the addition of increasing concentrations of sodium sulfate to a MB solution, showed that lifetime-based photoacoustic probing decreases linearly with monomer concentration. Similarly, the addition of 4 mM sodium dodecyl sulfate, a concentration that amplifies MB aggregation and reduces the monomer concentration by more than 20-fold, led to a signal decrease of more than 20 dB compared to a solution free of surfactant. These results suggest that photoacoustic imaging can be used to selectively detect the presence of monomers. We conclude by discussing the implementation of the monomer-dimer contrast mechanism for the development of an enzyme-specific activatable probe.
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Affiliation(s)
- Ekaterina Morgounova
- University of Minnesota, Department of Biomedical Engineering, Minneapolis, MN 55455, USA.
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22
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Rahimi Y, Goulding A, Shrestha S, Mirpuri S, Deo SK. Mechanism of copper induced fluorescence quenching of red fluorescent protein, DsRed. Biochem Biophys Res Commun 2008; 370:57-61. [PMID: 18348863 PMCID: PMC2527065 DOI: 10.1016/j.bbrc.2008.03.034] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 03/04/2008] [Indexed: 01/28/2023]
Abstract
The red fluorescent protein, DsRed, and a few of its mutants have been shown to bind copper ions resulting in quenching of its fluorescence. The response to Cu(2+) is rapid, selective, and reversible upon addition of a copper chelator. DsRed has been employed as an in vitro probe for Cu(2+) determination by us and other groups. It is also envisioned that DsRed can serve as an intracellular genetically encoded indicator of Cu(2+) concentration, and can be targeted to desired subcellular locations for Cu(2+) determination. However, no information has been reported yet regarding the mechanism of the fluorescence quenching of DsRed in the presence of Cu(2+). In this work, we have performed spectroscopic investigations to determine the mechanism of quenching of DsRed fluorescence in the presence of Cu(2+). We have studied the effect of Cu(2+) addition on two representative mutants of DsRed, specifically, DsRed-Monomer and DsRed-Express. Both proteins bind Cu(2+) with micromolar affinities. Stern-Volmer plots generated at different temperatures indicate a static quenching process in the case of both proteins in the presence of Cu(2+). This mechanism was further studied using absorption spectroscopy. Stern-Volmer constants and quenching rate constants support the observation of static quenching in DsRed in the presence of Cu(2+). Circular dichroism (CD)-spectroscopic studies revealed no effect of Cu(2+)-binding on the secondary structure or conformation of the protein. The effect of pH changes on the quenching of DsRed fluorescence in the presence of copper resulted in pK(a) values indicative of histidine and cysteine residue involvement in Cu(2+)-binding.
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Affiliation(s)
- Yasmeen Rahimi
- Department of Chemistry & Chemical Biology Indiana University Purdue University Indianapolis Indianapolis, IN 46202
| | - Ann Goulding
- Department of Chemistry & Chemical Biology Indiana University Purdue University Indianapolis Indianapolis, IN 46202
| | - Suresh Shrestha
- Department of Chemistry & Chemical Biology Indiana University Purdue University Indianapolis Indianapolis, IN 46202
| | - Sweetie Mirpuri
- Department of Chemistry & Chemical Biology Indiana University Purdue University Indianapolis Indianapolis, IN 46202
| | - Sapna K. Deo
- Department of Chemistry & Chemical Biology Indiana University Purdue University Indianapolis Indianapolis, IN 46202
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