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Praveen Mishra - One of the best experts on this subject based on the ideXlab platform.

  • Interaction of Fluorescent Gold Nanoclusters with Transition Metal Dichalcogenides Nanosheets: A Spectroscopic Study
    Journal of Luminescence, 2020
    Co-Authors: Arun Singh Patel, Anirban Chakraborti, Praveen Mishra
    Abstract:

    Abstract In this paper, the interaction of few tens of atoms containing Gold Nanoclusters with two dimensional nanosheets of transition metal dichalcogenides nanosheets has been explored. The Gold Nanoclusters have been synthesized using chemical reduction method in presence of protein molecules as stabilizing agent. The transition metal dichalcogenides nanosheets of molybdenum disulfide (MoS 2 ) has been chemically exfoliated. Different microscopic and optical spectroscopic tools have been used for characterizing the physical properties of the Gold Nanoclusters and the two dimensional nanosheets of MoS 2 . The Gold Nanoclusters exhibit fluorescence emission at 690 nm. However, the interaction with transition metal dichalcogenides diminishes drastically the fluorescence intensity of the Nanoclusters. The time resolved fluorescence study shows that the fluorescence lifetime of fluorescent materials can be altered in presence of MoS 2 nanosheets, and the energy transfer phenomena can be observed.

Zhanguang Chen - One of the best experts on this subject based on the ideXlab platform.

  • Highly fluorescent Gold Nanoclusters based sensor for the detection of quercetin
    Journal of Nanoparticle Research, 2012
    Co-Authors: Zhanguang Chen, Sihua Qian, Junhui Chen, Xi Chen
    Abstract:

    In this contribution, novel luminescent Gold Nanoclusters were synthesized by utilizing bovine serum albumin as templates with a simple, rapid, and one-pot procedure. The as-prepared Gold Nanoclusters were highly dispersed in aqueous solution and emitted an intense red fluorescence under UV light (365 nm). They exhibited strong fluorescence and the maximum excitation and emission wavelengths were 480 and 613.5 nm. In addition, the bovine serum albumin-stabilized Gold Nanoclusters were successfully utilized as novel fluorescent probes for the detection of quercetin for the first time. It was found that the addition of quercetin induced the strong fluorescence intensity of the Gold Nanoclusters to decrease. The decrease in fluorescence intensity of the Gold Nanoclusters caused by quercetin allowed the sensitive detection of quercetin in the range of 8.9 × 10−8–1.8 × 10−4 mol L−1. The detection limit for quercetin is 1.8 × 10−8 mol L−1 at a signal-to-noise ratio of 3. The present sensor for quercetin detection possessed a low detection limit and wide linear range. In addition, the real samples were analyzed with satisfactory results.

  • Protein-templated Gold Nanoclusters as fluorescence probes for the detection of methotrexate
    The Analyst, 2012
    Co-Authors: Zhanguang Chen, Sihua Qian, Xi Chen, Wenhua Gao, Yuejuan Lin
    Abstract:

    In this contribution, bovine serum albumin stabilized Gold Nanoclusters as novel fluorescent probes were successfully utilized for the detection of methotrexate for the first time. Our prepared Gold Nanoclusters exhibited strong emission with peak maximum at 633.5 nm. However, the addition of methotrexate induced the strong fluorescence intensity of the Gold Nanoclusters to decrease. The decrease in fluorescence intensity of the Gold Nanoclusters caused by methotrexate allowed the sensitive detection of methotrexate in the range of 0.0016 μg mL−1 to 24 μg mL−1. The detection limit for methotrexate is 0.9 ng mL−1 at a signal-to-noise ratio of 3. The present sensor for methotrexate detection possessed a low detection limit and wide linear range. In addition, the real samples were analyzed with satisfactory results.

  • Protein-templated Gold Nanoclusters based sensor for off-on detection of ciprofloxacin with a high selectivity.
    Talanta, 2012
    Co-Authors: Zhanguang Chen, Sihua Qian, Junhui Chen, Jie Cai, Ziping Cai
    Abstract:

    In this contribution, bovine serum albumin stabilized Gold Nanoclusters as novel fluorescent probes were successfully utilized for the detection of ciprofloxacin for the first time. Our prepared Gold Nanoclusters exhibited strong emission with peak maximum at 635 nm. Cu(2+) was employed to quench the strong fluorescence of the Gold Nanoclusters, whereas the addition of ciprofloxacin caused the fluorescence intensity restoration of the Cu(2+)-Gold Nanoclusters system. The increase in fluorescence intensity of Cu(2+)-Gold Nanoclusters system caused by ciprofloxacin allows the sensitive detection of ciprofloxacin in the range of 0.4 ng mL(-1) to 50 ng mL(-1). The detection limit for ciprofloxacin is 0.3 ng mL(-1) at a signal-to-noise ratio of 3. The present sensor for ciprofloxacin detection possesses a low detection limit and wide linear range. In addition, the real samples were analyzed with satisfactory results.

Arun Singh Patel - One of the best experts on this subject based on the ideXlab platform.

  • Interaction of Fluorescent Gold Nanoclusters with Transition Metal Dichalcogenides Nanosheets: A Spectroscopic Study
    Journal of Luminescence, 2020
    Co-Authors: Arun Singh Patel, Anirban Chakraborti, Praveen Mishra
    Abstract:

    Abstract In this paper, the interaction of few tens of atoms containing Gold Nanoclusters with two dimensional nanosheets of transition metal dichalcogenides nanosheets has been explored. The Gold Nanoclusters have been synthesized using chemical reduction method in presence of protein molecules as stabilizing agent. The transition metal dichalcogenides nanosheets of molybdenum disulfide (MoS 2 ) has been chemically exfoliated. Different microscopic and optical spectroscopic tools have been used for characterizing the physical properties of the Gold Nanoclusters and the two dimensional nanosheets of MoS 2 . The Gold Nanoclusters exhibit fluorescence emission at 690 nm. However, the interaction with transition metal dichalcogenides diminishes drastically the fluorescence intensity of the Nanoclusters. The time resolved fluorescence study shows that the fluorescence lifetime of fluorescent materials can be altered in presence of MoS 2 nanosheets, and the energy transfer phenomena can be observed.

  • Interaction of Fluorescent Gold Nanoclusters with Transition Metal Dichalcogenides Nanosheets: A Spectroscopic Study
    arXiv: Materials Science, 2018
    Co-Authors: Arun Singh Patel, Anirban Chakraborti
    Abstract:

    In this paper, the interaction of few tens of atoms containing Gold Nanoclusters with two dimensional nanosheets of transition metal dichalcogenides nanosheets has been explored. The Gold Nanoclusters have been synthesized using chemical reduction method in presence of protein molecules as stabilizing agent. The transition metal dichalcogenides nanosheets of molybdenum disulfide (MoS$_2$) has been chemically exfoliated. Different microscopic and optical spectroscopic tools have been used for characterizing the physical properties of the Gold Nanoclusters and the two dimensional nanosheets of MoS$_2$. The Gold Nanoclusters exhibit fluorescence emission at 690 nm. However, the interaction with transition metal dichalcogenides diminishes drastically the fluorescence intensity of the Nanoclusters. The spectroscopic methods used for understanding the interaction in the system reveals the absence of energy transfer and dynamic nature of the fluorescence quenching.

Yu Chen - One of the best experts on this subject based on the ideXlab platform.

  • Study of Glucose Binding Protein Encapsulated Gold Nanoclusters by Molecular Dynamic Simulation
    Materials Science Forum, 2019
    Co-Authors: Boy Marsaputra Panjaitan, Karina Kubiak-ossowska, David J. S. Birch, Yu Chen
    Abstract:

    Protein encapsulated Gold Nanoclusters has attracted great attention for their excellent fluorescent properties and potential biomedical applications. Glucose Binding Protein (GBP) has a high sensitivity and selectivity to glucose binding that makes them ideal for biosensor development. It is anticipated that GBP encapsulated Gold Nanoclusters could be a promising glucose sensor. Here we investigated the growth of Gold Nanoclusters in GBP using Molecular Dynamics (MD) simulation. To facilitation the nucleation of Gold Nanoclusters at specific sites, cysteine mutations were introduced in GBP. It is found that the nucleation site of Gold Nanoclusters inside mutant GBP are different from those in native GBP. Gold Nanoclusters were formed near the mutated cysteine and tyrosine residues. Glucose remained in the binding site of a mutant GBP with Gold Nanoclusters although no conformational change was observed in MD simulation, similar to a native GBP. This work suggests the possibility of growing Gold Nanoclusters in the designed site within GBP and a new glucose sensor based on mutated GBP protected Gold Nanoclusters.

  • Locating the nucleation sites for protein encapsulated Gold Nanoclusters: a molecular dynamics and fluorescence study
    Physical chemistry chemical physics : PCCP, 2015
    Co-Authors: Ben Allan Russell, Karina Kubiak-ossowska, David J. S. Birch, Paul A. Mulheran, Yu Chen
    Abstract:

    Fluorescent Gold Nanoclusters encapsulated by proteins have attracted considerable attention in recent years for their unique properties as new fluorescence probes for biological sensing and imaging. However, fundamental questions, such as the nucleation sites of Gold Nanoclusters within proteins and the fluorescence mechanism remain unsolved. Here we present a study of the location of Gold Nanoclusters within bovine serum albumin (BSA) combining both fully atomistic molecular dynamic (MD) simulations and fluorescence spectroscopic studies. The MD simulations show Gold clusters growing close to a number of cysteine sites across all three domains of BSA, although just two major sites in domains IIB and IA were found to accommodate large clusters comprising more than 12 atoms. The dependence of the fluorescence on pH is found to be compatible with possible nucleation sites in domains IIB and IA. Furthermore, the energy transfer between tryptophan and Gold Nanoclusters reveals a separation of 29.7 A, further indicating that Gold Nanoclusters were most likely located in the major nucleation site in domain IIB. The disclosure of the precise location of the Gold Nanoclusters and their surrounding amino acid residues should help better understanding of their fluorescence mechanism and aid their optimization as fluorescent nanoprobes.

  • Fluorescence anisotropy of protein - Gold Nanoclusters
    2012 12th IEEE International Conference on Nanotechnology (IEEE-NANO), 2012
    Co-Authors: Jens U. Sutter, David J. S. Birch, Yu Chen
    Abstract:

    Red-emitting Gold Nanoclusters (BSA-Au 25 ) have been synthesized in Bovine Serum albumin and found to have a characteristic fluorescence lifetime of 1.25µs. Fluorescence anisotropy measurements of BSA-Au25 reveal a dramatic increase in protein size as the pH is reduced from 7 to 3.1, consistent with the change of BSA from N form to E form. This study suggests the possibility of exploiting fluorescent protein-Gold Nanoclusters to probe protein conformational changes in response to the local environment.

Guang Yang - One of the best experts on this subject based on the ideXlab platform.

  • The assembly of protein-templated Gold Nanoclusters for enhanced fluorescence emission and multifunctional applications.
    Acta biomaterialia, 2019
    Co-Authors: Yu Cao, Lai Wei, Jinjie Wang, Min Zhang, Xuexia Yang, Wenshuo Wang, Guang Yang
    Abstract:

    Abstract Protein-templated Gold Nanoclusters have attracted attention in fluorescence imaging due to their simple synthesis and good biocompatibility. However, limitations still exist such as poor colloid stability and undesirable fluorescence intensity. Here we describe the self-assembly of keratin-templated Gold Nanoclusters via a simple and mild preparation process, including keratin-templated synthesis of Gold Nanoclusters (AuNCs@Keratin), silver ions modification of AuNCs@Keratin (AuNCs-Ag@Keratin), and gadolinium ions-induced aggregation of AuNCs-Ag@Keratin (AuNCs-Ag@Keratin-Gd). It was demonstrated that the AuNCs-Ag@Keratin-Gd obtained an enhanced fluorescence intensity (6.5 times that of AuNCs@Keratin), high colloid stability for more than 4 months, and good biocompatibility. Moreover, the AuNCs-Ag@Keratin-Gd holds promise in multifunctional applications such as near-infrared (NIR) fluorescence imaging, magnetic resonance (MR) imaging, and redox-responsive drug delivery, extending the applicability of fluorescent Gold Nanoclusters, especially in biomedical fields. Statement of significance Assembly-induced fluorescence enhancement has been rarely reported on as it relates to the protein-templated Gold Nanoclusters (AuNCs). In this work, self-assembly of protein-templated AuNCs was developed for enhanced fluorescence intensity and multifunctional applications, including bioimaging and responsive drug delivery. A cysteine-rich protein, keratin, was utilized as the template to synthesize AuNCs, which underwent silver ion modification and gadolinium ion-induced aggregation. The silver modification of the keratin-templated AuNCs facilitated the formation of a dense aggregate after gadolinium ion-induced assembly, thus generating an enhanced fluorescence intensity. Such a mechanism was confirmed by fluorescence correlation spectroscopy analysis. We believe that this work will extend the applicability of the fluorescent Gold Nanoclusters, especially in biomedical fields, and provided an effective approach for the mechanism analysis of the assembly-induced fluorescence enhancement via fluorescence correlation spectroscopy.