Gold nanoclusters and fluorescence-based sensing

2017 ◽  
Author(s):  
◽  
Xi Chen
Keyword(s):  
Fluorescence Intensity ◽  
Cholesterol Oxidase ◽  
Gold Nanoclusters ◽  
Green Emission ◽  
Mapping Method ◽  
Metal Nanoclusters ◽  
Molecular Rotor ◽  
Great Resistance ◽  
University Of Missouri ◽  
Thermal Reversibility

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The main topic of this dissertation focuses on development of analytical methods, mainly modification and application of metal nanoclusters in fluorescence-based sensing. Based on bovine serum albumin passivated gold nanoclusters (AuNCs@BSA) we firstly developed a fluorescent biosensor platform, combining cholesterol oxidase with assistance of surfactant, for selective detection of water insoluble analyte, cholesterol in aqueous condition. Moreover, we designed a series of modification strategy to enhence thermal reversibility of AuNCs@BSA, aiming at reducing hysteresis remained during thermal cycles. Taking advantage of optimized thermal reversibility in terms of fully recoverable fluorescence intensity, analytical performance of modified AuNCs@BSA was investigated and an aqueous-phase temperature sensor was achieved. In addition to AuNCs, we developed novel glutathione stabilized copper NCs with green-emission in assistance of ascorbic acid reduction, which showed great resistance to nitro compounds. Further, analytical application of as-prepared Cu NCs to ratiometric sensing on explosive molecules, cooperating with AuNCs@BSA, was investigated. In the last, a novel and facile temperature mapping method using ionic liquid and organic fluorescent molecular rotor were described. Making use of viscosity-sensitive fluorescent dye, temperature was converted to ratio value of fluorescence intensity and recorded, enabling visualized thermal map.

A New Strategy to Construct Gold Nanoclusters-Based Optical Probe Using Luminescence Resonance Energy Transfer

2021 ◽  
Author(s):  
Shuyang Zhai ◽  
Wei Hu ◽  
Chen Fan ◽  
Wenqi Feng ◽  
Zhi-hong Liu
Keyword(s):  
Energy Transfer ◽  
Gold Nanoclusters ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Optical Probe ◽  
Luminescent Materials ◽  
Metal Nanoclusters ◽  
New Strategy ◽  
Photoluminescence Efficiency

Monolayer-protected metal nanoclusters (MPCs) are emerging as intriguing luminescent materials, but the construction of MPCs-based optical probe is still scarce because of both the limited photoluminescence efficiency of MPCs and...

scholarly journals Synthesis of Exosome-Based Fluorescent Gold Nanoclusters for Cellular Imaging Applications

2021 ◽  
Vol 22 (9) ◽  
pp. 4433
Author(s):  
Eun Sung Lee ◽  
Byung Seok Cha ◽  
Seokjoon Kim ◽  
Ki Soo Park
Keyword(s):  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Stokes Shift ◽  
Gold Nanoclusters ◽  
Human Colon ◽  
Cellular Imaging ◽  
Metal Nanoclusters ◽  
Human Colon Cancer ◽  
X Ray ◽  
High Concentrations

In recent years, fluorescent metal nanoclusters have been used to develop bioimaging and sensing technology. Notably, protein-templated fluorescent gold nanoclusters (AuNCs) are attracting interest due to their excellent fluorescence properties and biocompatibility. Herein, we used an exosome template to synthesize AuNCs in an eco-friendly manner that required neither harsh conditions nor toxic chemicals. Specifically, we used a neutral (pH 7) and alkaline (pH 11.5) pH to synthesize two different exosome-based AuNCs (exo-AuNCs) with independent blue and red emission. Using field-emission scanning electron microscopy, energy dispersive X-ray microanalysis, nanoparticle tracking analysis, and X-ray photoelectron spectroscopy, we demonstrated that AuNCs were successfully formed in the exosomes. Red-emitting exo-AuNCs were found to have a larger Stokes shift and a stronger fluorescence intensity than the blue-emitting exo-AuNCs. Both exo-AuNCs were compatible with MCF-7 (human breast cancer), HeLa (human cervical cancer), and HT29 (human colon cancer) cells, although blue-emitting exo-AuNCs were cytotoxic at high concentrations (≥5 mg/mL). Red-emitting exo-AuNCs successfully stained the nucleus and were compatible with membrane-staining dyes. This is the first study to use exosomes to synthesize fluorescent nanomaterials for cellular imaging applications. As exosomes are naturally produced via secretion from almost all types of cell, the proposed method could serve as a strategy for low-cost production of versatile nanomaterials.

scholarly journals Streptavidin-conjugated gold nanoclusters as ultrasensitive fluorescent sensors for early diagnosis of HIV infection

2018 ◽  
Vol 4 (11) ◽  
pp. eaar6280 ◽  
Author(s):  
Aditya Dileep Kurdekar ◽  
L. A. Avinash Chunduri ◽  
C. Sai Manohar ◽  
Mohan Kumar Haleyurgirisetty ◽  
Indira K. Hewlett ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Limit Of Detection ◽  
Gold Nanoclusters ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Metal Nanoclusters ◽  
Detection Range ◽  
In Silico Studies ◽  
P24 Antigen ◽  
Hiv 1

We have engineered streptavidin-labeled fluorescent gold nanoclusters to develop a gold nanocluster immunoassay (GNCIA) for the early and sensitive detection of HIV infection. We performed computational simulations on the mechanism of interaction between the nanoclusters and the streptavidin protein via in silico studies and showed that gold nanoclusters enhance the binding to the protein, by enhancing interaction between the Au atoms and the specific active site residues, compared to other metal nanoclusters. We also evaluated the role of glutathione conjugation in binding to gold nanoclusters with streptavidin. As proof of concept, GNCIA achieved a sensitivity limit of detection of HIV-1 p24 antigen in clinical specimens of 5 pg/ml, with a detection range up to1000 pg/ml in a linear dose-dependent manner. GNCIA demonstrated a threefold higher sensitivity and specificity compared to enzyme-linked immunosorbent assay for the detection of HIV p24 antigen. The specificity of the immunoassay was 100% when tested with plasma samples negative for HIV-1 p24 antigen and positive for viruses such as hepatitis B virus, hepatitis C virus, and dengue. GNCIA could be developed into a universal labeling technology using the relevant capture and detector antibodies for the specific detection of antigens of various pathogens in the future.

scholarly journals Green Chemical Synthesis of N-Cholyl-L-Cysteine Encapsulated Gold Nanoclusters For Fluorometric Detection of Mercury Ions

2021 ◽  
Author(s):  
Kasthuri Jayapalan ◽  
Sivasamy Arumugam ◽  
Rajendiran Nagappan
Keyword(s):  
Uv Light ◽  
Stokes Shift ◽  
Gold Nanoclusters ◽  
Green Emission ◽  
Fluorescence Analysis ◽  
Cost Effective ◽  
Single Step ◽  
Fluorometric Detection ◽  
Transmission Electron ◽  
Green Chemical Synthesis

Abstract Here we report a simple, single-step, cost-effective, environmentally friendly, and biocompatible approach using sodium salt of N-cholyl-L-cysteine (NaCysC) capped gold nanoclusters (AuNCs) with green emission properties at above the CMC in aqueous medium under UV-light irradiation. The primary and secondary CMC of NaCysC was found to be 4.6 and 10.7 mM respectively using pyrene as fluorescent probe. The synthesized AuNCs exhibit strong emission maxima at 520 nm upon excitation of 375 nm with a large Stokes shift of 145 nm. The surface functionality and morphology of NCs are studied by Fourier transform infrared spectroscopy, dymanic light scattering studies and transmission electron microscopy. The formation of AuNCs was completed within 5 h and exhibit high stability for more than 6 months. The NaCysC templated AuNCs selectively quenches the Hg2+ ions with higher sensitivity in aqueous solution over the other metal ions. The fluorescence analysis of Hg2+ showed a wide linear range from 15 to 120 µM and a detection limit was found to be 15 nM.

Protein-based fluorescent metal nanoclusters for small molecular drug screening

2014 ◽  
Vol 50 (89) ◽  
pp. 13805-13808 ◽  
Author(s):  
Yong Yu ◽  
Siu Yee New ◽  
Jianping Xie ◽  
Xiaodi Su ◽  
Yen Nee Tan
Keyword(s):  
Drug Screening ◽  
Screening Method ◽  
Gold Nanoclusters ◽  
Metal Nanoclusters

This communication reports a facile, fast (<10 min), and hitherto unreported drug screening method by comparing the fluorescence intensities of the in situ formed gold nanoclusters templated by drug-loaded proteins.

Fabrication of Fluorescent Cellular Probes: Hybrid Dendrimer/Gold Nanoclusters

2007 ◽  
Vol 1007 ◽  
Author(s):  
Chang Zhong ◽  
Yuping Bao ◽  
Dung M. Vu ◽  
R. Brian Dyer ◽  
Jennifer S. Martinez
Keyword(s):  
Noble Metal ◽  
Gold Nanoclusters ◽  
Water Soluble ◽  
High Yield ◽  
Reaction Yield ◽  
Biological Applications ◽  
Metal Nanoclusters ◽  
Proof Of Concept ◽  
Size Dependent ◽  
Metal Atoms

ABSTRACTFluorescent metal nanoclusters, which consist of collections of small numbers of noble metal atoms, are of great interest in photochemistry and photophysics due to their strong size-dependent emission. Historically their generation was confined to gaseous and solid phases; however, recently a unique organic/inorganic hybrid materials approach was developed that utilizes dendrimers as templates to protect nanoclusters from solution based fluorescence quenching. These hybrid dendrimer/gold nanoclusters are water-soluble and highly fluorescent. Yet there are several intrinsic deficiencies in their synthetic method: first, NaBH4, a toxic chemical, was used as reducing agent in the reaction; and second, the reaction yield was low due to the concurrent formation of large, non-emissive, gold particles. Here we report a particle-free method to produce dendrimer-encapsulated gold nanoclusters in high-yield. Proof of concept is demonstrated using OH-terminated poly(amidoamine) dendrimer and Au(PX3)3Cl (X = Ph, Me), but the approach can also be extended to the combination of other dendrimers and organic noble metal salts. Our approach yields fluorescent clusters with homogeneous size distribution. These clusters can be transferred to aqueous solution and used directly for biological applications.

scholarly journals Origin of the Bright Photoluminescence of Thiolate-protected Gold Nanoclusters: Confined Structural Water Molecules as Real Emitters

2021 ◽  
Author(s):  
Bo Peng ◽  
kun zhang
Keyword(s):  
Gold Nanoclusters ◽  
Electron Interaction ◽  
Water Molecules ◽  
Photoluminescence Intensity ◽  
Metal Nanoclusters ◽  
Structural Water ◽  
Ligand Interactions ◽  
Interfacial States ◽  
Bright Color ◽  
Interfacial Adsorption

The availability of a range of excited states has enriched zero-, one- and two- dimensional quantum nanomaterials with interesting luminescence properties, in particular for noble metal nanoclusters (NCs) as typical examples. But, the elucidation and origin of optoelectronic properties remains elusive. In this report, using widely used Au(I)-alkanethiolate complex (Au(I)-SRs, R = -(CH2)12H) with AIE characteristics as a model system, by judiciously manipulating the delicate surface ligand interactions at the nanoscale interface, together with a careful spectral investigations and an isotope diagnostic experiment of heavy water (D2O), we evidenced that the structural water molecules (SWs) confined in the nanoscale interface or space are real emitter centers for photoluminescence (PL) of metal NCs and the aggregate of Au(I)-SRs complexes, instead of well-organized metal core dominated by quantum confinement mechanics. Interestingly, the aggregation of Au(I)-SRs generated dual fluorescence-phosphorescence emission and the photoluminescence intensity was independent on the degree of aggregation but showed strong dependency on the content and state of structural water molecules (SWs) confined in the aggregates. SWs are different from traditional hydrogen bonded water molecules, wherein, due to interfacial adsorption or spatial confinement, the p orbitals of two O atoms in SWs can form a weak electron interaction through spatial overlapping, which concomitantly constructs a group of interfacial states with π bond characteristics, consequently providing some alternative channels (or pathways) to the radiation and/or non-radiation relaxation of electrons. Our results provide completely new insights to understand the fascinating properties (including photoluminescence, catalysis and chirality, etc.) of other low-dimension quantum dots and even for aggregation-induced emission luminophores (AIEgens). This also answers the century old debate on whether and how water molecules emit bright color.

scholarly journals Restricted intramolecular rotation of fluorescent molecular rotors at the periphery of aqueous microdroplets in oil

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jooyoun Kang ◽  
SangMoon Lhee ◽  
Jae Kyoo Lee ◽  
Richard N. Zare ◽  
Hong Gil Nam
Keyword(s):  
Fluorescence Intensity ◽  
Solution Viscosity ◽  
Bulk Solution ◽  
Molecular Rotor ◽  
Reaction Conditions ◽  
Dominant Mechanism ◽  
Alexa Fluor ◽  
Fluorescent Molecular Rotors ◽  
Phase Chemistry ◽  
Intramolecular Rotation

Abstract Fluorescent molecular rotor dyes, including Cy3, Cy5, and Alexa Fluor 555, dissolved in micron-sized aqueous droplets (microdroplets) in oil were excited, and the fluorescence intensity was recorded as function of time. We observed lengthening of the fluorescence lifetime of these dyes at the water–oil periphery, which extended several microns inward. This behavior shows that intramolecular rotation is restricted at and near the microdroplet interface. Lengthened lifetimes were observed in water microdroplets but not in microdroplets composed of organic solvents. This lifetime change was relatively insensitive to added glycerol up to 60%, suggesting that solution viscosity is not the dominant mechanism. These restricted intramolecular rotations at and near the microdroplet periphery are consistent with the reduced entropy observed in chemical reactions in microdroplets compared to the same reaction conditions in bulk solution and helps us further understand why microdroplet chemistry differs so markedly from bulk-phase chemistry.

Glutathione stabilized green-emission gold nanoclusters for selective detection of cobalt ion

2021 ◽  
Vol 254 ◽  
pp. 119628
Author(s):  
Rui-Xian Zhao ◽  
An-Yong Liu ◽  
Qiu-Lin Wen ◽  
Bi-Chao Wu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Gold Nanoclusters ◽  
Green Emission ◽  
Selective Detection ◽  
Cobalt Ion

scholarly journals N-Heterocyclic carbene-functionalized magic number gold nanoclusters

2018 ◽  
Author(s):  
Mina R. Narouz ◽  
Kimberly M. Osten ◽  
Phillip J. Unsworth ◽  
Renee W. Y. Man ◽  
Kirsi Salorinne ◽  
...  
Keyword(s):  
Gold Cluster ◽  
Gold Nanoclusters ◽  
Magic Number ◽  
Heterocyclic Carbenes ◽  
Metallic State ◽  
Metal Nanoclusters ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Improved Stability ◽  
Insight Into

Magic number metal nanoclusters are atomically precise nanomaterials that have enabled unprecedented insight into structure-property relationships in nanoscience. Thiolates are the most common ligand, binding to the cluster via a staple motif in which only central gold atoms are in the metallic state. The lack of other strongly-bound ligands for nanoclusters with different bonding modes has been a significant limitation in the field. Herein, we report a previously unknown ligand for gold (0) nanoclusters: N-heterocyclic carbenes (NHCs), which feature a robust metal-carbon single bond, and impart high stability to the corresponding gold cluster. The addition of a single NHC to gold nanoclusters results in significantly improved stability and catalytic properties in the electrocatalytic reduction of CO<sub>2</sub>. By varying the conditions, nature and number of equivalents of the NHC, predominantly or exclusively monosubstituted NHC-functionalized clusters result. Clusters can also be obtained with up to five NHCs, as a mixture of species.

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