Ligand-modulated synthesis of gold nanoclusters for sensitive and selective detection of folic acid

AbstractPrecisely changing the optical properties of gold nanoclusters (AuNCs) with different ligands offers a promising prospect for highly sensitive and selective drug sensing. In this study, AuNCs were synthesized with d-tryptophan (d-Trp) and its derivatives as the ligands. Optical measurements showed that d-Trp@AuNCs produced higher fluorescence intensity and shorter fluorescence emission wavelength than the d-Trp-derivatives-ligands protected AuNCs, indicating that the ligand-shell rigidity and core-shell charge transfer affected their fluorescent properties. At the excitation wavelength of 370 nm, the emission wavelength of d-Trp@AuNCs was 460 nm. The fluorescence changes revealed the high selectivity of d-Trp@AuNCs for detecting folic acid due to the static quenching and inner filter effect. In the presence of folic acid, the fluorescence of d-Trp@AuNCs was remarkably quenched with good linearity ranging from 6.3-100.0 μM (R2 = 0.997) and a detection limit of 5.8 μM. The proposed assay was successfully utilized to determine the amount of folic acid in human urine with recoveries from 94.3 to 107.3%. This work shows the great potential of d-Trp@AuNCs for detecting folic acid in real bio-samples. It also presents an effective strategy for preparation of the AuNCs with enhanced fluorescence efficiency by regulating the rigidity of the ligands shell and the core-shell charge transfer.

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Fluorescent Properties of Zn-Al Hydrotalcite and its Modified Products

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.148-149.1087 ◽

2010 ◽

Vol 148-149 ◽

pp. 1087-1090

Author(s):

Ji Xin Su ◽

Fei Fei Dong ◽

Ming Bo Zhang ◽

Shen Ping Zhang

Keyword(s):

Citric Acid ◽

Organic Compounds ◽

Fluorescence Intensity ◽

Adipic Acid ◽

Interlayer Spacing ◽

Fluorescence Property ◽

Emission Wavelength ◽

Excitation Wavelength ◽

Fluorescent Properties ◽

Maximum Emission

Zn-Al hydrotalcite exhibited fluorescence property without fluorescent substances intercalation. Its maximum excitation wavelength was 406nm and maximum emission wavelength was 523nm. In this study citric acid and adipic acid were introduced into the interlayer of LDH, which enlarged the interlayer spacing. It was found that the fluorescence property was influenced by anions in the interlayer of hydrotalcites. And it would be favorable to bind with other organic compounds to get photocatalysis materials for citric acid modified Zn-Al hydrotalcite. Meanwhile, the fluorescence intensity was enhanced greatly after modified by adipic acid, so it could be used as photocatalyst precursors.

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Fine-Tuning the Fluorescence Emission Wavelength of Gold Nanoclusters in the Protein-Directed Synthesis: The Effect of Silver Ions

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2012.6725 ◽

2012 ◽

Vol 12 (12) ◽

pp. 8879-8885 ◽

Cited By ~ 6

Author(s):

Baoshun Li ◽

Jianjun Li ◽

Junwu Zhao

Keyword(s):

Gold Nanoclusters ◽

Fluorescence Emission ◽

Silver Ions ◽

Fine Tuning ◽

Emission Wavelength ◽

Directed Synthesis

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Silica-Coated Fe3O4 Nanoparticles as a Bifunctional Agent for Magnetic Resonance Imaging and ZnII Fluorescent Sensing

Technology in Cancer Research & Treatment ◽

10.1177/15330338211036539 ◽

2021 ◽

Vol 20 ◽

pp. 153303382110365

Author(s):

Lin Qiu ◽

Shuwen Zhou ◽

Ying Li ◽

Wen Rui ◽

Pengfei Cui ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Contrast Agent ◽

Quantum Interference ◽

Inductively Coupled Plasma ◽

Fluorescence Emission ◽

Mri Contrast Agent ◽

Core Shell ◽

Resonance Imaging

Bifunctional magnetic/fluorescent core-shell silica nanospheres (MNPs) encapsulated with the magnetic Fe3O4 core and a derivate of 8-amimoquinoline (N-(quinolin-8-yl)-2-(3-(triethoxysilyl) propylamino) acetamide) (QTEPA) into the shell were synthesized. These functional MNPs were prepared with a modified stöber method and the formed Fe3O4@SiO2-QTEPA core-shell nanocomposites are biocompatible, water-dispersible, and stable. These prepared nanoparticles were characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), thermoelectric plasma Quad II inductively coupled plasma mass spectrometry (ICP-MS), superconducting quantum interference device (SQUID), TG/DTA thermal analyzer (TGA) and Fourier transform infrared spectroscopy (FTIR). Further application of the nanoparticles in detecting Zn2+ was confirmed by the fluorescence experiment: the nanosensor shows high selectivity and sensitivity to Zn2+ with a 22-fold fluorescence emission enhancement in the presence of 10 μM Zn2+. Moreover, the transverse relaxivity measurements show that the core-shell MNPs have T2 relaxivity (r2) of 155.05 mM−1 S−1 based on Fe concentration on the 3.0 T scanner, suggesting that the compound can be used as a negative contrast agent for MRI. Further in vivo experiments showed that these MNPs could be used as MRI contrast agent. Therefore, the new nanosensor provides the dual modality of magnetic resonance imaging and optical imaging.

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Impact of vibronic coupling effects on light-driven charge transfer in pyrene-functionalized middle and large-sized Metalloid Gold Nanoclusters from Ehrenfest dynamics.

Physical Chemistry Chemical Physics ◽

10.1039/d1cp02890a ◽

2021 ◽

Author(s):

Adrian Dominguez-Castro ◽

Thomas Frauenheim

Keyword(s):

Molecular Dynamics ◽

Charge Transfer ◽

Density Functional ◽

Theoretical Calculations ◽

Gold Nanoclusters ◽

Tight Binding ◽

Time Dependent ◽

Effective Strategy ◽

Dynamics Simulations ◽

Dependent Density

Theoretical calculations are an effective strategy to comple- ment and understand experimental results in atomistic detail. Ehrenfest molecular dynamics simulations based on the real-time time-dependent density functional tight-binding (RT-TDDFTB) approach...

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Measuring temperature heterogeneities during solar-photothermal heating using quantum dot nanothermometry

The Analyst ◽

10.1039/d0an02258f ◽

2021 ◽

Author(s):

Stephanie K. Loeb ◽

Haoran Wei ◽

Jae-Hong Kim

Keyword(s):

Quantum Dots ◽

Quantum Dot ◽

Fluorescence Emission ◽

Emission Wavelength ◽

Wavelength Shift ◽

Cdse Quantum Dots ◽

Photothermal Heating

The fluorescence emission wavelength shift of CdSe quantum dots due to heat-induced lattice dilatation is used to spatially resolve temperatures in solar photothermal systems.

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A SERS Study of Charge Transfer Process in Au Nanorod–MBA@Cu2O Assemblies: Effect of Length to Diameter Ratio of Au Nanorods

Nanomaterials ◽

10.3390/nano11040867 ◽

2021 ◽

Vol 11 (4) ◽

pp. 867

Author(s):

Lin Guo ◽

Zhu Mao ◽

Sila Jin ◽

Lin Zhu ◽

Junqi Zhao ◽

...

Keyword(s):

Charge Transfer ◽

Shell Structure ◽

Shell Structures ◽

Core Shell ◽

Absorption Bands ◽

Au Nanorods ◽

The Core ◽

Band Position ◽

Surface Enhanced Raman ◽

Core Shell Structure

Surface-enhanced Raman scattering (SERS) is a powerful tool in charge transfer (CT) process research. By analyzing the relative intensity of the characteristic bands in the bridging molecules, one can obtain detailed information about the CT between two materials. Herein, we synthesized a series of Au nanorods (NRs) with different length-to-diameter ratios (L/Ds) and used these Au NRs to prepare a series of core–shell structures with the same Cu2O thicknesses to form Au NR–4-mercaptobenzoic acid (MBA)@Cu2O core–shell structures. Surface plasmon resonance (SPR) absorption bands were adjusted by tuning the L/Ds of Au NR cores in these assemblies. SERS spectra of the core-shell structure were obtained under 633 and 785 nm laser excitations, and on the basis of the differences in the relative band strengths of these SERS spectra detected with the as-synthesized assemblies, we calculated the CT degree of the core–shell structure. We explored whether the Cu2O conduction band and valence band position and the SPR absorption band position together affect the CT process in the core–shell structure. In this work, we found that the specific surface area of the Au NRs could influence the CT process in Au NR–MBA@Cu2O core–shell structures, which has rarely been discussed before.

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Effect of Surface States on Charge-Transfer Dynamics in Type II CdTe/ZnTe Core–Shell Quantum Dots: A Femtosecond Transient Absorption Study

The Journal of Physical Chemistry C ◽

10.1021/jp202916v ◽

2011 ◽

Vol 115 (25) ◽

pp. 12335-12342 ◽

Cited By ~ 26

Author(s):

Sachin Rawalekar ◽

Sreejith Kaniyankandy ◽

Sandeep Verma ◽

Hirendra N. Ghosh

Keyword(s):

Quantum Dots ◽

Charge Transfer ◽

Transient Absorption ◽

Surface States ◽

Core Shell ◽

Type Ii ◽

Absorption Study ◽

Femtosecond Transient Absorption ◽

Charge Transfer Dynamics ◽

Effect Of Surface

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Laser-Excited Fluorescence of Dityrosine

Applied Spectroscopy ◽

10.1366/0003702953965678 ◽

1995 ◽

Vol 49 (11) ◽

pp. 1669-1676 ◽

Cited By ~ 14

Author(s):

Sahar F. Mahmoud ◽

Stephen E. Bialkowski

Keyword(s):

Ferrous Iron ◽

Ferric Iron ◽

Iron Concentration ◽

Fluorescence Emission ◽

Fluorescence Yield ◽

Photomultiplier Tube ◽

Alkaline Solutions ◽

Array Detector ◽

Fluorescence Maximum ◽

Fluorescence Efficiency

In this research, laser-excited fluorescence was examined for sensitive detection of aqueous dityrosine. Samples were excited with a 6.3-mW, 325-nm helium-cadmium laser focused into a small volume-fluorescence cell with a 10-cm lens. The resulting fluorescence emission was collected perpendicular to the excitation and detected with two different schemes. An optical bandpass filter was used with a photomultiplier tube for sensitive quantitative measurement, while a photodiode array detector was used in conjunction with a spectrograph for qualitative characterization of fluorescence emission spectra. Dityrosine detection on the order of 2 × 10−11 M was obtained with the use of the photomultiplier tube with bandpass optical filter. The dityrosine fluorescence yield is found to vary with the solution pH, the relative concentrations of ferric and ferrous iron, and the amount of dissolved oxygen. A maximum fluorescence yield is observed for iron-free, oxygen-free alkaline solutions. Fluorescence quenching by oxygen is a cumulative photolysis effect that diminished fluorescence yield with increased irradiation time. Flowing the solutions minimized photolysis effects in oxygenated solutions. Quenching by ferrous and ferric iron is found to be due primarily to complex formation. The ferrous iron complex appears to have a fluorescence efficiency of ∼20% of the free dityrosine. The ferric iron dityrosine complex appears to have two ferric ions per molecule at low iron concentration. Other complexes may form at different concentrations. Solvent effects on dityrosine absorption and fluorescence spectra were also investigated. A red shift in dityrosine fluorescence maximum was observed in 1 M trichloroacetic acid and in N, N-dimethylformamide. The fluorescence emission maximum was shifted to the blue in acetonitrile and glacial acetic acid. These shifts were attributed to typical solvochromic behavior.

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