Biologically active l-cysteine as a reducing/capping agent for controlled tuning of gold nanoparticles

In this communication, a greener methodology for the systematic tuning of spherically shaped gold nanoparticles is presented. Bioconjugated l-cysteine is used as a capping/reducing agent for the synthesis. The prepared nanoparticles are characterized by XRD, FTIR, UV-absorption, SEM and HRTEM measur...

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Bibliographic Details
Published in:Journal of alloys and compounds 2015-11, Vol.649, p.11-18
Main Authors: Sharma, Bindu, Rabinal, M.K.
Format: Article
Language:English
Subjects:
Active control
Alloys
Capping
Fluorescence
Gold
Gold quantum dots
Green approach
HRTEM
Nanoparticles
Optical absorption
Solvents
Tuning
XRD
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Summary:In this communication, a greener methodology for the systematic tuning of spherically shaped gold nanoparticles is presented. Bioconjugated l-cysteine is used as a capping/reducing agent for the synthesis. The prepared nanoparticles are characterized by XRD, FTIR, UV-absorption, SEM and HRTEM measurements to study their properties. The five different sizes of gold nanoparticles ranging from 3.9 nm to 5.6 nm are successfully synthesized. The results of optical absorption show a shift in plasmon peak with the increase in particle size and FTIR measurements confirm a strong binding of l-cysteine molecules on gold surface. The effect of l-cysteine concentration is studied and these results reveal the formation of a new metal-organic complex. This material shows solvent dependent visible fluorescence and the fluorescent intensity follows an ordered sequence with dipole moment of the solvents used. Metal to ligand charge transfer is found the reason for this behavior. The present gold nanoparticles may find potential applications in various fields of biological/chemical sciences as biologically conjugated materials. A greener and simple approach to synthesize biologically conjugated gold nanoparticles of tunable size. [Display omitted] •Greener approach for controlled size tuning of bioconjugated gold nanoparticles.•Biologically active l-cysteine molecule as capping/reducing agent for synthesis.•Five different sizes ranging from 3 to 6 nm gold nanoparticles are synthesized.•Formation of visibly fluorescent gold: l-cysteine organic complex.•Metal to ligand charge transfer is reason for fluorescence.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2015.06.160