Seed-mediated growth reaction of gold nanoparticles with L-amino acids via Mn(0) based reduction

Abstract

The emerging application of gold nanoparticles throughout the past few decades, in various fields of biology particularly in therapeutics, disease diagnosis and sensing have continuously motivated researchers to explore more about their affinity towards biomolecules. The detailed mechanistic study of interactions of the more biomolecules like proteins, peptides and oligonucleotides still remain less understood not only because of their complex structure but also several types of bonding interactions with the nanoparticle surface. Amino acids, being the smallest building unit of all the synthetic and naturally occurring peptides and proteins may be considered as a useful tool to study the protein-nanoparticle chemistry. Here seed mediated growth reaction of gold nanoparticles was studied in presence of various L-Amino acids using Mn metal powder as a reducing agent under low to high pH condition. Growth reaction of nanoparticles in presence of various biomolecules has been identified as a non-tedious and promising tool for fine-tuning over the morphology of several metal nanoparticles. Mn metal powder is a cheap, easily available transition element which is known to show variable reduction potential over a large range of pH of the medium. The incubation of spherical gold nanoparticles (15 nm) with L-amino acid (9 mM) and their growth reaction via Mn based reduction, casted some light on the different interactive modes of amino acids at different pH values and the spectral changes in the absorbance manifested the course of growth reaction via changes in the SPR band corresponding to aggregation or non-aggregation of gold nanoparticles.