Size controlled synthesis of biocompatible gold nanoparticles and their activity in the oxidation of NADH

Abstract

Size and shape controlled synthesis remains a major bottleneck in the research on nanoparticles even after the development of different methods for their preparation. By tuning the size and shape of a nanoparticle, the intrinsic properties of the nanoparticle can be controlled leading tremendous potential applications in different fields of science and technology. We describe a facile route for the one pot synthesis of gold nanoparticles in water using monosodium glutamate as the reducing and stabilizing agent in the absence of seed particles. The particle diameter can be easily controlled by varying the pH of the reaction medium. Nanoparticles were characterized using scanning electron microscopy, UV-vis absorption spectroscopy, cyclic voltammetry, and dynamic light scattering. Zeta potential measurements were made to compare the stability of the different nanoparticles. The results suggest that lower pH favours a nucleation rate giving rise to smaller particles and higher pH favours a growth rate leading to the formation of larger particles. The synthesized nanoparticles are found to be stable and biocompatible. The nanoparticles synthesized at high pH exhibited a good electrocatalytic activity towards oxidation of nicotinamide adenine dinucleotide (NADH).

Optimization of positively charged gold nanoparticles synthesized using a stainless-steel mesh and its application for colorimetric hydrogen peroxide detection

“…In this synthesis, the increase in precursor from 1 mM to 2 mM and 3 mM caused a slight increase in (+)AuNPs size from 30 nm, 32.6 nm and 35.1 nm, respectively (Table 1). This result was confirmed by the slight red-shift in plasmon absorption maximum from 537 nm to 538 nm as the precursor concentration was increased from 1 mM to 3 mM, which indicates an slight increase in the size of the (+)AuNPs [29,30]. Moreover, the assynthesized (+)AuNPs colloidal solution obtained from a high precursor concentration (2 mM and 3 mM) were unstable and precipitated, causing a decrease in (+)AuNPs concentration with time ( Fig.…”

“…The increase in (+)AuNPs size with increasing pH value can be explained by the instability of the as-synthesized (+)AuNPs with increasing pH [30]. In other words, the increase in pH from 4 to 6 leads to the destabilization of (+)AuNPs, causing aggregation and an increase in the size of the as-synthesized (+)AuNPs.…”

Spectroscopy-based study on the interaction between gold nanoparticle and poly(vinylpyrrolidone) molecules in a non-hydrocolloid

“…Since then, noble metal NPs have been attracting considerable interest in academia and industries, owing to their potential applications in the field of non-linear optics [3], photoluminescence [3], sensing [3,4], surface-enhanced Raman scattering [5], biomedicine [3][4][5][6], catalysis [3][4][5][6], photonics [5][6][7], memory devices [5][6][7], and heat transfer [8,9] and because of their unique physical, electronic, magnetic, thermal, optical, and biomedical properties. Among the various noble metal NPs, Au is widely studied by various research groups because it possesses distinctive catalytic activity, superb thermal stability, easy surface modification, low cytotoxicity, and excellent biocompatibility [6,[10][11][12].…”

Lantana camara Linn leaf extract mediated green synthesis of gold nanoparticles and study of its catalytic activity

“…At each concentration of the leaf extract, the particle size obtained by DLS study was larger than the particle size obtained by HRTEM study. This is due to the ligands attached to the surface of AuNPs (Gangula et al 2011;Chandran et al 2012). The surface charges (Zeta potential) of the AuNPs synthesized at 100 and 200 mg L -1 concentration of the leaf extract were -27.8 and -37.4 mV, respectively (see supporting information Fig.…”