Crystal Growth and Kinetic Behaviour of Pseudoalteromonas espejiana Assisted Biosynthesized Gold Nanoparticles

Abstract

Pseudoalteromonas espejiana (P. espejiana) is a marine bacterium known for its high resistance to alkalinity. The ability of P. espejiana to reduce Au (III) and biosynthesize gold nanoparticles (AuNPs) is found positive and was confirmed using UV-VIS, EDS, SEM, and TEM studies. Previously, many studies have been reported regarding the crystalline nature of AuNPs; therefore, this research aims at studying the crystal growth behaviour of AuNPs through DLS and TEM studies. Spherically shaped and monodispersed, AuNPs ranging between 5 to 160 nm were obtained with an average particle size of 62 nm. Also, to achieve maximum production of AuNPs, the reaction kinetic study was performed using an ICP-OES method and the effect of various parameters including pH, temperature, rpm, and concentration of substrate was analyzed. During the biosynthesis process, an appropriate phase of nucleation, crystal growth, and saturation was observed and this helped to determine the rate constants and order of reaction. The parameters such as pH profile (pH 9), temperature (30°C), agitation speed (150 rpm), and enzyme substrate ratio (2 : 3) were found to be the best fits for maximum production of low size AuNPs. This demonstrates that in initial few hours, a quick conversion of the ionic gold precursor takes place into metallic gold nuclei, trailed by crystal growth via coalescence of small nuclei. Subsequently, it can be concluded that coalescence processes drive the crystal growth process of AuNPs over a time interval and finally leads to saturation and no newer particle formation in the solution.

Artificial neural network approach for prediction of AuNPs biosynthesis by Streptomyces flavolimosus, characterization, antitumor potency in-vitro and in-vivo against Ehrlich ascites carcinoma

“…On the other hand, Gupta et al . 32 observed that with increasing of time, the AuNPs agglomerate and fuse to develop into larger crystals, and thus large-sized AuNPs are produced.…”

Tunable Nanomaterials of Intracellular Crystallization for In Situ Biolabeling and Biomedical Imaging

“…It was found that the induced resistance was mediated by copper oxidase CopA, which was reduced to Au(0) nanoparticles in the periplasm by the intermediate detoxification Au complex. , This is a biological way for bacteria to detoxify metal ions and an unnatural process of biomineralization. Second, there are studies on the complex structure of biosynthetic DNA–gold in Escherichia coli and Staphylococcus, which has fluorescence effect and is used for the bioresponsive fluorescence imaging of bacteria. , Different bacteria were used to explore the biosynthesis of gold nanoparticles, revealing that different bacterial biosynthetic pathways are inconsistent, leading to differences in efficiency and gold nanostructures. − …”