Green synthesis and characterization of zinc oxide nanoparticles using carboxylic curdlan and their interaction with bovine serum albumin

Abstract

Carboxylic curdlan (Cc), as a versatile β-1,3-polyglucuronic acid derivative, was used as both reducing and capping agents for the green synthesis of zinc oxide nanoparticles (ZnO NPs). The as-prepared Cc–ZnO NPs had the hexagonal wurtzite structure with maximum absorption at 370 nm assigned to the intrinsic band-gap absorption. Scanning and transmission electron microscopy (SEM and TEM) images showed that the Cc–ZnO NPs were spherical and agglomerated particles with an average diameter of 58 ± 6 nm. The interaction between Cc–ZnO NPs and bovine serum albumin (BSA) was evaluated using various spectroscopic techniques. The results indicated that the binding between Cc–ZnO NPs and BSA molecules occurred due to static quenching, leading to the formation of a ground state complex. Synchronous fluorescence spectra indicated changes in the microenvironment close to the tryptophan residues; circular dichroism spectra revealed conformational changes in the secondary structure of BSA, which were attributable to electrostatic interactions during the binding process.