Rapid microwave-assisted biosynthesis of chitooligosaccharide coated silver nanoparticles: assessments of antimicrobial activity for paediatric pulp therapy

Subhathira Rajasekaran, Sneha S Rao, Pandurang Appana Dalavi, Ashwini Prabhu, Sukumaran Anil, Jayachandran Venkatesan and Sham S Bhat

Abstract

Silver nanoparticles (AgNPs) have gained much attention in the treatment of dental caries due to their excellent antimicrobial activities. In this study, we have biosynthesised chitooligosaccharide coated silver nanoparticles (COS-AgNPs) using a rapid microwave-assisted method. The physical and chemical characterisations of biosynthesised COS-AgNPs were investigated using UV–visible spectroscopy (UV–vis), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) equipped with selected area electron diffraction (SAED). Further, the developed COS-AgNPs were assessed for antimicrobial activity on Streptococcus mutans. From the DLS analysis, the average particle size of the COS-AgNPs was found to be ~32 nm. The morphologies of the COS-AgNPs were monodisperse and spherical in shape. XRD peaks are coherent with the standard peaks of AgNPs. Antimicrobial activity of COS-AgNPs showed a significant zone of inhibition due to the synergistic effect of COS-AgNPs. Furthermore, the antibacterial potential of developed COS-AgNPs-Ca(OH)₂ paste was checked against Streptococcus mutans, Staphylococcus aureus, and Enterococcus faecalis. COS-AgNPs based composite paste showed better inhibition zone against the tested microbes. Hence, COS-AgNPs and COS-AgNPs-Ca(OH)₂ based paste materials will be promising biomaterials for pulp therapy in paediatric dentistry.