Physicochemical characterization and antibacterial activity of Rajata Bhasma and silver nanoparticle

Bhasma, an Ayurvedic metallo-mineral preparation, is claimed to be biologically produced nanoparticles. Rajata (silver) is a noble metal known for its antimicrobial activity. Rajata Bhasma (RB) is expected to be composed of nanoparticles. With all these facts in place, this study was conducted to evaluate RB for the presence of silver nanoparticle (SNP) and its antimicrobial effect.

The aim of this study is to analyze the physicochemical characterization, antibacterial activity of RB, and SNP.

RB was commercially ordered and SNP was prepared by Turkevich method. Characterization of RB was carried out by scanning electron microscopy (SEM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). SNP was characterized by ultraviolet (UV)-visible spectroscopy, transmission electron microscopy (TEM), and ICP-AES. Antibacterial activity of RB and SNP was carried out by well-diffusion method.

Analysis of RB by SEM revealed particles in range from 10 to 60 nm. UV-visible spectrum of the aqueous medium containing SNPs showed absorption peak at around 423 nm. The TEM analysis showed that SNP was spherical in the range of 5-50 nm and uniformly distributed without significant agglomeration. The content of silver in RB measured with ICP-AES was found to be 70.56% whereas in case of SNP was 65.23%. Staphylococcus aureus was found to be sensitive to both RB and SNP. Escherichia coli, Pseudomonas aeruginosa, and Enterococcus faecalis were found to be resistant to RB as well as SNP.

The current study shows that RB does have silver particles in the size of nanometers and also has mild antibacterial activity.