Toxicological study of silver nanoparticles on gut microbial community probiotic

Biomolecule present in onion, garlic, apple and papaya extracts can be used to reduce metal ions to nanoparticles in a single step green synthesis process. This biogenic reduction of metal ions to base metal is quite rapid, rapidly conducted at room temperature and pressure, and easily scaled up. Chemically synthesized silver nanoparticles (CH-AgNPs) and biologically synthesized silver nanoparticles (Bio-AgNPs) was proved under UV-vis absorption spectroscopy and observed plasmon peak maximum at 399 nm, 400 nm, 420 nm and 410 nm for Bio-AgNPs synthesized from garlic, onion, papaya and apple respectively and 398 nm for CH-AgNPs. The findings of Fourier Transformation Infrared Spectroscopy (FTIR) indicate that it is not just the size and shape of proteins, but the conformation of protein molecules that plays an important role for the formation of nanoparticles. The Scanning Electron Microscope (SEM) micrograph observed the size in the range 50-100 nm with spherical shape highly dense silver nanoparticles and Transmission Electron Microscope (TEM) results observed the particles spherical in shape and uniformly distributed without significant agglomeration. We analyzed only Bio-AgNPs from apple and papaya for FTIR, SEM and TEM. Toxicity of both CH-AgNPs and Bio-AgNPs were tested by using toxtrak test and calculate the toxic effect value in form of percentage inhibition (PI) against Bacillus subtilis and Escherichia coli. The PI of CH-AgNPs was much greater than the Bio-AgNPs synthesized from apple onion, garlic and followed by papaya. The observed PI value indicated that the gut microbial community probiotic B. subtilis and E. coli was killed in higher percentage of CH-AgNPs as compare to Bio-AgNPs synthesized from apple, onion garlic and papaya. Hence, Bio-AgNPs is the most suitable metallic coating material coat to drugs instead of CH-AgNPs in pharmaceutical industries.