Biofabrication of Silver nanoparticles by leaf extract of Andrographis serpyllifolia and their antimicrobial and antioxidant activity

Biofabrication of metallic nanoparticles have attracted the researchers of various disciplines for the past few decades, due to their wide range of applications in the various fields of electronics, textiles industries, nano medicine, biopharmacy and biotechnology. Keeping in view the above important applications, we have successfully biosynthesized the silver nanoparticles (AgNPs) using leaf extract of Andrographis serpyllifolia.  These green silver nanoparticles are characterized by using different spectroscopic methods like ultra violet-visible spectroscopy (UV-Vis), Fourier transform-infrared spectroscopy (FTIR), transmission electron microscope (TEM), Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The green As-AgNPs are characterized by spectral analysis by Nanodrop-UV-visible spectroscopy, the surface plasmon resonance peak of silver nanoparticles in colloidal solution, showed maximum absorption at 421 nm. Fourier transform-infrared spectroscopy results indicate the participation of N-H stretching of amides, carboxylic acids, ether groups and O-H hydroxyl groups and C−O stretching of alcohols are used in the formation of As-AgNPs. The XRD data indicate that As-AgNPs are the face-centered cubic structure in nature. The particle size analysis reveals that the biosynthesized As-AgNPs were spherical in shape and the average size is 6 ± 2 nm. The As-AgNPs are highly stable due the negative Zeta potential -27.2 mV indicates that the As-AgNPs are polydispersed in nature. The antimicrobial studies of As-AgNPs on different bacterial strains show effective antimicrobial activity when compared with the standard antibiotic. The biosynthesized As-AgNPs also showed excellent antioxidant activity by DPPH, Nitric oxide and Hydrogen peroxide method. Hence the biosynthesized silver nanoparticles can be used for various biomedical applications.