Green and ecofriendly synthesis of silver nanoparticles: Characterization, biocompatibility studies and gel formulation for treatment of infections in burns

The current study summarizes a unique green process for the synthesis of silver nanoparticles (AgNPs) by simple treatment of silver nitrate with aqueous extract of Ammania baccifera. Phytosynthesized AgNPs were characterized by various advanced analytical methods and studied for its use against infections associated with burns. Formation of AgNPs was observed by visual color change from colorless to dark brown and confirmed by UV-visible characteristic peak at 436 nm. Zeta potential, particle size and polydispersity index of nano-silver were found to be -33.1 +/- 1.12, 112.6 +/- 6.8 nm and 03 +/- 0.06 respectively. XRD spectra revealed crystalline nature of AgNPs whereas TEM confirmed the presence of mixed morphology of AgNPs. The overall approach designated in the present research investigation for the synthesis of AgNPs is based on all 12 principles of green chemistry, in which no man-made chemical other than the silver nitrate was used. Synthesized nano-silver colloidal dispersion was initially tested for minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against a panel of organisms involved in infections associated with burns (Pseudomonas aeruginosa (PA), Staphylococcus aureus (SA) and methicillin resistant S. aureus (MRSA)). MIC and MBC were found to be in range of 0.992 to 7.93 and 7.93 to 31.75 mu g/mL respectively. MBC was used for formulation of AgNP gel and tested for its efficacy using agar well diffusion method against PA, SA and MRSA. Comparative bactericidal efficacy of formulated gel (0.03% w/w) and marked formulation Silverex (TM) ionic (silver nitrate gel 02% w/w) showed equal zone of inhibition against all pathogenic bacteria. Formulated AgNP gel consisting of 95% lesser concentration of silver compared to marketed formulation was found to be equally effective against all organisms. Hence, the formulated AgNP gel could serve as a better alternative with least toxicity towards the treatment presently available for infections in burns. (C) 2016 Elsevier B.V. All rights reserved.