Biological Synthesis of Antimicrobial Silver Nanoparticles by Phaseolus vulgaris Seed Extract

Abstract

Biological synthesis of silver nanoparticles is generally a time-consuming process in comparison to chemical process. Despite voluminous reports on biological synthesis of silver nano particles, there is still a challenge to develop fast syn thesis of nanoparticles in the range of minutes/seconds through biological route. Several disadvantages are generally being posed by slow biological synthesis of silver nanoparticles including cost of operation. To overcome this difficulty, fast and simple method has been developed for the synthesis of silver nanoparticles, using Phaseolus vulgaris seed extract simply by increasing the temperature. The method is very quick and the color change of the reaction can be observed within 20 seconds. This process was able to synthesize silver nanoparticles within 80 seconds at 100oC which was confirmed by absorption peak at 413.79 nm in UV-visible spectrum. Initially, it was observed that P. vulgaris seed extract was unable to synthesize silver nanoparticles at 37oC even after 24 hours. The silver nanoparticles generated by this method were predominantly spherical in shape and in the range of approximately 4 to 30 nm in size, as characterized by transmission electron microscopy (TEM). On FTIR analysis, it was found that the nanoparticles possessed definite surface exposed groups. Generated silver nanoparticles showed antimicrobial activity against clinical isolates, Escherichia coli and Candida albicans. Thus, this biological process offers a simple, ecofriendly and very fast synthesis of antimicrobial silver nanoparticles.