Plant enzyme based biosynthesis of silver nanoparticles and Assessment of their antimicrobial properties

Abstract

Abstract Enzyme is a biological substance that acts as a catalyst in cellular metabolism without itself being altered in the reaction process. Enzyme α-amylase was extracted from germinated green gram (mungo bean, Vigna radiata) using 0.1 M acetate buffer and had been confirmed by the spectrophotometric method. The silver nitrate (AgNO3) solution of concentration of 100 mM was mixed with the enzyme in the ratio of 2:1 and kept at room temperature (280 C) for the period of 24 h to facilitate the bioconversion process. The colour of the mixture aliquot was colourless and after incubation it was transformed to brown colour solution. The optimum transformation period was found at 5 ½ h. The synthesized silver nanoparticles were characterized by instrumental analysis like UV – Vis spectrophotometer, Transmission electron microscopy (TEM) and X-ray diffraction (XRD). The stability of synthesised nanoforms were ascertained by Fourier-transform infrared (FTIR) spectroscopic study. The synthesized particles have been showed the absorption maxima (ʎmax) at 445 nm. A Photograph of TEM showed that the synthesized nanoparticles were spherical in shape and the average size was recorded as 36 nm. XRD analysis of the particles indicated that the particles were more or less homogenous in structure. The mixture of silver nitrate (AgNO3) and enzyme in the ratio of 2:1 manufactured a high number and stabilized the form of the nano metal and therefore the same blend solution was accustomed in future experiments. The aqueous solution having little alkaline (pH 8.3) favours maximum synthesis of nanoparticles. During the conversion process, the silver ion (Ag +) present in aqueous solution is transformed into a silver nano structure (nano Ag0). The prepared silver nanoparticles possess antimicrobial activity against three studied microorganisms such as Escherichia coli, Micrococcus luteus and Pseudomonas aeruginosa. The investigation concludes that the α-amylase enzyme present in the germinating green gram seed has potency for bioconversion of silver nitrate to silver nanoforms and the synthesized nanoparticles have antagonist efficaciousness against all studied microorganisms. It also threw light on the therapeutic prospectus of silver nanoparticles.