Abstracto

Prospective antimicrobial properties of hybrid chitosan-silver nanomaterials.

Ranjithkumar Rajamani

Nanoparticles and biopolymer nanocomposite synthesis from biologically derived extracts offers several advantages such as rapid synthesis, high yields and importantly, the lack of costly downstream processing required producing the particles for multiple applications. At present, nanomaterials are one the biggest branch for improving food shelf life due to external barrier and excellent antimicrobial properties. Moreover, nanoparticle synthesis from plant extracts tentatively offers a route for large scale production of commercially attractive nanoparticles. Hence, in this present study we selected a widely available leaf extract of Custard Apple as an aqueous extract for reducing silver nanoparticles from silver nitrate solution. The aqueous extract of custard apple showed positive result for alkaloids, flavonoids, saponins, carbohydrate, glycosides, phenol, protein and tannins. The calculated average crystallite size of the silver nanoparticles and chitosan - silver nanoparticles were found to be 23 nm and 74 nm from the breadth of the (110 and 111) reflection. In this present study, the prepared silver nanoparticles shown uniform spherical in shape with average particles size of 22.14 to 73.14 nm with high aggregation. The prepared chitosan silver nanoparticles showed uniform cubic in shape with average particles size of 241.82 nm. The larger silver nanoparticles may be due to the aggregation of the smaller ones. This may be due to availability of different quantity and nature of capping agents present in the prepared plant extract. Antibacterial activity prepared silver and chitosan-silver nanoparticles were investigated against different human pathogens by well diffusion method. Our present study revealed that the biosynthesized nanoparticles and biopolymer nanocomposite showed significant antibacterial activity against chosen bacterial pathogens. The prepared chitosan silver composite showed maximum zone of inhibition against E.coli, followed by Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. Also, the present work exposed chitosan-silver nanocomposite showed maximum antibacterial against Gram negative pathogen when compare to Gram positive. The obtained results in the present study indicate that the prepared nanocomposite could be suitable for biological applications in food packing, preservation and medical however, biocompatibility studies are needed.