Enzymatic Browning Modulates Properties of Silver Nanoparticles Produced with Banana Peel Extract

The present study investigated the possible influence of enzymatic browning of banana peel over the production of silver nanoparticles (AgNPs). Firstly, aqueous extracts of banana peel were prepared at different times after peeling and they were used as reducing and stabilizing agents for the production of AgNPs as monitored by visual inspection and spectrophotometry. Hydrodynamic diameters, polydispersity indexes, and Zeta potentials of the produced AgNPs were evaluated. Besides, antimicrobial activities of the AgNPs produced in the moment of peeling and after up to 2 h were assessed. As longer the period of time passed after peeling, AgNPs produced showed a tendency to decrease the size, to become with Zeta potential more negative, and to stabilize their polydispersity indexes. Antimicrobial assays showed that the two tested AgNPs were similarly effective against Escherichia coli and Staphylococcus aureus at 128 and 256 mu M, respectively. This study demonstrated that banana peels extracts obtained after different times affected the production of AgNPs in different manners, producing AgNPs with distinct characteristics, such as hydrodynamic diameter, Zeta potential, and polydispersity index. Moreover, all tested AgNPs showed antimicrobial activity.