Impact of Physical Attributes on Proficient Phytosynthesis of Silver Nanoparticles Using Extract of Fresh Mulberry Leaves: Characterization, Stability and Bioactivity Assessment

Abstract

Application of green chemistry towards phytosynthesis of nanoparticles has gained attention of environment friendly world due to its simple, rapid, stable, eco-friendly and cost-effective property. But there are limitations to this growing interest, as the dimension and geometry of nanoparticles produced through phytosynthesis often varies greatly. To overcome the problem, current study deals with the assessment of reducing effect of the plant extract at different light intensity, pH and temperatures. Current study reports that the optimal condition for phytosynthesis of silver nanoparticles was neutral pH (pH 7), 25 °C and diffuse light (230 lx). It was observed that rapid synthesis of silver nanoparticles takes place with increase in light intensity, alkalinity and temperature, as revealed by quick appearance of dark brown colouration on addition of extract. But rapid synthesis leads to the formation of large size particles with increase in polydispersity as revealed from TEM analysis and were found to be instable through zeta potential analysis. It was observed that at acidic pH nanosilver formation does not takes place, while at low temperature it takes more time for nanosilver formation, but both conditions were found to be unstable. Nanosilver formed at neutral pH and 25 °C under diffuse light gives the size dimension of 18.11 ± 2.55 and 18.94 ± 5.30 nm with zeta potential of + 36.4 and + 37.4 mV respectively indicating stability, besides that they were found to be stable under long storage condition as revealed by UV–Visible spectrophotometric analysis. Silver nanoparticles formed under optimized condition of pH 7 and at 25 °C were found to be bioactive as it showed potentiality to extend the shelf life of post harvest mulberry leaves by 7 days.