Green synthesis of silver nanoparticles using Ziziphus joazeiro leaf extract for production of antibacterial agents

The green synthesis of silver nanoparticles represents an important strategy for production of alternative antibacterial agents. Herein, the reduction of silver nanoparticles is provided by the action of leaf extract of Ziziphus joazeiro. The as-synthesized material presented pH-dependent behavior that affects the kinetics of nanoparticles nucleation and the following aggregation. Alkaline and acidic environment favors the increasing polydispersity of nanoparticles providing the production of different distribution of particle size. At neutral condition (pH 7), particles with lower size and reduced aggregation degree are obtained and present antibacterial activity against S. aureus and E. coli. The number of viable cells for both systems (from initial culture containing 10(4) colonies) reached negligible counting after 5 h of interaction with silver nanoparticles prepared at neutral pH.