International Journal of Nanotechnology and Allied Sciences <p>International Journal of Nanotechnology and Allied Sciences (IJNAS; ISSN: 2523-9252) is a peer-reviewed, open access,&nbsp; international journal that considers articles on all aspects of nanotechnology and allied sciences.</p> PSM en-US International Journal of Nanotechnology and Allied Sciences 2523-9252 Parameters’ Optimization for the Green Synthesis of Silver Nanoparticles from Ziziphus spina-christi Leaves and their Antibacterial Activities against Antibiotic Sensitive and Resistant Bacteria <p>The present work aimed to optimize eco-friendly and rapid green method for the synthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of <em>Ziziphus spina-christi</em> (ZSC) and evaluated their anti-bacterial activity against sensitive and resistant Gram-positive and Gram-negative bacterial strains.&nbsp; Factors influencing the rate of biosynthesis reaction (pH, reaction time, temperature, and reactants’ ratio) were optimized. Various analytical techniques were used to confirm the formation of green synthesized AgNPs and to investigate their size and morphology. The UV-visible analysis of AgNPs solution revealed a single absorption peak at 418 nm indicating the formation of small particles. Fourier transform infrared spectroscopy (FTIR) analysis of the synthesized AgNPs confirmed the role of ZSC as reducing agent for (Ag<sup>+</sup>) ions as well as a stabilizing agent. The synthesized AgNPs were found to be spherical in shape and crystalline in nature with an average size of 32 nm. AgNPs showed significant antibacterial activities against both sensitive and resistant pathogenic <em>S. aureus</em> and <em>E. coli</em> bacteria strains and even exceeded the activities of standard antibiotic drugs (vancomycin and ciprofloxacin) in the case of resistant bacteria. Based on the results of the present work, green synthesized AgNPs could be an alternative option to overcome the ever-increasing challenge posed by antibiotic-resistant bacterial strains taking into account the cost of production and antibacterial efficacy of the nanoparticles.</p> Abdulqawi A. Numan Mashhour Ahmed Samir Osman Mohammed Mohyeddine Al-Qubati Khaled A. Al-Tahami Abdulsalam Halboup Copyright (c) 2021 PSM 2021-11-23 2021-11-23 5 2 10 25