Preparation, characterization of silver nanoparticles and their potential pharmaceutical applications

Abstract

The synthesis of nanometer-sized nanoparticles with antibacterial properties is of significant interest for the development of new pharmaceutical products. A key aspect of nanotechnology is the development of rapid and reliable experimental protocols for the synthesis of nanomaterials with controlled chemical composition, size, low polydispersity, and scalability. In this study, a one-step green synthesis route for stable silver nanoparticles (AgNPs) with a narrow size distribution is reported. Silver nitrate was used as the metal precursor, while biocompatible chondroitin sulfate (ChS) served both as a reducing and stabilizing agent. The reaction was carried out in an aqueous medium under continuous stirring at temperatures ranging from 25°C to 80°C. The formation of AgNPs was indicated by a color change from a transparent solution to light red and subsequently to dark reddish-brown. The synthesized nanoparticles were characterized by UV–VIS spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The results confirmed the formation of ChS-coated AgNPs. TEM analysis revealed well-dispersed, spherical nanoparticles with an average size below 20 nm, significantly smaller than the hydrodynamic diameter (~80 nm) obtained by DLS measurements. A characteristic surface plasmon resonance (SPR) peak at approximately 417–420 nm further confirmed nanoparticle formation. Increasing the reaction time from 3 to 24 hours resulted in higher absorption intensity and a slight blue shift of the SPR peak, indicating an increase in nanoparticle concentration and a slight decrease in particle size. The antibacterial activity of the AgNPs was evaluated using the Kirby–Bauer method, demonstrating effective bactericidal activity against Escherichia coli and Staphylococcus aureus. Determination of the minimum inhibitory concentration (MIC) is currently in progress, with preliminary results obtained.