An Adapted Synthesis Method and Physicochemical Characterization of Colloidal Silver Dispersions for Prospective Biocidal Materials

Introduction. The growing resistance of microorganisms to conventional antimicrobial agents has intensified interest in colloidal silver dispersions as alternative biocidal systems. Their functional properties are strongly governed by particle size, morphology, surface state, and aggregation behavior, all of which depend on synthesis and stabilization conditions. This study aimed to develop a laboratory-adapted glucose–citrate method for the preparation of a starch-stabilized colloidal silver dispersion and to characterize its physicochemical properties. Silver nanoparticles were synthesized by sequential addition of 0.1 M glucose, sodium citrate, and starch to a 2 mM AgNO₃ solution at 60 °C under continuous stirring. The synthesis was performed for 30 min, and aliquots were collected every 5 min for in situ analysis by UV–Vis spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), dynamic light scattering (DLS), and electrophoretic light scattering. Results. A distinct surface plasmon resonance band was observed at 400–450 nm. Its intensity increased linearly with synthesis time (𝑟=0.999), indicating progressive nanoparticle formation. FTIR spectra supported starch adsorption on the nanoparticle surface. SEM revealed predominantly spherical particles with diameters of 50–100 nm. DLS showed a dominant hydrodynamic diameter of approximately 10 nm, a low polydispersity index (0.02), and a zeta potential of −46.7 mV, indicating high colloidal stability. Conclusions. The proposed protocol yields a stable, narrowly dispersed silver nanoparticle formulation and may provide a useful basis for developing biocidal materials. Further studies should assess antimicrobial activity, cytotoxicity, storage stability, and the relationship between physicochemical characteristics and biocidal performance.