One-Pot Hydrothermal Synthesis of Benzalkonium-Templated Mesostructured Silica Antibacterial Agents

Novel mesostructured silica microparticles are synthesized, characterized, and investigated as a drug delivery system (DDS) for antimicrobial applications. The materials exhibit a relatively high density (0.56 g per 1 g SiO2) of benzalkonium chloride (BAC), pore channels of 18 Å in width, and a high surface area (1500 m2/g). Comparison of the small-angle X-ray diffraction (SAXRD) pattern with Barrett–Joyner–Halenda (BJH) pore size distribution data suggests that the 18 Å pores exhibit short-range ordering and a wall thickness of ca. 12 Å. Drug release studies demonstrate pH-responsive controlled release of BAC without additional surface modification of the materials. Prolonged drug release data were analyzed using a power law (Korsmeyer–Peppas) model and indicate substantial differences in release mechanism in acidic (pH 4.0, 5.0, 6.5) versus neutral (pH 7.4) solutions. Microbiological assays demonstrate a significant time-dependent reduction in Staphylococcus aureus and Salmonella enterica viability above 10 and 130 mg L–1 of the synthesized materials, respectively. The viability of cells is reduced over time compared to control samples. The findings will help in widening the use of BAC as a disinfectant and bactericidal agent, especially in pharmaceutical and food industries where Gram-positive and Gram-negative bacterial contamination is common