Mesoporous silica as a natural antimicrobial carrier

Mesoporous silica structures were synthesized as MCM-41 and SBA-15 from two different mole ratios of their constituents to test their capacity and feasibility for the controlled release of the natural antimicrobial allyl isothiocyanate (AITC). Pore filling by vapor phase AITC approached 100%. Infrared spectroscopy of the adsorbed phase confirmed it to be liquid-like. Controlled release as desorption was dictated by the pore size distribution of each material with up to 90% of the available AITC desorbed over 96 h. Release from the SBA-15 systems occurred as a “burst release” with 65% desorbed in the first 12 h compared with only 20% from the MCM-41 systems. The antimicrobial activity of the released (vapor-phase) ATIC was compared with that from liquid AITC in tests with the microorganisms Escherichia coli, Bacillus cereus, and Pichia anomola. The lethal activity of the released AITC against these microorganisms was unaffected by adsorption and desorption processes, demonstrating the MCM-41 and SBA-15 mesoporous silica structures represent a novel controlled release vector against selected food-borne pathogenic microorganisms.