The Use of Porous Silica Particles as Carriers for a Smart Delivery of Antimicrobial Essential Oils in Food Applications

The objective of this study was to design, develop, and quantify the effectiveness of a simple method to facilitate the smart delivery of antimicrobial essential oils (EOs) via their absorption into a chemically bound high surface area support material. To this end, Santa Barbara Amorphous 15 (SBA-15) was functionalized by means of a post-synthetic reaction using (3-aminopropyl)triethoxysilane (APTES) to create an amine-terminated SBA-15 (SBA-APTES), and functionalization was confirmed by FTIR, TGA, and N2 isotherm analysis. Amine-modified SBA-15 was then grafted to a 3-glycidyloxypropyltrimethoxysilane (GPTS)-modified silicon (Si) surface (Si-GPTS), and subsequent attachment to the GPTS-modified surface was confirmed through XPS, dynamic contact angle, and SEM analysis. The smart delivery devices (SBA-15 and SBA-APTES) were then loaded with antimicrobial oregano essential oil (OEO) and the antimicrobial activity was assessed against common food spoilage microorganisms Escherichia coli, Bacillus cereus, Staphylococcus aureus, and Pseudomonas fluorescens. Antimicrobial activity results indicate that both SBA-OEO and SBA-APTES-OEO have good antimicrobial activity and that functionalization of bare SBA-15 with APTES has no effect on antimicrobial activity (P > 0.05) compared to SBA-OEO. Moreover, it appears that direct surface coating of the modified SBA to a surface substrate may not provide a significant quantity of oil needed to elicit an antimicrobial response. Nevertheless, given the strong absorption properties of SBA materials, good antimicrobial activity, and the GRAS nature of SBA-OEO and SBA-APTES-OEO, the results found in this study open potential applications of the functionalized carrier materials.