Exploiting redox activity of MIL-100(Fe) carrier enables carvacrol prolonged antimicrobial activity

The design of efficient food contact materials that maintain optimal levels of food safety is of paramount relevance to reduce the increasing foodborne illnesses. In this work, we develop a smart composite MOF-based material that fosters a unique prolonged antibacterial activity. The composite is obtained by entrapping a natural preserving food molecule, carvacrol, into the mesoporous MIL-100(Fe) material following a direct and biocompatible impregnation method and obtaining particularly high payloads. By exploiting the intrinsic redox nature of MIL-100(Fe) material it is possible to achieve a prolonged activity against E. coli bacteria due to a triggered two-step carvacrol release of films containing the carvacrol@MOF composite. Essentially, it was discovered that based on the underlying chemical interaction among MIL-100(Fe) and carvacrol, it is possible to undergo a reversible charge transfer process between the metallic MOF counterpart and the carvacrol upon certain physical stimuli. During this process, the preferred carvacrol binding site has been monitored by IR, Mössbauer and EPR spectroscopies and is supported by theoretical calculations.