MOF-Based Erodible System for On-Demand Release of Bioactive Flavonoid at the Polymer-Tissue Interface

Plant-derived compounds incite applications virtually on every biomedical field due to the expedient antioxidant, anti-inflammatory and antimicrobial properties in conjunction with a natural character. Here, quercetin (QCT), a flavonoid with therapeutic potentials relevant to the oral environment, was encapsulated within metal-organic frameworks (MOFs) to address the concept of on-demand release of phytochemicals at the biointerface. We verified the applicability of a microporous MOF (ZIF-8) as a controlled-release system for QCT, as well as investigated the incorporation of QCT@ZIF-8 microparticles into a dental adhesive resin for desirable therapeutic capabilities at the tooth-restoration interface. QCT was encapsulated within the frameworks through a water-based, one-step synthetic process. The resulting QCT@ZIF-8 microparticles were characterized with respect to chemical composition, crystal structure, thermal behavior, micromorphology, and release profile under acidic and physiological conditions. A model dental adhesive formulation was enriched with the bioactive microparticles; both the degree of conversion (DC) of methacrylic double bonds and the polymer thermal behavior were accounted for. The results confirm that crystalline QCT@ZIF-8 microparticles with attractive loading capacities, submicron sizes, high thermal stability and responsiveness to environmental pH change were successfully manufactured. The concentration of QCT@ZIF-8 in the resin system was a key factor to maintain an optimal DC plateau and rate of polymerization. Essentially, one-step encapsulation of QCT in biocompatible ZIF-8 matrices can be easily achieved, and QCT@ZIF-8 microparticles proved as smart platforms to carry bioactive compounds with potential use to prevent microbial and enzymatic degradation of hard tissues and extracellular matrix components.