Tannic Acid-Based Multilayers Anchoring Anthocyanin-Loaded Mesoporous Silica Microcapsules: A Synergistic Hydrogel...

Anthocyanins (ACNs) are natural bioactive compounds with promising anti-colitis potential; however, their poor stability in the gastrointestinal tract limits effective colonic delivery. To address this challenge, this study developed a tannic acid (TA)-based multilayer hydrogel delivery system incorporating ACN-loaded microcapsules. In this system, TA participates in the formation of a mesoporous silica nanoparticles (MSN)-associated TA-Fe^{3 +} coordination network, which is subsequently embedded within a sodium alginate (SA)/Ca^{2 +} hydrogel matrix. ACNs were first loaded into MSN, followed by the deposition of a TA-Fe^{3 +} coating to form microcapsules with an encapsulation efficiency of 87.20%. These microcapsules were subsequently embedded in an SA hydrogel to obtain the final formulation, designated AMTS (ACNs@MSN@TA-Fe^{3 +}@SA). In vitro simulated digestion showed that AMTS reduced the premature loss of ACNs during gastrointestinal transit and maintained a relatively stable detectable ACN fraction in the digestion medium, supporting the protective role of the carrier and its potential for subsequent delivery to the simulated colonic enzymatic phase.  In vivo results showed that AMTS alleviated DSS-induced colonic injury, reduced inflammatory responses, and enhanced intestinal barrier integrity. Compared with free ACNs, AMTS produced more pronounced improvements across several evaluated indices. Collectively, these findings indicate that AMTS represents a promising oral delivery platform to support the potential colonic delivery of ACNs and enhance their protective efficacy in the DSS-induced colitis model, and may offer a practical strategy for the oral delivery of structurally labile natural bioactive compounds.