Edible Metal–Phenolic Nanoarchitecture with pH-Responsive GI Transit and Mucoadhesive Retention for Oral Vitamin Delivery

Oral vitamin supplements must survive gastric degradation yet achieve efficient intestinal absorption, requirements that conventional carriers address separately but rarely synchronize. Here, we present a supramolecular polyphenol-based micronutrient nanoarchitecture (SPNut), an edible metal–organic framework analogue composed entirely of generally recognized as safe (GRAS)-certified food-grade materials, featuring a calcium-cross-linked alginate core and an iron(III)–tannic acid metal–phenolic network shell. SPNut undergoes pH-triggered structural transformation, contracting into a protective state in the stomach (pH 2.1) and swelling with polyphenol-mediated mucoadhesion (∼70%) in the intestine (pH 7.4). This modular platform accommodates a panel of 12 vitamin formulations, achieves >50% encapsulation efficiencies for representative B vitamins, and retains >90% of representative labile payloads after 80 days. In vivo, vitamin C-loaded SPNut achieves 1.8-fold higher systemic exposure than free vitamin C with levels elevated to 8 h. SPNut establishes edible supramolecular coordination architectures as a scalable chassis for oral micronutrient fortification.