Carbohydrate polymer-based nanoarmor systems for probiotic gastrointestinal delivery: Strategies, applications, and perspectives.

Probiotics have shown great potential for promoting human health. However, their viability is reduced during gastrointestinal transit owing to harsh conditions (e.g., gastric acidity, bile salts, and digestive enzymes). Recently, nanoarmor-based encapsulation has attracted extensive attention for probiotic protection and targeted delivery. In particular, carbohydrate polymers and their hybrid systems have emerged as important building blocks for constructing biocompatible and gastrointestinal-responsive probiotic nanoarmor. Previous reviews mainly focused on conventional probiotic encapsulation, hydrogel-based delivery, and live biotherapeutic systems. This review focused on hybrid nanoarmor constructed directly on probiotic surfaces, particularly systems based on chitosan, cellulose derivatives, hyaluronic acid, and β-glucan. Moreover, the roles of carbohydrate polymer-based nanoarmor systems in the protection, responsive release, targeting, and bioactivity regulation were systematically discussed. In addition, the preparation strategies, representative applications, and key research highlights of these nanoarmor systems were systematically summarized and compared. The critical synthesis indicated that polymer chemical structure, molecular weight, charge density, crosslinking, and degradability govern the interfacial assembly, gastrointestinal stability, mass transfer, mucoadhesion, and coating disassembly. It revealed that nanoarmor design required a balance among probiotic protection, viability, and release rather than maximizing coating stability alone. Finally, challenges and future perspectives in this field were outlined.