Hybrid clay-biopolymer nanocomposites as multifunctional materials for biomedical and environmental applications

Clay-biopolymer nanocomposites have emerged as a versatile materials platform that couples the surface reactivity and structural diversity of nanoclays with the biocompatibility and chemical functionality of biopolymers such as chitosan, alginate, and gelatin. Despite their broad application in biomedical and environmental fields, existing reviews largely catalogue individual studies rather than interrogate the interfacial mechanisms that govern performance. This review advances three central arguments. First, the polymer-clay interface is the primary determinant of composite performance; DFT calculations confirm pronounced crystal-face selectivity in biopolymer adsorption, refuting the assumption of surface homogeneity that pervades much of the empirical literature. Second, cross-system comparison across nanoclay families reveals transferable design principles that single-system studies obscure, demonstrating that genuine synergy arises from interfacial coupling rather than additive component contributions, with implications for both adsorption efficiency and mechanical reinforcement. Third, the review extends mechanistic analysis to layered double hydroxides, polymer-enhanced geosynthetic clay liners, and injectable bioprinting inks, domains underrepresented in prior surveys. Fabrication strategies including electrospinning, cryogelation, and 3D bioprinting are critically assessed for their capacity to translate interfacial design into clinically and industrially viable products. Across biomedical applications spanning tissue engineering, drug delivery, and wound healing, and environmental applications encompassing dye, heavy metal, and emerging pollutant removal, the evidence consistently supports mechanism-based rather than correlation-driven design. Priorities for future research include integrated computational modelling, standardised cross-system reporting protocols, and systematic nanotoxicity and long-term biocompatibility evaluation.