From Petro-Polymers to Biopolymers: Chitosan Strategies for Sustainable Hemodialysis

Hemodialysis (HD) remains the most widely adopted renal replacement therapy for patients with end-stage kidney disease; however, its delivery entails a substantial environmental burden due to high water and energy consumption and extensive reliance on single-use synthetic polymeric membranes. As the global prevalence of chronic kidney disease increases, the ecological footprint of dialysis systems has become a critical challenge for sustainable healthcare. Conventional HD membranes, based on petroleum-derived polymers, provide controlled permeability but are inherently non-renewable, non-biodegradable, and susceptible to fouling and bio-incompatibility, underscoring the need for alternative, more sustainable materials. Chitosan has emerged as a promising biopolymer owing to its biodegradability, intrinsic antimicrobial activity, chemical versatility, and favorable hemocompatibility. This review presents a comprehensive analysis of chitosan-based hybrid membranes for HD, with emphasis on sustainability-driven material innovation. The structural chemistry and functional properties of chitosan are discussed in relation to molecular weight, degree of deacetylation, and supramolecular organization, followed by a comparative assessment of chitosan derived from crustacean, insect, fungal, and cephalopod sources. Attention is given to fungal chitosan as a naturally deacetylated, high-purity, and reproducible biomaterial aligned with circular bioeconomy principles. Eco-innovative extraction and purification strategies, including enzymatic and low-energy processes, are critically examined alongside membrane fabrication approaches such as polymer blending, electrospinning of hollow fibers, and functionalization strategies aimed at improving hemocompatibility, antimicrobial performance, and fouling resistance. Key challenges related to membrane reuse, scale-up, regulatory compliance, and clinical translation are also addressed. Overall, this review highlights fungal-derived chitosan as a sustainable platform for next-generation HD membranes.