Chitosan and its derivatives in 3D printing: Printability, properties, and applications

3D printing shows great potential for customized design for the food industry and the biomedicine field. In 3D food printing, chitosan and chitooligosaccharides have been used to regulate material flow behavior and shape fidelity, while chitosan and its derivatives have attracted extensive attention in the field of 3D bioprinting due to their unique biocompatibility, biodegradability, and functional diversity. However, existing studies and reviews lack mechanism-based guidance for formulation design across different matrices. This review provides a perspective from matrix to performance and interaction to elucidate how chitosan molecular characteristics interact with diverse matrices and determine printing performance, rheological behavior, and microstructure. Key properties, including printability, rheological properties, morphological characterization, functional groups, water states, thermal properties, sensory properties, and textural profiles, are systematically integrated to establish relationships between structure and property during process relevant to 3D printing. By bridging molecular-level mechanisms with practical formulation and processing strategies, this review offers viable guidance for chitosan modifications, concentration optimization, printing parameter adjustment, and practical applications. The proposed framework identifies current challenges and future research directions for scalable and standardized 3D printing applications, serving as a reference for industrial applications across diverse systems and printing situations.