Tailoring Bioink Properties via Nanofibrous Polyelectrolyte Complexes of Distinct Polymeric Classes for Cartilage...

Cartilage is a specialized connective tissue with limited self-regenerative ability, and current cartilage-related trauma treatments often fail to achieve consistent healing. Developing bioinks that closely mimic the native physical, mechanical, and biological microenvironment of cartilage is a critical challenge in tissue engineering. Here, we present a systematic study on the development of composite bioinks reinforced with nanofibrous polyelectrolyte complexes (PECs) derived from various categories of biopolymers: proteins (gelatin), mucopolysaccharides (chondroitin sulfate), and polysaccharides (alginate) in combination with chitosan. By integrating PECs of distinct biochemical origin into a BSA-alginate matrix, we demonstrate precise modulation of key bioink properties relevant for cartilage tissue engineering. Our findings reveal that incorporating PECs significantly enhances crosslinking density, in vitro stability, and mechanical strength (>120 kPa compressive modulus and >170 kPa tensile modulus). All of the bioinks exhibit excellent printability, shape fidelity, shear-thinning behavior, and cytocompatibility. Specifically, bioinks incorporated with gelatin-chitosan and chondroitin sulfate-chitosan PECs demonstrated proliferation of encapsulated primary chondrocytes and production of cartilage-specific glycosaminoglycans within the bioprinted constructs after 14 days of in vitro culture. This work highlights the pivotal role of tailored PEC compositions in tuning the physicochemical, mechanical, and biological performance of natural polymer-based bioinks. Our approach provides a versatile platform for engineering next-generation cartilage-biomimetic bioinks, offering significant promise for advancing cartilage tissue engineering.