Rapid, organic-solvent-free freeze-thaw fabrication of pure chitosan sponges for scalable potential wound dressing applications

• An organic-solvent-free freeze-thaw strategy is developed for the rapid fabrication of pure chitosan sponges, eliminating the need for lyophilization and organic solvents. This method reduces production time and cost by over 90 % compared to traditional approaches, addressing the limitations of conventional chitosan sponge fabrication techniques. • The resulting sponge exhibits high mechanical strength (26.35 kPa at 1.57 % solid content) without the use of potentially harmful crosslinkers, overcoming the mechanical limitations of conventional pure chitosan sponges. It demonstrates excellent biocompatibility and accelerates wound epithelialization by 67 % in SD rat models. • This scalable and environmentally sustainable method establishes a new paradigm for biomaterial manufacturing, with potential applications in emergency wound care and tissue engineering. Future research will focus on optimizing large-scale production and exploring its applications in composite materials and drug delivery systems. Chitosan sponges hold significant promise for advanced wound dressings; however, their widespread adoption is hindered by complex and costly fabrication processes that depend on organic solvents, lyophilization, and alkaline immersion. Here, we introduce a novel organic-solvent-free freeze-thaw strategy to overcome these challenges. The integration of ammonium bicarbonate into acetic acid-dissolved chitosan, followed by a single freeze-thaw cycle (freezing at -20 °C and thawing at 26 °C within 1 hour), results in the spontaneous formation of pure chitosan sponges. The resulting material exhibits exceptional tensile strength (26.35 kPa at 1.57 % solid content) without the use of potentially harmful crosslinkers. This approach eliminates the need for energy-intensive lyophilization and organic solvents, thereby reducing production time and cost by over 90 % compared to traditional methods. In vivo studies using SD rat models demonstrate 67 % faster epithelialization compared to gauze controls, along with full biocompatibility attributed to the inherent biological properties of pure chitosan. With minimal equipment requirements, environmental sustainability, and high scalability, this method establishes a new benchmark for biomaterial manufacturing. Its potential for clinical translation in emergency wound care and tissue engineering applications is underscored, pending further validation.