Optimized microfluidic blow spinning process for single-step manufacturing of crosslinked chitosan nanofilaments using a quality-by-design approach.

Nanofibrous patches composed of chitosan (CS) present promising solutions for wound healing by supporting cell growth and enabling controlled drug release. This study introduces a new single-step microfluidic blow-spinning process that blends CS with polyethylene oxide (PEO) and crosslinks it with tripolyphosphate (TPP) using a series of laminar flow chips integrated into a blow-spinning apparatus. The microfluidic mixing between PEO and CS solutions at different concentrations was simulated with computational fluid dynamics (CFD). This manufacturing process was optimized through a Design of Experiment Approach (DOE) consisting of a 24 full-level screening design followed by a Box-Behnken optimization design. Design spaces correlating the CS concentration, the flow rate ratio between TPP solution and CS/PEO solution, and the air pressure with the filaments' mean diameter, diameter distribution, and deposition time were defined. These design spaces were used to select the process conditions suitable to obtain filaments with a mean diameter of 295 nm, a diameter distribution width approaching 150 nm, and a deposition time higher than 30 min. The good agreement between the predicted and experimental properties validated the design spaces. The crosslinked sample presented a higher water stability than the uncrosslinked one, retaining the fibrous structure with a swelling ratio of 470 ± 60 %. The cytotoxicity test on HaCaT keratinocyte cells showed no significant reduction in cell viability or protein content, confirming the patch's safety and compatibility for biomedical applications.