Photo-cross-linked Gelatin Microfibers

Objective: Gelatin is a protein derived from partial hydrolysis of collagens has been widely used in pharmaceutical and medical fields as sealants for vascular prostheses, drug delivery carrier, etc, due to its biological origin, nonimmunogenicity, biodegradability, biocompatibility and relatively low cost. Gelatin nano/micro-fibers can be electrospun from fluorinated alcohol, but cross-linking is mainly by toxic cross-linker such as glutaraldehyde to improve fibers water-resistance and mechanical strength. In this context, alternative non-toxic spinning solvent and cross-linking method are needed. The objective of this pilot study is to electrospin gelatin micro-fibers from non-toxic solvent (e.g., water), and to make them water insoluble by photo-cross-linking.

Method: Methacylated gelatin was synthesized from type A porcine skin gelatin (10%) and methacrylate anhydride (MA) in DPBS at 50 °C. The mixture was dialyzed against water using dialysis tubing for 1 week at 40 °C to remove salts and resultant methacrylic acid. The solution was further lyophilized for 1 week. Gelatin with three different methacrylation degrees was compared. The methacrylated gelatin was dissolved in PBS/ethanol (1:1) at various ratios. 1% of photoinitiator was also added to enable methacrylated gelatin for photo-cross-linking. The solution was fed into a stainless spinneret tube by a syringe pump at 0.3 mL/h for electrospinning. In-situ UV irradiation at 140 mW/cm²was used to cross-link the gelatin microfibers.

Result: Methcrylated gelatin at concentrations between 80 – 125 mg/mL in non-toxic PBS/ethanol (1:1) solution could be electrospun into microfibers. Photo-cross-linked gelatin microfibers showed swelling in PBS/ethanol (1:1) but not dissolved after 28 hours immersion. Uncross-linked microfibers electrospun from raw and methacrylated gelatin rapidly dissolved in PBS/ethanol (1:1).

Conclusion: Photo-cross-linking provides a non-toxic route to prepare water insoluble gelatin micro-fibers for tissue engineering applications.