Wound dressing application of castor oil- and CAPA-based polyurethane membranes

The objective of this study was to investigate and compare the effects of two different types of polyols on properties of synthesized polyurethanes (PUs), to develop biomedical applications of these materials. Polyurethane membranes were prepared from two different polyols (castor oil and CAPA 7201) as wound healing films. The chemical, physical, mechanical and biological properties of the prepared membranes were studied. Both films had smooth surfaces, with no signs of pores and cracks. CAPA-based polyurethane showed higher crystallinity and lower thermal stability compared to the other polyurethanes. Results of contact angle and water vapor transmission rate (WVTR) showed no significant differences between two different polyols used in PU synthesis. The water absorption of the CAPA-based PU (5.67%) was higher than the castor oil-based PU (0.76%) after immersion in water for 3 days at 37 °C. The values of WVTR were obtained as 260 and 285 g/m2/day for PCL and castor oil-based PUs, respectively. CAPA-based PU membrane showed 4 MPa tensile strength and about 550% elongation at break which is higher than the other samples (1.7 MPa and 100%). The viability of L-929 mouse cell line in contact with CAPA-based PU film was greater than 80% and showed a lack of toxicity of the synthesized polymer. The in vivo wound healing model evaluation using a full-thickness rat model experiment was carried out within 13 days. The wound size reduction of castor oil and CAPA-based PUs reached to 99% compared to 68% in gauze sample on the 13th day after surgery. The in vivo results revealed that PUs derived from CAPA 7201 was milder and led to less inflammatory response compared to castor oil which consequently was completely filled with new epithelium without any significant adverse reactions. Consequently, results confirmed the potential use of CAPA-based PU in biomedical field.