The objective of this research was to synthesize biocompatible polyurethanes, with suitable mechanical properties to be used as biomaterials. Polyurethanes were synthesized with polyols derived from castor oil and isophorone diisocyanate (IPDI), hexamethylene diisocyanate and 4,4’-methylenebis (cyclohexyl isocyanate), with the addition of polycaprolactone/chitosan (PCL/Ch). The materials were evaluated for their mechanical properties by determining the stress-strain curves, thermogravimetric analysis, differential scanning calorimetry analysis and contact angle. The biological response of the materials was evaluated by measuring in vitro cell viability on the L-929 mouse fibroblast cell line. The mechanical properties of polyurethanes vary according to the type of polyol and diisocyanate used. The best results were obtained with transesterification-modified polyols with cycloaliphatic diisocyanates. The best results were found for polyurethane synthesized with IPDI and the modified polyol (P.3): 17 MPa of maximum stress at break, 0.937 MPa of Young’s modulus, elongation greater than 250%. Polyurethanes do not have toxic effects and cell viability values exceed 70% on the L-929 fibroblast line. The addition of PCL/Ch improves the cell viability of polyurethanes. The results indicate that the polyurethanes synthesized with polyols derived from castor oil can be used in the design of biomaterials due to the mechanical and biological properties obtained.

Polyurethanes (PUs) are generating increasing interest in the biomedical field due to its characteristic properties. The objective of this article was review general properties of PUs and related with their biomedical applications, also to show the importance of the synthesis of PUs and how each one of the reagents used influences both mechanical properties and biological response of the designed medical devices. It is important to look for a correlation between mechanical properties and biological properties from the synthesis process of the PUs which allow to maintain the biocompatibility required by each medical device. In this work, the PUs are evaluated into three groups of applications: equipment and surgical instruments, temporary applications within the body, and permanent applications within the body. This review can show the broad field of use of PUs in biomedical applications.

Biological activities from polyurethanes (PUs) synthesized from polyols (derived from castor oil) and isophorone diisocyanate were evaluated. In vitro degradability was evaluated by phosphate buffered saline (PBS) and antibacterial degradation with Escherichia coli and Pseudomonas aeruginosa. The biocompatibility was analyzed by: i) the antimicrobial activity against E. coli, S. aureus and P. aeruginosa, and ii) in vitro cytotoxicity assays using mouse embryonic fibroblast cell line L-929 in direct contact with the PUs and with NIH/3T3 cells in indirect contact with the PUs degradation products. PUs with polyol P1 (2,64% molar relation of pentaerythritol and castor oil) was the material with better biodegradation properties: 1.125±0.110% in 72 h by PBS at 100 ºC. In general, all materials were degraded up to 1.000±0.223% and 2.251±0.010% in 72 h by E. coli and P. aeruginosa, respectively. On the other hand, it was determined a close relationship between functionality of polyol and bacterial inhibition. The antibacterial effect of the PUs decreased by 67% for E. coli, 55% for S. aureus and 56% for P. aeruginosa after 24 h. Chemical modification of castor oil did not generate a cytotoxic effect on the tested cell lines. The evaluated materials are suggested as candidates to obtain biomaterials due to their mechanical properties and biocompatibility presented in untransformed cells.