Synthesis and characterization of biodegradable polyurethanes for controlled drug release

摘要

Polyurethanes made from degradable polyester and aliphatic diisocyanates were versatile polymers with good biocompatibility, biodegradability and desired mechanical properties, which could be used as biomaterials for tissue engineering and drug delivery. in this work, polyurethane acrylate (PUA) monomers synthesized from bifunctional hydroxy-terminated poly(epsilon-caprolactone) (PCL) with various molecular weights (1500,3300 or 5000) and alkyl diisocyanates (isophorone diisocyanate (IPDI)or 1,6-hexamethylene diisocyanate (HDI)) were functionalized with hydroxyethyl methacrylate. Six PUAs were prepared and characterized with FTIR, NMR and GPC. These monomers were polymerized under UV light to form six cross-linked PUA membranes, which were characterized with DSC, TGA and XRD. It showed that the membranes were stable under a temperature lower than 300oC. The PUAs with long chain PCL (≥3300) were found partially crystallized with melting points between 30 and 40 oC. Contact angle analysis and the swelling of membranes in water and THF were carried out. It was found that the membrane made from PCL(1500)/HDI was more hydrophilic. Therefore it degraded faster than other PUA membranes in both H2O2 and lipase solutions according to the weight-loss analysis. It lost nearly 40% of the weight after 7 days' incubation in H2O2 solution under 37oC with shaking. The PUA membranes were then loaded with tetracycline hydrochloride, a water soluble antibiotic to investigate their drug releasing profiles by monitoring the drug concentration in PBS. The results indicated that all membranes almost released the drug in a constant rate in the first 8 days. Among them two PUA membranes made from PCL(5000)/HDI and PCL(3300)/IPDI respectively releasing most of the loaded drug have potential to be used as biodegradable carriers for controlled drug release.