A Study on the Behavior of a Polyurethane Drug Carrier in Various pH Media

Polyurethane nano- and micro-structures have been studied intensively in the last decade as drug delivery systems for various herbal extracts as well as pure active biological substances. Their biocompatibility, haemocompatibility, safe degradation, and low-cost production are just a few advantages of these materials that were already used in numerous medical applications (catheters, surgical drapes, wound dressing). The primary purposes of this study include obtaining empty polyurethane microstructures and the assessment of their modifications in media with different pH values. A mixture of two aliphatic diisocyanates and an aqueous phase based on a polyether were used during the synthesis process. The size, homogeneity, and surface charge were studied using a Cordouan Technol. Zetasizer, while the pH measurements were conducted with a portable pH Meter Checker®, Hanna Instruments. The results showed the obtaining of an almost homogeneous sample containing microstructures with sizes ranging between 139 and 151 nm, with a pH value of approximately 6.78 and a Zeta potential of 24.6. Expected decreases in microparticles' sizes were observed in all types of media during a 15-days experiment, but the process was accelerated by a low pH when an increase of the Zeta potential value was noticed as well. Our data provide new information about the degradation process of the polyurethane microstructures on the one hand and the drug release rate of these materials when used as drug carriers, on the other hand.