No abstract

Resorbable polyhydroxyalkanoates (PHAs) have been studied for the first time as a biomaterial for production of ureteral stents. For manufacturing of stents, the solutions of polyesters in chloroform were poured into silicone tubes. In the static version of the method, the tube was clamped at the lower end to prevent leakage of the solution and fixed vertically until the solvent completely evaporated. In the dynamic version, the tube was regularly turned over, both ends being open, until the evaporation of the solvent. A polyester tube was formed along the inner walls of the silicone tube, which was then mechanically removed from the matrix tube. Based on the physical-chemical properties of PHA of various chemical compositions and the rheological properties of polymer solutions, the applicability of the poly (3-hydroxybutyrate-co-4-hydroxybutyrate [P(3HB/4HB)] copolymer and a blend of the poly (3-hydroxybutyrate) homopolymer with polycaprolactone for stent preparation was shown. The physical and mechanical characteristics of the experimental samples from 10% solutions of P(3HB/4HB) (10 mol. % 4HB) and P(3HB)/PCL(25/75), in terms of mechanical strength (Young's modulus and stress at break), were close to those of a commercial polyurethane stent. It was shown that there was no hydrolysis of the samples in phosphate buffer at physiological pH values. The exposure of stents in a nephrostomy with urine flow showed a smaller degree of their incrustation by urinary salts and colonization by microorganisms in comparison with control stents made of polyurethane. Thus, a technique was developed for the production of polymer tubes by evaporation from a solution; a series of tubes with dimensional characteristics suitable for use as ureteral stents was obtained.