Amphiphilic diblock copolymers inhibit the formation of encrustation on the surface of biodegradable ureteral stents in vitro and in vivo

Abstract

Ureteral stents have been used to treat a variety of urinary diseases for decades. However, the complication of encrustation often impedes its therapeutic effectiveness and service after indwelling in human body. In the present study, in order to surmount this problem, amphiphilic block copolymer, methoxypoly (ethylene glycol)-b-poly (Ɛ-caprolactone) (mPEG-PCL), was used to endow poly (l-lactide-ran-Ɛ-caprolactone) (PLACL) with hydrophilicity by solvent blending. The hydrophilicity, degradability, anti-encrustation (both in vitro and in vivo) and biocompatibility of the developed ureteral stents were assessed using water contact angle, electronic universal material testing machine, SEM, EDS, ICP-OES, dynamic urinary circulation model and a rat model. A progressive increase in the water contact angle and degradation rate was observed with the increase in mPEG-PCL concentration from 1 % to 5 % w/w in the mPEG-PLACL blends. In addition, according to ICP-OES results, approximately 38.86 % Ca and 60.55 % Mg was inhibited after 7 days immersion in dynamic urinary circulation model. Also, in the seventh week of indwelling the developed ureteral stents in rat model, compared with the hydrophobic PLACL, 71 % Ca and 93 % Mg was inhibited. Moreover, histological evaluations showed that mPEG-PCL/PLACL blends decreased tissue inflammation with favorable biocompatibility. As a result, this developed hydrophilic ureteral stents had great potential to become an ideal urological medical device.