Dual-functional PAAm/SA-Ca²⁺ hydrogel coating on polyurethane surfaces with lubrication and anti-encrustation functions

Polyurethane (PU) is widely used for ureteral stent, due to its low cost, good shape memory, and excellent biocompatibility. However, a major drawback of PU stents is their susceptibility to encrustation, where mineral deposits accumulate on the stent surface, potentially leading to blockage and infection. To address these challenges, this work proposes a polyacrylamide sodium alginate-calcium ion (PAAm/SA-Ca 2+ ) hydrogel coatings on PU and systematically evaluated the lubrication properties, mechanical stability, and anti-encrustation property of the coatings. PAAm/SA-Ca²⁺ hydrogel coatings of ~ 60 μm were successfully constructed on polyurethane surfaces using 3-(Trimethoxysilyl)propyl methacrylate (TMSPMA) as a bridging agent. Friction tests showed that friction coefficient of the coated surface was reduced from 0.85 (pristine PU) to 0.07, significantly enhancing the lubrication performance of PU. In vitro simulated urine mineralization immersion experiments confirmed that the modified surface reduced encrustation deposition by 92% within 7 days.