Inner surface modification of polyurethane ureteral stents using plasma-enhanced chemical vapor deposition to improve the resistance to encrustation in a pig model

PURPOSE: We developed a ureteral stent with a non-fouling inner surface using plasma micro-surface modification technology. This study aimed to evaluate the safety and efficacy of this stent in animal model. MATERIALS AND METHODS: Ureteral stents were placed in five Yorkshire pigs. A bare stent was inserted on one side and an inner surface-modified stent was inserted on the other side. Two weeks after stenting, laparotomy was performed to harvest the ureteral stents. The changes in the inner surface were grossly evaluated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In addition, if encrustation was observed, the components were analyzed using Fourier transform infrared spectroscopy. Urine cultures were used for safety assessment. RESULTS: In all models, urine cultures did not show any bacterial growth before and after stenting, and stent-related complications were not identified. Hard materials were palpable in four bare models. Palpable material was not identified in the modified stent. Calcium oxalate dihydrate/uric acid stones were identified in two bare stents. In the SEM images with EDS, biofilm formation was confirmed in the bare stents. Biofilm formation was significantly less on the inner surface of the modified stent, and the intact surface of the modified stent was larger than that of the bare stent. CONCLUSIONS: The application of a specialized, plasma-enhanced, chemical vapor deposition technology to the inner surface of ureteral stents was safe and showed resistance to biofilm formation and encrustation.