Biodegradable cross-linked poly(L-lactide-co-ε-caprolactone) networks for ureteral stent formed by gamma irradiation under vacuum

Abstract

The poly(L-lactide-co-ε-caprolactone) (PLCL) ureteral stent creeps and loses shape stability, increasing the risk of stent tube dislocation. The rubbery biodegradable cross-linked PLCL networks were prepared through gamma irradiation under vacuum in the presence of trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate (PET4A), and pentaerythritol triacrylate (PETA). At a standard sterilization dose of 25 kGy, the gel content and network density of PLCL networks increased with increasing crosslinking agent content (1, 3, 5, 7 wt%), and crosslinking efficiency decreased in the order of PETA > PET4A > TMPTA. The average molecular weight (Mc¯) between two crosslinks ranged from 2000 to 105 g/mol. To perform the beneficial semi-interpenetrated polymer network and characterized by the principle, the networks were processed in several doses (25, 50, 75, 100, and 125 kGy). In place of the Charlesby-Pinner equation, the irradiation cross-linking followed the Chen-Liu-Tang equation. The PLCL network with 7 wt% PETA had a gel fraction of 83%, tensile strength of 34.7 MPa, and tensile set value as low as 5%. Furthermore, degradation in vitro was slowed down. Thus, PLCL networks with appropriate elasticity and flexibility, inherent biodegradability, and excellent biocompatibility can provide a promising alternative method for soft tissue repair engineering, such as ureteral stents.