Biodegradable weft-knitted intestinal stents: fabrication and physical changes investigation in vitro degradation

Biodegradable stents can alleviate intestinal obstruction and stenosis in patients. The objective of this study was to develop a biodegradable polydioxanone (PDO) stent using weft-knitting technology and then investigate its biodegradation behaviors in vitro. PDO monofilament with linear density of 100 ± 10 tex was knitted into a tubular stent using a tubular weft-knitting machine. The physical and mechanical properties were evaluated according to the British standard BS EN 13895:2003 and ISO 7198:1998. The biodegradation behaviors of PDO weft-knitted stent in a phosphate buffer solution (pH = 6.8 ± 0.2, 37 ± 0.5 °C) were then investigated. The results showed that the stent maintained more than 60% of its original radial force above 12 weeks. During the 16 weeks of degradation, weight, crystallization, and pH change indicated the degradation medium was diffused into the chain segments of low molecular weight due to the rupture of ester bonds in the monofilament. Fourier transform infrared spectroscopy results demonstrated that the chemical structure of PDO polymer is stable during the in vitro degradation. In conclusion, this biodegradable stent can find valuable applications in treatment of intestinal obstruction and stenosis clinically.