Degradation behaviors of bioabsorbable P3/4HB monofilament suture in vitro and in vivo

The biodegradable behaviors of monofilament suture made from bacterial biopolyester poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) was investigated both in lipase solution and by implant into rat tergal muscles. Results showed that the monofilament suture lost its tensile strength gradually accompanied by decrease of molecular weight. The suture retained ∼65% of its original strength after lipase degradation for 12 weeks, whereas the molecular weight decreased from 4.5 x 10⁵ to 3.8 x 10⁵. However, the crystallinity of the suture, after lipase degradation for 12 weeks, increased from 27 to 33%. This may ascribe to improve orientation arrangement of molecular chain in the monofilament after the fragment from amorphous regions dissolved in the buffer solution. The roughness of surface morphology increased with degradation. Rat implantation showed no remarkable tissue responses during in vivo degradation. Foreign body reactions were much milder than chromic catgut, which is one of the most common commercially available sutures.