PCL-b-PLLA diblock copolymers with high performance to replace polyoxymethylene for tissue ligation clips

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Surgical Devices

Background:

• Current absorbable tissue ligation clips made from biodegradable polymers lack the rigidity and toughness of polyoxymethylene (POM) clips.
• There is a need for biodegradable alternatives that match the mechanical properties of conventional non-absorbable clips.

Purpose of the Study:

• To design and synthesize biodegradable copolymers of poly(ε-caprolactone) (PCL) and poly(L-lactide) (PLLA) with random and block architectures.
• To evaluate the mechanical properties, biodegradability, and in vivo performance of these novel copolymers for tissue ligation applications.

Main Methods:

• Synthesis of random (P(CL-r-LLA)) and diblock (PCL-b-PLLA) copolymers.
• Characterization of copolymer crystallinity and mechanical strength.
• Evaluation of clip closure force, degradation profiles, and subcutaneous implantation in rats.

Main Results:

• Diblock copolymer PCL-b-PLLA exhibited higher crystallinity and superior mechanical strength compared to random copolymer P(CL-r-LLA).
• BP15 clips (15 mol% CL) demonstrated a closure force comparable to commercial POM clips (27.9 ± 1.4 N vs. 29.0 ± 2.4 N).
• BP15 clips maintained structural integrity and closure function for two weeks, with favorable subcutaneous implantation outcomes in rats.

Conclusions:

• Biodegradable diblock copolymers of PCL and PLLA offer a promising alternative to POM for absorbable tissue ligation clips.
• The developed BP15 clips possess suitable mechanical properties, controlled degradation, and biocompatibility for surgical applications.
• These novel clips address the limitations of current biodegradable options, providing both rigidity and toughness simultaneously.