Pendant allyl crosslinking as a tunable shape memory actuator for vascular applications

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Medical Device Engineering

Background:

• Minimally-invasive surgery requires advanced medical devices with specific material properties.
• Thermo-responsive shape memory polymers (SMPs) are of interest for their ability to change shape with temperature.
• Existing SMPs need optimization for mechanical strength, biodegradability, and biocompatibility for in-body applications.

Purpose of the Study:

• To develop a new class of thermo-responsive SMPs with tunable properties for minimally-invasive vascular applications.
• To create a combinatorial approach for optimizing SMP material characteristics.
• To evaluate the thermomechanical, shape memory, and biocompatibility properties of the novel SMPs.

Main Methods:

• Synthesized a new class of thermo-responsive SMPs: x%poly(ε-caprolactone)-co-y%(α-allyl carboxylate ε-caprolactone) (x%PCL-y%ACPCL).
• Utilized pendant, photocrosslinkable allyl groups to enable facile property tuning.
• Investigated thermomechanical properties, shape memory behavior, molecular weight, gel content, endothelial compatibility (in vitro), and vascular compatibility (in vivo).

Main Results:

• Subtle changes in allyl composition drastically altered thermomechanical and shape memory properties.
• Materials exhibited highly elastic, switch-like shape recovery near 37°C.
• In vitro endothelial compatibility was comparable to tissue culture polystyrene (TCPS) and 100%PCL; in vivo vascular compatibility was demonstrated in a murine model.

Conclusions:

• A new class of thermo-responsive SMPs with readily tunable properties was successfully created.
• These SMPs show excellent, switch-like shape recovery near body temperature and promising biocompatibility.
• The developed SMPs are suitable for minimally-invasive vascular applications, aligning with the trend towards less invasive surgical procedures.