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

Abstract

Thermo-responsive shape memory polymers (SMPs) can be fit into small-bore incisions and recover their functional shape upon deployment in the body. This property is of significant interest for developing the next generation of minimally-invasive medical devices. To be used in such applications, SMPs should exhibit adequate mechanical strengths that minimize adverse compliance mismatch-induced host responses (e.g. thrombosis, hyperplasia), be biodegradable, and demonstrate switch-like shape recovery near body temperature with favorable biocompatibility. Combinatorial approaches are essential in optimizing SMP material properties for a particular application. In this study, a new class of thermo-responsive SMPs with pendant, photocrosslinkable allyl groups, x%poly( -caprolactone)-co-y%( -allyl carboxylate -caprolactone) (x%PCL-y%ACPCL), are created in a robust, facile manner with readily tunable material properties. Thermomechanical and shape memory properties can be drastically altered through subtle changes in allyl composition. Molecular weight and gel content can also be altered in this combinatorial format to fine-tune material properties. Materials exhibit high elastic, switch-like shape recovery near 37 °C. Endothelial compatibility is comparable to tissue culture polystyrene (TCPS) and 100%PCL in vitro and vascular compatibility is demonstrated in vivo in a murine model of hindlimb ischemia, indicating promising suitability for vascular applications.

Heparin-functionalized polymer graft surface eluting MK2 inhibitory peptide to improve hemocompatibility and anti-neointimal activity

“…As for a surface model, we chose PCL substrate because it is one of representative polymers used for developing synthetic vascular grafts due to excellent biocompatibility, slow biodegradability and mechanical compliance [4, 33]. Especially, PCL has demonstrated to be suitable for the design of implantable material in vascular tissue engineering because their appropriate biodegradability (> 1 year) proved to minimize infection risk/inflammatory response, and promoted favorable endothelialization for blood vessel reconstruction.…”

Polymeric nanobiocomposites for biomedical applications

“…As an earliest initiative, Usuki et al 84,85 used compatibilizing/coupling agent (i.e., amino acid) while developing polyamide 6-clay nanobiocomposites. Similarly, Lopez et al 102 studied the performance of polypropylene grafted maleic anhydride (MAH) and polypropylene grafted diethyl maleate as compatibilizing agents.…”

“…One of the most noticeable advantages of the shape memory polymers is their ability to be used for minimally invasive surgery; the mechanism is that the shape memory polymers can be designed to fit into small incisions and upon deployment into the body they reach their functional shapes. 84 Exploiting this mechanism, Liu et al 85 developed new type of composites which were able to deliver of growth factors along with shape memory function. The poly (e-caprolactone) (c-PCL) and hydroxyapatite nanoparticles scaffolds were chemically fabricated; and the volume of scaffolds was reduced by using hot compression, and these compressed scaffolds attained their functional shape upon exposure to the body temperature.…”

Biodegradable shape memory polyurethanes with controllable trigger temperature

“…Polymer blends from poly(L-lactide-co-caprolactone) (PLCL) and poly(L-lactide-co-glycolide) (PLGA) showed good performance of shape fixity and shape recovery at 37 C and could be potentially used as a material for self-expanded vascular polymer stents or vascular closure devices [34] . The shape memory actuator for vascular applications from photocrosslinkable allyl groups, poly(-caprolactone)-co-(-allyl carboxylate -caprolactone) was reported by Boire et al [35] . The trigger temperature could be tuned around body temperature by controlling the molecular weight and gel content [35] .…”

“…The shape memory actuator for vascular applications from photocrosslinkable allyl groups, poly(-caprolactone)-co-(-allyl carboxylate -caprolactone) was reported by Boire et al [35] . The trigger temperature could be tuned around body temperature by controlling the molecular weight and gel content [35] . Biodegradable terpolymers of L-lactide/glycolide/-caprolactone (LA/GL/Cap) were selected for porous shape-memory scalffolds by Rychter et al [36] .…”