Design of a Smart Nerve Conduit Based on a Shape‐Memory Polymer

Abstract

The peripheral nervous system (PNS) may be damaged by traffic accidents and natural disasters. Nerve repair and regeneration are unique clinical challenges for surgeons. A smart nerve conduit (SNC) is designed that can significantly simplify the surgery process and achieve optimal peripheral nerve regeneration (PNR) by automatic gradual lengthening. For this purpose, five macromers with different rac‐lactide to glycolide weight ratios are synthesized and the characteristics of the synthesized networks are studied. Cyclic thermomechanical measurements indicate the robustness of molecular structure for shape‐memory function. Body‐water‐responsive shape‐memory behavior is evaluated by use of angle‐recovery measurements. The shape‐recovery time of the polymer is adjusted by selection of comonomer ratio and the overall gradual‐recovery function of a device can be realized by a suitable combination of different copolymers. Thus a trisegment smart nerve conduit is fabricated from this polymer system by electrospinning and is shown to gradually recover in an in vitro experiment under stimulated physiological conditions, that is, body‐liquid environment (36 °C water). In vitro culture and qualitative immunocytochemistry of Schwann cells are used to assess the biocompatibility of the fabricated SNC.

Construction of Small‐Diameter Vascular Graft by Shape‐Memory and Self‐Rolling Bacterial Cellulose Membrane

“…While successful for large diameter (>5 mm) high‐flow vessels, these synthetic materials are compromised by both thrombogenicity and compliance mismatch in low‐flow for small‐diameter blood vessels . Shape‐memory polymers (SMPs), proposed as biomaterials for minimally invasive surgical devices, have gained increased attention over the last several years . Heat, light, or the local chemical environment can activate the shape memory processes .…”

Biodegradable Shape Memory Polymers in Medicine

“…These techniques, however, are energy transduction processes and still rely on heating of the material to trigger shape recovery. Similarly, solvent‐based approaches can be used in which the polymer is plasticized, lowering the thermal transition of the material and enabling shape recovery . BSMPs that have been used in medical applications that directly respond to alternative stimuli include a pH sensitive PU functionalized with pyridine functionalities, a hydrogel sensitive to two different ions, providing a multi‐shape memory polymer (MSMP, i.e.…”

“…In comparison to the development of methodologies for vascular, skeletal muscle, and nerve tissue, considerable effort has been devoted to the use of BSMPs in bone tissue engineering. Fibrous scaffolds prepared by electrospinning have shown promising results in enhancing osteoblast proliferation, alkaline phosphatase activity, and mineralization .…”

High performance shape memory foams with isocyanate-modified hydroxyapatite nanoparticles for minimally invasive bone regeneration

“…Shape memory polymers (SMPs) have recently gained attention in biomedical applications, such as smart sutures [1], tissue engineering [2], vascular stents [3], bladder sensors [4] and nerve repairing [5].The SMPs are smart materials which could recover their original shapes from deformed secondary shapes in response to external stimuli such as heat [6], moisture [7], UV light [8] and magnetic field [9]. This feature permits SMP foams to be implanted into the body in compact secondary shapes through minimally invasive surgery and then recover to their original shapes upon exposure to an external stimulus such as body temperature [1,[10][11][12].…”