| The peripheral nervous system (PNS) is a complex and comprehensive system consisting of numerous nerves outside the human brain and spinal cord [1]. The major function of PNS is to connect organs and limbs with the central nervous system (CNS) [1]. Each year, 200,000 patients in the USA are treated surgically for PNS injuries caused by stretch and compression injuries, trauma and other surgical procedures [2]. The transplantation of autologous nerve grafts is the gold standard for connecting nerve gaps that are a maximum of 5 mm in length [3]. However, the availability of donor nerves with appropriate length is extremely limited, the harvested donor nerves may mismatch the size of injured nerve, and an additional surgical site with associated risks is required.;Many studies reported that the experimentally and clinically confirmed biodegradable material graft modes are better alternatives for improving the defects. Some studies focused on collagen gels as nerve conduits for nerve regeneration, however the repair was limited to gaps less than 30 mm [4]. The goal in this research is to create a new thermoplastic elastomer biomaterial with controlled and appropriate biodegradation rate and time for NGCs in PNS repair. The use of biodegradable block copolymers consisting of both hard hydrophobic and soft hydrophilic segment can provide a flexible, partially-hydrated and biocompatible biomaterial for on demand and on-site fabrication of cellular constructs for PNS repair at hospitals rather than in factories.;In this study, poly(ethylene glycol) (PEG; B blocks) and various degrees of polymerization of poly(L-lactic acid) (PLLA; A blocks) were synthesized via ring-opening polymerization to form ABA triblock copolymers. The chemical, thermal and mechanical properties were characterized by nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and tensile failure testing. Average water swelling ratio and degradation time were also investigated.;Characterization results showed that longer PLLA block chains resulted in copolymers with a slower rate of degradation, a higher strength modulus, and a higher elongation at failure. The melting point and crystallinity of the copolymer also decreased. Degradable thermoplastic elastomers with the appropriate melting point, water absorbability, and Young's modulus hold great promise for further application as NGCs for PNS repair. |
