PLLA-PEG-PLLA Triblock Copolymers as Biodegradable Thermoplastic Elastomers for Nerve Guidance Channels


Yang Hu


Yang Hu, Robert Newman, Dr. Adam Ekenseair

Author Affiliation: 

Northeastern University


The peripheral nervous system (PNS) is fragile and can be easily damaged by trauma or injury. Over 1.8 million patients in the US suffer from PNS injuries each year, and only around 40 % of them will regain normal function by the current gold standard in surgical treatment, autologous nerve grafts. In particular, this method is ineffective for defects greater than 3 cm in length. Nerve guidance channels (NGCs) consisting of modified and degradable thermoplastic elastomers have been studied to bridge the nerve defects to prevent the need for additional surgeries and side effects, including the harvest of donor nerve grafts. In this study, we developed and synthesized a series of A-B-A type triblock copolymers of PLLA-b-PEG-b-PLLA. This series of copolymers will melt at high temperatures and solidify into a flexible solid that is biodegradable and biocompatible at body temperature, thus enabling NGC fabrication by 3D printing via extrusion equipment. The resulting block copolymers were characterized by GPC, DSC, and 1H NMR to determine molecular weight, polymer structure, and thermal behavior. In addition, equilibrium water content, degradation rates, and mechanical properties were all evaluated and correlated to polymer structure.