Biomodeling and fabricating of a hybrid PU-collagen nerve regeneration conduit

A new technique for preparing double layer polyurethane (PU)-collagen nerve conduits for peripheral nerve repair via a double-nozzle low-temperature deposition manufacturing (DLDM) system has been developed. The DLDM system is based on a digital prototyping approach, and uses a combination of thermally induced phase separation and freeze-drying. With this system, two kinds of biomaterials with different properties can be combined to produce scaffold structures with good biocompatibility in the inner layer and with the desired mechanical strength protruded by the outer layer. The forming precision is high, the wall thickness can be controlled, and a tight connection between the two layers can be achieved. The effects of changing the processing parameters and the material temperature on the structure of the scaffolds have been investigated. Ideal peripheral nerve repair conduits, comprising an outer microporous layer of polyurethane (PU) and internal oriented filaments of collagen, have been manufactured through optimizing the processing parameters and the biomaterial concentrations.