Damage the peripheral nerve are very common effect of accidents, physical conflict as well as during surgical intervention. Structural and function composition of nervous system is difficult to mimic by a biofunctional implant, so the most popular surgery procedure are autograft transplantation. It is named clinical gold standard for repairing critical nerve gaps [1]. An alternative approach to nerve autograft is entubulation of nerve gaps using nerve conduits or nerve guides made of synthetic or natural polymers. It seems that, potential candidates for this application are nanocomposite membrane materials. Membrane based on polymer ensures permeability and also guarantees such properties as mechanical, physicochemical and electrical which enhance regeneration and healing process of damaged nerves. Additionally, both polymer groups: natural or synthetic used as a candidate for this implant are resorbable, they creating space to regenerative the damage tissue and after these process degraded into body [2][3].
The work presents results of investigations on porous nanocomposite materials basing on resorbable aliphatic polyesters i.e. polycaprolactone and carbon nanoforms such as nanotubes (CNT), graphite oxide (GO) and graphene (GR). The porous membrane were obtaining combining two method: phases inversion and casting. Thin membrane (250-350µm) were characterized by mechanical properties (tensil strength, Young’s modulus) and physicochemical properties (wettability and surface energy measurements). Results of mechanical test showed that homogenous nanometric carbon fillers influence to higher Young’s modulus (for PCL/GR E=206 MPa when for PCL membrane E=165 MPa). The most hydrophilic surface characterized membrane with GO nanofiller. Nanocomposite membranes: PCL/GR and PCL/GO shown good electrical conductivity better then PCL/CNT (Fig 1). Porous microstructure of the nanocomposites was investigated using SEM/EDS. It was found, that the different carbon nanoforms (tubes; CNT, flakes-shaped; GR, GO) influenced on the shape, size and distribution of pores in the material. The biological test were made used iPS cells and MCF-7 breast cancer cells. Live/Dead Assay (LIVE/DEAD® Viability / Cytotoxicity kit) was used to investigate cell adhesion, viability, and proliferation rate and assessed with fluorescent microscope (live cells emit green fluorescence). The test results : materials and biological proved that the PCL membrane modified with graphene (PCL/GR) was the most suitable for further use due to its distinguishing electrical, physico-chemical, and mechanical properties as well as its regular porosity. The model of implant with this materials were made with SolidWorks program.
This study was performed within the framework of funding for statutory activities of AGH University of Science and Technology in Krakow, Faculty of Materials Science and Ceramics (11.11.160.617)
References:
[1] X. Gu, F. Ding, and D. F. Williams, Neural tissue engineering options for peripheral nerve regeneration, Biomaterials, vol. 35, no. 24, pp. 6143–6156, 2014
[2] D. F. Stamatialis, B. J. Papenburg, M. Gironés, S. Saiful, S. N. M. Bettahalli, S. Schmitmeier, and M. Wessling, Medical applications of membranes: Drug delivery, artificial organs and tissue engineering, J. Memb. Sci., vol. 308, no. 1–2, pp. 1–34, 2008
[3] F. Tavangarian and Y. Li, Carbon nanostructures as nerve scaffolds for repairing large gaps in severed nerves, Ceram. Int., vol. 38, no. 8, pp. 6075–6090, 2012