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Replacement of peripheral nerve autografts with tissue engineered nerve grafts will potentially resolve the lack of nerve tissue especially in patients with severe concomitant soft tissue injuries. This study attempted to fabricate a tissue engineered nerve graft composed of electrospun PCL conduit filled with collagen‐hyaluronic acid (COL‐HA) sponge with different COL‐HA weight ratios including 100:0, 98:2, 95:5 and 90:10. The effect of HA addition on the sponge porosity, mechanical properties, water absorption and degradation rate was assessed. A good cohesion between the electrospun PCL nanofibers and COL‐HA sponges were seen in all sponges with different HA contents. Mechanical properties of PCL nanofibrous layer were similar to the rat sciatic nerve; the ultimate tensile strength was 2.23 ± 0.35 MPa at the elongation of 35%. Additionally, Schwann cell proliferation and morphology on three dimensional (3D) composite scaffold were evaluated by using MTT and SEM assays, respectively. Rising the HA content resulted in higher water absorption as well as greater pore size and porosity, while a decrease in Schwann cell proliferation compared to pure collagen sponge, although reduction in cell proliferation was not statistically significant. The lower Schwann cell proliferation on the COL‐HA was attributed to the greater degradation rate and pore size of the COL‐HA sponges. Also, dorsal root ganglion assay showed that the engineered 3D construct significantly increases axon growth. Taken together, these results suggest that the fabricated 3D composite scaffold provide a permissive environment for Schwann cells proliferation and maturation and can encourage axon growth.

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This study was designed to develop a drug delivery system based on poly(Nisopropylacrylamide) (pNIPAM) hydrogel and a suitable solvent to enhance solubility and local release of curcumin. pNIPAM hydrogel was synthesized by radical polymerization. The chemical, mechanical and physical properties and biocompatibility of pNIPAM hydrogel were investigated as an implantable and rechargeable drug reservoir. Curcumin was loaded within pNIPAM hydrogel during swelling by using two different solvents; methanol, an organic solvent, and low molecular weight polyethylene glycol (PEG200), a polymeric solvent. The results of drug solubility showed that using PEG200 can increase curcumin solubility more than commonly used organic solvents such as methanol. Also, the release profile of drug-loaded hydrogels demonstrated that PEG200 has a superior effect on the cumulative amount of released curcumin (33.163 ± 0.319 μg/ml) compared to methanol (8.765 ± 0.544 μg/ml) during 1 week. Based on our results, curcumin-loaded hydrogels did not show any cytotoxicity, and pNIPAM/PEG combination represented an antibacterial effect within 12 hours. Accordingly, it can be concluded that pNIPAM hydrogel in combination with low molecular weight PEG200 could be used as an efficient drug delivery system to preserve and provide sustained release of curcumin as a hydrophobic drug. K E Y W O R D S applications, biomaterials, drug delivery systems 1 | INTRODUCTION Curcumin, a natural organic compound, has been shown to have anti-inflammatory, antioxidant, anticarcinogenic, and antiangiogenic activity. 1 It is a lipophilic compound

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Although reprocessed drill bits have been in clinical use as a cost-saving measure, their performance has not been critically evaluated in comparison with the performance of unused drill bits. The effect of three commonly used reprocessing methods on the geometry and mechanical performance of 2.5 mm orthopaedic drill bits was investigated and compared with that for unused drill bits. Four mechanically significant drill parameters including chisel edge, chisel edge angle, point angle, and lip length of 36 drill bits in four groups were measured and compared. Group A included unused drill bits. Group B included drill bits reprocessed once by one company whereas group C included those reprocessed twice by the same method. Group D included drill bits reprocessed once by another company. For mechanical performance, a test set-up was developed in which the time of travel of the drill bits through layers of cortical and trabecular synthetic bone materials under constant compressive force were measured. The geometrical parameters were found to be significantly altered as a result of the reprocessing methods. A linear relationship was derived to relate the chisel edge to the drill time through cortical and trabecular bones. The mechanical performance of drill bits is correlated largely to the chisel edge length. A larger chisel edge is correlated to a reduced drill time, particularly in the cortical bone.

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