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In this work, we present a biomimetic fibrous scaffold containing two biomolecules. A biocompatible poly(L-lactide-co-e-caprolactone) mesh was fabricated by an electrospinning method, and then acrylic acid was grafted on the mesh to introduce a carboxyl group through γ-ray irradiation. Subsequently, the epidermal growth factor (EGF) and gelatin were coupled to the mesh through the EDC reaction. The modified mesh presents a consistent fibre diameter (874.4 ± 178.5 nm), with carboxyl groups (1.3 mM). EGF (171.7 ng mg−1 mesh) and gelatin (67.2 ± 30.5 μg mg−1 mesh) were successfully coupled on the mesh. The coupled EGF and gelatin promoted the cell viability 1.5-times higher than that from a non-modified mesh. In particular, the EGF on the meshes independently allowed hMSC to present a 3-times greater involucrin expression and enabled improved procollagen secretion, implying trans-differentiation of hMSC to keratinocyte-like cells. Therefore, the co-immobilization strategy of biomolecules using radiation technology may be an alternative tool for tissue engineering applications.

To accomplish long-term use of specific parts of steel, welding technology is widely applied. In this study, to compare the efficiency in improving mechanical properties, rolled steel (SS400) was welded with stainless steel (STS304) by both CO2 welding method and MIG (metal inert gas) welding method, respectively. Multi-tests were conducted on the welded specimen, such as X-ray irradiation, Vickers’ Hardness, tensile test, fatigue test and fatigue crack growth test. Based on the fatigue crack growth test performed by two different methods, the relationship of da/dN was analyzed. Although the hardness by the two methods was similar, tensile test and fatigue properties of MIG welded specimen are superior to CO2 welded one.

One of the interesting strategies for developing the artificial blood vessels is to generate multi-layered scaffolds for mimicking the structure of native blood vessels such as the intima, media, and adventitia. In this study, we prepared dual-layered poly(L-lactide-co-ɛ-caprolactone) (PLCL) scaffolds with micro- and nanofibers as a basic construct of the vessel using electrospinning methods, which was functionalized using a gelatin through acrylic acid (AAc) grafting by γ-ray irradiation. Based on the microfibrous platform (fiber diameter 5 μm), the thickness of the nanofibrous layer (fiber diameter 700 nm) was controlled from 1.1 ± 0.8 to 32.2 ± 1.7 μm, and the mechanical property of the scaffolds was almost maintained despite the increase in thickness of the nanofibrous layer. The successful AAc graft by γ-ray irradiation could allow the gelatin immobilization on the scaffolds. The proliferation of smooth muscle cells (SMC) on the scaffolds toward a microfibrous layer was approximately 1.3-times greater than in the other groups, and the infiltration was significantly increased, presenting a wide cell distribution in the cross-section. In addition, human umbilical vein endothelial cell (HUVEC) adhesion toward nanofibrous layer was well-managed over the entire surface, and the accelerated proliferation was observed on the gelatin-functionalized scaffolds presenting the well-organized gap-junctions. Therefore, our biomimetic dual-layered scaffolds may be the alternative tools for replacing the damaged blood vessels.

It is well known that fatigue failure occur on welded structures in industrial application due to the repetitive load force. In order to decrease the fatigue failure, we analysed the mechanical properties based on their structural aspect, roll steel (SS 400) welded onto stainless steels (STS 304) by CO2 gas as well as structure roll steel welded onto itself. We compared the hardness, tensile and fatigue properties with two kinds of samples which had no defects on the welding part observed by X-ray topographic analysis. It was recognized that the tensile and fatigue strength of SS 400 welded onto itself by CO2 gas was higher than that of SS 400 welded onto STS 304.