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The effect of micromachined substrata with biomaterial coatings on cells behaviours

Authors Lu, Xiong
Issue Date 2001
Summary Biomaterials refer to synthetic materials used to replace part of a living system or to function in intimate contact with living tissue in the treatment of disease or injury. In clinical applications, implant, prostheses, or prosthetic device, which is made from biomaterials, are widely used to improve the life quality of human being. Success of these applications relies on the favourable response of living cells to these foreign materials. The interactions at the interface between the biomaterials and the biological systems determine whether implantation is successful. The interaction between the surface topography and biological cells is one of the areas need to be studied quantitatively. In this study, microfabrication technique, which has been widely used in microelectronic devices, has been used to produce precisely controlled surface topography for evaluating cells reaction to surface geometry quantitatively. In detail, microgrooves with 6 different groove widths (4, 8, 16, 24, 30, 38 μm) and 3 different groove depths (2, 4, 10 μm) were made on silicon wafer by the microfabrication. Then, titanium (Ti) and Ca/Phydroxyapatite (HA) thin films were coated on the microgrooves by radiofrequency magnetron sputtering. Ca/P would transform into HA after heat treatment. After that, human osteoblast-like cells and myblasts were cultured and seeded on the microgrooved surfaces. Finally the cells were fixed, dehydrated and examined with SEM. Quantitative data were obtained by analyzing the SEM micrographs statistically. In the analysis, orientation angle (OA) is used to evaluate the contact guidance introduced by microgroove and form index (FI) is employed to describe the cell shape change or cell morphology change. The study found that the osteoblasts OA increases with groove width despite of different experiment conditions while the FI decreases with groove width and the effect of width on cells behaviours becomes weak when width reaches certain value. Groove widths in the range of 4 to 16 μm can affect cells behaviours significantly. Increase of groove depth can strengthen the orientation effect. The groove depth is less important than width and it can only affect cell orientation effectively when it is proportional to groove width. The effect of microgroove on cell behaviours is more obvious at the early stage of cell culture and become weak with increasing culture time. No difference of cells orientation on HA and Ti microgrooves is observed. It means the surface chemistry influence is not significant, if only consider the OA. In other words, the finding of topographic effect on OA of one material surface may be transferred to other surface. However, FI, which index the cell shape change, indicates that different surface will result in different conclusion because of the synergetic effects of the surface chemical properties and surface topographic properties. Thus the results of topographic effect on cells behaviours from one material surface cannot simply apply to the other material surface. Generally speaking, the results of topographic effect study on one type of cells cannot be transferred other type. This study found that there is no significant difference in the OA values between osteoblasts and the myoblasts after one-day culture. However, the myoblast FI is larger than that of osteoblast under the same culture conditions. This indicates that previous research results of other type of cells behaviours should not directly apply to the case of osteoblasts on HA surface, which is a focus of orthopaedics and dental applications.
Note Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2001
Language English
Format Thesis
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