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Title: Effects of silicon-based nanomaterials on cell adhesion and differentiation
Other Titles: Ji yu gui yuan su de na mi cai liao dui xi bao tie fu he fen hua de ying xiang
Authors: Qi, Suijian (戚穗堅)
Department: Department of Biology and Chemistry
Degree: Doctor of Philosophy
Issue Date: 2009
Publisher: City University of Hong Kong
Subjects: Nanostructured materials.
Cell adhesion.
Cell differentiation
Notes: CityU Call Number: TP248.25.N35 Q25 2009
xviii, 154 leaves : ill. (some col.) 30 cm.
Thesis (Ph.D.)--City University of Hong Kong, 2009.
Includes bibliographical references (leaves 136-154)
Type: thesis
Abstract: With the development of nanomaterials, the interactions of nanomaterials with biological system have attracted increasing research interests these years. By the in vitro biological studies of nanomaterials, people can get better knowledge on the cell-material interactions so as to make better use of the nanomaterials. Silicon-based nanomaterials (SiBNs), a group of semiconductor nanomaterials, have been shown to be good candidates for electronic and photonic devices, field effect transistors, biosensors, biological material and devices, and even drug delivery vehicles arising from their novel physical, chemical and biological properties. The biological studies for SiBNs play a very important role in the research and development of this group of nanomaterials. This work herein is mainly divided into two parts to describe the biological studies of silicon nanowires (SiNWs), one of the most important SiBNs. Part I is based on the studies of SiNWs in suspension form, while part II is based on the studies of SiNWs in the substrate form (SiNWs arrays with SiNWs vertically aligned on the silicon wafer). In the first part of the thesis, the cytotoxic effects of SiNWs suspensions on several mammalian cell lines and the effects of SiNWs suspensions on cell adhesion and spreading using the HepG2 cell line as a model investigation were presented. The results demonstrated that the viability of the cells responded to SiNWs suspensions in a dose-dependent manner. The lowest cell viability (about 70%) took place under the highest concentration of SiNWs suspension treatment (100 μg/ml). And the decrease in cell viability was mainly due to the decreased adhesion abilities of the cells under SiNWs environment, rather than due to influence to cell cycle distribution. The results also demonstrated that SiNWs suspensions treatment would lead to the decrease in the adhered cell number, the change of the adhesion and spreading morphology of the cells, and the down-regulation of the adhesion-associated genes; SiNWs suspensions might affect HepG2 cell adhesion and spreading through the integrin- type I collagen pathway. In the second part of the thesis, the fabrication of SiNWs arrays with SiNWs vertically aligned on the silicon wafer by electroless metal assisted etching method were presented. The cytotoxic effects of SiNWs arrays, the effects of SiNWs arrays on cell adhesion and spreading using the HepG2 cell line as a model investigation and the effects of SiNWs arrays on cell differentiation using the MC3T3-E1 cell line as a model investigation were studied. By electroless metal assisted etching method, SiNWs arrays with different density of SiNWs could be fabricated and easily modified with collagen. The SiNWs arrays have unique nanostructure surfaces, thus provide a good platform for the cellular behavior study. Results showed that SiNWs arrays had good biocompatibility, could enhance the cell-substrate adhesion force, but restrict cell spreading. SiNWs array with high density of SiNWs pattern (H-) as well as all the collagen coated arrays (H+, M+ and L+) was found not only enhanced preosteoblast differentiation, but also trans-differentiated the preosteoblast into adipocyte. SiNWs array with medium or low density of SiNWs pattern (M- and L-) could not enhance MC3T3-E1 preosteoblast differentiation, but could induce MC3T3-E1 to trans-differentiate into adipocytes.
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