Novel Metal and Silicon Oxide Engineered Substrates to Control Cell Alignment
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Engineered biomaterials with micron- and sub-micron-scale topographical features are designed to mimic the in vivo functions of extracellular matrix (ECM) on promoting desirable biological changes by manipulating the behaviors of cells. Three newly developed silicon oxide-based substrates, and their effect on the alignment behavior of biological cells was investigated. All substrates were fabricated using a technologically advanced integrated circuit (ICs) based technique of chemical-mechanical polishing (CMP). These substrates are not intended for biological applications. Chapter 3 investigated the ability of a novel two-dimensional (2D) tungsten (W) and silicon oxide (SiO2) micron and sub-micron scale patterned substrates to influence the alignment behavior of cells under different experimental conditions of (1) symmetry of the substrates comb structures, (2) cell type, (3) incubation time, and (4) serum-content in the culture media. Results from the pattern-dependent cell behavior indicate that adherent cells on 10 μm line widths symmetric comb structures (equal W and SiO2 parallel lines) exhibited the highest alignment performance; on which, ~54±3 % of Vero cells and ~70±4 % of prostate cancer (PC3) cells, respectively, oriented themselves within ±10° parallel to the W lines y-axis. A time-course study to understand the pattern-dependent cell behavior indicated that after ~36 hours of incubation, cells reached a peak alignment rate of ~67±7 %. Additionally, a culture media-dependent Vero cells alignment on 10 μm line widths symmetric comb structures was conducted. Three different culture media were used, the baseline medium with fetal bovine serum (FBS), serum-free medium (SFM), and SFM supplemented with FBS. Results indicate that ~85±1 %, ~40±6 % and ~76±4 % of cells oriented themselves within ±10° parallel to the W lines y-axis, respectively. Results indicate that the alignment behavior of cells on symmetric comb structures is; (1) W line widths dependent, (2) incubation time-dependent, and (3) serum-dependent. Cells on 10 μm W lines width symmetric comb structures exhibited the highest alignment performance within ±10˚ parallel to the W lines y-axes. However, on asymmetric comb structures with unequal width of parallel W and SiO2 lines, results indicate that the alignment of Vero cells is SiO2 line width-dependent, rather than W line widths. A mathematical model was developed to understand and predict the geometry-dependent cell behavior on both symmetric and asymmetric comb structures. Results indicate that experimental and modeled are consistent. Furthermore, the effect of antimycin A, a bacterial toxin in the culture media on the alignment behavior of human dermal fibroblast (GM5565) cells was investigated on the same 2D W/SiO2 substrates. Results revealed that ~68±2 %, and ~37±5 % of GM5565 cells oriented themselves within ±20° parallel to the W lines y-axis, with and without the presence of antimycin A in the culture media, respectively. Findings demonstrate the adverse effect of antimycin A in the culture media on the alignment behavior of cells. Chapter 4 investigated the effect of single-species protein (human and bovine serum albumin (HSA, and BSA), fibronectin (FN), vitronectin (VN), and collagen (Col-IV)) and FBS on the alignment behavior of mammalian Vero cells. Two experimental pathways are conducted in which single species proteins or FBS is used as (a) supplement for SFM, and (b) pre-adsorbed on the substrates prior to seeding the cells. Results indicate that protein as a supplement for the SFM, rather than pre-adsorbed, induced higher cell alignment. Chapter 5 investigated the effect of a novel three-dimensional (3D) substrate of tantalum (Ta) trenches and SiO2 (lines) fabricated to mimic the in vivo effect of ECM in inducing a preferential cell alignment. The results of pattern-dependent cell alignment indicate that ~91±3 % of cells on 10 μm trench’s width comb structure, oriented themselves within ±10° parallel to the Ta trenches’ y-axis. This was hypnotized by higher selective adhesion to Ta (trenches’ sidewalls and bottom included) rather than SiO2. Chapter 6 investigated the effect of a novel 3D monolithic substrate of Ta lines and trenches on the alignment behavior of Vero cells as a function of topography. The substrate was developed to isolate the effect of materials (Ta) from the 3D Ta/SiO2 substrate developed and investigated in Chapter 5. Results indicate that ~72±9 % of cells on the 10 μm trench width Ta comb structure, oriented themselves within ±10° parallel to the Ta trenches’ y-axis. The decrease in cell alignment on the 3D Ta monolithic substrate in comparison to the 3D Ta/SiO2 substrate is regarded to the Ta effect on cell alignment.
Cite this version of the work
Hassan Moussa (2019). Novel Metal and Silicon Oxide Engineered Substrates to Control Cell Alignment. UWSpace. http://hdl.handle.net/10012/14708