Light-Induced Dielectrophoretic Manipulation of DNA

AbstractLight-induced dielectrophoretic movement of polystyrene beads and λ-DNA is studied using thin films of amorphous hydrogenated silicon as local photoaddressable electrodes with a diameter of 4μm. Positive (high-field seeking) dielectrophoretic movement is observed for both types of objects. The absence of strong negative (low-field seeking) dielectrophoresis of DNA at high frequencies is in agreement with the similarity of the dielectric constants of DNA and water, the real part of the dielectric function. The corresponding imaginary part of the dielectric function governed by the conductivity of DNA can be determined from a comparison of the frequency dependence of the dielectrophoretic drift velocity with the Clausius-Mossotti relation

Biocompatibility Assessment of SiC Surfaces After Functionalization with Self Assembled Organic Monolayers

AbstractThe biocompatibility of 6H-SiC (0001) surfaces was increased by more than a factor of six through the covalent grafting of NH2 terminated self-assembled monolayers (SAM) using APDEMS and APTES molecules. Surface functionalization began with a hydroxyl, OH, surface termination. The study included two NH2 terminated surfaces obtained through silanization with APDEMS (aminopropyldiethoxymethylsilane) and APTES (aminopropyltriethoxysilane) molecules (hydrophilic surfaces) and a CH3 terminated surface produced via alkylation with 1-octadecene (hydrophobic surface). H4 human neuroglioma and PC12 rat pheochromocytoma cells were seeded on the functionalized surfaces and the cell morphology was evaluated with atomic force microscopy (AFM). In addition, 96 hour MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays were employed to evaluate the cell viability on the SAM modified samples. The biocompatibility was enhanced with a 2 fold (171-240%) increase with 1-octadecene, 3-6 fold (320-670%) increase with APDEMS and 5-8 fold (476-850%) increase with APTES with respect to untreated 6H-SiC surfaces.</jats:p