silicon and tetramethylrhodamine-isothiocyanate

In this work, a method for preconcentrating samples in 1 cm long, 50-150 μm wide open microchannels is presented. Platinum electrodes were positioned at the channel ends, voltage was applied, and charged analyte was preconcentrated at the oppositely charged side during continuous supply of sample. The preconcentration was initially studied in a closed system, where an influence on the analyte position from a pH gradient, generated by water electrolysis, was observed. In the open channel, the analyte distribution after preconcentration was evaluated using MALDI-MS with the channel as MALDI target. MALDI matrix was applied with an airbrush or by electrospray matrix deposition and by using the latter technique higher degrees of crystallization in the channels were obtained. After preconcentrating a 1 nM cytochrome c solution for 5 min, corresponding to a supplied amount of 1.25 fmol, a signal on the cathodic channel end could be detected. When a solution of cytochrome c trypsin digest was supplied, the peptides were preconcentrated at different positions along the channel depending on their charge.

Topics: Cytochromes c; Electrodes; Electrophoresis, Microchip; Fluorescent Dyes; Hydrogen-Ion Concentration; Peptide Fragments; Platinum; Rhodamines; Silicon; Spectrometry, Mass, Electrospray Ionization; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Cell interactions with biomaterials are affected by surface topographic and chemical cues. Although it is well-known that nanometrical grooves/ridges structure modulates cellular spreading, elongation, and alignment, the combinational influence of surface topographic and chemical cues is not well studied. In this study, nano-textured silicon substrata with parallel ridges of 90, 250, or 500 nm wide, separated by grooves with equal width, were fabricated by electron beam lithography and dry etching techniques. Osteoblast-like cells, MG-63, were cultured on the patterned substrata with or without pre-adsorption of fibronectin. The cell morphology was imaged by scanning electron microscopy, and analyzed by image software. We found that FN coating initially modulated cellular spreading, length, and orientation on all types of grooved surfaces. However, after 24 h of culture, the cell morphology was not affected by FN coating on the 250-nm and 500-nm surfaces, while FN decreased cell alignment on the 90-nm surfaces. Our results suggest that surface chemical cues influence the initial cell-substratum contact, while the long-term cellular morphology is dictated by surface topographic cues.

Topics: Actins; Biocompatible Materials; Cell Culture Techniques; Cell Line; Cell Nucleus; Cell Shape; Cells, Cultured; Fibronectins; Fluorescein-5-isothiocyanate; Fluorescent Dyes; Humans; Indoles; Models, Biological; Osteoblasts; Plasma; Rhodamines; Silicon; Spectrometry, Fluorescence; Substrate Specificity; Surface Properties; Vinculin