We report on Langmuir-Blodgett (LB) characterization of 4- [5-(dicyanomethanidyl)thien-2-yl]-Ncetylpyridinium (C16H33-PDCNT). Surface pressure-area isotherms of monolayers were investigated at T ) 291 K. LB films of Y-and Z-type were characterized by means of UV-vis and FTIR spectroscopies. The compound is photobleachable and undergoes a change in molecular structure in monolayer and in solution. The molecule strongly absorbs in the visible region due to a charge transfer band both in homogeneous solution and LB films. Depending upon dipping conditions, a sharp absorption band appears at about 422 nm that could be attributed to molecular aggregates, probably of H-type. Both the 422 nm band and the broad charge transfer band at longer wavelength are photobleachable, and the former could have potential applications for optical data storage. The molecule seems to possess a large second-order hyperpolarizability, and non-centrosymmetric Z-type LB films could have promising nonlinear optical properties.
The effects of growing the Saos-2 human osteosarcoma cell line onto surfaces containing -CH(3), -OH, -COOH, -NH(2), and C6H5 groups obtained by silane modification were examined. These cells were used because of the great importance of bone cells in many aspects of biomaterials research. Silane-modified surfaces were characterized by contact angle measurements and, subsequently, surface energies were calculated. Cells grown on clean glass, as well as those grown on glass surfaces containing the functional groups cited above, were examined by light and scanning electron microscopy and assessed for their growth characteristics (i.e., determination of cell number and Ki67 antigen expression). The data presented seemed to indicate that if Saos-2 cells are grown on silane-modifed surfaces containing the methyl (CH(3)), hydroxyl (OH), and phenyl (C6H5) functional groups, their proliferation is slowed down while growth of these cells on glass surfaces modified with amino (NH(2)) and carboxyl (COOH) groups did not significantly affect growth. Once it was demonstrated that these three functional groups induce significant variations in proliferation, cells grown on these surfaces were also tested for apoptosis and expression of important markers of bone cell differentiation (i.e., osteonectin and osteopontin) by flow cytometry and eventual rearrangement of these markers by fluorescence microscopy. The data suggested that growth of Saos-2 cells on CH(3) induces the most evident morphological changes while growth of these cells on OH and C6H5 brings about the greater variations in osteonectin and osteopontin. We hypothesized that these changes are indicative of an increase in differentiation of Saos-2 cells when grown on the OH and C6H5 groups.
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