RESUMO
Surface-enhanced Raman scattering (SERS) is spectroscopic technique with ultra-sensitivity and high selectivity and has attracted great attention because of the potential applications in various fields. P-aminothiophenol (PATP) is often used as SERS probe molecule because it is easy to adsorb on SERS substrates and produce high-quality SERS signals. TiO2 is extensively used as photocatalyst although its photocatalytic efficiency is still needed to be improved. Noble metal-modified TiO2 is one of current important techniques for maximizing the efficiency of photocatalytic efficiency. In this article, a kind of bifunctional SERS substrates, Ag/TiO2 nanotubes, with photocatalysis property were prepared, the TiO2 NTs were prepared by anodic oxidation and noble metal Ag nanoparticles were deposited on the surface of TiO2 NTs by photoreduction method. The photocatalysis of PATP on Ag/TiO2 NTs and on Ag mirror substrates were studied. The SERS signals of PATP were decreased with the ultraviolet irradiation time, however, on Ag mirror substrates, SERS intensity of PATP was slightly changed, which indicated the photocatalysis reaction of PATP on Ag/TiO2 NTs substrates. The kinetics analysis results indicate that the kinetics of the photocatalysis follows the first order of the dynamical reaction.
RESUMO
To investigate the effects of wt-p53 gene on proliferation and differentiation of K562 cells and to explore the feasibility of wt-p53 in leukemia gene therapy, pC53-SN(3), containing wt-p53 cDNA, and temperature-sensitive p53 mutant pN53cG(Val135) which behaved like wt-p53 at 32.5 degrees C, were introduced into p53-null K562 cells respectively by lipofectin mediated DNA transfection. In the presence of G418, K-SN(3) and K-pN53cG clones expressing P53 protein were selected. The effects of exogenous wt-p53 gene on the proliferation and differentiation of K562 cells were studied by detection of cell growth curves, leukemic colony formation, cell cycle analysis and DNA fragmentation, TdT-mediated dUTP nick end labeling (TUNEL) and benzidine staining. The results showed: (1) The level of p53 mRNA in K-SN(3) cells was lower than that in K-pN53cG cells by RT-PCR. (2) K-SN(3) and K-pN53cG(32.5 degrees C) cells proliferated more slowly than the control K562 cells, and their colony formation was obviously suppressed. The cells in G(0)/G(1) phase increased, and the cells in S phase decreased. These features were more obvious in K-pN53cG(32.5 degrees C). (3) K-pN53cG(32.5 degrees C) showed the feature of apoptosis and K-SN(3) showed the characteristics of erythroid lineage differentiation. It was indicated that exogenous of wt-p53 was capable of inhibiting the proliferation of K562 cells and inducing apoptosis of the cells at higher p53 level and interestingly, inducing the cells differentiation on erythroid lineage at lower p53 level.
