Antibacterial activity of ultrathin platinum islands on flat gold against Escherichia coli

Nanoporous Au exhibits high antibacterial activity (AA) without releasing reactive oxygen species or metal ions, instead its AA depends on the work function (WF) because cell walls are affected by peculiar electronic states at the surface. Based on this mechanism, a flat surface without nanostructure should show high AA if the WF of the surface is suitably tuned. To verify this, ultrathin Pt islands with high WF was fabricated on flat Au by underpotential deposition (UPD) of copper and subsequent redox replacement with Pt, and the AA of the Pt/Au substrate on Escherichia coli was evaluated. The Pt/Au substrate showed higher AA than Pt and Au surfaces, and a positive relationship between AA and WF was demonstrated. In addition, first principles calculations were performed to investigate the mechanism for the high WF of the Pt/Au substrate. The findings suggest that the high WF of the Pt/Au substrate is at least partly due to charge transfer from Au to Pt

Inactivation of HeLa cells on nanoporous gold

Nanoporous metals strongly affect organic matter; however, there is a poor understanding of their effects on cells. The present work shows that HeLa cells on nanoporous gold (NPG) were less active than those on flat gold (FG) with no nanoporous structure. Initially, HeLa cells adhered to the NPG over a period of more than 10 h, then the adhered cells subsequently exhibited apoptosis that was not related to anoikis. ELISA analyses showed that the conformational change of fibronectin was more greatly induced by NPG than FG. First-principles calculations and molecular dynamics simulations were performed to investigate the conformational change in the RGD sequence and the integrin signaling. The simulations suggested that the extended form of integrin, with an open headpiece, was not generated owing to the conformational change of RGD, and the outside-in signals could not be intracellularly transmitted via the integrin binding to the fibronectin on NPG, resulting in cell death

Influence of lifestyle choices on risks of CYP1B1 polymorphisms for prostate cancer.

Cytochrome P450 1B1 (CYP1B1) converts xenobiotics to carcinogens and how lifestyle choices may interact with CYP1B1 polymorphisms and affect prostate cancer risk was assessed. Blood genomic DNA from a Caucasian population was analysed at polymorphic sites of the 5' untranslated region of CYP1B1 using TaqMan genotyping assays. Overall, drinker status and minor alleles at rs2551188, rs2567206 and rs10175368 were associated with prostate cancer. Linkage was observed between rs2551188, rs2567206, rs2567207 and rs10175368, and the G-C-T-G haplotype (major allele at respective sites) was decreased in cancer. Interestingly when classified by lifestyle factors, no associations of genotypes were found for non-smokers and non-drinkers, whereas on the contrary, minor type at rs2567206 and rs10175368 increased and major G-C-T-G decreased risk for cancer among smokers and drinkers. Interestingly, rs2551188, rs2567206 and rs10175368 minor genotypes correlated with increased tissue CYP1B1 as determined by immunohistochemistry. Further, rs10175368 enhanced luciferase activity and mobility shift show stronger binding of nuclear factor for the minor allele. These results demonstrate smoking and alcohol consumption to modify the risks of CYP1B1 polymorphisms for prostate cancer which may be through rs10175368, and this is of importance in understanding their role in the pathogenesis and as a biomarker for this disease

タンパク質コンフォメーション地形の計算統計力学

京都大学新制・課程博士博士(エネルギー科学)甲第24009号エネ博第445号新制||エネ||84(附属図書館)京都大学大学院エネルギー科学研究科エネルギー応用科学専攻(主査)教授 馬渕 守, 教授 土井 俊哉, 教授 濵 孝之学位規則第4条第1項該当Doctor of Energy ScienceKyoto UniversityDGA

Sterilization by a Pulsed Electric Field with Dendritic Gold Electrodes

The dendritic gold electrodes effectively inactivated Escherichia coli (E. coli) by pulsed electric field (PEF) sterilization. Two phenomena are involved: (1) The dendritic structures induce a dielectrophoretic (DEP) force which drives E. coli toward the vicinity of the dendrites. (2) High-intensity electric fields around the dendrite tips distort the cell walls of E. coli as a result of potential disturbance, which subsequently kill the E. coli. The inactivation rate of E. coli on the dendritic electrodes depended on the pulse frequency more strongly than on an as-sputtered smooth electrode, suggesting that the DEP force is operative during PEF sterilization

Dissimilar joining of alumina to aluminum at room temperature without applying a loading by two-step deposition

Low temperature joining is desirable for aluminum-ceramics joining because aluminum has a large coefficient of thermal expansion. In the present work, joining of Al₂O₃ to Al was performed at room temperature by the two-step deposition method including Ni electroless deposition and Cu electrodeposition. The joining strength was increased, and the fracture mode changed from a fracture at the Ni/Al₂O₃ interface to that in the Al₂O₃ substrate by using a porous Al₂O₃ or by etching a dense Al₂O₃ surface. Thus, the present work demonstrates that Al₂O₃ and Al are successfully joined at room temperature without applying a load by the deposition method