The formation of a Pt skin layer with predominantly (111)-oriented facets induced by dissolution of Fe atoms in a Pt-Fe alloy for fuel cell applications is investigated for the first time by using in situ electrochemical STM in 0.1 M HClO4 solution.

Layer-by-layer (LbL) films were prepared by an alternate deposition of phenylboronic acid-bearing poly(allylamine hydrochloride) (PBA-PAH) and poly(vinyl alcohol) (PVA) on the surface of a quartz slide to develop thin films that can be decomposed in response to hydrogen peroxide (H2O2). The PBA-PAH/PVA films decomposed in the presence of H2O2; the degree and kinetics of decomposition depend on the concentration of H2O2 and on the pH of the solution. For example, the film decomposition completely occurred in 30 min in 1.0 mM H2O2 solution at pH 7.4, while it took 180 min in 0.1 mM H2O2 solution. The H2O2-induced decomposition of the film can be explained in terms of the oxidative scission of the carbon-boron bond in PBA residues in the PBA-PAH chains. A potential use of the PBA-PAH/PVA films in developing H2O2-sensitive delivery systems was suggested.

Phenylboronic acid-bearing poly(allylamine)/poly(vinyl alcohol) layer-by-layer films coupled with glucose oxidase decomposed in the presence of glucose under physiological conditions.

No abstract

No abstract

Cyclooxygenase-2 (COX-2) plays an important role in angiogenesis and cancer progression. Since many tumor cells exhibit COX-2 expression, functional imaging of COX-2 expression using celebrex (CBX, a COX-2 inhibitor) may provide not only a non-invasive, reproducible, quantifiable alternative to biopsies, but it also greatly complements pharmacokinetic studies by correlating clinical responses with biological effects. Moreover, molecular endpoints of anti-COX-2 therapy could also be assessed effectively. This study aimed at measuring uptake of Tc-EC-CBX in COX-2 expression in tumor-bearing animal models. In vitro Western blot analysis and cellular uptake assays were used to examine the feasibility of using Tc-EC-CBX to measure COX-2 activity. Tissue distribution studies of Tc-EC-CBX were evaluated in tumor-bearing rodents at 0.5-4 h. Dosimetric absorption was then estimated. Planar scintigraphy was performed in mice, rats and rabbits bearing tumors. In vitro cellular uptake indicated that cells with higher COX-2 expression (A549 and 13762) had higher uptake of Tc-EC-CBX than lower COX-2 expression (H226). In vivo biodistribution of Tc-EC-CBX in tumor-bearing rodents showed increased tumor:tissue ratios as a function of time. In vitro and biodistribution studies demonstrated the possibility of using Tc-EC-CBX to assess COX-2 expression. Planar images confirmed that the tumors could be visualized with Tc-EC-CBX from 0.5 to 4 h in tumor-bearing animal models. We conclude that Tc-EC-CBX may be useful to assess tumor COX-2 expression. This may be useful in the future for selecting patients for treatment with anti-COX-2 agents.

Purpose: The aim of this study was to evaluate 99m Tc-ethylenedicysteine-glucosamine (EC-DG)

No abstract