Overoxidized polypyrrole colloids imprinted with L-lactate were prepared to evaluate the performance of the overoxidation pseudo-template technique developed by the authors. A polypyrrole colloid that had been prepared from a mixture of monomer (pyrrole), dopant (L-lactate), steric stabilizer (poly(vinylpyrrolidone)) and oxidizing agent (peroxodisulfate) was electrochemically overoxidized at +1.5 V vs Ag/AgCl to create a complementary cavity for recognition of the molecules, which were structurally similar to dopant, through dedoping. As a target molecule for enantioselective uptake into the overoxidized colloid, we selected alanine, which is structurally different from the template (lactate) only in one side chain (alanine, -NH2; lactic acid, -OH). The overoxidized polypyrrole colloid showed higher affinity for L-alanine than for D-alanine, and an uptake ratio (L/D) of as high as 11 +/- 4 was observed under optimum conditions. Uptake reached equilibrium in 10 min, thanks to the high surface area and short diffusion length in the colloidal particle. Further, to confirm the complementarity of the cavity, the effect of side chain size on uptake of several alpha-amino acids was examined to indicate that the uptake amount decreased with increasing molecular volume of the L-amino acids.
Self-assembled monolayers consisting of 3,3′-thiodipropionic acid and n-decyl mercaptan formed on gold electrodes have been studied for sensitive and selective determination of Cu 2+ and Ag + ions. The monolayers were found to provide both superior sensitivities and stabilities even in the presence of protein. Various factors, such as solution pH and concentration time, were optimized to obtain detection limits of 2×10 -9 M and 6×10 -8 M for Cu 2+ and Ag + ions at an S/N ratio of 2 by linear-sweep anodic stripping voltammetry. In the presence of albumin, the currents of the modified electrode, 1.75 times as great as those for the bare electrode, show a significant performance improvement over the previously reported cellulose coated electrode (1.13 times). One of the main advantages of using this electrode is an excellent antifouling activity against protein adsorption, coupled with highly selective metal-ion suppression/concentration capabilities, which can be attained without using a mercury film for preconcentration.
In this study, adhesion of the Cu/Cu-Mn stacked interconnections to glass (SiO2) substrates was evaluated and the results were correlated with a detailed analysis of the reaction layer between the Cu-Mn and the chemical vapour deposited SiO2. When the Mn concentrations were varied, an abrupt change in the adhesion properties was observed; the practical adhesion properties were obtained in the Cu/Cu-Mn interconnections with Mn concentrations at 8% and higher. To clarify the chemical nature and the microstructure of the reaction layer at the interface between the Cu-x Mn (x = 4, 10 at. %) and the SiO2 layers was analysed using angle-resolved x-ray photoelectron spectroscopy and transmission electron microscope-electron energy loss spectroscopy. These observations indicated that the cross-sectional structure along the reaction layer of the Cu–10 at. % Mn sample can be divided into two regions: in the high Mn region, the Mn-Si complex oxide and the SiO2 mixture phase are preferable due to a decrease in the oxygen fraction near the Cu-Mn layer, whereas in the low Mn region, MnOx and SiO2 mixture are stable. The Mn-Si complex oxide was observed only in the high adhesive sample (Mn 10 at. %). These results suggest that the existence of the chemical bond of the Mn-Si complex oxide improved the interfacial adhesion between the Cu/Cu-Mn stacked interconnections and the glass substrates.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.