Remote sensing is a fast developing field. The ability to detect various elements in secluded or inaccessible areas holds great opportunities. We present a new electrochem. flow cell which was developed as part of an autonomous flow system for measuring heavy metals in aquatic environments. The system was designed for remote sensing. Our system can utilize different com. available electrodes and apply a range of electrochem. methods. The system was studied through both electrochem. expts. and simulation. The potential of the platform was demonstrated by analyzing seawater spiked with Cd. Good agreement was found between our results and those obtained by ICP-MS anal. [on SciFinder(R)]

Gold nanoparticles, AuNPs, capped with mercaptocarboxylic acids followed by silver pptn. develop latent fingermarks on paper as high quality "neg." impressions. This effect stems from hydrogen bonding between the carboxylic group and the paper cellulose and may improve the yield of latent fingermarks since the results are less dependent on sweat compn. [on SciFinder(R)]

Gold nanoparticles, AuNPs, capped with mercaptocarboxylic acids followed by silver precipitation develop latent fingermarks on paper as high quality "negative" impressions. This effect stems from hydrogen bonding between the carboxylic group and the paper cellulose and may improve the yield of latent fingermarks since the results are less dependent on sweat composition.[on SciFinder (R)]

A self-assembled polymer of linear polyethylenimine (LPEI) on indium tin oxide (ITO) is found to stabilize the titanium-doped vanadium oxide film. After modification by LPEI, the oxide film shows good cycling stability, and sustains over 1500 cycles in a three-electrode system, a remarkable improvement compared to that without LPEI modification. [on SciFinder(R)]

A simple and cost effective sol-gel process for producing vanadium dioxide thin films was developed via thermolysis of V2O5·nH2O (n ≈ 2) VV precursors prepd. by dissolving vanadium powder or V2O5 powder in 30% hydrogen peroxide solns. After spin-coating on fused silica substrates and annealing at 750° in vacuum, without any intermediate gas reducing step, the major phase VO2(M, monoclinic phase) was found in both of the films based on V-H2O2 and V2O5-H2O2 precursor, exhibiting large transmittance changes (> 40%) in the IR region (> 2000 nm) and small hysteresis loop width (< 5°) which were comparable to reported epitaxial VO2 films. The two films have similar metal-to-insulator transition temp. τC = 62.5°, lower than the classical value of 68° for VO2 thin films. In addn., the method enables simple doping, as found for 0.56 at.% W-doped VO2 films. This intrinsically simple soln. process followed by one-step annealing makes it potentially useful in smart window applications. [on SciFinder(R)]

Electrochem. detn. of Hg(II) in aquatic solns. on bare and modified glassy carbon electrode (GCE) is reported. Optimizing the parameters used for a bare GCE, such as the electrolyte soln., the potential and time of deposition, resulted in linear response over a large range of Hg(II) concns. (4-160 ppb) using linear sweep anodic stripping voltammetry. Modification of the electrode with 4,4’-disulfanediyldibenzenediazonium (DSBD) yielded a lowest detection limit of 1 ppb. Two procedures for DSBD synthesis are described for the 1st time, and the product was characterized by microanal., FTIR and 1H-NMR. The electrochem. attachment of DSBD to the electrode was studied and compared with the electrochem. behavior of DSBD analogous mols., i.e. 4-aminophenyl disulfide, p-aminothiophenol and Ph disulfide. [on SciFinder(R)]

Novel biocompatible hybrid-material composed of iron-ion-cross-linked alginate with embedded protein molecules has been designed for the signal-triggered drug release. Electrochemically controlled oxidation of Fe(2+) ions in the presence of soluble natural alginate polymer and drug-mimicking protein (bovine serum albumin, BSA) results in the formation of an alginate-based thin-film cross-linked by Fe(3+) ions at the electrode interface with the entrapped protein. The electrochemically generated composite thin-film was characterized by electrochemistry and atomic force microscopy (AFM). Preliminary experiments demonstrated that the electrochemically controlled deposition of the protein-containing thin-film can be performed at microscale using scanning electrochemical microscopy (SECM) as the deposition tool producing polymer-patterned spots potentially containing various entrapped drugs. Application of reductive potentials on the modified electrode produced Fe(2+) cations which do not keep complexation with alginate, thus resulting in the electrochemically triggered thin-film dissolution and the protein release. Different experimental parameters, such as the film-deposition time, concentrations of compounds and applied potentials, were varied in order to demonstrate that the electrodepositon and electrodissolution of the alginate composite film can be tuned to the optimum performance. A statistical modeling technique was applied to find optimal conditions for the formation of the composite thin-film for the maximal encapsulation and release of the drug-mimicking protein at the lowest possible potential.[on SciFinder (R)]

Novel biocompatible hybrid-material composed of iron-ion-crosslinked alginate with embedded protein mols. has been designed for the signal-triggered drug release. Electrochem. controlled oxidn. of Fe2+ ions in the presence of sol. natural alginate polymer and drug-mimicking protein (bovine serum albumin, BSA) results in the formation of an alginate-based thin-film crosslinked by Fe3+ ions at the electrode interface with the entrapped protein. The electrochem. generated composite thin-film was characterized by electrochem. and at. force microscopy (AFM). Preliminary expts. demonstrated that the electrochem. controlled deposition of the protein-contg. thin-film can be performed at microscale using scanning electrochem. microscopy (SECM) as the deposition tool producing polymer-patterned spots potentially contg. various entrapped drugs. Application of reductive potentials on the modified electrode produced Fe2+ cations which do not keep complexation with alginate, thus resulting in the electrochem. triggered thin-film dissoln. and the protein release. Different exptl. parameters, such as the film-deposition time, concns. of compds. and applied potentials, were varied in order to demonstrate that the electrodeposition and electrodissoln. of the alginate composite film can be tuned to the optimum performance. A statistical modeling technique was applied to find optimal conditions for the formation of the composite thin-film for the maximal encapsulation and release of the drug-mimicking protein at the lowest possible potential. [on SciFinder(R)]

Nanoelectrode ensembles (NEEs) have been fabricated by the electrodeposition of Au nanoparticles (AuNPs) on single-layer graphene oxide (GO) sheets coated on a glassy carbon electrode (GCE). The fabricated NEEs show a typical sigmoidal shaped voltammetric profile, arising from the low coverage d. of AuNPs on GCE and large distance among them, which can be easily controlled by varying the electrodeposition time. As a proof of concept, after the probe HS-DNA is immobilized on the NEEs through the Au-S bonding, the target DNA was detected with the methylene blue intercalator. The authors’ results show that the target DNA can be detected as low as 100 fM, i.e. 0.5 amol DNA in 5 μL soln. [on SciFinder(R)]

Nanoelectrode ensembles (NEEs) have been fabricated by the electrodeposition of Au nanoparticles (AuNPs) on single-layer graphene oxide (GO) sheets coated on a glassy carbon electrode (GCE). The fabricated NEEs show a typical sigmoidal shaped voltammetric profile, arising from the low coverage density of AuNPs on GCE and large distance among them, which can be easily controlled by varying the electrodeposition time. As a proof of concept, after the probe HS-DNA is immobilized on the NEEs through the Au-S bonding, the target DNA is detected with the methylene blue intercalator. Our results show that the target DNA can be detected as low as 100 fM, i.e. 0.5 amol DNA in 5 μL solution.[on SciFinder (R)]