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A novel electrochemical sensor was developed for sensitive and selective detection of mercury(II), based on thymine--[Hg.sup.2+]--thymine (T--[Hg.sup.2+]--T) coordination chemistry. This strategy exploited the cooperativity of proximate poly-T oligonucleotides in coordination with [Hg.sup.2+]. Ferrocene (Fc)-tagged poly-T oligonucleotides were immobilized on the electrode surface via self-assembly of the terminal thiol moiety. In the presence of [Hg.sup.2+], a pair of poly-T oligonucleotides could cooperatively coordinate with [Hg.sup.2+], which triggered a conformational reorganization of the poly-T oligonucleotides from flexible single strands to relatively rigid duplexlike complexes, thus drawing the Fc tags away from the electrode with a substantially decreased redox current. The response characteristics of the sensor were thoroughly investigated using capillary electrophoresis and electrochemical measurements. The results revealed that the sensor showed a sensitive response to [Hg.sup.2+] in a concentration range from 1.0 nM to 2.0 [micro]M, with a detection limit of 0.5 nM. Also, this strategy afforded exquisite selectivity for [Hg.sup.2+] against a reservoir of other environmentally related metal ions, compared to existing anodic stripping voltammetry (ASV) techniques. In addition, this sensor could be implemented using minimal reagents and working steps with excellent reusability through mild regeneration procedure. It was expected that this cost-effective electrochemical sensor might hold considerable potential in on-site applications of [Hg.sup.2+] detection.

Aptamer-based rolling circle amplification (aptamer-RCA) was developed as a novel versatile electrochemical platform for ultrasensitive detection of protein. This method utilized antibodies immobilized on the electrode surface to capture the protein target, and the surface-captured protein was then sandwiched by an aptamer-primer complex. The aptamer-primer sequence mediated an in situ RCA reaction that generated hundreds of copies of a circular DNA template. Detection of the amplified copies via enzymatic silver deposition then allowed enormous sensitivity enhancement in the assay of target protein. This novel aptamer-primer design circumvented time-consuming preparation of the antibody-DNA conjugate for the common immuno-RCA assay. Moreover, the detection strategy based on enzymatic silver deposition enabled a highly efficient readout of the RCA product as compared to a redox-labeled probe based procedure that might exhibit low detection efficiency due to RCA product distance from the electrode. With the platelet-derived growth factor B-chain (PDGF-BB) as a model target, it was demonstrated that the presented method was highly sensitive and specific with a wide detection range of 4 orders of magnitude and a detection limit as low as 10 fM. Because of the wide availability of aptamers for numerous proteins, this platform holds great promise in ultrasensitive immunoassay.

Electrochemical and surface enhanced Raman scattering (SERS) spectroelectrochemical measurements were used to report the studies of the structure and anticorrosion features of two kinds of self-assembled monolayers (SAMs) of IP6 at the silver surface under various pH values, 1.27 and 13. Based on in situ SERS electrochemical measurements, a tentative explanation for the difference in corrosion potentials of two kinds of the silver surfaces in the presence of SAMs formed from completely protonated or deprotonated IP6 molecules are presented.

Research was conducted to examine the hydrogen abstraction reaction PH3 + H -> PH2 + H2 viva an ab initio direct dynamic approach. The objective was to obtain electronic structure information, including geometries, gradients, force constants and energies at selected points along the minimum energy path. Results are in satisfactory agreement with available experimental results and demonstrates that the forward reaction is favored over the reverse reaction.

The hydrogen-abstraction reactions of the radical NH(X3Sigma-) with methane and ethane were investigated via ab initio molecular orbital theory and the canonical variational transition-state theory. The geometries of the reactants, transition states and products were optimized at the UHF, UMP2, UMP4(sdq) and UQCISD levels of theory, and the forward and reverse reaction potential barriers were computed accurately at the UQCISD(T)/6-311+G(3df,2p) and Gaussian 2 levels.

The proof-of-principle of a terminal protection assay of small-molecule-linked DNA is described. This strategy is shown for quantitative analysis of the interaction of folate with a tumor biomarker of folate receptor (FR) and a detection limit of 3 pM FR is achieved with desirable specificity and sensitivity, showing that the terminal protection assay has offered a promising platform for small molecule-protein interaction studies.

A novel electrochemical genotyping strategy is developed that is based on gap ligation reaction with surface hybridization detection. This method has shown intrinsic high sensitivity for direct genomic analysis and specificity with discriminativity of single nucleotide variations.

A reusable electrochemical aptasensor is developed for the single-step detection of platelet-derived growth factor B-chain (PDGF-BB) based on proximity-dependent surface hybridization assay. The surface proximity-dependent surface hybridization assay might create a new method for developing high-performance biosensors in sensitive, selective and reusable detection of proteins.

A series of novel dendritic beta-diketone ligands, 1-phenyl-3-[G-n]-4-phenylacetyl-5-pyrazolone (n = 0-3, G = polyaryl ether), are synthesized by introducing Frechet-type dendritic branches and the corresponding [Tb.sup.3+]-cored dendritic complexes are characterized. The photophysical studies have indicated that the dendritic complexes in solution displayed enhanced luminescence with increasing dendron generation.

An efficient synthesis route that could easily produce high-quality MCM-48 at room temperature by using a hemicyanine dye-cetyltrimethylammonium bromide mixture as the structure-directing agent is presented. The result show that, upon addition of the dye surfactant to the starting mixtures, the mesostructured silica undergoes an intrinsic phase-transition process, however, specific dye geometry is required to obtain MCM-48 at room temperature.

The first mixed films of porphyrin and fullerene with hydrogen bonding on tin oxide (SnO2) as well as indium tin oxide electrolyte is reported to reveal efficient photocurrent generation. The results show that hydrogen bonding is a highly promising methodology for the construction of molecular photoelectrochemical devices.

he dechlorane family of flame retardants, which includes Mirex (also known as Dechlorane), Dechlorane Plus (DP), and Dechloranes (Dec) 602, 603, and 604, were manufactured at a facility along the Niagara River, upstream of Lake Ontario. Some of these compounds remain in use. In a previous study, we found Mirex and Dec602 to have greater bioaccumulation potentials than Dec604 and DP based on calculated biota-sediment accumulation factors (BSAFs). In this study, analogues of Dec604, containing fewer bromines and mixed substitutions of bromine and chlorine, were identified in Lake Ontario sediment and fish using high and ultrahigh resolution mass spectrometric techniques. The tribromo-Dec604 (Br3Dec604) analogue, known as Dechlorane 604 Component B (Dec604 CB), was present in lake trout and whitefish at concentrations of 10-60 ng/g lipid weight, approximately 50-200 times greater than concentrations measured for Dec604. In addition, BrDec604 and Br2Dec604 analogues, and mixed Br2Cl2Dec604, Br3ClDec604, Br2CIDec604, and BrCl2Dec604 analogues were also present. We have shown that solutions of Dec604 and Dec604 CB exposed to UV-light undergo photodebromination and give rise to the analogues found in sediment and fish. Dec604 CB and other lesser halogenated analogues of Dec604 show greater bioaccumulation potentials than Dec604, Dec602 and DP, based on BSAFs, which highlight the need to consider likely impurities and degradation products in the assessment of persistent, bioaccumulative, and toxic compounds. [ABSTRACT FROM AUTHOR]

A newrare earth metal and samarium-catalyzed C(sp3)–Hbond activation is reported in which 2-alkylazaarenes and propargylicalcohols were converted to indolizines. This process operates undermild conditions and solvent-free conditions. A broad scope of couplingpartners has been established, and a likely mechanism has also beensuggested. [ABSTRACT FROM AUTHOR]

Monitoring aspects of human performance during various activities has recently become a highly investigated research area. Many new commercial products are available now to monitor human physical activity or responses while performing activities ranging from playing sports, to driving, and even sleeping. However, monitoring cognitive performance biomarkers, such as neuropeptides, is still an emerging field due to the complicated sample collection and processing, as well as the need for a clinical lab to perform analysis. Enzyme-linked immunosorbent assays (ELISAs) provide specific detection of biomolecules with high sensitivity (picomolar concentrations). Even with the advantage of high sensitivity, most ELISAs need to be performed in a laboratory setting and require around 6 h to complete. Transitioning this assay to a platform where it reduces cost, shortens assay time, and is able to be performed outside a lab is invaluable. Recently developed paper diagnostics provide an inexpensive platform on which to perform ELISAs; however, the major limiting factor for moving out of the laboratory environment is the measurement and analysis instrumentation. Using something as simple as a digital camera or camera-enabled Windows- or Android-based tablets, we are able to image paper-based ELISAs (P-ELISAs), perform image analysis, and produce response curves with high correlation to target biomolecule concentration in the 10 pM range. Neuropeptide Y detection was performed. Additionally, silver enhancement of Au NPs conjugated with IgG antibodies showed a concentration-dependent response to IgG, thus eliminating the need for an enzyme–substrate system. Automated image analysis and quantification of antigen concentrations are able to be performed on Windows- and Android-based mobile platforms. [ABSTRACT FROM AUTHOR]