An electrochemical sensor for phenylephrine based on molecular imprinting.

Molecularly imprinted polymers (MIPs) were applied as molecular recognition elements to an electrochemical sensor for phenylephrine. A MIPs membrane was created on a glassy carbon electrode. SEM revealed a gradual change on the morphology of modified electrodes as the ratios of function monomer and cross-linking varied. When the ratio was 4:40, the surface morphology between the imprinted electrode (M-electrode) and the control electrode (N-electrode) became unambiguously different. This artificial receptor exhibited high selectivity for the template compared to closely related analogue. The response of the sensor varied in different concentration range might due to the heterogeneity of the MIPs membrane. This sensor was also used to determine phenylephrine in tablet samples.

Chemical sensing based on catalytic nanomotors: motion-based detection of trace silver.

A motion-based chemical sensing involving fuel-driven nanomotors is demonstrated. The new protocol relies on the use of an optical microscope for tracking changes in the speed of nanowire motors in the presence of the target analyte. Selective and sensitive measurements of trace silver ions are illustrated based on the dramatic and specific acceleration of bimetal nanowire motors in the presence of silver. Such nanomotor-based measurements would lead to a wide range of novel and powerful chemical and biological sensing protocols.

Metal-chelating and dansyl-labeled poly(N-isopropylacrylamide) microgels as fluorescent Cu2+ sensors with thermo-enhanced detection sensitivity.

We report on the fabrication of Cu2+-sensing thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) microgels labeled with metal-chelating acceptor and fluorescent reporter moieties. Cu2+ detection sensitivity can be considerably enhanced via thermo-induced collapse of the sensing matrix, which can easily optimize the relative spatial distribution of Cu2+-binding sites and fluorescence readout functionalities. A novel picolinamine-containing monomer with Cu2+-binding capability, N-(2-(2-oxo-2-(pyridine 2-yl-methylamino)ethylamino)ethyl)acrylamide (PyAM, 3), was synthesized at first. Nearly monodisperse Cu2+-sensing microgels were prepared via emulsion polymerization of N-isopropylacrylamide (NIPAM) in the presence of a nonionic surfactant, N,N'-Methylene-bis(acrylamide) (BIS), PyAM (3), and fluorescent dansylaminoethyl- acrylamide (DAEAM, 5) monomers at around neutral pH and 70 degrees C. At 20 degrees C, as-synthesized microgels in their swollen state can selectively bind Cu2+ over other metal ions (Hg2+, Mg2+, Zn2+, Pb2+, Ag+, and Al3+), leading to prominent quenching of fluorescence emission intensity. Above the volume phase transition temperature, P(NIPAM-co-PyAM-co-DAEAM) microgels exhibit increased fluorescence intensity. It was observed that Cu2+ detection sensitivity can be dramatically enhanced via thermo-induced microgel collapse at elevated temperatures. At a microgel concentration of 3.0x10(-6) g/mL, the detection limit drastically improved from approximately 46 nM at 20 degrees C to approximately 8 nM at 45 degrees C. The underlying mechanism for this novel type of sensor with thermotunable detection sensitivity was tentatively proposed.

A novel poly(vinyl chloride) matrix membrane sensor for batch and flow-injection determinations of thiocyanate, cyanide and some metal ions.

A poly(vinyl chloride) matrix membrane sensor for the selective determination of thiocyanate has been developed based on the use of copper(II)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex (Cu-PADAP) as a novel charged carrier, and o-nitrophenyloctyl ether (o-NPOE) as a solvent mediator. The sensor displays a significantly enhanced response towards SCN(-) ions over the concentration range 7.0 x 10(-6) to 1.0 x 10(-2) mol L(-1) with a detection limit of 5.6 x 10(-6) mol L(-1) and a calibration slope of -57.5 +/- 0.5 mV decade(-1). The sensor exhibits a long life-span, long-term stability, high reproducibility, and a fast response time. The selectivity coefficients of some anions were calculated using the separate solutions method, and found to be in the following order: SCN(-) > ClO(4)(-) > I(-) > Sal(-) > NO(2)(-) > Br(-) > NO(3)(-) = CH(3)COO(-) > Cl(-) > SO(4)(2-) = PO(4)(3-). The effects of the pH and ionic membrane additives (e.g. tridodecylmethylammonium chloride, TDMAC and potassium tetrakis[bis(3,5-trifluoromethyl)phenyl] borate, KTFPB) were examined. The sensor was used for the determination of SCN(-) ions in saliva and urine samples collected from some smoker and non-smoker donors. The developed sensor was also applied to determine the cyanide content in electroplating waste water samples after its conversion into thiocyanate. The application of the sensor to monitor the potentiometric titration of Ag(+) and Hg(2+) using SCN(-) resulted in sharp inflection breaks at the equivalent points. The data obtained using the proposed sensor correlate very well with results collected using the standard methods of thiocyanate, cyanide and metal analysis.

Advanced porous gold nanofibers for highly efficient and stable molecular sensing platforms.

Porous gold nanofibers are fabricated through templated electrochemical routes in porous alumina membranes. Gold-silver alloy is electrochemically deposited in the nanocylinders of the porous alumina templates and then the silver phase is selectively dealloyed. The resulting nanofibers present a nanoporous network with a pore dimension of approximately 10 nm and notable surface-enhanced Raman scattering (SERS) efficiencies which are at least seven times higher than from the smooth solid gold nanofibers without porosity. The relative SERS enhancement on porous gold is directly proved by imaging with a Raman microscope for conjugated porous gold/solid gold single nanorods.

Surface chemistry effects on the performance of an electrochemical DNA sensor.

E-DNA sensors are a reagentless, electrochemical oligonucleotide sensing platform based on a redox-tag modified, electrode-bound probe DNA. Because E-DNA signaling is linked to hybridization-linked changes in the dynamics of this probe, sensor performance is likely dependent on the nature of the self-assembled monolayer coating the electrode. We have investigated this question by characterizing the gain, specificity, response time and shelf-life of E-DNA sensors fabricated using a range of co-adsorbates, including both charged and neutral alkane thiols. We find that, among the thiols tested, the positively charged cysteamine gives rise to the largest and most rapid response to target and leads to significantly improved storage stability. The best mismatch specificity, however, is achieved with mercaptoethanesulfonic and mercaptoundecanol, presumably due to the destabilizing effects of, respectively, the negative charge and steric bulk of these co-adsorbates. These results demonstrate that a careful choice of co-adsorbate chemistry can lead to significant improvements in the performance of this broad class of electrochemical DNA sensors.

[Analytical-equipment method for the estimation of the organism health condition and all it's systems after radiation].

Software for estimation of the health state of human body and its systems on the basis of blood parameters is described. The software uses ACS-ENOFIT analytical model based on image recognition theory and cluster analysis. This analytical method makes it possible to assess the state of patient's health and the state of each of the 10 body systems. Thus, prophylactic X-ray examination based on measurement of blood parameters makes it possible to reveal various disorders at different stages of development.

Evaluación de un nuevo método turbidimétrico para la cuantificación de Beta-2 microglubulina en suero / Evaluation of a new turbidimetric analysis for the Beta-2 microglobulin cuantification in serum

Se ha evaluado el nuevo inmunoanálisis turbidimétrico para la determinación cuantitativa de la â-2 microglobulina desarrollado por Spinreact. El procedimiento se lleva a cabo de manera totalmente automática en el analizador de bioquímica clínica RA-500 con un intervalo analítico de 0,3 a 11 mg/l y límite de detección de 0,023 mg/l. Los coeficientes de variación obtenidos fueron inferiores a 5,2% para todos los niveles ensayados. El procedimiento evaluado es lineal dentro del intervalo de medida. La comparación con un Elisa (IMX, Abbot) mostró un coeficiente de correlación de 0,98, apreciándose la existencia de errores sistemáticos proporcionales constantes, probablemente debido a la diferente estandarización y, por tanto, diferentes valores de referencia de ambos métodos. El límite superior del intervalo de referencia (95 percentil) fue 43,6 mg/l. En conclusión, este nuevo método turbidimétrico puede considerarse un procedimiento adecuado para la medida fiable y precisa de la Beta-2 microglobulina, con un amplio intervalo analítico y una alta detectabilidad

The new turbidimetric analysis for the â-2microglobulin quantitative determination, developed by Spinreact, has been evaluated. The procedure is performed in a completely automatic way in the RA-500 clinical biochemistry analyser with an analytic interval ranging from 0,3 to 11 mg/l and 0,023 mg/l detection limit. All the variation coefficients obtained in this way were lower than 5,2% for all trial levels. The evaluated procedure is linear inside the measurement range. The comparison with Elisa (IMX, Abbot) showed an auto-correlation coefficient of 0,98, evidencing the existence of constant proportional systematic errors, due probably to different standards, and thus to different reference values in both methods. The reference interval upper limit (95 percentile) was 43,6 mg/l. Thus we can conclude that this new turbidimetric method is an adequate procedure to measure the Beta-2microglobulin in a reliable and accurate way, with a wide analytic range and high detection ability

Biomaterials. New Chinese biochip center straddles business, academe.

Last month, U.S.-trained entrepreneur and researcher Cheng Jing was named head of a new, two-pronged biochip venture here that will be highly unusual even for China, which has been experimenting with academic-industrial arrangements in recent years. One part is a for-profit company backed by $48 million from a combination of national and academic partners and overseas venture capital. The second piece is a nonprofit national center with nearly $10 million in research funding from the Ministry of Science and Technology.

Trends in analytical instrumentation.

Methods for deriving chemical information from a variety of systems and environments have changed dramatically in the last decade. Unique principles from physics, chemistry, and biology are the basis for sophisticated instruments that incorporate computers for data acquisition, reduction, and interpretation. Such analytical systems have shown orders-of-magnitude improvements in sensitivity, specificity, and speed, yet with greater simplicity and lower price. The increasing importance of analytical instrumentation requires reexamination of its coverage in educational curricula and of the role of the analytical chemist in its further development and application.