A simple, one-step method for fabricating single biologically functionalized conducting-polymer (polypyrrole) nanowire on prepatterned electrodes and its application to biosensing was demonstrated. The biologically functionalized polypyrrole was formed by the electropolymerization of an aqueous solution of pyrrole monomer and the model biomolecule, avidin- or streptavidin-conjugated ZnSe/CdSe quantum dots, within 100 or 200 nm wide by 3 mum long channels between gold electrodes on prefabricated silicon substrate. When challenged with biotin-DNA, the avidin- and streptavidin-polypyrrole nanowires generated a rapid change in resistance to as low as 1 nM, demonstrating the utility of the biomolecule-functionalized nanowire as biosensor. The method offers advantages of direct incorporation of functional biological molecules into the conducting-polymer nanowire during its synthesis, site-specific positioning, built-in electrical contacts, and scalability to high-density nanoarrays over the reported silicon nanowire and carbon nanotube biosensors.

A facile technique for fabrication of individually addressable, conducting polymer nanowire arrays of controlled dimension, high aspect ratio, and site-specific positioning using electrodeposition between electrodes in channels created on semiconducting and insulating surfaces that can be easily scaled up is reported. In addition, the ability to create “arrays” of conducting polymer nanowires of same or different materials on the same chip has been demonstrated. The fidelity, quality, and electrical properties of single polypyrrole and polyaniline nanowires have been examined by SEM and I−V characteristics. Dendrite-free conducting polymer nanowires completely confined within the channels with full dimension control were observed. I−V characteristic of such nanowires show the ohmic nature of the contact with Au electrode.

Sol-gel-derived glasses have emerged as a new class of materials well suited for the immobilization of biomolecules. As a consequence, they are also finding new applications as platforms for chemical sensors. Room temperature (or lower) processing conditions, chemical inertness, negligible swelling effects, tunable porosity, and the high purity of sol-gel-derived glasses make them ideal for many types of sensor applications. We

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Metformin treatment, now widely prescribed in polycystic ovary syndrome, is aimed at correcting the associated insulin resistance, but it has also been shown to directly inhibit ovarian steroidogenesis. The mechanisms, however, by which metformin inhibits estradiol production in human granulosa cells remains unknown. Granulosa luteal cells were incubated with metformin, insulin, or combined metformin and insulin treatment, and aromatase mRNA expression was quantified using real-time RT-PCR. Enzyme activity was assessed by the conversion of (3)H-androstenedione to estrone and estradiol. Metformin's effect on the expression of specific untranslated first exon aromatase promoters was analyzed using semiquantitative PCR. The involvement of MAPK kinase (MEK)/ERK pathway was investigated by immunoblotting for aromatase, phosphorylated, and total ERK-1,2 from cells cultured as above with/without the MEK inhibitor PD98059. Metformin significantly inhibited basal and insulin-stimulated aromatase mRNA expression, with parallel results from the aromatase activity assay and protein assessment. This suppression was via down-regulation of aromatase promoter II, I.3, and 1.4 expression and was reversed by the addition of PD98059. Involvement of the ERK signaling pathway was demonstrated by the significant increase in phosphorylated ERK-1,2 with the combined metformin and insulin treatment. We have shown for the first time in human granulosa cells that metformin signficantly attenuated basal and insulin-stimulated P450 aromatase mRNA expression and activity, via silencing of key promoters. This occurred by activation of MEK/ERK pathway, which negatively regulated aromatase production. This is an important consideration given metformin's widespread use in polycystic ovary syndrome and may further support a possible therapeutic indication in estrogen-dependent breast tumors.

Tetraethyl orthosilicate (TEOS) derived sol−gel films have been utilized for the electrochemical polymerization of aniline. The presence of electroactive polyaniline (PANI) within the porous skeleton of the TEOS sol−gel films has been confirmed using cyclic voltammetry, UV−visible, infrared spectroscopy, and scanning electron microscopic measurements.

A biosensor for glucose utilizing glucose oxidase (GOX) covalently coupled to poly(o‐amino benzoic acid) (PAB; a carboxy‐group‐functionalized polyaniline) is described. Amperometric response measurements conducted via unmediated and mediated (with ferrocene carboxylic acid and tetrathiafulvalene) reoxidation of GOX show that glucose can be detected over a wide range of concentrations. An enzyme‐conducting polymer‐mediator model provides for better charge transport in a biosensor. The optimal response, obtained at pH 5.5 and 300 K, lies in the 1–40 mM range. A kinetic plot yields the value of the apparent Michaelis–Menten constant, Kmapp. The operational stability of the PAB‐based glucose biosensor was experimentally determined to be about 6 days. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 662–667, 2000

Immobilization of lactate dehydrogenase (LDH) has been carried out on electrochemically prepared polyaniline (PANI) ®lms. The results of the photometric and amperometric response measurements conducted on such LDHaPANI electrodes show the response time as 90 s and shelf-life as about two weeks at 4±10 C indicating that these conducting polymer-enzyme electrodes can be used as a pyruvate sensor.