I1

POTENTIAL (V)

Fig. 2 Differential pulse voltammograms for the oxidation signal of Au at PGE in TBS at (a) wild-type (WT) probe-modified Au nanoparticle after hybridization with WT target; (b) mutant (MT) probe-modified Au nanoparticle after hybridization with WT target; (c) WT probe-modified Au nanoparticle after hybridization with no target on PGE surface; and (d) WT probe-modified Au nanoparticle after hybridization with non-complementary target.

that the PCR product contained WT DNA. When the MT probe was hybridized with the WT target, about one-half of the signal was obtained indicating the presence of SNP (Fig. 2b). Nearly a similar electrochemical response was obtained from the attachment of Au nanoparticle-modified WT probe onto bare PGE (Fig. 2c). No electrochemical signals could be obtained when the noncomplementary target was immobilized on the PGE surface (Fig. 2d).

The intrinsic redox activity of DNA was employed for detecting the duplex formation on a PGE-based biosensor by Wang et al.[17'18] Inosine-substituted probes and monitoring of the electrochemical guanine oxidation signal for hybridization events offer several advantages over the common use of external indicators including the appearance of a new peak, a flat background, and simplicity. Inosine is a hypoxanthine ribonucleoside, one of the basic compounds comprising cells, and also a precursor to adenosine and uric acid. In guanine signal-based electrochemical DNA biosensor schemes, inosine-substituted probes have been intensively used,[19,20] because they are electrochemically inactive. When an inosine-substituted probe-modified electrode is exposed to the target DNA, the guanine signal appears after hybridization. The selectivity of the new device of Wang et al.[17] was demonstrated for the detection of a SNP in the BRCA1 breast cancer gene. Such low-cost, renewable graphite transducers provided an attractive alternative to conventional carbon electrodes used for transducing DNA hybridization. The device offered a greatly simplified operation and held promise for decentralized genetic testing by eliminating the regeneration step and an external electro-active indicator.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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