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Herein, an ultra-sensitive photoelectrochemical biosensor based on Ti

A novel enhanced photoelectrochemical DNA sensor, based on a TiO

An electrochemical biosensor was developed based on a steric hindrance hybridization assay to allow the highly sensitive detection of streptavidin. In the steric hindrance hybridization assay, the signaling strand DNA (sig-DNA) was labeled at the 3' end with CdSe quantum dots (QDs) and at the 5' end with biotin, and capturing strand DNA (the complementary strand of sig-DNA) was labeled at the 5' end with thiol. The steric hindrance effect generated by streptavidin which was bound with the signaling DNA strand. The streptavidin limited the ability of the sig-DNA to hybridize with the cap-DNA, which were linked on the surface of a gold electrode. Therefore, the concentration of streptavidin was detected indirectly based on the concentration of CdSe QDs on the electrode surface. The concentration of CdSe QDs on the electrode surface was detected by differential pulse anodic stripping voltammetry. Under optimal conditions, the streptavidin detection range using the as-prepared biosensor was 1.96pg/mL to 1.96µg/mL and the detection limit was 0.65pg/mL. The experimental results showed that the electrochemical biosensor could detect streptavidin rapidly and accurately.

A novel strategy for the enhancement of electrochemiluminescence (ECL) was developed by combining CdSe quantum dots (QDs) with graphene oxide-chitosan (GO-CHIT). The ECL sensor fabricated with CdSe QDs/GO-CHIT composite exhibited high ECL intensity, good biocompatibility and long-term stability, and was used to detect of cytochrome C (Cyt C). The results show that the ECL sensor has high sensitivity for Cyt C with the linear range from 4.0 to 324 μM and the detection limit of 1.5 μM. Furthermore, the ECL sensor can selectively sense Cyt C from glucose and bovine serum albumin (BSA).

A novel enzymatic hydrogen peroxide sensor was successfully fabricated based on the nanocomposites containing of Ag/C nanocables and gold nanoparticles (AuNPs). Ag/C nanocables have been synthesized by a hydrothermal method and then AuNPs were assembled on the surface of Ag/C nanocables. The nanocomposites were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). The above nanocomposites have satisfactory chemical stability and excellent biocompatibility. Cyclic voltammetry (CV) was used to evaluate the electrochemical performance of the Ag/C/Au nanocomposites at glassy carbon electrode (GCE). The results indicated that the Ag/C/Au nanocomposites exhibited excellent electrocatalytic activity to the reduction of H(2)O(2). It offered a linear range of 6.7×10(-9) to 8.0×10(-6) M, with a detection limit of 2.2×10(-9) M. The apparent Michaelis-Menten constant of the biosensor was 51.7×10(-6) M. These results indicated that Ag/C/Au nanocomposites have potential for constructing of a variety of electrochemical biosensors.