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Abstract: We developed a novel electrochemiluminescence (ECL) ethanol biosensor based on and alcohol dehydrogenase (ADH) immobilized by graphene/bovine serum albumin composite film. The graphene film was directly formed on a glassy carbon electrode surface via an in situ reduction of graphene oxide (GO) and was immobilized during its formation. The graphene film acted as both a decorating agent for immobilization of and a matrix to immobilize bovine serum albumin (BSA), meanwhile BSA not only acted as a reductant to reduce GO, but also provided a friendly environment for ADH immobilization. Furthermore, ADH was separated from by the electron-conductive graphene/BSA composite film to retain its enzymatic activity. The experimental results indicated that the biosensor had excellent electrochemical activity, ECL response to ethanol and stability. Such a design of –graphene/BSA film to modify electrode holds a great promise as a new biocompatible platform for the development of enzyme-based ECL biosensors. [Copyright &y& Elsevier]

Abstract: Biosensor based on DNA hybridization holds great potential to get higher sensitivity as the optimal DNA hybridization efficiency can be achieved by controlling the distribution and orientation of probe strands on the transducer surface. In this work, an innovative strategy is reported to tap the sensitivity potential of current electrochemiluminescence (ECL) biosensing system by dispersedly anchoring the DNA beacons on the gold nanoparticles (GNPs) array which was electrodeposited on the glassy carbon electrode surface, rather than simply sprawling the coil-like strands onto planar gold surface. The strategy was developed by designing a “signal-on” ECL biosensing switch fabricated on the GNPs nanopatterned electrode surface for enhanced ultra-sensitivity detection of Hg2+. A 57-mer hairpin-DNA labeled with ferrocene as ECL quencher and a 13-mer DNA labeled with Ru(bpy)3 2+ as reporter were hybridized to construct the signal generator in off-state. A 31-mer thymine (T)-rich capture-DNA was introduced to form T–T mismatches with the loop sequence of the hairpin-DNA in the presence of Hg2+ and induce the stem-loop open, meanwhile the ECL “signal-on” was triggered. The peak sensitivity with the lowest detection limit of 0.1nM was achieved with the optimal GNPs number density while exorbitant GNPs deposition resulted in sensitivity deterioration for the biosensor. We expect the present strategy could lead the renovation of the existing probe-immobilized ECL genosensor design to get an even higher sensitivity in ultralow level of target detection such as the identification of genetic diseases and disorders in basic research and clinical application. [Copyright &y& Elsevier]