An ultrasensitive photoelectrochemical biosensor based on [Ru(dcbpy)(2)dppz](2+) /Rose Bengal dyes co-sensitized fullerene for DNA detection

Though preferable progresses have been achieved to improve the photoelectric performance of fullerene (C-60 NPs) by sensitized structure in photoelectrochemical (PEC) field, further application inevitably suffers from the inherent scarcities of heavy metal-involved quantum dots as sensitizers containing restricted sensitization effect, complex preparation and biological toxicity. In this work, a PEC biosensor based on [Ru(dcbpy)(2)dppz](2+)/Rose Bengal dyes co-sensitized C-60 NPs was constructed for ultrasensitive DNA (a fragment sequence of p53 gene) detection. With the merits of low toxicity and accessible operation, [Ru(dcbpy)(2)dppz](2+)/Rose Bengal dyes exhibited a further sensitization efficiency towards C-60 NPs. Through modifying wide band gap C-60 NPs with two narrower band gap dyes ([Ru(dcbpy)(2)dppz](2+) and Rose Bengal) to form a cascade-type energy band structure, the photoelectric conversion of C-60 NPs was significantly improved and the visible light absorption was markedly promoted, leading to an exceptional photocurrent signal. Additionally, Nt center dot BstNB I enzyme-assisted target recycling amplification was employed to convert a limited quantity of target to numerous SiO2 NPs-labeled DNA sequences (the signal quencher), resulting in a sharp decrement of photocurrent since a dramatic increment of steric hindrance on the modified electrode surface, which was performed to quantitatively estimate target. The proposed PEC biosensor for DNA detection possessed a wide linear range from 0.1 fM to 1 nM with a calculated detection limit of 37 aM. This work opened up an intriguing avenue for determination of various targets such as DNAs, microRNAs and proteins, and exhibited desirable application potential in the clinic researches, cancer therapies and other related subjects.