Highly sensitive determination of ssDNA and real-time sensing of nuclease activity and inhibition based on the controlled self-assembly of a 9,10-distyrylanthracene probe.

We report here a fluorescent biosensor for highly sensitive determination of single-stranded DNA (ssDNA) with remarkable fluorescence enhancement and label-free sensing of S1 nuclease activity and inhibition in real time based on ssDNA-controlled self-assembly of a 9,10-distyrylanthracene (DSA) probe with the aggregation-induced emission (AIE) property, thereby avoiding a sophisticated fabrication process and aggregation-caused quenching (ACQ) effect. Compared with previous technologies, this assay has some advantages. First, since the DSA probe can be synthesized through a simple and effective synthetic route and the sensing technology adopts the unlabelled ssDNA, this biosensor shows advantages of simplicity and cost efficiency. Besides, for the determination of ssDNA, S1 nuclease, and inhibitor, the DSA-based probe provides high sensitivity and a good linear relationship due to the AIE property. As a result, we determined the DNA 24-mer concentration as low as 150 pM, and we are able to detect ssDNA lengths with a linear range from 6mer to 24mer (R = 0.998) as well as DNA 24-mer concentrations with a linear range from 0 to 200 nM (R = 0.998) and S1 nuclease concentrations with a linear range from 6 to 32 U ml(-1) (R = 0.995), respectively. Moreover, the fluorescent intensity with various concentrations of S1 nuclease becomes highly discriminating after 3-16 min. Thus, it is possible to detect nuclease activity within 3-16 min, which demonstrates another advantage of a quick response of the present biosensor system.