Sensitive fluorescent assay for copper (II) determination in aqueous solution using copper-specific ssDNA and Sybr Green I

This paper reports a fluorescent turn-off assay for sensitive detection of Cu2+ in an aqueous solution by using a copper-specific ssDNA Cu100 and Sybr Green I. By monitoring the fluorescence changes arose from different interactions of Sybr Green I with Cu100 and Cu100/Cu2+ complex, the Cu2+ could be linearly detected from 5.57 to 250ppb, with a detection limit of 5.57ppb. The feasibility of this assay was demonstrated by detecting Cu2+ in certified reference materials and spiked water samples with satisfactory results. [Display omitted] •A copper-specific ssDNA named Cu100 was firstly proposed.•The recognition ability of Cu100 to Cu2+ was preliminary verified.•A fluorescent assay for Cu2+ detection was designed based on Cu100 and Sybr Green I.•This assay provides a linear range of 5.57–250ppb and a detection limit of 5.57ppb.•It is hoped that the Cu100 can be applied as an alternative of the Cu2+-dependent DNAzyme.