Dual-mode sensing strategy based on carbon dots for sensitive and selective detection of molybdate ions.

Abstract

Twokinds of carbon dots with the maximum fluorescence peak of 492 nm (named as G-CDs) and 607 nm (named as R-CDs) were synthesized. In the presence of MoO42- ions, the fluorescence of R-CDs at 607 nm can be quenched, which canprobably beassigned to their aggregation caused by MoO42-, while that of G-CDs at 492 nm remained unchanged. For the first time, aratiometric fluorescence probe was developed for MoO42- ions detection. In the range 0.25 ~ 100 μM, the fluorescence ratio (F492/F607) of theprobe was linearly related to MoO42- concentration, and the detection limit was 61.5 nM, which fully meets the minimum detection requirements of MoO42- ions in drinking water. On the other hand, when MoO42- was introduced, asignificant fading phenomenon of R-CDs can be observed with thenaked eye; thereby, the colorimetric method can also be proposed. Based on above, the ratiometric fluorometric/colorimetric dual-mode sensing method was established for MoO42- anion quantification. Compared with the traditional analysis methods, the results obtained by multimodal sensing can be mutually verified, which effectively improves the accuracy and reliability. The dual-mode assay proposed in this work provides an alternative scheme to meet the need of sensing target compoundsin complex matrices.