Visual sensor application of a graphene quantum dot-semiconductor quantum dot nanohybrid based on ratiometric fluorescence

A novel ratiometric fluorescence probe consisting of CdTe quantum dots (QDs) and amine functionalized graphene quantum dots (GQDs) is designed for the detection of Fe(II) ions. Amine-GQDs were prepared with pyrene as a precursor while CdTe QDs were prepared with tellurium powder and cadmium chloride dihydrate. The characterization of both QDs prepared were discussed in the report. An optimised concentration of GQDs and CdTe QDs was used in the preparation of the ratiometric fluorescence probe to obtain an appropriate fluorescence intensity ratio and observable fluorescence colorimetric change. It was found that the ratiometric fluorescent probe has a sensitivity of 0.2μM for ferrous ions. The selectivity of the ratiometric fluorescent probe was also studied against other transition metal that are commonly biologically found.