A ratiometric magnesium sensor using DNAzyme-templated CdTe quantum dots and Cy5

DNAzyme-templated CdTe quantum dots (DNAzyme-CdTe QDs) were synthesized through a facile one- step route and the obtained QDs were used to fabricate a novel ratiometric magnesium sensor. Crosslinking and surface modification process of QDs were not the necessary step in this synthesis. By catalyzing the DNAzyme sensing system, composed of DNAzyme- CdTe QDs and Cy5 labeled substrate strand, Mg2+ was detected. The fluorescent intensity ratio between CdTe QDs and Cy5 showed a good linear relationship with Mg2+concentration. The sensor displayed a wide range of linear response (0–20 nM), low detection limit (0.3 nM, (S/N = 3)), good reproducibility, stability and selectivity.