Bifunctional ratiometric fluorescent probe for sensing anthrax spore biomarker and tetracycline at different excitation channels

Multifunctional fluorescent probes have received increasing attention for the sake of atom economy and high -density integration. Herein, CdTe quantum dots (QDs) modified with Eu3+ were synthesized as the bifunc-tional ratiometric fluorescent probe for sensing two hazardous substances tetracycline (TC) and anthrax spore biomarker 2,6-dipicolinic acid (DPA) at different excitation channels, based on the discrepant excitation wavelengths of Eu3+ and the fluorescence quenching of CdTe QDs after interaction with them. Both DPA and TC enhanced the red emission of Eu3+ via antenna effect but caused the green emission of CdTe QDs to quench. Interestingly, the excitation wavelengths of Eu3+ after coordinating with DPA and TC were 275 and 386 nm, respectively. On this basis, CdTe QDs-Eu3+ achieved the bifunctional ratiometric detection of DPA (lambda ex = 275 nm) and TC (lambda ex = 386 nm) with different excitation channels. Both DPA and TC were selectively detected by CdTe QDs-Eu3+ with rapid response (DPA-1 min, TC-1 min) and high sensitivity (DPA-LOD 0.3 mu M, TC-LOD 2.2 nM). CdTe QDs-Eu3+ were applied to analyzing DPA and TC in food, biological and environmental samples. Satisfactory spiked recoveries (80.0-119.0 %) and relative standard deviations (0.5-8.4 %) were obtained for measuring DPA and TC in these samples.

Automated summary

In this study, CdTe quantum dots (QDs) modified with Eu3+ were synthesized as a bifunctional ratiometric fluorescent probe for the simultaneous detection of tetracycline and anthrax spore biomarker. The probe exhibited distinct fluorescence properties for the two substances in different excitation channels. It demonstrated rapid response, high sensitivity, and good applicability in analyzing various samples.