A Label-Free Aptamer-Based Fluorescent Assay for Cadmium Detection

Selective detection of ultratrace amounts of cadmium (Cd2+) is extremely important for food safety and environmental monitoring because of its toxicity and widespread use. In this work, we developed a facile, rapid, sensitive, and highly selective method for the detection of Cd2+ based on a label-free aptasensor using an unmodified double-stranded deoxyribonucleic acid-specific dye (PicoGreen). The linear range was 0.10–100 µg/mL, and the detection limit (0.038 ng/mL) was lower than the guideline from the World Health Organization for Cd2+ in drinking water (3 ng/mL). The sensor exhibited excellent selectivity towards Cd2+ ions. We tested the aptasensor in application to a series of real water samples spiked with different concentrations of Cd2+. Compared with atomic absorption spectrometry, the results showed good tolerance to the matrix effect. The developed approach shows great potential for on-site and high-throughput analysis in routine monitoring.