A Highly Sensitive “on-off” Time-Resolved Phosphorescence Sensor Based on Aptamer Functionalized Magnetite Nanoparticles for Cadmium Detection in Food Samples

Abstract

Cadmium contamination is a severe threat to food safety. Therefore, the development of sensitive and selective cadmium detection strategies is urgently required. The elimination of background autofluorescence generated from the food matrix is critical to the optical assay for cadmium detection. Herein, a time-resolved phosphorescence sensor based on an “on-off” strategy was developed for cadmium determination in food samples. The phosphorescence nanoparticles were used as a luminous material to minimize the interference of background autofluorescence. The cadmium-binding aptamer was immobilized onto the magnetic beads and combined with a black hole quencher 1 (BHQ1) with complementary DNA as the target recognition element. With the presence of cadmium, the cadmium-binding aptamer bound to cadmium specifically and resulted in the release of BHQ1. The free BHQ1 remained in the solution after magnetic separation and quenched the phosphorescence. The phosphorescence intensity was negatively related to the concentration of cadmium. Under optimal conditions, the time-resolved phosphorescence sensor showed a linear response to cadmium concentration within a range from 0.05 to 5 ng mL−1 and with a detection limit of 0.04 ng mL−1. This “on-off” time-resolved phosphorescence sensor was successfully applied for cadmium detection in spring water and clam samples, which provided a rapid and straightforward method.

A Simple and Rapid “Signal On” Fluorescent Sensor for Detecting Mercury (II) Based on the Molecular Beacon Aptamer

“…Aptamers have received more and more attention in the construction of biosensors in the past few years. Recently, various strategies based on aptamers for metal ion detection have been developed, including Hg 2+ [16,17], Pb 2+ [18], Cd 2+ [19] and so on. Studies had shown that thymine-thymine (T-T) mismatched duplexes in DNA can selectively bind closely to Hg 2+ to form thymine-Hg 2+ -thymine (T-Hg 2+ -T)-mediated DNA duplexes [12].…”

Detection of Cadmium(II) in Aquatic Products Using a Rolling-Circle Amplification-Coupled Ratio Fluorescent Probe Based on an Aptamer–Peptide Conjugate

“…Rapid industrialization in recent years has led to increases in the use of Cd 2+ . Cadmium-containing pollutants in the aquatic environment are becoming increasingly common, exacerbating Cd 2+ contamination of aquatic products. − To regulate the market and ensure the safety of food for humans, the World Health Organization set a standard of limited detection amount of Cd 2+ in drinking water as 0.003 mg L –1 and the Chinese government has established a maximum residue limit for Cd 2+ in food (0.0001 mg L –1 for aquatic products). , However, Cd 2+ overload in aquatic products is still common. − Food has been reported to be one of the major sources of Cd 2+ exposure. Cd 2+ were detected in seaweeds, crustaceans, shellfish, and cephalopods .…”

“…3−5 To regulate the market and ensure the safety of food for humans, the World Health Organization set a standard of limited detection amount of Cd 2+ in drinking water as 0.003 mg L −1 and the Chinese government has established a maximum residue limit for Cd 2+ in food (0.0001 mg L −1 for aquatic products). 6,7 However, Cd 2+ overload in aquatic products is still common. 8−10 Food has been reported to be one of the major sources of Cd 2+ exposure.…”