Visualized electrochemiluminescence detection of trace copper in practical food samples

Copper as a widely applied element in food supply chain can cause serious contamination issues that threats food safety. In this research, we present a quick and visible method for trace copper ion (Cu²⁺) quantification in practical food samples. Polymer dots (Pdots) were firstly conjugated with a copper-specific DNA aptamer and then tailored with rhodamine B (RhB) to extinguish the electrochemiluminescence (ECL) signal through a resonance energy transfer process. The selective release of RhB leads to signal restoration when exposed to trace Cu²⁺ levels, achieving remarkable linearity with the logarithm of Cu²⁺ concentration within the range of 1 ng/L to 10 μg/L with an impressively low limit of detection at 11.8 pg/L. Most notably, our device was also applicable on visualizing and quantifying trace Cu²⁺ (∼0.2 μg/g) in practical Glycyrrhiza uralensis Fisch. samples, underscoring its potential as a tool for the early prevention of potential copper contamination in food samples.