Switch-Type\nElectrochemiluminescence Aptasensor for\nAFB1 Detection Based on CoS Quantum Dots Encapsulated in Co-LDH and\na Ferrocene Quencher

Among the various aflatoxin B1 (AFB1) assays, performing\naccurate\ndetection is difficult because false positives and false negatives\nare frequent due to limited sensitivity, expensive equipment, or inadequate\npretreatment during operation. Here, an “off–on”\nswitch-type electrochemiluminescence (ECL) aptasensor armed with cobalt–sulfur\nquantum dots was encapsulated in hollow cobalt-layered double hydroxide\nnanocages as an enhanced luminescent probe (Co-LDH@QDs), and a ferrocene-modified\naptamer (Fc-APT) was used as a luminescent quencher. In general, when\nFc-APT was hybridized with complementary DNA modified with a DNA nanotetrahedron,\nelectron transfer between ferrocene and Co-LDH@QDs was facilitated,\nleading to efficient quenching of the ECL intensity into an “off”\nstate in the absence of AFB1. In the presence of AFB1, the intensity\nof ECL increased with an increasing AFB1 concentration after Fc-APT\nspecifically recognized that AFB1 was detached from the electrode\ninterface to achieve an “on” state. The linear range\nof the proposed ECL aptasensor for AFB1 detection was 0.1 pg mL<sup>–1</sup> to 10 ng mL<sup>–1</sup>, with a detection\nlimit of 0.03 pg mL<sup>–1</sup>. We successfully employed\nthe proposed ECL aptasensor for corn application, which provides an\neconomical and simple alternative to complex and costly enzyme-linked\nimmunoassays. The switch-type ECL aptasensor provides quick, accurate,\nand prospective technological support for pinpoint management of food\nsafety.