A label-free electrochemical aptasensor combined Au/Ag@ZIF-8 and dual amplification strategy for sensitive detection of β-lactoglobulin

β-lactoglobulin (β-LG) is a major allergen in milk what can provoke intense allergic reactions. Therefore, an accurate and efficient method is required for sensitive detection of β-LG. A label-free electrochemical aptasensor utilizing Au/Ag@ZIF-8 and dual amplification strategy has been designed for the detection of β-LG. Au/Ag@ZIF-8 nanocomposite is used as the electrode modification material, which has abundant relative surface area and exceptional conductivity behavior, and it can also serve to immobilize DNA strands. By combining RecJf exonuclease and hybridization chain reaction (HCR) dual amplification strategy, an apparent enhancement of electrochemical signal is obtained. β-LG undergoes target cycling in the effect of RecJf exonuclease, which dislodges complementary strand cDNA and further triggers HCR to provide a large number of sites for methylene blue embedding. The detection range of this aptasensor is 0.01–1000 ng/mL in the optimal detection conditions, with a limit of detection (LOD) of 5.37 pg/mL. The constructed electrochemical aptasensor possesses the superiorities of good specificity, preeminent accuracy and satisfied stability in the detection of β-LG. Moreover, it also demonstrates satisfactory detection performance in the detection of real samples, which indicates that the electrochemical aptasensor has a broad application prospect in protecting food safety and health.