Highly conductive MXene-Au NPs and high current AuPd NPs/UiO-66 electrochemical sensor combining multiple signal amplification strategies for tetracycline detection

Abstract

Tetracycline (TET) was the most commonly used antibiotic in animal husbandry because of its low price, low toxicity, and wide range of antimicrobial effects. Here, an electrochemical sensor for TET detection was developed using MXene-Au NPs nanocomposites combined with the signal probe MB/AuPd NPs/UiO-66, leveraging multiple signal amplification strategies. The sensor was used in situ grown gold nanoparticles (Au NPs) in MXene with a multilayer structure as the electrode modification material. The current signal was significantly increased by a factor of 1.42 due to the large specific surface area and high electrical conductivity of the modified material. Meanwhile, AuPd NPs/UiO-66 loaded with methylene blue (MB) was also utilized as a signal probe, which combines the advantages of high current signal, good stability and low cost. Then dual signal amplification strategies were used to increase the sensitivity of the sensor. Taking advantage of the longer length of the aptamer (Apt), one Apt is cleverly designed to link three ssDNA, which releases three ssDNA when the target was present, acting as a triple signal amplification. A large number of signal probes can be attached to the electrodes after assembling the cycle using catalytic hairpins assembly (CHA), which has the advantage of low cost and fast response time. Ultimately in the presence of the target the signal probes can be attached to the electrode in large numbers, which improved the signal response. Under the best conditions, the detection range of the sensor was 0.001–500 ng/mL, and the limit of detection (LOD) was 0.789 pg/mL.