Two kanamycin electrochemical aptamer-based sensors using different signal transduction mechanisms: A comparison of electrochemical behavior and sensing performance

Two typical kanamydn-A (KAN-A) electrochemical aptamer-based sensors employing different signal transduction mechanisms were deliberately designed and constructed with a similar structure. One sensor (sensor-1) was based on the classical probe conformation changing mode (PCCM) with a methylene blue (MB) label used as an electrochemical tag; the other sensor (sensor-2) used the target-induced signal probe shifting (TISPS) method with a free MB label in the assay solution. The difference in signal transduction mechanisms resulted in big differences in basic electrochemical behavior and comprehensive sensing performance. The results show that both sensor types exhibit different electrochemical behavior in square wave voltammetry, cyclic voltammetry, and in sensitivity, with detection limits of 3.0 nM for sensor-1 and 60.0 pM for sensor-2 in buffer. When validated for practical and quantitative detection of tap water and milk samples, both sensing methods performed well with detection limits of <260 nM and measurement times of <40 min. In addition, accuracy was good with mean recoveries of 72.3-92.6% and precision was acceptable with a relative standard deviation (RSD) of <= 14.2%. The basis for the similarities and differences in performance is also presented. (C) 2019 Elsevier B.V. All rights reserved.