Terminal Deoxynucleotidyl Transferase Extension-Dominated In Situ Signal Attenuation-Free Electrochemical Platform and Its Logic Gate Manipulation

Abstract

Signal generation of traditional electrochemical biosensors suffers from the random diffusion of electroactive probes in a electrolyte solution, which is accompanied by poor reaction kinetics and low signal stability from complex biological systems. Herein, a novel circuit system with autonomous compensation solution ohmic drop (noted as “fast-scan cyclic voltammetry (FSCV)”) is developed to solve the above problems, and employed to achieve terminal deoxynucleotide transferase (TdT) and its small molecule inhibitor analysis. At first, a typical TdT-mediated catalytic polymerization in the conditions of original DNA, deoxythymine triphosphate (dTTP) and Hg2+ is applied for the electrode assembly. The novel electrochemical method can provide some unattenuated signals due to in situ Hg redox reaction, thus improving reaction kinetics and signal stability. This approach is mainly dependent on TdT-mediated reaction, so it can be applied properly for TdT investigation, and a detection limit of 0.067 U ml−1 (S/N = 3) is achieved successfully. More interesting, we also mimic the function of TdT-related signal communication in various logic gates such as YES, NOT, AND, N-IMPLY, and AND-AND-N-IMPLY cascade circuit. This study provides a new method for the detection of TdT biomarkers in many types of diseases and the construction of a signal attenuation-free logic gate.