Surface-functionalized MoS2 ultrathin nanosheets for electrochemical monitoring terminal deoxynucleotidyl transferase activity based on in-situ polymerized DNA

Abstract

An efficient electrochemical biosensing strategy for terminal deoxynucleotidyl transferase (TdT) activity is developed based on thionin functionalized MoS2 ultrathin nanosheets (Th/MoS2 UTNS) and TdT-induced DNA polymerization. MoS2 ultrathin nanosheets is firstly achieved via a facile pyrolytic approach assisted by g-C3N4 sacrificial template. Followed by subsequent surface-functionalization with thionin, the Th/MoS2 UTNS composite is obtained and designed as a sensing platform for TdT activity detection. In this approach, TdT catalyzes the polymerization of deoxyribonucleotides triphosphate (dNTP) substrate of 50% dATP-50% dTTP to the 3′-OH terminus of DNA primer and in-situ produces dsDNA consequently, which can be strongly immobilized onto thionin by intercalation and electrostatic interaction, resulting in a decreased redox signal of thionin. The proposed sensor exhibits a wide linear response for TdT in the range from 0.01 U to 2.44 U with a low detection limit of 0.0025 U. By elucidating an efficient biosensing platform on the basis of surface engineered MoS2 ultrathin nanosheets, this work sheds light on the development of novel strategy for detecting other nucleic acid or protein analytes.