Construction of a Novel Colitoxin DNA Biosensor Based on Cross-Linker-Free Fixation of Probe Fragments on the Interface of Rugby-Ball-Shaped CoS₂ Submicroparticles and Poly(2-thiophenesulfonyl chloride) Composite Film

Abstract

Rugby-ball-shaped CoS 2 (rCoS 2 ) submicroparticles have been synthesized via a simple hydrothermal reaction. The rCoS 2 submicroparticles were then casted on a glassy carbon electrode and served as a highly conductive and large surface area platform for the electrosynthesis of poly(2-thiophenesulfonyl chloride) (pTSC), using 2-thiophenesulfonyl chloride as the monomer. The stepwise modification process was characterized by attenuated total reflectance−Fourier transform infrared spectroscopy (ATR-FTIR) and different electrochemical technologies. The stable pTSC layer was utilized as a functional interface to immobilize amino-modified probe DNA via a facile sulfonyl−amino condensation reaction, without the assistance of any other cross-linkers. Because of the synergistic effect of rCoS 2 and pTSC from the hybrid material, the developed DNA biosensor could detect target DNA over a wide dynamic range, from 1.0 × 10 −13 to 1.0 × 10 −7 M, with the detection limit down to 1.1 × 10 −14 M. Benefiting from the steady electropolymerization film of pTSC and the stable sulfamide bond between the amino-modified DNA and pTSC, the biosensor also showed high stability, reusability, and reproducibility.