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

Rugby-ball-shaped CoS2 (rCoS2) submicroparticles have been synthesized via a simple hydrothermal reaction. The rCoS2 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 rCoS2 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 elec...