Highly Sensitive Indicator‐Free Impedance Sensing of DNA Hybridization Based on Poly(m‐aminobenzenesulfonic acid)/TiO₂ Nanosheet Membranes with Pulse Potentiostatic Method Preparation

Abstract

A direct electrochemical detection procedure for DNA hybridization by using the electrochemical signal changes of conductive poly(m-aminobenzenesulfonic) acid (PABSA)/TiO(2) nanosheet membranes, which were electropolymerized by using the pulse potentiostatic method, is reported. Due to the unique properties of TiO(2) nanoparticles, m-aminobenzenesulfonic acid monomers tend to be adsorbed around the particles, and the electropolymerization efficiency is greatly improved. The combination of TiO(2) nanoparticles and PABSA resulted in a nanocomposite membrane with unique and novel nanosheet morphology that provides more activation sites and enhances the surface electron-transfer rate. These characteristics were propitious for the magnification of PABSA electrochemical signals and the direct detection of DNA hybridization. Owing to the presence of abundant sulfonic acid groups, PABSA could overcome the drawbacks of polyaniline and be used to detect bioanalytes at physiological pH. DNA probes could be covalently attached to the sulfonic groups through the amines of DNA sequences by using an acyl chloride cross-linking reaction. After immobilization of probe DNA, the electrochemical impedance value increased significantly compared to that of PABSA/TiO(2) nanosheet membranes, and then decreased dramatically after the hybridization reaction of the probe DNA with the complementary DNA sequence compared to that of the probe-immobilized electrode. Electrochemical impedance spectroscopy was adopted for indicator-free DNA biosensing, which had an eminent ability for the recognition between double-base mismatched sequences or non-complementary DNA sequences and complementary DNA sequences. A gene fragment, which is related to one of the screening genes for the transgenically modified plants, the cauliflower mosaic virus 35S gene was satisfactorily detected. This is the first report for the indicator-free impedance DNA hybridization detection by using PABSA/TiO(2) membranes under neutral conditions.

Controllable fabrication of Au micro/nanostructures on self-doped polyaniline nanofibers via electrochemical deposition and its application for DNA immobilization

“…The peak currents at the nanoSPAN/GCE (curve b) increased compared with those of curve a. This was attributed to the net-like structure of nanoSPAN increasing the specific surface area of the electrode and good conductivity of nanoSPAN accelerating the redox reactions of [Fe(CN) 6 ] 3-/4- [25]. After the electrodeposition of Au, the peak currents in curves c, d, e and f further increased, indicating that nanoSPAN and Au micro/nanostructures synergistically facilitate the electron transfer between [Fe(CN) 6 ] 3-/4-and electrode surface.…”

“…Bode plots of logarithmic impedance (log Z) versus the logarithmic frequency from 10 5 to 1 Hz for the bare GCE, nanoSPAN/GCE and Au/nanoSPAN/GCEs prepared by the four described methods were recorded ( Figure 4) [25,26]. An obvious decrease in the impedance was observed between curves a and b.…”

Synergistic Effect of MWNTs/CeO2/CHIT Film for Detection of CdSe Nanoparticle Labeled Sequence‐Specific of 35S Promoter of Cauliflower Mosaic Virus Gene

“…This could be attributed to the excellent electronic conductivity and the large surface area originated from CeO 2 or MWNTs and the accumulation ability of CHIT with the negatively charged ferricyanide ions. In particular, the integrated introduction of MWNTs and CeO 2 in the CHIT (curve d) amplified the peak current by 2.44 times which revealed the presence of synergistic effects [24,25]. After the probe ssDNA was immobilized on the MWNTs/CeO 2 /CHIT modified electrode, the peak current decreased obviously (curve e).…”

Green-synthesized gold nanoparticles decorated graphene sheets for label-free electrochemical impedance DNA hybridization biosensing

“…Thus, in the field of biosensing, it is particularly suited to the detection of binding events and sensitive to changes in interfacial impedance upon bio-recognition events occurring at the surface/electrolyte interface (Hu et al, 2010). In addition, it is also a valuable tool in characterizing surface modifications, e.g.…”