Electrochemical Impedance Sensing of DNA Hybridization on Conducting Polymer Film-Modified Diamond

Abstract

The impedimetric sensing of DNA hybridization on polyaniline/polyacrylate (PANI/PAA)-modified boron-doped diamond (BDD) electrode has been investigated. An ultrathin film of PANI-PAA copolymer was electropolymerized onto the diamond surfaces to provide carboxylic groups for tethering to DNA sensing probes. The electrochemical impedance and the intrinsic electroactivity of the polymer-diamond interface were analyzed after the hybridization reaction with target and non-target DNA. The impedance measurement shows changes in the impedance modulus as well as electron-transfer resistance at the stage of probe DNA immobilization (single-strand), as well as after hybridization with target DNA (double-strand). DNA hybridization increases the capacitance of the polymer-DNA layer and reduces the overall impedance of the DNA-polymer-diamond stack significantly. The polymer-modified BDD electrode shows no detectable nonspecific adsorption, with good selectivity between the complementary DNA targets and the one-base mismatch targets. The detection limit was measured to be 2 x 10(-8) M at 1000 Hz. Denaturing test on the hybridized probe and subsequent reuse of the probe indicates chemical robustness of the sensor. Our results suggest that electropolymerization followed by the immobilization of biomolecules is a simple and effective way of creating a functional biomolecular scaffold on the diamond surface. In addition, label-free electrochemical impedance method can provide direct and noninvasive sensing of DNA hybridization on BDD.

Synthetic diamond films as a platform material for label‐free protein sensors

“…The field-effect in NCD substrates, caused by negatively charged DNA at the surface, has been reported in our previous work on real-time impedimetric DNA detection [10] as well as in other publications [9,28] and will not be discussed here. A negligible field-effect in the NCD substrate was observed during CRP treatment, reflected by the lack of impedance variations in the semi-circle.…”

Diamond nano-wires, a new approach towards next generation electrochemical gene sensor platforms

“…The overall performance of the diamond nano-wire DNA sensor in comparison to published data available in the literature for Au, [43][44][45][46] and polycrystalline diamond, [47] using comparable DNA mere structures are shown in Fig. 5e [47]). Sensing by diamond nano-wires is about 100 to 1000 better than using smooth surfaces from Au and diamond.…”

Evolution towards the implementation of point-of-care biosensors

“…Cai et al (2004) immobilized ssDNA onto Si electrodes, and demonstrated that they were able to distinguish complementary DNA from DNA containing 4-base mismatches as compared to the immobilized probe DNA (Cai et al, 2004). Gu et al (2005) and Vermeeren et al (2007) even succeeded in single-nucleotide polymorphism (SNP) sensitivity, the latter in real-time (Gu et al, 2005), (Vermeeren et al, 2007). Fig.…”

“…Adapted from (Nebel et al, 2007). Gu et al (2005) functionalized p-type diamond with a PANI/polyacrylic acid (PAA) composite polymer films using CV. The p-type diamond working electrode was treated with the aniline and PAA monomeric solution, and by potential cycling the monomers were polymerized onto the electrode.…”