Functionalized polyaniline nanowires for biosensing

Conducting polymers and related nanomaterials are widely used for different biosensing applications. In the present work gold nanoparticles (AuNP) incorporated polyaniline nanowires (PAn-NW) were used for fabrication of a novel biosensing platform. PAn-NW with AuNP (8–10 nm) was treated with β-mercaptoethylamine (MEA) that leads to the formation of the NH2 functionalized PAn-AuNP in dispersed form. Immobilizing the functionalized dispersion on the Pt electrode makes a biosensing platform suitable for attachment of different biomolecules via NH2 functionality and sensing of the target elements in turn. Efficiency of the system as oligonucleotide (dA–dT) sensor was examined by immobilizing a single stranded oligonucleotide (ssdA) and monitoring its hybridization with target nucleotide (ssdT) following cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The system works well even at concentrations as low as 10−18 M (of target nucleotide) and produces substantially large peak current (mA) in DPV. On the other hand it produces a huge change in impedance at low frequencies (EIS), after hybridization with complementary strand.