Enhanced Electrochemical Activity of a Hollow Carbon Sphere/Polyaniline-Based Electrochemical Biosensor for HBV DNA Marker Detection.

Herein, we present a novel, simple, and ultrasensitive electrochemical DNA (E-DNA) sensor based on hollow carbon spheres (HCS) decorated with polyaniline (PANI). A thiolated 21-mer oligonucleotide, characteristic of HBV DNA, is immobilized via electrodeposited gold nanoparticles on HCS-PANI. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) are used to characterize the electrochemical properties of the prepared nanocomposite. Scanning electron microscopy is employed to investigate the morphological texture of the fabricated modifier. An enhanced intrinsic signal of PANI is probed to evaluate the biosensing ability of the prepared modifier. The proposed biosensor allows for the detection of the target sequences of HBV DNA at a concentration as low as 10 fM (i.e., 109 DNA copies/mL). In addition, this biosensor demonstrated good capability to differentiate between the perfectly matched target oligonucleotide and three nucleotide-mismatched oligonucleotides. Furthermore, the HCS/PANI-based E-DNA sensor indicates highly sensitive detection of HBV DNA in real samples.