Electrochemical DNA Biosensor for Detection of Hepatitis C Virus Using a 3D Poly-L-Lysine/Carbon Nanotube Film

Hepatitis C represents a critical global health crisis, causing approximately 1.4 million deaths annually. Although 98% of cases are treatable, only about 20% of infected individuals know their hepatitis C virus (HCV) status, highlighting the urgent need for rapid and more efficient diagnostic management. Viral genetic material can be detected in serum or plasma within just one week of exposure, making it the most reliable marker and the gold standard for active HCV infection diagnosis. In this study, a biosensor was developed to detect conserved nucleotide sequences of HCV using a 3D surface electrode composed of poly-L-lysine (PLL) and carbon nanotubes (CNTs). PLL is a positively charged biocompatible polymer rich in amine groups, attractive for the immobilization of proteins, DNA, and other biomolecules. PLL was employed to construct a 3D surface with vertically aligned CNTs, achieving a high electron transfer rate. Cyclic voltammetry technique and scanning electron microscopy (SEM) were used to characterize the sensor platform, and analytical responses were measured by differential pulse voltammetry. This HCV biosensor detected the hybridization event by a significant reduction in DPV peaks in the presence of the ferri/ferrocyanide redox probe, without any intercalator agents. DNA responses were observed in phosphate-buffered saline (PBS) and cDNA-spiked serum samples, demonstrating its analytical specificity. These findings represent advances in analytical tools that can effectively address the challenges of timely diagnosis for asymptomatic HCV carriers.