Detection and discrimination of recombinant plasmid encoding hepatitis C virus core/E1 gene based on PNA and double-stranded DNA hybridization.

Development of an electrochemical DNA biosensor for direct detection and discrimination of double-stranded plasmid (ds-Pl) without the need for denaturation of the target plasmid sample using a peptide nucleic acid (PNA) oligomer as the probe is described. This goal was achieved by modification of gold electrode with 6-mercapto-1-hexanol following monolayer self-assembly of cysteine conjugated 20-mer PNA oligomer probe, complementary to the HCV core/E1 region, which binds to ds-Pl and forms PNA/ds-Pl structure. The significant variation in differential pulse voltammetric response of methylene blue on the probe modified electrode upon contacting with complementary double-strand plasmid to form PNA/ds-Pl triplex structure is the principle of target plasmid detection. The results indicated that the reduction peak current was linear with the concentration of complementary strand in the range of 10-300 pg/μl with a detection limit of 9.5 pg/μl.