Modeling of DNA hybridization detection using methylene blue as an electroactive label

Mathematical modeling of methylene blue (MB) signal in ssDNA and dsDNA on pencil graphite electrode is described. A DNA biosensor was developed based on MB signal. The probe and target DNAs were 20 mer oligonucleotides corresponding to consensus sequence of HPV major capsid protein L1 gene. Hybrids of various complementary and non-complementary oligonucleotides with the probe were considered as dsDNA with different hybridization degrees. Modeling was developed by incorporation of only the stable forms of dsDNA hybrids. Effect of hybridization degree on current signal in various forms was studied. A factor named AHP (Average Hybridization Percentage) for verifying the hybridization events was defined. Results showed that there is a significant mathematical relation between the calculated AHP and MB signals.