Electrochemical detection of human papilloma virus (HPV) target DNA using MB on pencil graphite electrode

The present paper describes the use of methylene blue (MB) as an electroactive label on a pencil graphite (lead) electrode (PGE) to provide a well-defined recognition interface for the detection of HPV target DNA. In order to construct the sensor, a 20-mer single strand oligonucleotide probe related to human papilloma virus (HPV) major capsid protein L1 gene was immobilized on the PGE electrode. Hybridization event between the probe and its complementary sequence was studied by measurement of MB signal accumulated on the PGE using square wave voltammetry (SWV) method. Some hybridization experiments with non-complementary oligonucleotides were carried out to examine the selectively of the sensor to the target DNA from other DNAs related to Hepatitis C virus (HCV), fungi, and bacterial genes. Moreover, some factors affecting the function of sensor including electrode activation and probe immobilization condition were also investigated. The data showed that the constructed electrode detects the target DNA with detection limit of 1.2 ng mu l(-1) and discriminates it from various DNAs originated from a wide variety of organisms.