The high demand for devices with higher sensitivity as well cost-efficiency has put tremendous pressure on the biosensors field. The numerous advantages of Field effect transistors (FETs) such as small size, fast response, label free response, and possibility of on-chip integration of biosensor arrays with a future prospect of low-cost mass production, make their development highly desirable. An elec-trochemical deoxyribonucleic acid (DNA) biosensor using a synthesized ferrocene-based DNA interca-lator as a redox marker was investigated. A peptide nucleic acid (PNA) was employed as a capture probe and co-immobilized on electrodes with 6-mecarpto-hexanol (MCH) to control the surface density of the probe, and hybridized with complementary DNA. After hybridization, a ferrocene-based intercalator was introduced to bind with the PNA-DNA duplex and change the surface potential. Biologically sen-sitive field-effect transistor (BioFET) was used to monitor the DNA recognition. As confirmation, elec-trochemical impedance spectroscopy (EIS) was also used to characterize the different modification steps. Differential pulse voltammetry (DPV) was employed to evaluate the electrochemical signal of the intercalator, related to its interaction with the PNA-DNA duplex. An optimization of the PNA probe surface density was also tried, with the density being controlled by the MCH ratio in solution. Hybridi-zation of PNA-DNA with a PNA/MCH ratio of 1:29 was obtained in BioFET and EIS, the employed intercalator showed to have poor stability, both in application in BioFET as in DPV. Different ratios were tried and the use of different electrodes was also exploit
