Fabrication of a novel impedimetric biosensor for label free detection of DNA damage induced by doxorubicin.

In this work, a novel impedimetric biosensor has been fabricated for detection of DNA damage induced by doxorubicin (DX). Cytochrome P450 reductase (CPR) is required for electron transfer from nicotinamide adenine dinucleotide phosphate (NADPH) to cytochrome P450 (CP450) which causes DX to undergo a one-electron reduction of the p-quinone residue to form the semiquinone radical resulting in the generation of free hydroxyl radical which causes DNA damage. After modification of bare glassy carbon electrode (GCE) with multiwalled carbon nanotubes (MWCNTs) and chitosan (Ch), CPR and CP450 were co-immobilized onto the surface of Ch/MWCNTs/GCE by cross-linking CPR, CP450 and Ch through addition of glutaraldehyde. Then, the DNA was assembled onto the surface of CPRCP450/Ch/MWCNTs/GCE to fabricate the biosensor (DNA/CPRCP450/Ch/MWCNTs/GCE). Modifications applied to the bare GCE to fabricate the biosensor were characterized by CV, EIS and SEM. The DNA/CPRCP450/Ch/MWCNTs/GCE was treated in the damaging solution (DX + NADPH) which caused a significant DNA damage and the exposed DNA bases reduced the electrostatic repulsion of the negatively charged redox probe leading to Faradaic impedance changes. Performance of the biosensor for detection of DNA damage in the presence of Spinach extract was also examined and finally, an indirect impedimetric method was developed for determination of DX.