Disposable DNA biosensor with the carbon nanotubes–polyethyleneimine interface at a screen-printed carbon electrode for tests of DNA layer damage by quinazolines
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A screen-printed carbon working electrode within a commercially available screen-printed three-electrode assembly was modified by using a composite of multiwalled carbon nanotubes (MWCNT) dispersed in polyethylenimine (PEI) followed by covering with the calf thymus dsDNA layer. Several electrochemical methods were used to characterize the biosensor and to evaluate damage to the surface-attached DNA: square wave voltammetry of the [Ru(bpy)3]2+ redox indicator and mediator of the guanine moiety oxidation, cyclic voltammetry and electrochemical impedance spectroscopy in the presence of the [Fe(CN)6]3−/4− indicator in solution. Due to high electroconductivity and large surface area of MWCNT and positive charge of PEI, the MWCNT–PEI composite is an advantageous platform for the DNA immobilization by the polyelectrolyte complexation and its voltammetric and impedimetric detection. In this respect, the MWCNT–PEI interface exhibited better properties than the MWCNT–chitosan one reported from our laboratory previously. A deep DNA layer damage at incubation of the biosensor in quinazoline solution was found, which depends on the quinazoline concentration and incubation time.
KeywordsScreen-printed carbon electrode DNA biosensor Carbon nanotubes Polyethylenimine Quinazoline
This work was supported by the Applied Research Project of the Ministry of Education of Slovak Republic (AV/4/0103/06) and Scientific Grant Agency VEGA project (1/0852/08). The authors thank gratefully Assoc. Prof. Š. Stankovský, Assoc. Prof. K. Špirková, and Assoc. Prof. S. Jantová (STU in Bratislava) for the quinazoline preparatives and Dr. G. Ziyatdinova (Kazan State University, Kazan, Russia) for help with the impedimetric measurements.
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