Electrochemical DNA Sensor Based on Poly(Azure A) Obtained from the Buffer Saturated with Chloroform

Abstract

Electropolymerized redox polymers offer broad opportunities in detection of biospecific interactions of DNA. In this work, Azure A was electrochemically polymerized by multiple cycling of the potential in phosphate buffer saturated with chloroform and applied for discrimination of the DNA damage. The influence of organic solvent on electrochemical properties of the coating was quantified and conditions for implementation of DNA in the growing polymer film were assessed using cyclic voltammetry, quartz crystal microbalance, and electrochemical impedance spectroscopy. As shown, both chloroform and DNA affected the morphology of the polymer surface and electropolymerization efficiency. The electrochemical DNA sensor developed made it possible to distinguish native and thermally and chemically damaged DNA by changes in the charge transfer resistance and capacitance.

Electrochemical Sensing of Idarubicin—DNA Interaction Using Electropolymerized Azure B and Methylene Blue Mediation

“…Nevertheless, it was obvious that, in the presence of chloroform, the peaks of monomeric and polymeric forms were much better resolved and defined. The influence of chloroform was previously considered for Azure A electropolymerization [21]. As was shown, the polymer deposited in the presence of the solvent contained more pores and showed higher adsorption capabilities than that obtained from aqueous media.…”

“…Then, it was immersed in 5 mL of 0.1 M HEPES buffer containing 0.03 M NaCl, pH 7.0 (in some experiments, saturated with chloroform as mentioned above) and 0.5 mM Azure B. The electropolymerization conditions of the Azure B were determined in [21,22] and used as follows. The electrode was polarized at 1.0 V for 300 s, then the potential of the electrode was cycled 20 times between −0.4 and 1.1 V with a scan rate of 100 mV/s.…”

“…In this respect, the use of redox active but not electroconductive polymers as matrices for DNA immobilization and signal generation can be advantageous. Recently, we have shown that the electropolymerization of phenazine and acridine dyes, e.g., proflavine [19], Azure A and Azure B [20,21], followed by DNA adsorption results in high sensitivity of the electrochemical properties of the coatings to DNA intercalation and damage. Indeed, they showed high sensitivity in anthracycline determination, though their signals were limited by the solubility of monomers in water and the moderate efficiency of electropolymerization protocol.…”

Polyelectrolyte–Dye Interactions: An Overview

“…The metachromatic action of cationic dyes is particularly helpful in determining the charges of biopolymers and proteins [ 73 ]. The specific interaction of the polymerized cationic dye azure A and the biological polyelectrolyte DNA was utilized to detect and discriminate DNA damage [ 74 ]. The electrostatic forces and the difference in the negative charges on the repetitive polysaccharide units of sodium heparin and sodium alginate led to different degrees of metachromasy induced in the cationic dyes azure B and toluidine blue [ 75 , 76 ].…”

Electrochemical DNA Sensor Based on Acridine Yellow Adsorbed on Glassy Carbon Electrode

“…However, their application in the assembly of DNA sensors is limited mostly by hybridization detection and anchoring other redox labels. Recently, we have shown the possibility to assemble DNA sensors based on the electropolymerization of Azure A and Azure B followed by electrostatic adsorption of native DNA [36][37][38]. The DNA sensors were successfully applied for sensitive determination of anthracycline.…”