Electrochemical determination of purine and pyrimidine bases using copper doped cerium oxide nanoparticles

Abstract

Deoxyribonucleic acid (DNA), a primary unit of heredity in all types of organisms, consists of purine and pyrimidine bases in such a way that the amount of guanine (GU) is equal to cytosine (CY) and the amount of adenine (AD) is equal to thymine (TY). Any abnormalities in the concentration of these four bases will have significant influence on disease diagnosis, crime detection and biocomputing applications of DNA. Hence, identification and quantification of either individual or group of these DNA bases are important for diagnosis of certain diagnosis and genetic disorders. In the present work, we report the fabrication of an efficient electrochemical sensor for simultaneous determination of purine (GU, AD) and pyrimidine (CY, TY) bases using Cu doped CeO₂ nanoparticles modified glassy carbon electrode (Cu-CeO₂/GCE). The direct electrocatalytic activities of DNA bases have been studied using voltammetric techniques in phosphate buffer solution (PBS, pH 7.0) without any enzyme or mediator. 3 wt% Cu doped CeO₂ modified GCE showed two well defined anodic peaks each towards the oxidation of purine and pyrimidine bases with significant peak to peak potential separation of 312 mV (AD-GU) and 200 mV (TY-CY) which were large enough for the selective and simultaneous determination of these bases in their mixture. Under optimum conditions, calibration plots for the simultaneous detection of the purine and pyrimidine bases were linear in the concentration range of 0.1-500 μM for AD, 1-650 μM for GU, 1-300 μM for TY and 1-250 for CY with the lowest detection limit values of 0.021, 0.031, 0.024, and 0.038 μM respectively. Additionally, the developed sensor exhibited good repeatability, reproducibility, sufficient stability and good anti-interference ability and was successfully applied for simultaneous detection of AD, GU, TY and CY in denatured DNA sample with satisfactory results.

Keywords: Adenine; Cu-CeO(2) nanoparticles; Cytosine; Deoxyribonucleic acid; Electrochemical sensor; Guanine; Thymine.