Simultaneous electrochemical determination of DNA nucleobases using AgNPs embedded covalent organic framework.

Abstract

Anefficient electrochemical biosensor has beendeveloped for the simultaneous evaluation of DNA bases using AgNPs-embedded covalent organic framework (COF). The COF (p-Phenylenediamine and terephthalaldehyde) was synthesized by reflux (DMF; 150°C; 12h) and the nanoparticles were embedded from the aqueous solutions of AgNO3 and NaBH4. The nanocomposite-modified COF was confirmed by spectral, microscopic, and electrochemical techniques. The nanocomposite material was deposited on aglassy carbon electrode (GCE) and the redox behavior of AgNPs was confirmed by cyclic voltammetry. The electrocatalytic activities of DNA bases were analyzed by differential pulse voltammetry (DPV) in a physiological environment (PBS; pH = 7.0) based on simple and easy-to-use electrocatalyst. The AgNPs-COF/GCE showed well-defined anodic peak currents for the bases guanine (+ 0.63V vs. Ag/AgCl), adenine (+ 0.89V vs. Ag/AgCl), thymine (+ 1.10V vs. Ag/AgCl), andcytosine (+ 1.26V vs. Ag/AgCl) in a mixture as well as individuals with respect to the conventional, COF, and AgNPs/GCEs. The AgNPs-COF/GCE showed linear concentration range of DNA bases from 0.2-1000µM (guanine; (G)), 0.1-500µM (adenine (A)), 0.25-250µM (thymine (T)) and 0.15-500µM (cytosine (C)) and LOD of 0.043, 0.056, 0.062, and 0.051µM(S/N = 3), respectively. Thedeveloped sensor showedreasonable selectivity, reproducibility (RSD = 1.53 ± 0.04%-2.58 ± 0.02% (n = 3)), and stability (RSD = 1.22 ± 0.06%-2.15 ± 0.04%; n = 3) over 5days of storage) for DNA bases. Finally, AgNPs-COF/GCE was used for the determination of DNA bases in human bloodserum, urine and saliva samples with goodrecoveries (98.60-99.11%, 97.80-99.21%, and 98.69-99.74%, respectively).