Abstract
In this study, we developed a modified glassy carbon electrode (GCE) with graphene oxide, multi-walled carbon nanotube hybrid nanocomposite in chitosan (GCE/GO-MWCNT-CHT) to achieve simultaneous detection of four nucleobases (i.e., guanine (G), adenine (A), thymine (T) and cytosine (C)) along with uric acid (UA) as an internal standard. The nanocomposite was characterized using TEM and FT-IR. The linearity ranges were up to 151.0, 78.0, 79.5, 227.5, and 162.5 µM with a detection limit of 0.15, 0.12, 0.44, 4.02, 4.0, and 3.30 µM for UA, G, A, T, and C, respectively. Compared to a bare GCE, the nanocomposite-modified GCE demonstrated a large enhancement (~36.6%) of the electrochemical active surface area. Through chronoamperometric studies, the diffusion coefficients (D), standard catalytic rate constant (Ks), and heterogenous rate constant (Kh) were calculated for the analytes. Moreover, the nanocomposite-modified electrode was used for simultaneous detection in human serum, human saliva, and artificial saliva samples with recovery values ranging from 95% to 105%.
Highlights
Deoxyribonucleic acid (DNA) is an important bio-macromolecule which plays a critical role in the storage of genetic information and the overall functioning of biological systems [1,2,3,4,5]
We developed a novel nanocomposite of graphene oxide (GO)-multi-walled carbon nanotube (MWCNT) hybrid in chitosan (CHT) for the modification of a glassy carbon electrode (GCE) surface (GCE/GO-multi-walled carbon nanotubes (MWCNTs)-CHT) and utilized this modified GCE for the simultaneous determination of all four DNA bases in presence of uric acid (UA) as the internal standard
Uric acid (UA), guanine (G), adenine (A), thymine (T), cytosine (C), graphene oxide (GO, 2 mg/mL, dispersion in water), chitosan (CHI), potassium ferricyanide (III), potassium ferrocyanide (II), potassium chloride, phenol: chloroform: isoamyl alcohol (24:25:1 v/v), acetic acid, hydrochloric acid, sulfuric acid, and human serum (H4522-20 mL) were all acquired from Sigma–Aldrich (Oakville, ON, Canada)
Summary
Deoxyribonucleic acid (DNA) is an important bio-macromolecule which plays a critical role in the storage of genetic information and the overall functioning of biological systems [1,2,3,4,5]. Brett et al [7] were the first to report the electrochemical oxidation of all four DNA bases at a GCE in highly basic conditions In their method, linear ranges for detecting all nucleobases were quite narrow: from 0.2 to 10 μM for purines and 1 to 20 μM for pyrimidines [7]. To the best of our knowledge, no study has been done to detect all four bases simultaneously in the presence of UA using nanocomposite modification of GCE Both GO and MWCNT have been widely used nanomaterials for the modification of electrodes since they possess excellent mechanical flexibility, bio-compatibility, stability, large surface area, and high electrochemical conductivity [10,22,23,24]. GCE/GO-MWCNT-CHT can serve as an excellent platform for simultaneously detecting all four DNA bases and UA with good sensitivity
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