Fast and Ultrasensitive Electrochemical Detection for Antiviral Drug Tenofovir Disoproxil Fumarate in Biological Matrices

Abstract

Tenofovir disoproxil fumarate (TDF) is an antiretroviral medication with significant curative effects, so its quantitative detection is important for human health. At present, there are few studies on the detection of TDF by electrochemical sensors. This work can be a supplement to the electrochemical detection of TDF. Moreover, bare electrodes are susceptible to pollution, and have high overvoltage and low sensitivity, so it is crucial to find a suitable electrode material. In this work, zirconium oxide (ZrO₂) that has a certain selectivity to phosphoric acid groups was synthesized by a hydrothermal method with zirconyl chloride octahydrate as the precursor. A composite modified glassy carbon electrode for zirconium oxide-chitosan-multiwalled carbon nanotubes (ZrO₂-CS-MWCNTs/GCE) was used for the first time to detect the TDF, and achieved rapid, sensitive detection of TDF with a detection limit of sub-micron content. The ZrO₂-CS-MWCNTs composite was created using sonication of a mixture of ZrO₂ and CS-MWCNTs solution. The composite was characterized using scanning electron microscopy (SEM) and cyclic voltammetry (CV). Electrochemical analysis was performed using differential pulse voltammetry (DPV). Compared with single-material electrodes, the ZrO₂-CS-MWCNTs/GCE significantly improves the electrochemical sensing of TDF due to the synergistic effect of the composite. Under optimal conditions, the proposed method has achieved good results in linear range (0.3~30 μM; 30~100 μM) and detection limit (0.0625 μM). Moreover, the sensor has the merits of simple preparation, good reproducibility and good repeatability. The ZrO₂-CS-MWCNTs/GCE has been applied to the determination of TDF in serum and urine, and it may be helpful for potential applications of other substances with similar structures.

Keywords: Tenofovir disoproxil fumarate; biological samples; differential pulse voltammetry; multiwalled carbon nanotubes; zirconium oxide.

Figure 1

The X-ray diffraction (XRD) patterns of ZrO₂ (a), CS-MWCNTs (b) and ZrO₂-CS-MWCNTs composites (c).

Figure 2

Scanning electron microscope (SEM) images of the ZrO₂ (a), CS-MWCNTs (b) and ZrO₂-CS-MWCNTs composites (c,d).

Figure 3

Cyclic voltammetry (CV) diagrams (a) and Nyquist plots (b) obtained on different electrodes in a solution of 5 mM K₃[Fe(CN)₆]^3−/4− and 0.1 M KCl (a: GCE, b: ZrO₂/GCE, c: CS−MWCNTs/GCE, d: ZrO₂−CS−MWCNTs/GCE).

Figure 4

Differential pulse voltammetry (DPV) diagrams (a), current response (b) and the relationship diagram between peak potential and pH (c) of Tenofovir disoproxil fumarate (TDF) on ZrO₂−CS−MWCNTs/GCE at different pH values.

Figure 5

(a) CV diagrams of TDF on ZrO₂−CS−MWCNTs/GCE at different scan rates (0.03 V/s ~ 0.24 V/s); (b) the plot of the peak current versus v^1/2; (c) the plot of logI_p versus logv; (d) the plot of the peak potential versus lnv.

Figure 6

(a) DPV diagrams of different concentrations of TDF (0.3 μM~100 μM); (b) the linear relationship between the peak current and TDF concentration in the range of 0.3 μM~30 μM and 30 μM~100 μM.