Moxifloxacin Hydrochloride Electrochemical Detection at Gold Nanoparticles Modified Screen-Printed Electrode

Abstract

It appeared that either the carbon paste or the screen-printed carbon electrodes that were modified with gold nanoparticles (AuNPs) gave rise to the largest current responses after a rapid screening of various nanomaterials as modifiers of carbon composite electrodes in view of designing an electrochemical sensor for Moxifloxacin Hydrochloride (Moxi). The screen-printed electrode (SPE) support was preferred over the carbon paste one for its ability to be used as disposable single-use sensor enabling the circumvention of the problems of surface fouling encountered in the determination of Moxi. The response of AuNPs modified SPE to Moxi was investigated by cyclic voltammetry (CV) (including the effect of the potential scan rate and the pH of the medium), chronoamperometry, and differential pulse voltammetry (DPV) after morphological and physico-chemical characterization. DPV was finally applied to Moxi detection in phosphate buffer at pH 7, giving rise to an accessible concentration window ranging between 8 µM and 0.48 mM, and the detection and quantification limits were established to be 11.6 µM and 38.6 µM, correspondingly. In order to estimate the applicability of Moxi identification scheme in actual trials, it was practiced in a human baby urine sample with excellent recoveries between 99.8 % and 101.6 % and RSDs of 1.1-3.4%, without noticeable interference.

Keywords: Moxifloxacin hydrochloride (Moxi); carbon paste electrodes; carbon screen-printed electrodes; differential pulse voltammetry; gold nanoparticles (AuNPs); modified electrodes.

Figure A1

EDX spectra and SEM micrographs (insets) of (A) BCPE, (B) NCOMCPE, (C) GORGMCPE, (D) ZCNTMCPE, (E) SCCMCPE and (F) GNMCPE with its histogram, respectively.

Figure A2

EDX mapping pictures of (A) NCOMCPE, (B) GORGMCPE, (C) ZCNTMCPE, (D) SCCMCPE and (E) GNMCPE, respectively.

Figure A3

(A) CVs of 1.0 mM Moxi in 0.01 M B-R (pH = 7.0) and scan rate 50 mV s⁻¹ measured on the various investigated electrodes as presented in the experimental section. (B) The corresponding Nyquist plots for the studied sensors (bottom right inset: the best fitted equivalent circuit). (C) The analytical curves obtained from performing DPV measurements at scan rate 10 mV s⁻¹ with sensing platforms ZCNTMCPE, NCOMCPE, SCCMCPE, GORGMCPE, GNMCPE and GNMSPE.

Figure 1

Scanning electron microscopy (SEM) micrographs of the screen-printed electrode surfaces (A: screen-printed electrode (SPE) and B: gold nanoparticles modified SPE (GNMSPE) accompanied with its histogram); (C) transmission electron microscopy (TEM) micrograph of Au nanoparticles; and, (D) XRD pattern of GNMSPE.

Figure 2

(A) Cyclic voltammetry’s (CVs) of 1.0 mM Moxi on GNMSPE recorded at various potential scan rates (v). Inset: variations of anodic peak current (Ipa) with the square root of scan rate (v^1/2) for BSPE and GNMSPE. (B) Variation of the anodic signal potential of GNMSPE with the logarithm of scan rate.

Figure 3

(A) CVs of 1.0 mM Moxi on GNMSPE in 0.01 M B-R buffer with different pH values at scan rate 50 mV s⁻¹. Inset: variation of anodic peak current (I_pa) for BSPE and GNMSPE as function of pH. (B) Nyquist plots of Moxi on GNMSPE at different pH values. (C) Variation of anodic peak current (I_pa) obtained for successive analyses at increasing times (1–30 min.) using the same GNMSPE in B–R buffer pH 7.0 containing 1.0 mM Moxi. Inset: the corresponding CVs.

Figure 4

(A) Chronoamperograms at GNMSPE for different concentration of Moxi (0.0–1.0 mM). Insets: Variations of I vs. t^−1/2 built from chronoamperograms (right) ant plot of the corresponding slopes against Moxi concentration (left). (B) Variation of I_cat/I_f ratio versus t^1/2.

Figure 5

Calibration plot for Moxi, Inset: corresponding differential pulse voltammetry’s (DPVs) for successive addition of Moxi in B-R buffer solution of pH 7.0 at scan rate = 10 mV s⁻¹ using GNMSPE and illustrative picture of a typical SPE used in this work.

Figure 6

Calibration plot of Moxi in a urine sample prepared in B-R buffer solution (pH 7.0) using GNMSPE. Inset A: separate detection of 200 µM Moxi with 200 µM paracetamol by DPV in the same solution. Inset B: I) calibration plot for Moxi in the presence of 200 µM paracetamol, and II) calibration for paracetamol in the presence of 200 µM Moxi. Inset C: detection of 200 µM Moxi alone or in the presence of 200 µM ascorbic acid, dopamine, uric acid or estradiol).