Bi2O3/ZnO nanocomposite: Synthesis, characterizations and its application in electrochemical detection of balofloxacin as an anti-biotic drug

Abstract

In the present work, a chemically modified electrode has been fabricated utilizing Bi₂O₃/ZnO nanocomposite. The nanocomposite was synthesized by simple sonochemical method and characterized for its structural and morphological properties by using XRD, FESEM, EDAX, HRTEM and XPS techniques. The results clearly indicated co-existence of Bi₂O₃ and ZnO in the nanocomposite with chemical interaction between them. Bi₂O₃/ZnO nanocomposite based glassy carbon electrode (GCE) was utilized for sensitive voltammetric detection of an anti-biotic drug (balofloxacin). The modification amplified the electroactive surface area of the sensor, thus providing more sites for oxidation of analyte. Cyclic and square wave voltammograms revealed that Bi₂O₃/ZnO modified electrode provides excellent electrocatalytic action towards balofloxacin oxidation. The current exhibited a wide linear response in concentration range of 150-1000 nM and detection limit of 40.5 nM was attained. The modified electrode offered advantages in terms of simplicity of preparation, fair stability (RSD 1.45%), appreciable reproducibility (RSD 2.03%) and selectivity. The proposed sensor was applied for determining balofloxacin in commercial pharmaceutical formulations and blood serum samples with the mean recoveries of 99.09% and 99.5%, respectively.

Keywords: Chemically modified electrode; Drug analysis; Voltammetry; ZnO nanoparticles.

Graphical abstract

Fig. 1

XRD pattern of ZnO, Bi₂O₃ and Bi₂O₃/ZnO nanocomposite.

Fig. 2

Low magnification, high magnification FESEM image, and EDAX spectra of (A–C) Bi₂O₃ nanoparticles, (D–F) ZnO nanoparticles, and (G–I) Bi₂O₃/ZnO nanoparticles.

Fig. 3

TEM, HRTEM, and SAED pattern of (A–C) Bi₂O₃ nanoparticles, and (D–F) Bi₂O₃/ZnO nanocomposite.

Fig. 4

FTIR spectra of ZnO, Bi₂O₃ and Bi₂O₃/ZnO nanocomposite.

Fig. 5

(A) XPS survey spectra of Bi₂O₃ and Bi₂O₃/ZnO, (B, C) XPS core level spectra of Bi 4f, and O 1s in Bi₂O₃, and (D–F) XPS core level spectra of Bi 4f, O 1s, and Zn 2p in Bi₂O₃/ZnO sample.

Fig. 6

Nyquist plots from EIS at bare GCE, Bi₂O₃/GCE, ZnO/GCE and Bi₂O₃/ZnO/GCE in 5 mM K₃ [Fe (CN)₆] in 0.1 M KCl solution. Inset: Corresponding equivalent circuit [Rs (Q[Rct W])].

Fig. 7

(A) Cyclic voltammograms and (B) square wave voltammograms for determination of BLF (300 nM) at pH 4.5 in 0.2 M BR buffer at bare GCE and modified GCE.

Fig. 8

(A) Cyclic voltammograms of 300 nM BLF in 0.2 M BR buffer at Bi₂O₃/ZnO/GCE at varying pH values (2.5–6.5); Inset: Cyclic voltammograms of 300 nM BLF in 0.2 M BR buffer at Bi₂O₃/ZnO/GCE at varying pH values (7.9–12). (B) Plot of E_p (V) vs. pH values.

Scheme 1

Plausible oxidation mechanism of balofloxacin.

Fig. 9

(A) Square wave voltammograms of BLF at different concentrations (150–1000 nM) in 0.2 M BR buffer at pH 4.5. (B) Plot of I_p (μA) vs. concentration (nM).