Development of an electrochemical biosensor for impedimetric detection of tetracycline in milk

Abstract

Abstract: This study dealt with the fabrication of an impedimetric biosensor based on nanomaterial modified with pencil graphite electrode for the detection of tetracycline (TET) in milk samples. For response of the impedimetric aptasensor to be improved, the influence of different parameters (immobilization time of reduced grapheme oxide, time of aptamer, and TET binding, and concentration of aptamer) was optimized. In optimum conditions, the aptasensor provided a concentration range within 1 × 10^-16 - 1 × 10^-6 M and with a limit of detection of 3 × 10^-17 M TET. The proposed impedimetric aptasensor was then used in milk samples analysis, and the acceptable recovery was achieved ranging from 92.8 to 102.1%. According to this study, the combination of an aptamer and electrochemical impedance spectroscopy is a promising method for detection of TET in milk samples with high reproducibility and stability.

Keywords: Antibiotics detection; Aptasensor; Electrochemical impedance spectroscopy; Nanocomposite; Reduced graphene oxide.

Fig. 1

A FTIR spectra of grapheme oxide (GO) and reduced grapheme oxide (RGO) and B SEM images of (a) modified PGE, (b) RGO/PGE, and (c) AuNPs/RGO/PGE

Fig. 2

The CVs (a) and Nyquist plots (b) of different modified electrodes in 5.0 mM Fe(CN)₆^4−/3− containing 0.1 M KCl, potential range of − 0.1 to 0.70 V with scan rate of 50 mV s⁻¹, Conditions for EIS: the frequency range of 0.01 to 10⁵ Hz at the potential of 150 mV

Fig. 3

Influence of a immobilization time of RGO on the peak current, b immobilization time of aptamer, c aptamer concentration and d immobilization time of TET on the ∆R_ct electrode in 5.0 mM Fe(CN)₆^4−/3− containing 0.1 M KCl solution. The error bars represented the standard deviation (SD) (n = 3)

Fig. 4

a calibration plot for ΔR_ct versus Log concentration of TET, b Nyquist diagram for different concentration of TET, (a-k) 1.0 × 10⁻¹⁶, 1.0 × 10⁻¹⁵, 1.0 × 10⁻¹⁴, 1.0 × 10⁻¹³, 1.0 × 10⁻¹², 1.0 × 10⁻¹¹, 1.0 × 10⁻¹⁰, 1.0 × 10⁻⁹, 1.0 × 10⁻⁸, 1.0 × 10⁻⁷, 1.0 × 10⁻⁶ M, respectively. In 5.0 mM Fe(CN)₆^4−/3− containing 0.1 M KCl solution, The error bars represented the standard deviation (SD) (n = 3), c Selectivity of the fabricated aptasensor (n = 3) with streptomycin, penicillin G and sulfadiazine instead of TET, at the same concentrations (1 × 10^–9 M). The error bars represented the SD (n = three electrodes)