Exploring a green and precise approach based on graphene oxide-cobalt ferrite nanocomposite for detection and quantification of vitamin B9 and antibacterial assessment

Abstract

In this study, magnetic cobalt ferrite/graphene oxide (CoFe₂O₄/GO) sorbent was synthesized and used in magnetic dispersive micro-solid phase extraction (MD-µ-SPE) combined to spectrofluorometric as a green, precise, and effective method to separate and detect of vitamin B9 in food and biological samples. The structure, morphology and magnetic properties of CoFe₂O₄/GO nanocomposite was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-Ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). Four parameters of pH, sorbent dose, temperature, and sonication time were selected as effective variables on the process and optimized by central composite design (CCD). Under optimized conditions, the linear range, limit of detection, intra-day (repeatability) and inter-day (intermediate) precision were obtained 15-750 ng mL^-1, 3.96 ng mL^-1, 3.3-3.8%, and 4.2-4.9%, respectively. The material's antimicrobial potency also evaluated, showcasing notable inhibitory action against both Gram-negative Escherichia coli bacteria, with a zone of inhibition measuring 17.5 mm at the highest concentration, and Gram-positive Staphylococcus aureus bacteria, which displayed a 14.5 mm ZIO at similar concentrations. To the best of our knowledge, this is the first report on using CoFe₂O₄/GO for vitamin B9 extraction and detection. This work introduces a novel, eco-friendly, and effective analytical platform that combines the magnetic properties of CoFe₂O₄ with the high surface area and functional groups of GO for targeted vitamin analysis. These results demonstrate that the synthesized nanocomposite possesses both excellent adsorption capability and antibacterial activity.

Keywords: Antibacterial activity; Central composite design; CoFe2O4/GO; Food and biological samples; Nanocomposite; Vitamin B9.

Fig. 1

(a) FT-IR spectra, (b) XRD pattern, (c) VSM analysis, (d) EDX analysis and (e) Mapping analysis images related to synthesized materials of GO, CoFe₂O₄ and CoFe₂O₄/GO.

Fig. 2

(a) FE-SEM images, and (b) Zeta potential diagram of CoFe₂O₄/GO nanocomposite.

Fig. 3

3-D response surface, counter, and diagnostic plots for determination of vitamin B9. (a) pH and sorbent dose, (b) Sorbent dose and temperature, (c) Temperature and ultrasonic time, (d) Normal probability plot, and (e) The predicted values vs. the actual values.

Fig. 4

(a) The effect of desorption solvent type on the determination of vitamin B9, (b) The effect of desorption solvent volume on the determination of vitamin B9.

Fig. 5

a) Evaluation of stability and reusability of CoFe₂O₄/GO nanocomposite, (b) FT-IR analysis of (i) fresh CoFe₂O₄/GO, and (ii) CoFe₂O₄/GO after eight cycles.

Fig. 6

Inhibition zones of E. coli (a) and S. aureus (b) microorganisms based on four concentrations of 0.06, 0.12, 0.24 and 0.48 mg mL⁻¹ of GO, CoFe₂O₄ and CoFe₂O₄/GO materials.

Fig. 7

Assessment of the greenness and practical applicability of the developed method using (a) the AGREE tool and (b) the BAGI tool.