Roles of Phase Purity and Crystallinity on Chloramphenicol Sensing Performance of CuCo₂O₄/CuFe₂O₄-based Electrochemical Nanosensors

Abstract

For the first time, the influences of phase purity and crystallinity on the electrochemical and electrocatalytic properties of CuCo2O4 (CCO) and CuFe2O4 (CFO)-based electrochemical sensors for the detection of chloramphenicol (CAP) are reported. A series of CCO and CFO nanoparticles were prepared by a modified coprecipitation method and then annealed at different temperatures under air (400 °C, 600 °C, 800 °C, and 1000 °C). Surface morphology, the evolution of the crystallite size, and crystalline phase transition, as well as phase purity of CCO and CFO at each annealing temperature, were characterized via different techniques. Their electrochemical properties were analyzed using cyclic voltammetry and differential pulse voltammetry measurements conducted with a PalmSens3 workstation. Results obtained show that the phase purity and crystallinity have decisive effects on their electrocatalytic activity, conductivity, and adsorption efficiency. Under an optimized condition (more namely, annealed 600 °C), both CCO and CFO samples offer high phase purity with low percent of CuO side phase (below 38%), small enough size with a large number of defects and available active sites; particularly, the cubic CFO nanoparticles are present due to its tetragonal phase transition. The modified electrodes with CCO-600 and CFO-600 exhibit a better voltammetric response, a higher synergistic electrocatalytic activity, and a greater electrochemical performance of comparing to other modified electrodes. They respond linearly to chloramphenicol (CAP) in the range from 2.5 to 50 μM. Furthermore, they display am excellent long-term stability, reproducibility, and good selectivity, as well as their capacity of detecting CAP in the real milk sample.

Enhancing the chloramphenicol sensing performance of Cu–MoS2 nanocomposite-based electrochemical nanosensors: roles of phase composition and copper loading amount

“…This is consistent with many previous reports for the electrochemical reduction process of CAP occurring at the electrode surface. 38,[43][44][45][46] In both cases, with and without the presence of CAP, the reduction peak at around À0.4 V to À0.5 V could be ascribed to the irreversible reduction of residual hydroxyl or other functional groups on the commercial SPE surface. 46 R-NO 2 + 4e…”

“…38,[43][44][45][46] In both cases, with and without the presence of CAP, the reduction peak at around À0.4 V to À0.5 V could be ascribed to the irreversible reduction of residual hydroxyl or other functional groups on the commercial SPE surface. 46 R-NO 2 + 4e…”

Bio-AgNPs-based electrochemical nanosensors for the sensitive determination of 4-nitrophenol in tomato samples: the roles of natural plant extracts in physicochemical parameters and sensing performance

“…Furthermore, it was observed that the reduction potential slightly shifted to the more negative direction along with the increased 4-NP concentration, which is attributed to the involvement of protons and the change in the pH value around the electrode interface. 17 …”

“…Furthermore, it was observed that the reduction potential slightly shied to the more negative direction along with the increased 4-NP concentration, which is attributed to the involvement of protons and the change in the pH value around the electrode interface. 17 In comparison with two other modied electrodes, the GT-AgNPs exhibited the highest electrochemical sensitivity up to 1.25 mA mM À1 cm À2 along with the lowest detection limit of 4-NP of about 0.42 mM in the wider linear range from 0.5 to 50 mM. The electrochemical sensitivity of MP-AgNPs was calculated to be 1.04 mA mM À1 cm À2 with a detection limit of about 0.63 mM in the concentration linear range from 1 to 50 mM.…”

“…15 Nonetheless, some critical problems need to be further understood regarding the effects of the morphology, size distribution, and crystallinity of bio-AgNPs synthesized from the various bio-reducing agents on the selectivity and sensitivity of the sensor. 16,17 We have synthesized bio-AgNPs from various natural plant extracts, including green tea leaves (Camellia sinensis), mangosteen peel (Garcinia mangostana), and grapefruit peel (Citrus paradisi) by a simple electrochemical method. Herein, we aim to gain insight into the inuences of the phytochemical components and content in each plant extract on the physicochemical parameters of the created bio-AgNPs such as particle size, crystallinity, and distribution.…”