Magnetic Flower-like Fe-Doped CoO Nanocomposites with Dual Enzyme-like Activities for Facile and Sensitive Determination of H₂O₂ and Dopamine

Abstract

Herein, a new series of magnetic Fe-doped CoO nanocomposites (Fe-CoO NCs) with dual enzyme-like activities (peroxidase and oxidase) were successfully synthesized. The molar ratio of Fe3+/Co2+ salts during the solvothermal process determined the morphology and catalytic activity of the NCs. Among them, the flower-like 0.15Fe-CoO NCs showed high peroxidase-mimicking activity over a wider pH range of 4–5 and a temperature range of 30–50 °C. Such nanozymes were applied for constructing a facile and sensitive colorimetric sensor to detect H2O2 and dopamine (DA) in the linear ranges of 6–20 and 2–10 μM with limits of detection (LODs) of 4.40 and 1.99 μM, respectively. The excellent magnetic separation performance and successful DA detection in human urine samples validated the promising application of CoO-based nanozymes in medical diagnosis. The superior catalytic behaviors of 0.15Fe-CoO NCs could be ascribed to the high surface area, open mesoporous structure, increased surface active species, and the facile redox of Fe3+/Fe2+ and Co3+/Co2+. Based on the results of the fluorescent probe and radical trapping tests, the possible mechanism that Fe doping promoted the decomposition of H2O2 to produce hydroxyl radical (•OH) and superoxide radical (•O2 –) was proposed.

CoO Nanozymes with Multiple Catalytic Activities Regulate Atopic Dermatitis

“…It can be seen from the figure that the CoO nanoparticles prepared at 270 • C had a higher POD-like catalytic activity. More importantly, we did not observe an SOD-like catalytic activity on CoO nanoparticles prepared at 320 • C. Some of the literature mentions that flower-like nanozymes will show a higher enzyme-like catalytic activity due to their larger specific surface area [53]. Based on this, we speculate that the change in the catalytic activity of the enzyme-like enzymes after the change in the morphology of CoO nanozymes is also derived from the change in the specific surface area and the opening of surfactant sites.…”

“…CoO nanozymes with three types of enzyme catalytic activities have not been reported yet, and most CoO nanozymes only have oxidase-/peroxidase-like catalytic activity [53]. A single enzyme-like catalytic activity greatly limits the application of CoO nanozymes in the biomedical field, so CoO nanozymes with multiple types of enzyme-like catalytic activities broaden their application scenarios.…”

“…However, in previous studies, CoO nanoparticles have often been doped with other substances as part of the catalyst. Few studies have used CoO nanoparticles alone as catalysts to participate in the reaction, and most of the related enzyme-like catalytic activities were peroxidase-like or oxidase-like [53][54][55][56]. In this paper, we prepared CoO nanoparticles with a "cluster" morphology, and the morphology of CoO nanoparticles can be changed by changing the reaction temperature.…”

“…Co 3 O 4 nanozymes are widely used in cancer therapy, antiviral, magnetic resonance imaging (MRI), and targeted drug delivery [49][50][51]. At present, many studies have reported that CoO nanozymes with POD-like activity prepared by a variety of synthetic methods have extremely high application value in biosensing [52][53][54][55]; CoO nanostructures have the advantages of high stability, large specific surface area, and easy redox [56,57]. However, pure CoO nanoparticles show poor electrical conductivity and tend to self-aggregate to cover active sites.…”

Recent progress in 0D optical nanoprobes for applications in the sensing of (bio)analytes with the prospect of global health monitoring and detailed mechanistic insights

“…In this regard, Liu and Liu et al reported a new series of magnetic flower-like CoO nanocomposites (Fe–CoO NCs) doped with 0.15Fe, possessing peroxidase and oxidase dual enzyme mimetic activities for the rapid and selective chromogenic detection of H 2 O 2 and dopamine (DA) with an LOD of 4.40 and 1.99 μM, respectively. 164 The introduction of Fe herein was beneficial for the easy magnetic separation of the nanocomposite. Initially, the Fe 2+ in the doped Fe compounds was oxidized to Fe 3+ by decomposing H 2 O 2 to ˙OH, which then oxidized the chromogenic substrate TMB.…”