Fiber-in-Tube Design of a CuFe₂O₄@Conducting Polymer with Synergistically Enhanced Peroxidase-like Activity for Total Antioxidant Capacity Assays

Abstract

The exploration of novel nanozymes with a high catalytic efficiency is crucial for their biosensing applications. Intricate hollow nanostructures possess distinct hierarchical open and porous features, usually presenting fascinating physicochemical properties. In this work, we have demonstrated the fabrication of a hierarchical fiber-in-tube CuFe2O4@conducting polypyrrole (PPy) nanostructure for peroxidase mimicking. Owing to the unique confined structure and synergistic effect, an exceptional peroxidase-like performance of CuFe2O4@PPy is achieved compared with the pristine CuFe2O4 nanofibers and PPy nanotubes alone. The prepared catalyst displays a desirable long-term and cycling stability. The experimental results demonstrate the key role of the formation of hydroxyl radicals for peroxidase mimicking. Based on the outstanding peroxidase-like activity, a high-efficiency ascorbic acid (AA) colorimetric sensor is developed, also displaying a satisfactory selectivity. Furthermore, according to the high sensitivity of the CuFe2O4@PPy nanotubes to detect AA, a total antioxidant capacity (TAC) sensor for a series of real samples has been developed. This work provides a new approach to construct efficient nanozymes with high efficiencies and develop a simple TAC assay with further vision in the fields of biosensing and food technology.

Fabrication of a Tubular CuO/NiO Biomimetic Nanozyme with Synergistically Promoted Peroxidase-like Performance for Isoniazid Sensing

“…When TMB is mixed with H 2 O 2 and the CuO/NiO NT suspension, a significant absorption at 651 nm with a blue color appears, suggesting the formation of oxidized TMB (oxTMB) (Figure a). , By contrast, control experiments demonstrate the key role of each component of TMB, H 2 O 2 , and CuO/NiO NTs on the POD-like activity. The effect of the pH of the reaction system on the POD-like catalytic activity is also investigated, presenting the highest POD-like activity at pH = 4.0 (Figure b), which might be attributed to the improved interactions between the CuO/NiO NTs and POD-like substrates under such conditions in accordance with previous reports. − In addition, we have explored the POD-like activities of CuO/NiO NTs with varied feeding contents of the copper precursor, demonstrating the best catalytic property of the CuO/NiO-3 NTs (Figure c,d). Furthermore, the prepared CuO/NiO NTs have also shown better POD-like activity than the single-component samples, which is 13.2-fold and 4.2-fold as high as that of bare CuO and NiO catalysts, implying that a synergy between the two components is achieved from an efficient electron transfer between NiO and CuO and fast mass transportation in the tubular channel. , Subsequently, the durability and recyclability of the obtained CuO/NiO NTs are investigated, presenting an almost unchanged POD-like activity for about two weeks in durability and a POD-like activity of 89.5% after five cycles, indicating a desirable storage stability and superior recyclability property of the catalyst (Figure S3).…”

Rational Design of Conducting Polymer-Derived Tubular Carbon Nanoreactors for Enhanced Enzyme-like Catalysis and Total Antioxidant Capacity Bioassay Application

“…In this work, we focus on the catalytic property of the Fe@NC NTs for POD mimicking. Similar to the previously reported nanozymes, the pH value and temperature employed in the catalytic system have a strong influence on the POD-like catalytic activity. − Compared with the catalytic activity under pH values from 2.0 to 6.0, pH = 4.0 is found to be the optimum pH condition (Figure c). Moreover, Figure S5 depicts that the desirable catalytic performance can be realized after incubating at around 25 °C for 5 min.…”

“…This result also indicates the essential role of the tubular structure of Fe@NC-20-700 NTs in improving the affinity. Additionally, the affinity of as-prepared Fe@NC-20-700 NTs for H 2 O 2 and TMB is also comparable to that of HRP (H 2 O 2 : 3.70 mM, TMB: 0.434 mM) and much better than many other nanozymes (Table S2), ,,− demonstrating its excellent enzyme-like catalytic efficiency.…”

Dimensionality reduction boosts the peroxidase-like activity of bimetallic MOFs for enhanced multidrug-resistant bacteria eradication

“…2a, Co–Fe NDs could oxidize TMB in the presence of H 2 O 2 to form a blue substance (ox-TMB), with a significant absorption peak at 652 nm. 28,29 In contrast, H 2 O 2 or Co–Fe NDs alone did not cause significant color changes. This result indicated that Co–Fe NDs only had peroxidase-like activity.…”