Copper Ion-Induced Self-Assembled Aerogels of Carbon Dots as Peroxidase-Mimicking Nanozymes for Colorimetric Biosensing of Organophosphorus Pesticide

Abstract

Establishing a rapid and sensitive biosensing method for organophosphorus pesticide (OP) is essential because of its pollution to the environment and potential harm to human health. In the report, copper ion-induced selfassembled aerogels of carbon dots are coupled with acetylcholinesterase and choline oxidase to construct a multienzyme cascade catalysis-based colorimetric biosensor for the detection of OP dichlorvos. The copper−carbon dot aerogels (Cu-CDs) are massively fabricated using copper as the metal binding sites and carbon dots derived from sodium tartrate and adenine as building units. The Cu-CDs are verified to possess high peroxidase-mimicking activity toward the hydrogen peroxide-oxidation of o-phenylenediamine. It is revealed that the generation of reactive oxygen species (ROS) including •OH, •O 2 − , and 1 O 2 is involved in the peroxidase-mimicking process, and the high peroxidase-mimicking activity of Cu-CDs results from the synergistic effects of abundant ROS, fast Cu(II)/Cu(I) redox cycling, plentiful catalytically active metal sites, and three-dimensional porous structures. The dichlorvos biosensor achieves a linear range of 0.02−0.3 μM with a limit of detection of 7.6 nM. The proposed sensor is successfully applied to detect dichlorvos in real samples, including cabbage, pakchoi, and lake water, and the results compare well with those from a reference gas chromatography method.

NIR-II-Responsive Versatile Nanozyme Based on H2O2 Cycling and Disrupting Cellular Redox Homeostasis for Enhanced Synergistic Cancer Therapy

“…It can be seen that Cu 2p, Ag 3d, and Se 3d elemental signals were observed in the XPS spectrum of CSA. In the Cu 2p spectra (Figure H), the peaks at 931.7 and 951.2 eV were assigned to Cu + or Cu 0 , and the peaks at 933.92 and 954.62 eV were assigned to Cu 2+ , ,, implying a mixed valence state of copper elements in the synthesized CSA nanoparticles. For the high-resolution XPS of Se 3d (Figure I), the peaks at 53.8 and 53.3 eV corresponded to Se 3d 3/2 and Se 3d 5/2 , respectively, and the peak at 57.8 eV is due to SeO x . − In the Ag 3d spectrum (Figure J), the appearance of the peaks at 368.5 and 374.5 eV was indexed to Ag 3d 5/2 and Ag 3d 3/2 , respectively, demonstrating that the valence state of Ag was zero and the formation of pure metallic Ag on the surface of CS. , These results indicated that the as-prepared CSA possesses desirable characteristics for biomedical applications.…”

“…These results validated that CSA indeed has the potential to generate • OH, O 2 •– , and 1 O 2 and that its catalytic activity could be enhanced by laser irradiation. The possibly catalytic mechanisms can be described as follows ,, normalC normalu + + H 2 O 2 → normalO normalH • + normalC normalu 2 + + normalO normalH − normalO normalH • + H 2 O 2 → normalO 2 • − + H 2 normalO + H + H 2 normalO + normalO 2 • − → normalO 2 1 + normalO normalH − + H 2 O 2 normalC normalu 2 + + normalO 2 • − → normalO 2 1 + normalC normalu + In the catalytic system of CSA, H 2 O 2 was adsorbed on the CSA surface and activated by Cu(I) in CSA, leading to the generation of • OH, while...…”

“…Nanozymes, synthetic materials possessing one or more enzyme mimicking activity, − have garnered considerable attention in recent years. Due to their controlled synthesis, high stability, and tunable catalytic activities, nanozymes have been extensively employed in a variety of applications, biosensing, cancer therapy, imaging, and so on. − Recently, a wide array of nanozymes, such as metal oxides, − metal nanoparticles, carbon nanomaterials, , and their composites, have been utilized for the treatment of various diseases based on their enzyme-like activities. However, the insufficient catalytic efficiency within the tumor microenvironment remains a considerable challenge.…”