Synthesis of Cu-doped carbon dot/chitosan film composite as a catalyst for the colorimetric detection of hydrogen peroxide and glucose

Abstract

The use of colloidal nanoparticles suffers from the drawbacks of potential color interference and substrate-induced aggregation. To overcome the limitations, a catalyst was developed by crosslinking Cu-doped carbon dots (Cu-CDs) with chitosan. Cu-CDs with high peroxidase activity were prepared by using a rapid microwave-assisted method. The Cu-CDs containing 6.88% of Cu had an average particle size of 2.25 nm and exhibited 9% of fluorescence quantum yield. The nanozyme/film composite was prepared by crosslinking between the amino groups of Cu-CDs and those of chitosan via a glutaraldehyde linker. A H2O2-mediated tetramethylbenzidine (TMB) oxidation reaction was use to evaluate the peroxidase activity of the film. Based on the TMB color changes, colorimetric assays were developed for the detection of H2O2 and glucose at an absorption wavelength 652 nm. Under the optimal conditions, the linear ranges for H2O2 and glucose were 0.625–40 µM and 1.9–125 µM, respectively, and the detection limits were 0.12 µM and 0.69 µM, respectively. The colorimetric assay was also applied to analyze diluted human serum samples spiked with glucose. Furthermore, this biodegradable, non-toxic, and easy-to-handle nanozyme composite could be stored for over 4 weeks without a significant decrease in activity. Graphical abstract

A novel coumarin derivative-modified cellulose fluorescent probe for selective and sensitive detection of CN− in food samples

“…4d, the N 1s signal peak appeared at 400.7 eV, which conforming to the C–N group, and this suggested that there was a low carbon bonded nitrogen content on the DCB-CA surface. 29 These results indicated that the synthesized DCB-CA probe was rich in carbon, and that the functional groups contained oxygen and trace amounts of nitrogen.…”

Tablet-Based Sensor: A Stable and User-Friendly Tool for Point-of-Care Detection of Glucose in Urine

“…The TMB concentration played a crucial role in the colorimetric detection assay, as it directly influenced the formation of the blue-colored product through oxidation by HRP in the presence of H 2 O 2 . Excessive TMB concentrations led to over-oxidation, resulting in a black-blue color [ 38 ] and causing the signal to saturate and give false readings, while a low TMB concentration resulted in a weak signal and decreased assay sensitivity. To determine the ideal TMB concentration, we conducted experiments using a range of TMB concentrations from 5 to 40 mM dissolved in DMSO.…”

A template-free assembly of Cu,N-codoped hollow carbon nanospheres as low-cost and highly efficient peroxidase nanozymes

“…See DOI: https://doi.org/ 10.1039/d2an01488b a The talent culturing plan for leading disciplines of Shandong Province, School of Chemistry, Chemical Engineering and Materials, Jining University, Qufu, Shandong, 273155, P.R China. E-mail: shajq2002@126.com b CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China more active sites; 24,25 meanwhile, the copper has a synergistic effect with nitrogen and thus improves the catalytic performance. 26,27 Based on the above points, it has great significance to develop another strategy to combine hollow spherical structures with Cu,N-codoping into carbon-based materials for low-cost and highly efficient nanozymes.…”

“…20–22 For instance, Hui Wei reported that N-doped rGO exhibited higher peroxidase performance than the rGO by 100-fold. 23 In addition, the doped low-cost metal, especially copper, could enhance the electrical conductivity of the carbon catalyst and generate more active sites; 24,25 meanwhile, the copper has a synergistic effect with nitrogen and thus improves the catalytic performance. 26,27 Based on the above points, it has great significance to develop another strategy to combine hollow spherical structures with Cu,N-codoping into carbon-based materials for low-cost and highly efficient nanozymes.…”