Hemin@carbon dot hybrid nanozymes with peroxidase mimicking properties for dual (colorimetric and fluorometric) sensing of hydrogen peroxide, glucose and xanthine.

The multifunctional hemin@carbon dot hybrid nanozymes (hemin@CD) with simultaneous peroxidase-like activity and fluorescence signalling property was prepared for the first time. Based on these properties, hemin@CD was applied to develop a dual-channel fluorescent probe for H ₂ O ₂ and H ₂ O ₂ -based biocatalytic systems. By virtue of the peroxidase-like activity, hemin@CD can catalyze the oxidative coupling of 4-aminoantipyrine with phenol in the presence of H ₂ O ₂ to form a pink-red quinoneimine dye with a maximum absorbance at 505 nm. Under the excitation wavelength of 480 nm, the green fluorescence of hemin@CD peaks at 540 nm and is quenched by the generated quinoneimine dye due to an inner filter effect, and also by H ₂ O ₂ because of dynamic quenching. Thus, a colorimetric and fluorimetric dual-channel optical probe for H ₂ O ₂ is obtained. Due to the glucose/xanthine transformations under formation of H ₂ O ₂ by the relevant oxidase catalysis, the probe can be applied for detection of glucose and xanthine. The colorimetric detection limits for H ₂ O ₂ , glucose and xanthine are 0.11, 0.15, 0.11 μM, and the and fluorimetric detection limits are 0.15, 0.15, 0.12 μM, respectively. Graphical abstractSchematic representation of the colorimetric and fluorimetric dual probe for H ₂ O ₂ , glucose and xanthine based on the multifunctional emin@carbon dot) hybrid nanozymes with simultaneous peroxidase-like activity and fluorescence signalling property.