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. Schematic 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.