Boron-doped g-C 3 N 4 supporting Cu nanozyme for colorimetric-fluorescent-smartphone detection of α-glucosidase

Background: Due to that the higher activity of nanozymes would bring outstanding performance for the nanozyme-based biosensing strategies, great efforts have been made by researchers to improve the catalytic activity of nanozymes, and novel nanozymes with high catalytic activity are desired. Considering the crucial role in controlling blood glucose level, strategies like colorimetric and chemiluminescence to monitor alpha-glucosidase are developed. However, multi -mode detection with higher sensitivity was insufficient. Therefore, developing triple -mode detection method for alpha-glucosidase based on great performance nanozyme is of great importance. Results: In this work, a novel nanozyme Cu-BCN was synthesized by loading Cu on boron doped carbon substrate g-C 3 N 4 and applied to the colorimetric-fluorescent-smartphone triple -mode detection of alpha-glucosidase. In the presence of H 2 O 2 , Cu-BCN catalyzed the generation of 1 O 2 from H 2 O 2 , 1 O 2 subsequently oxidized TMB to blue colored oxTMB. In the presence of hydroquinone (HQ), the ROS produced from H 2 O 2 was consumed, inhibiting the oxidation of TMB, which endows the possibility of colorimetric and visual on -site detection of HQ. Further, due to that the fluorescence of Mg-CQDs at 444 nm could be quenched by oxTMB, HQ could also be quantified through fluorescent mode. Since alpha-glucosidase could efficiently hydrolyze alpha-arbutin into HQ, the sensitive detection of alpha-glucosidase was realized. Further, colorimetric paper -based device ( c -PAD) was fabricated for on site alpha-glucosidase detection. The LODs for alpha-glucosidase via three modes were 2.20, 1.62 and 2.83 U/L respectively, high sensitivities were realized. Significance: The nanozyme Cu-BCN possesses higher peroxidase-like activity by doping boron to the substrate than non -doped Cu-CN. The proposed triple -mode detection of alpha-glucosidase is more sensitive than most pre- vious reports, and is reliable when applied to practical sample. Further, the smartphone-based colorimetric paper -based analytical device ( c -PAD) made of simple materials could also detect alpha-glucosidase sensitively. The smartphone-based on -site detection provided a convenient, instrument -free and sensitive sensing method for alpha-glucosidase.