@article{Mao2023, 
author = {Guobin Mao and Silu Ye and Wen Yin and Yang Yang and Xinghu Ji and Jin He and Yingxia Liu and Junbiao Dai and Zhike He and Yingxin Ma},
title = {Ratiometric fluorescent Si-FITC nanoprobe for immunoassay of SARS-CoV-2 nucleocapsid protein},
year = {2023},
journal = {Nano Research},
volume = {16},
number = {2},
pages = {2859-2865},
keywords = {SARS-CoV-2, ratiometric fluorescent probe, Si-FITC nanoparticles, ELISA},
url = {https://www.sciopen.com/article/10.1007/s12274-022-5005-z},
doi = {10.1007/s12274-022-5005-z},
abstract = {Coronavirus disease 2019 (COVID-19) highlights the importance of rapid and reliable diagnostic assays for the management of virus transmission. Here, we developed a one-pot hydrothermal method to prepare Si-FITC nanoparticles (NPs) for the fluorescent immunoassay of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (N protein). The synthesis of Si-FITC NPs did not need post-modification, which addressed the issue of quantum yield reduction during the coupling reaction. Si-FITC NPs showed two distinct peaks, Si fluorescence at λem = 385 nm and FITC fluorescence at λem = 490 nm. In the presence of KMnO4, Si fluorescence was decreased and FITC fluorescence was enhanced. Briefly, in the presence of N protein, catalase (CAT)-linked secondary antibody/reporter antibody/N protein/capture antibody immunocomplexes were formed on microplates. Subsequently, hydrogen peroxide (H2O2) and Si-FITC NPs/KMnO4 were injected into the microplate together. The decomposition of H2O2 by CAT resulted in remaining of KMnO4, which changed the fluorescence intensity ratio of Si-FITC NPs. The fluorescence intensity ratio correlated significantly with the N protein concentration ranging from 0.02 to 50.00 ng/mL, and the detection limit was 0.003 ng/mL, which was more sensitive than the commercial ELISA kit with a detection limit of 0.057 ng/mL. The N protein concentration can be accurately determined in human serum. Furthermore, the COVID-19 and non-COVID-19 patients were distinguishable by this method. Therefore, the ratiometric fluorescent immunoassay can be used for SARS-CoV-2 infection diagnosis with a high sensitivity and selectivity.}
}