@article{Mao2023, 
author = {Guobin Mao and Yang Yang and Shijie Cao and Silu Ye and Yifang Li and Wei Zhao and Hongwei An and Yingxia Liu and Junbiao Dai and Yingxin Ma},
title = {Ratiometric fluorescence immunoassay of SARS-CoV-2 nucleocapsid protein via Si-FITC nanoprobe-based inner filter effect},
year = {2023},
journal = {Nano Research},
volume = {16},
number = {4},
pages = {5383-5390},
keywords = {severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Si-fluorescein isothiocyanate (FITC) nanoparticles, ratiometric fluorescent probe, inner filter effect, enzyme-linked immunosorbent assay (ELISA)},
url = {https://www.sciopen.com/article/10.1007/s12274-022-4740-5},
doi = {10.1007/s12274-022-4740-5},
abstract = {The global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has necessitated rapid, easy-to-use, and accurate diagnostic methods to monitor the virus infection. Herein, a ratiometric fluorescence enzyme-linked immunosorbent assay (ELISA) was developed using Si-fluorescein isothiocyanate nanoparticles (FITC NPs) for detecting SARS-CoV-2 nucleocapsid (N) protein. Si-FITC NPs were prepared by a one-pot hydrothermal method using 3-aminopropyl triethoxysilane (APTES)-FITC as the Si source. This method did not need post-modification and avoided the reduction in quantum yield and stability. The p-nitrophenyl (pNP) produced by the alkaline phosphatase (ALP)-mediated hydrolysis of p-nitrophenyl phosphate (pNPP) could quench Si fluorescence in Si-FITC NPs via the inner filter effect. In ELISA, an immunocomplex was formed by the recognition of capture antibody/N protein/reporter antibody. ALP-linked secondary antibody bound to the reporter antibody and induced pNPP hydrolysis to specifically quench Si fluorescence in Si-FITC NPs. The change in fluorescence intensity ratio could be used for detecting N protein, with a wide linearity range (0.01–10.0 and 50–300 ng/mL) and low detection limit (0.002 ng/mL). The concentration of spiked SARS-CoV-2 N protein could be determined accurately in human serum. Moreover, this proposed method can accurately distinguish coronavirus disease 2019 (COVID-19) and non-COVID-19 patient samples. Therefore, this simple, sensitive, and accurate method can be applied for the early diagnosis of SARS-CoV-2 virus infection.}
}