A tyrosinase-induced fluorescence immunoassay for detection of tau protein using dopamine-functionalized CuInS₂/ZnS quantum dots.

Chen, Li; Lin, Jianwei; Yi, Jinquan; Weng, Qinghua; Zhou, Ying; Han, Zhizhong; Li, Chunyan; Chen, Jinghua; Zhang, Qian

Rapid, highly sensitive detection of tau protein and other neurodegenerative biomarkers remains a significant hurdle for diagnostic tests for Alzheimer's disease. In this work, we developed a novel tyrosinase (TYR)-induced tau aptamer–tau–tau antibody (anti-tau) sandwich fluorescence immunoassay to detect tau protein that used dopamine (DA)-functionalized CuInS2/ZnS quantum dots as the fluorophore. CuInS2/ZnS core/shell quantum dots with high luminescence, low toxicity, and excellent biocompatibility were successfully fabricated and decorated with DA through amide conjugation. Meanwhile, TYR was conjugated with anti-tau by a click reaction. When DA-functionalized CuInS2/ZnS quantum dots were added to the sandwich system, TYR catalyzed the transformation of DA to dopamine quinone, which acted as an effective electron acceptor and triggered fluorescence quenching. The fluorescence intensity of the immunoassay based on DA-functionalized CuInS2/ZnS quantum dots shows good performance in terms of linearity with the logarithm of tau protein concentration, with a linear concentration range from 10 pM to 200 nM. This work is the first to use a TYR-induced fluorescence immunoassay for the rapid detection of tau protein, paving a new way for the detection of disease biomarkers.

TAU proteins; QUANTUM dots; PHENOL oxidase; IMMUNOASSAY; FLUORESCENCE; FLUORESCENCE quenching

Analytical & Bioanalytical Chemistry, 2019, Vol 411, Issue 20, p5277

1618-2642

Academic Journal

10.1007/s00216-019-01909-9