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An Enzyme Cascade-Based Electrochemical Immunoassay Using a Polydopamine-Carbon Nanotube Nanocomposite for Signal Amplification

An Enzyme Cascade-Based Electrochemical Immunoassay Using a Polydopamine-Carbon Nanotube Nanocomposite for Signal Amplification

Yue Zhang, Deng Pan, Qing Zhou, Jinjin Zhao, Ning Pan, Yuanjian Zhang, Li-Xin Wang, Yanfei Shen

J Mater Chem B. 2018 Dec 28;6(48):8180-8187.

PMID: 32254937

Abstract:

By coupling tyrosinase (Tyr) and β-galactosidase (Gal) into one redox-cycling scheme, an enzyme cascade-based electrochemical immunosensor with boosted selectivity and sensitivity was constructed using polydopamine-functionalized multiwalled carbon nanotube (MWCNTs-PDA) nanohybrid modified electrodes. The MWCNTs-PDA nanohybrid presented a 5 times enhanced capability for antibody conjugation, which was responsible for signal amplification. In the proposed enzyme cascade scheme, Gal was captured on the immunosensor surface by a sandwiched immunoreaction, which catalyzed phenyl β-d-galactopyranoside (P-GP) into phenol based on a hydrolysis reaction. The resulting phenol was used as a substrate of Tyr, which was catalyzed to catechol and subsequently to o-quinone. The o-quinone was then electrochemically reduced to catechol, forming a redox cycle between catechol and o-quinone. The enzyme cascade-based immunoassay not only significantly amplified the electrochemical signal, but also led to a high selectivity. Taking the detection of CEA as an example, the enzyme cascade-based electrochemical immunosensor showed a detectable range of 10 pg mL-1 to 10 ng mL-1 and a low detection limit of 8.39 pg mL-1 (S/N = 3), which was superior/comparable to those using other methodologies in previous reports. The selectivity of the enzyme cascade-based immunosensor was 44-80% higher than that of a single enzyme-based immunosensor. This work shows great potential of the coupling enzyme cascade in immunosensing for clinical diagnosis with boosted selectivity and sensitivity.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP2818588	Phenyl-β-D-galactopyranoside		2818-58-8	Price

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