Electrocatalysis of Copper Sulfide Nanoparticle-Engineered Covalent Organic Frameworks for Ratiometric
Yana Chen1, Shuangling Wang2, Jujie Ren1
1Hebei Provincial Key Laboratory of Photoelectric Control on Surface and Interface, College of Science, Hebei University of Science and Technology, Shijiazhuang 050018, China.
Abstract:
Amyloid-β oligomer (AβO) is widely regarded as a reliable biomarker for the early diagnosis of Alzheimer's disease (AD). In this study, a signal on-off ratiometric electrochemical immunosensor has been developed for ultrasensitive detection of AβO. To achieve the dual-signal ratiometric strategy, ultrasmall copper sulfide nanoparticle-engineered covalent organic framework hybrid nanocomposites (CuS@COFs) were utilized as excellent electrocatalysts toward hydroquinone (HQ) oxidation to produce detectable signals. Meanwhile, electroactive thionine (Thi) and Aβ antibody-modified gold nanoparticles (Thi-AuNPs-Ab bioconjugates) were designed as another electrochemical indicator. Based on these two signals, an ultrasensitive sandwich-like electrochemical immunosensor was established for AβO detection. The introduction of AβO resulted in a remarkable decline in the electrochemical signal of HQ but an increase in the signal of Thi. Under optimum conditions, the ratios between the double signals (IThi/IHQ) showed a proportional linear relationship with the AβO concentration (1 pM-1 μM) with a low detection limit of 0.4 pM (S/N = 3), and the biosensor was able to determine the content of AβO in real cerebrospinal fluid samples with satisfactory results. The ratiometric strategy proposed in our study offers a sensitive and efficient approach for early diagnosis of AD, and this work will promote the further applications of engineered COFs in electrochemical sensors.
