Alzheimer’s disease (AD) threatens the health of elderly people. Amyloid-β protein (Aβ 42 ) is considered to be a critical protein in the development of AD and a predictive biomarker for the diagnosis of AD. In this study, a dual-wavelength ratiometric electrochemiluminescence (DWR-ECL) sensor was developed for sensitive detection of Aβ 42 . A [email protected] 2 @Au nanomaterial was used as the energy receptor, and gold nanoparticles (AuNPs)-modified graphitic carbon nitride nanosheets (g-C 3 N 4 NSs) were employed as the energy donor. Au-g-C 3 N 4 NSs exhibits a highly stable ECL signal with an emission center at 460 nm, which overlaps with the [email protected] 2 @Au UV–vis absorption spectrum also well stimulates the emission of Ru(bpy) 3 2 + at 620 nm, manufacturing ECL resonance energy transfer (RET) with a good performance. Therefore, an ECL-RET system was established. AuNPs functionalized the surface of g-C 3 N 4 NSs, not only providing a good substrate to fix primary antibodies (Ab1) (Au–N) but also increasing the electron transport rate of g-C 3 N 4 NSs on the surface of the electrode. Furthermore, titanium dioxide nanoparticles (TiO 2 NPs) due to high specific surface area were applied to load numerous Ru(bpy) 3 2 + and AuNPs, and the obtained [email protected] 2 @Au nanomaterials were introduced to combine secondary antibody (Ab2), thus remarkably amplifying the ECL signal. Under optimal experiments, on the basis of the ratio of I 460nm / I 620nm ( I is the ECL intensity), the linearity range of Aβ 42 is from 1 × 10 –5 to 200 ng/mL with a limit of detection (LOD) of 2.6 fg/mL (S/N = 3). The results indicate that the designed DWR-ECL immunosensor has satisfactory stability, high sensitivity, good reproducibility, and excellent specificity, and it can be applied in clinical diagnosis.
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Qin et al. (2021) studied this question.