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In accurately diagnosing Alzheimer's disease (AD) and distinguishing AD from other dementia, the concentration ratio of amyloid-beta 42 (Aβ

Ultrasensitive and accurate monitoring of ultralow-level biomarkers is imperiously needed in clinical diagnosis. So far, exploring high-performance photocathodes and developing new sensing strategies have remained central challenges in photoelectrochemical bioassays. Herein, a two-dimensional (2D) pyrene covalent organic framework (COF, PAF-130) is exemplified for the first time as a high-performance photocathode for precise immunosensing of α-synuclein (α-Syn) by integrating a DNAzyme-induced signal cycle amplification strategy with Ag nanoparticles (NPs)-mediated liposomal immunoassay. Through sequential immunobinding, lysis treatment, and acidolysis, numerous Ag+ ions are released, and then they activate the DNAzyme, which further recycles the cleavage of hairpin DNA (HDNA) on the photoelectrode and induces signal cycle amplification. As a result, an ultralow detection limit (3.6 fg/mL) and a wide linear range (10-5-103 ng/mL) are achieved, which surpass those of most methods reported so far. The proposed sensing approach can be readily extended to detect various biomarkers by substituting the biorecognition events, providing great promise for biomedical and related applications.

Ultrasensitive and accurate detection of biomarkers in serum is of great importance for disease diagnosis and treatment. So far, the commonly used single-mode signal suffers from certain instinct drawbacks that restrict assay performances. Herein, we report the proof-of-concept fabrication of a split-type photoelectrochemical (PEC) and electrochemical (EC) dual-modal aptasensor for ultrasensitively tracing tumor necrosis factor-α, a noteworthy biological biomarker with essential clinical importance. By smart integrating molybdenum disulfide QDs/zeolitic imidazolate framework-8@ZnO nanorod arrays with a methylene blue-liposome-mediated signal amplification strategy, "dual signal-on" detection is accomplished based on a sandwich reaction of the target with aptamer-anchored carboxyl magnetic beads and an aptamer-confined MB liposome. Linear ranges of 5 fg/mL-5 μg/mL (detection limit 1.46 fg/mL) for PEC and 10 fg/mL-0.5 μg/mL (detection limit 6.14 fg/mL) for EC are obtained, respectively. An independent signal transduction mechanism supports the accuracy improvement, and a separate biological process from a translator enables convenient fabrication, short-time consumption, wider linearity, as well as outstanding reproducibility and stability in practical application. This work presents a universal bioassay route with prospects in biomedical and related areas.