Progress in (Photo)electrochemical Biosensors for the Detection of Amyloid-Beta Oligomer

Alzheimer's disease (AD) has become a neurodegenerative disease with an increasing incidence rate and a large economic and social burden worldwide. Amyloid-beta oligomer (AβO) has been confirmed as a key neurotoxic species and a core diagnostic biomarker in AD. Traditional methods for AβO detection have drawbacks, such as cumbersome operation, high cost, and dependence on sophisticated instruments, hindering their transformation into fast and real-time detection techniques. (Photo)electrochemical biosensors have attracted much attention due to their inherent advantages, such as high sensitivity, low cost, portability, and ease of miniaturization. This review systematically summarizes the latest progress of (photo)electrochemical biosensors for AβO detection, mainly based on two sensing modes: direct detection and sandwich-type detection. We comprehensively elaborated on the sensing performances and recognition elements, such as antibodies, aptamers, peptides, and molecularly imprinted polymers. The integration of functional nanomaterials and signal amplification strategies was emphasized to improve the sensitivity, selectivity, and stability of biosensors. In addition, we discussed the existing challenges and looked forward to the future development direction for the early diagnosis of AD. This article aims to provide a systematic reference for the rational design and practical application of advanced biosensors in biomarker detection and AD-related precision medicine.