Near-Infrared Fluorescent Probe for the Early Diagnosis of Alzheimer's Disease.

Alzheimer's disease (AD) is a common progressive neurodegenerative disease characterized by abnormal deposition of amyloid-β protein (Aβ) and the formation of neurofibrillary tangles (NFT). Although there are drugs available for clinical treatment, they do not fundamentally cure AD, so early diagnosis and intervention for AD are essential. In recent years, near-infrared fluorescent (NIRF) probes have been widely used in diagnosing AD due to their advantages of high tissue penetration, low autofluorescence interference, and non-invasiveness. This paper reviewed the recent progress of NIRF probes in AD. We described the effects of NIRF probes on AD biomarkers, including Aβ protein, Tau tangles, mitochondrial viscosity, reactive oxygen species, copper ions, zinc ions, and so on. In detail, we also described the optical properties, in vitro detection, and in vivo imaging of NIRF probes based on different dyes and their derivatives, such as curcumin, Boron dipyrromethene, Quinoline, and Donor-Acceptor. Despite significant progress, NIRF probes remain challenging in imaging and treating AD in vivo. Their selectivity and sensitivity need to be improved due to the complex structure of brain tissue and interfering factors. In conclusion, studying NIRF probes provides us with new ideas. Through further optimization, these probes may be used for early diagnosis and treatment detection of AD to better cope with the challenges brought by AD.