Shedding light on Alzheimer's disease: Recent advances in highly selective fluorescent probes

Alzheimer's disease (AD) is the predominant neurodegenerative disorder, affecting approximately 60–80 % of all patients diagnosed with dementia globally. Given the intricate nature of AD's pathogenesis, numerous biologically active substances have gained attention, including amyloid-β plaques (Aβ), TAU proteins, metal ions, and reactive oxygen/nitrogen/sulfur species. The development of small-molecule fluorescent probes targeting these molecules has emerged as a promising avenue for the diagnosis and treatment of AD. Despite significant progress, challenges remain in the field of AD-related fluorescent probes. One such challenge is achieving high selectivity and sensitivity towards the target biomolecules amidst the complex biological milieu. Furthermore, further investigation is required to address the probe stability, bioavailability, and biocompatibility issues in order to guarantee their efficacy in clinical applications. It is imperative that further innovation be pursued in the design and synthesis of fluorescent probes that are specifically tailored to AD. The integration of advanced imaging techniques, such as fluorescence imaging, may enhance the sensitivity and spatial resolution of these probes, facilitating early diagnosis and monitoring of disease progression. This review presents a systematic examination of the multifunctional fluorescent probes developed over the last five years, highlighting their structures, properties, and applications in targeted diagnosis and imaging of AD. By elucidating the probe design principles and mechanisms of action, we aim to provide insights into their potential applications in clinical research on AD.