Iterative Design of Near-Infrared Fluorescent Probes for Early Diagnosis of Alzheimer's Disease by Targeting Aß Oligomers.

ABSTRACT

Amyloid-ß oligomers (AßOs), crucial toxic proteins in early Alzheimer's disease (AD), precede the formation of Aß plaques and cognitive impairment. In this context, we present our iterative process for developing novel near-infrared fluorescent (NIRF) probes specifically targeting AßOs, aimed at early AD diagnosis. An initial screening identified compound 18 as being highly selective for AßOs. Subsequent analysis revealed that compound 20 improved serum stability while retaining affinity for AßOs. The most promising iteration, compound 37, demonstrated exceptional qualities a high affinity for AßOs, emission in the near-infrared region, and good biocompatibility. Significantly, ex vivo double staining indicated that compound 37 detected AßOs in AD mouse brain and in vivo imaging experiments showed that compound 37 could differentiate between 4-month-old AD mice and age-matched wild-type mice. Therefore, compound 37 has emerged as a valuable NIRF probe for early detection of AD and a useful tool in exploring AD's pathological mechanisms.