# Fluorescent probes for detection of misfolded protein oligomers in Alzheimer's Disease and related disorders

> **NIH NIH R21** · UNIVERSITY OF SOUTH FLORIDA · 2024 · $228,457

## Abstract

Fluorescent Probes for Detection of Misfolded Protein Oligomers in Alzheimer's
 Disease and Related Disorder
 There is significant evidence that the clinical symptoms of Alzheimer’s Disease (AD) and related disorders
are closely linked to the formation and proliferation of small oligomers that precede the emergence of the
prominent late-stage fibrils and plaques. Therefore, amyloid beta oligomers (AβOs) are the most direct
biomarkers for monitoring the onset and progression of AD. Attempts at utilizing this biomarker, however, have
been severely hampered by the dearth of techniques for the reliable detection of AβOs in biological samples and
tissues. While oligomer-selective antibodies have provided important insights into AβOs, their use doesn't extend
to detecting oligomer populations in vivo, let alone monitoring their temporal evolution. The overall objectives
of this proposal are therefore to identify small oligomer-selective dyes for the detection of AβOs and to validate
their specificity for AβOs, and potentially related oligomers, in tissues of animal models of AD and patient tissue.
 Multiple laboratories have observed that in vivo Aβ assembly displays not only purely sigmoidal but also
biphasic ThT kinetics. We have shown that the onset of biphasic ThT kinetics directly correlates with the onset
and rapid increase in prefibrillar oligomer populations with increases in monomer concentrations. Here we
propose to use this transition from essentially oligomer-free sigmoidal to oligomer-dominated biphasic kinetics
to screen a selection of readily available fluorescent dyes for their selectivity for AβOs over AβFs and monomers.
An initial test of this approach already yielded a highly promising dye candidate. Our preliminary data also
indicate that this dye specifically stains oligomer deposits in animal models of AD.
 While very encouraging, the utility of our current oligomer-selective dye requires further validation. In
addition, we seek to identify multiple chemically and structurally distinct oligomer-selective dyes to improve the
chances to develop one of them into a PET probe for in vivo imaging of oligomers. We will therefore extend our
current screen for AβO-selective dyes to a larger set of fluorescent dyes selected from different dye categories. In
parallel, we will scrutinize whether the current dye reliably detects AβOs at various stages of the disease, and
does so in animal models as well as patient tissues. Promising novel AβO-selective dyes identified through our
screening assay will be subjected to the same ex vivo validation of their specificity in tissues.
 We anticipate that these experiments will yield multiple promising AβO-selective dyes with application for
fundamental studies of oligomer formation, for the development of new assays for detecting AβOs ex vivo, and,
most importantly, as the detection moiety for a future oligomer-selective PET probe for antemortem in vivo
oligomer imaging in patients.

## Key facts

- **NIH application ID:** 10788369
- **Project number:** 5R21AG077735-02
- **Recipient organization:** UNIVERSITY OF SOUTH FLORIDA
- **Principal Investigator:** David E Kang
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $228,457
- **Award type:** 5
- **Project period:** 2023-03-01 → 2025-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10788369

## Citation

> US National Institutes of Health, RePORTER application 10788369, Fluorescent probes for detection of misfolded protein oligomers in Alzheimer's Disease and related disorders (5R21AG077735-02). Retrieved via AI Analytics 2026-06-12 from https://api.ai-analytics.org/grant/nih/10788369. Licensed CC0.

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