Spatiotemporal Imaging of Catechol Aldehydes in Neural Tissue

Catechol aldehydes (CAs), particularly 3,4-dihydroxyphenylacetaldehyde (DOPAL) and 3,4-dihydroxyphenylglycolaldehyde (DOPEGAL), are potently cytotoxic and have been implicated in pathogenesis of neurodegenerative disorders. Understanding the dynamics of CAs in the brain is crucial for elucidating neurodegenerative pathways. Herein, we present an innovative fluorescent sensor system designed for the selective imaging of CAs within cells and neural tissues. This system employs a dual-reaction trigger, utilizing o-phenylenediamine's selectivity for aldehydes and phenylboronic acid for catechols, generating a specific Förster Resonance Energy Transfer (FRET) signal for CAs. Importantly, we have integrated fluorescence lifetime imaging microscopy (FLIM) with FRET (FLIM-FRET) to enhance detection accuracy while mitigating issues like spectral crosstalk and photobleaching. This dual-reaction FLIM-FRET system allows for the precise visualization of endogenous CAs in the substantia nigra and locus coeruleus of mice, the primary sites of CA production. Notably, this method represents a significant advancement in our ability to study these critical brain regions, as it uniquely enables the tracking of CAs spread across different parts of the brain, addressing a critical gap in the field, as no existing methods allow for such detailed localization of CAs across different brain regions. By enabling precise visualization of CAs within neural tissues, our method enhances understanding of their roles in disease progression.