Development of a hemicyanine-based turn-on probe for MAO-A imaging in metabolic disorders in vivo and in serum.

In this study, A fluorescent/photoacoustic dual-modal probe HD-MAO for hemicyanine derivatives was successfully designed and synthesized, achieving high-sensitivity and high-specificity detection of monoamine oxidase A (MAO-A). Through the ingenious combination of the specific MAO-A recognition group and the hemipanocyanine fluorophore, the probe produced a significant enhancement of the intramolecular charge transfer (ICT) effect after enzymatic digestion, showing the synergistic activation characteristics of fluorescence (∼730 nm) and photoacoustic (∼700 nm) signals, with a detection limit of 0.806 mg/L. In the diet-induced obese mouse model, HD-MAO successfully revealed a significant increase in liver MAO-A activity, which was highly consistent with the serum test results, providing molecular imaging evidence for the early diagnosis of metabolic diseases. The probe behaves stably under physiological conditions and shows no cross-reaction to common interferents. Serum detection experiments further confirm its clinical applicability. This study not only provides an innovative tool for the research on MAO-A-related mechanisms, but also opens up a new approach for the early diagnosis and treatment monitoring of metabolic diseases.