Activatable NIR Fluorescence Probe for Epinephrine Detection and Bioimaging Based on Anionic Heptamethine Cyanine

Area of Science:

• Analytical Chemistry
• Biochemistry
• Organic Chemistry

Background:

• Epinephrine (EP) is a vital catecholamine, but in vivo detection is challenging due to material limitations in current methods.
• Existing EP detection techniques are often unsuitable for biological applications.

Purpose of the Study:

• To design and develop a novel organic small molecule fluorescent probe for sensitive and selective in vivo detection of epinephrine.
• To enable bioimaging of epinephrine in living systems.

Main Methods:

• An anionic heptamethine cyanine dye was utilized for its near-infrared (NIR) fluorescence and biocompatibility.
• A chemical cascade reaction was employed, where epinephrine's secondary amine initiates probe activation via nucleophilic attack and cyclization.
• Specificity was achieved as primary amines or compounds lacking a β-OH group exhibit weaker reactivity.

Main Results:

• The probe demonstrated a linear fluorescence response to epinephrine concentrations ranging from 2-75 μmol/L.
• A low detection limit of 0.4 μmol/L was achieved with a high recovery rate of 94.78-111.32%.
• Successful bioimaging of epinephrine in living cells and an epinephrine analogue in nematodes was accomplished.

Conclusions:

• The developed fluorescent probe offers a sensitive, selective, and biocompatible method for in vivo epinephrine detection.
• This probe facilitates real-time monitoring and imaging of epinephrine in biological environments, overcoming previous limitations.