Selective Catecholamine Recognition with NeuroSensor 521: A Fluorescent Sensor for the Visualization of Norepinephrine in Fixed and Live Cells

A method for the selective labeling and imaging of catecholamines in live and fixed secretory cells is reported. The method integrates a tailored approach using a novel fluorescence-based turn-on molecular sensor (NeuroSensor 521) that can exploit the high concentration of neurotransmitters and acidic environment within secretory vesicles for the selective recognition of norepinephrine and dopamine. The utility of the method was demonstrated by selectively labeling and imaging norepinephrine in secretory vesicles such that discrimination between norepinephrine- and epinephrine-enriched populations of chromaffin cells was observed. This method was validated in fixed cells by co-staining with an anti-PNMT antibody.