Red- and Far-Red-Emitting Zinc Probes with Minimal Phototoxicity for Multiplexed Recording of Orchestrated Insulin Secretion.

Zinc biology, featuring intertwining signaling networks and of critical importance to human health, witnesses exciting opportunities in the big data era of physiology. Here, we report a class of red- and far-red-emitting Zn 2+ probes with K d values ranging from 190 nM to 74 μM, which are particularly suitable for real-time monitoring the high concentration of Zn 2+ /insulin co-released during vesicular secretory events. Compared to the prototypical rhodamine-based Zn 2+ probes, the new class exploits morpholino auxochromes which eliminates phototoxicity during long-term live recording from isolated islets. A Si-rhodamine-based Zn 2+ probe with high turn-on ratio (> 100), whose synthesis was enabled by a new route featuring late-stage N-alkylation, allowed simultaneous recording of Ca 2+ influx, mitochondrial signal, and insulin secretion in isolated mouse islets. The time-lapse multicolor fluorescence movies and their analysis, enabled by red-shifted Zn 2+ and other orthogonal physiological probes, highlight the potential impact of biocompatible fluorophores on the fields of islet endocrinology and system biology.