Asymmetric Si-rhodamine scaffolds: rational design of pH-durable protease-activated NIR probes in vivo.

A group of asymmetric Si-rhodamine scaffolds was designed for protease-activated NIR probes. Dual pH-inertia for both spirocyclized fluorescent probes and fluorescent products of zwitterions form over a wide range of pH (4.0-11.0). Leucine aminopeptidase (LAP) and gamma-glutamyl transpeptidase (GGT) were monitored by fluorescent imaging in vivo.