Rational Design of pH-Independent and High-Fidelity Near-Infrared Tunable Fluorescent Probes for Tracking Leucine Aminopeptidase In Vivo

Accurate detection of target analytes and generationof high-fidelityfluorescence signals are particularly critical in life sciences andclinical diagnostics. However, the majority of current NIR-I fluorescentprobes are vulnerable to pH effects resulting in signal distortion.In this work, a series of fluorescence-tunable and pH-independentprobes are reported by combining optically tunable groups of unsymmetricSi-rhodamines and introducing the methoxy instead of the spiro ringon the benzene ring at position 9. To validate the concept, the leucineaminopeptidase response site was introduced into Si-2,6OMe-NH ( 2 ) with the best optical properties to synthesize Si-LAP for monitoring the intrahepatic LAP in vivo. Therefore,the design approach may provide a new and practical strategy for designinginnovative functional fluorescent probes and generating high-stabilityand high-fidelity fluorescent signals.