A smart NIR fluorescent probe for the highly selective detection of palladium

A tailor-made colorimetric and NIR fluorescent probe for Pd-0 was developed by introducing allyl chloroformate into the methylene blue (MB) fluorophore. The probe exhibited vivid color change and significant fluorescence enhancement towards Pd-0, accompanied with excellent selectivity and sensitivity. No absorption and fluorescence response could be observed towards other metal ions. The fluorescence intensity of this probe showed a linear response to Pd-0 in the concentration range of 0-2 mu M with a detection limit of 5.7 nM. Moreover, living cell imaging results indicated that this probe holds promising application prospects for detecting intracellular Pd-0 species based on its low cytotoxicity and specific turn-on NIR emission.