A novel cell-penetrating Janus nanoprobe for ratiometric fluorescence detection of pH in living cells

摘要

pH regulates the function of many organelles and plays a pivotal role in requiring multitud cellular behaviors. Compared with single fluorescent probes, ratio fluorescent probes have higher sensitivity and immunity to interference. Herein, a novel Janus ratio nanoprobe was developed for intracellular pH detection. Modified rhodamine B probe and fluorescein isothiocyanate (FITC) were individually encapsulated in the independent hemispheres of Janus microparticles fabricated via Pickering emulsion. Moreover, it exhibits a satasified ratiometric detection of pH compared to the previous core-shell structure and organic small molecule probe. Accordingly, the Janus nanoprobe possesses many important features as an attractive sensor, including high antijamming capability, excellent stability, good reversibility and low cytotoxicity. Variations of the two fluorescence intensities (Fgreen/Fred) resulted in a ratiometric pH fluorescent sensor, which can respond to wide range of pH values from 3 to 8. To be more specific, with a single excitation wavelength of 488 nm, there are dual emission bands centered at 538 nm and 590 nm. Also the Janus nanoprobe displays a excellent linear relationship in the physiologically relevant pH range of 4.0-6.0. Consequently, detecting of pH and imaging was successfully achieved in living cells, which provides a simple and reliable method for detecting intracelluar pH and other similar substances.