A New Hemicyanine-based Fluorophore for Monitoring pH and Lysosome Imaging

Abstract

On account of long wavelength emission and high stability, a hemi-cyanine skeleton of 2,3,3-trimethyl-1-(3-sulfopropyl)-3H-benzo[f]indolinium was condensed with 6-hydroxy-7-morpholin-4-yl-methyl-naphthalene-2-carbaldehyde in the presence of acetic anhydride. The new probe displays a sensitive absorption and fluorescence according to the pH value changes and exhibits an excellent linearity of the relative emission intensity (I₆₇₀/I₅₈₀) vs. pH in the pH range of 7.0–9.5 with a correlation coefficient of 0.993. Moreover, compared to the commercialized LysoTracker Green DND-26 the probe is targeting to the lysosomal imaging in HeLa cells and, thus, can be further used as a near-infrared fluorescent probe for cellular research.