Rational Design of Near-Infrared Carbon Dots as Polarity-Sensitive Fluorescent Probe and Imaging of Lipid Droplet

Abstract

Polarity plays an important role in establishing and reflecting numerous complex physiological functions and pathological effects associated with energy metabolism and cell signaling. Monitoring the variation of polarity, particularly the polarity of lipid droplets (LDs), in cells and tissues is of great significance in biomedical research and clinical diagnosis. Herein, the novel near-infrared (NIR) carbon dots (CDs) based fluorescent nanoprobe is presented to serve the stringent requirements of polarity targeting and imaging with high polarity sensitivity, high fluorescence quantum yield, superior photostability and photobleaching resistance, excellent permeability and biocompatibility. The absorption and emission wavelength shifts are in response to an increased ambient polarity (Δf) in which the emission reaches to the NIR region at 700 nm. This nanoprobe can specifically colocalize with LDs and effectively imaging the polarity changes in LDs and living cells. This work present effective strategies and foundations for construction of NIR CDs, helps for designing new polarity and LDs selective probes, and has implications for accelerating a deep insight of polarity-related processes and diagnosis of relevant diseases.