Highly Efficient Red/NIR-Emissive Fluorescent Probe with Polarity-Sensitive Character for Visualizing Cellular Lipid Droplets and Determining Their Polarity

Abstract

Lipid droplets (LDs), which are ubiquitous organelles existing in almost all eukaryotic cells, have attracted a lot of attention in the field of cell biology over the last decade. For the biological study of LDs via fluorescence imaging, the superior LD fluorescent probes with environmental polarity-sensitive character are highly desired and powerful but are very scarce. Herein, we have newly developed such a kind of fluorescent probe named LDs-Red which enables us to visualize LDs and to further reveal their polarity information. This fluorescent probe displays the advantages of intense red/near-infrared emission, high LD staining specificity, and good photostability; thus, it would be very useful for LD fluorescence imaging application. As a result, the three-dimensional confocal imaging to visualize spatial distribution of LDs and the multicolor confocal imaging to simultaneously observe LDs and other cellular organelles have been realized using this new LD fluorescent probe. Furthermore, the polaritysensitive emission character of this probe enables us to quantitatively determine the LD polarity via spectral scan imaging. Consequently, the cancer cells (HepG2, HeLa, and Panc02) displaying lower polarity of LDs than the normal cells (L929, U251, and HT22) have been systematically demonstrated. In addition, this polarity-sensitive probe displaying shorter fluorescence wavelengths in cancer cells than in normal cells has an important and potential ability to distinguish them.

Donor–Acceptor–Acceptor-Conjugated Dual-State Emissive Acrylonitriles: Investigating the Effect of Acceptor Unit Order and Biological Imaging

“…Remarkably, the emission signals of TPA-AN-PhBT and TPA-BT-ANPh overlapped with the black spots in the bright field. This shows that these dyes possibly stain lipid droplets, as per our experience and previous reports. − …”

Selective Visualization of Tumor Cell Membranes and Tumors with a Viscosity-Sensitive Plasma Membrane Probe

“…More and more research has revealed that the microenvironment of cells will change significantly after carcinogenesis. For example, the viscosity of the subcellular organelles (such as mitochondria and lysosomes) of cancerous cells has been reported to be significantly greater than that of normal cells. ,, However, the viscosity changes of plasma membranes after carcinogenesis remain unknown. To find out whether the plasma membrane viscosity of tumor and normal cells is different, we used the viscosity-sensitive probe TPA-S to stain tumor cells (HeLa, HepG2, 4T1, MCF) and normal cells (HEK293T, RAW264.7).…”

A fluorescent probe for lipid droplet polarity imaging with low viscosity crosstalk

“…13,14,20–24,26,28–42 On the other hand, most of the probes as LD polarity indicators exhibit poor resistance to photobleaching. 21,26,34,43,44 This feature may significantly block their application in biosensing due to the fact that photostability is a pre-requisite for long-term tracking of analyte changes in living cells. In this respect, the triphenylamine group (TPA) with significant AIE (aggregation induced emission) characteristics has been introduced into polarity-sensitive chromophores to overcome this drawback.…”