Simultaneous monitoring of polarity changes of lipid droplets and lysosomes with two-photon fluorescent probes

Dynamic Excimer (DYNEX) Imaging of Lipid Droplets

“…A close inspection of the droplet images (Figures B,C and S15) clearly exhibited lower polarity in the inner core of the droplets, in agreement with the aforementioned arrangement . Interestingly, compared with the CCD-18Co line, the tumoral CT26.WT cell line exhibited lipid droplets with slightly lower polarity, consistent with previous works. ,,− This observation supports the idea of a higher lipid content in the tumoral line due to altered, proliferative metabolism.…”

“…For these measurements, once lipid droplet pixels were segmented using DYNEX, we extracted polarity E T 30 values (Figure ) via multiparametric microscopy by combining the time-gated intensity ratio and fluorescence lifetime information (see the SI for experimental details and Figures S11–S13). Heretofore, there have been some efforts to characterize intracellular polarity employing fluorescence microscopy techniques using emission spectra, fluorescence intensity, and ratiometric measures. − Nevertheless, biological samples present important difficulties for quantitative imaging that are overcome by our methodology Table and Figure S14 show the E T 30 values recovered from lipid droplets of CCD-18Co and CT26.WT cells.…”

Lipid Droplet-Specific Fluorescent Probe for In Vivo Visualization of Polarity in Fatty Liver, Inflammation, and Cancer Models

“…Significantly, the fluorescence enhancement was about 278-fold, which was much more sensitive than most of the reported LD-polarity probes (Table S1 and Figure S2). − ,− The polarity-sensitive property might be due to the fact that large charge separation and the excited-state energy of LD-TTP were dissipated in high-polarity media, leading to nonradiative relaxation of the excited energy to quench the fluorescence substantially . Meanwhile, a good linearity between fluorescence intensities ( F max ) and polarity (Δ f ) was obtained within a wide range from 0.258 (10% water) to 0.312 (80% water) according to the linear equation: F = 873,651.7 – 2,821,060 × Δ f , ( R 2 = 0.9829) (Figure b), confirming the high sensitivity of LD-TTP toward micropolarity changes.…”

“…Because of its noninvasiveness, high sensitivity, superior spatiotemporal resolution, and simple operation, the fluorescence imaging technique has become a powerful tool for the real-time and in situ detection of biomolecules at subcellular levels and in vivo . − Until now, although a large number of fluorescent probes have been reported for specific imaging LDs, ,− few are polarity-sensitive. − ,− In addition, most of the polarity-sensitive probes are only limited for dynamic imaging of LDs. − Due to the lack of research on various disease models, the clear elucidation of the intrinsic relationship between diseases and LD polarity has not been really achieved. Currently, the disease model using LD polarity mainly focuses on the diagnosis of cancer at the level of cells or animal tissues/organs. ,,− To our knowledge, the visualization of LD polarity in vivo models, such as inflammation or clinical cancer patient samples, remains underexplored.…”

1,2,4-Triaminobenzene as a Fluorescent Probe for Intracellular pH Imaging and Point-of-Care Ammonia Sensing

“…Among these fluorescent probes, two-photon-based fluorescent materials ,, have been paid much attention due to their good cell penetration, low biological toxicity, simple preparation, high sensitivity, and lower background interference. Currently, a plethora of two-photon-based fluorophores have been applied to design fluorescent probes for microenvironment detection (e.g., polarity, pH, and viscosity , ). But most of these fluorophores require complicated synthesis processes and professional operation with single-functional ability.…”