Visualizing Cholesterol Uptake by Self‐Assembling Rhodamine B‐Labeled Polymer Inside Living Cells via FLIM‐FRET Microscopy

Abstract

Atherosclerosis is a widespread and hazardous disease characterized by the formation of arterial plaques mostly composed of fat, cholesterol, and calcium ions. The direct solubilization of cholesterol represents a promising, atheroprotective strategy to subside lipid blood levels and reverse atherosclerosis. This study deals with the in‐depth analysis of polymer‐mediated cholesterol dissolution inside living human cells. To this end, a recently described multifunctional block‐polymer is labeled with Rhodamine B (RhoB) to investigate its interaction with cells via fluorescence microscopy. This gives insight into the cellular internalization process of the polymer, which appears to be clathrin‐ and caveolae/raft‐dependent endocytosis. In cell single particle tracking reveals an active transport of RhoB polymer including structures. Förster resonance energy transfer (FRET) measurements of cells treated with a fluorophore‐tagged cholesterol derivative and the RhoB polymer indicates the uptake of cholesterol by the polymeric particles. Hence, these results present a first step toward possible applications of cholesterol‐absorbing polymers for treating atherosclerosis.

Robust Inclusion Complex of Topotecan Comprised within a Rhodamine-Labeled β-Cyclodextrin: Competing Proton and Energy Transfer Processes

“…The aim is to have a real control over the intracellular and in vivo drug “biofate”, which is considerably related to the clinical therapeutic effect of the medicament. The topic of FRET measurements in cells treated with rhodamine-based supramolecular systems has previously been studied and is still of great interest nowadays [ 84 , 85 , 86 , 87 ]. FRET generates fluorescence signals that are susceptible to molecular conformation, association, and separation at a scale of 1–10 nm [ 88 ].…”

Rhodamine-Tagged Polymethacrylate Dyes as Alternative Tools for Analysis of Plant Cells

“…There are also reported biological studies on RhB conjugated with poly(ε-caprolactone) to determine both in vivo and in vitro quantitative dynamics of polymer nanoparticles in various animal cells and tissues [ 18 ], or oligonucleotides to monitor their uptake by cells [ 19 ]. The advantageous high-level microscopic visualization has been supported by RhB labels in poly(vinyl alcohol) hollow microparticles by confocal laser scanning microscopy (CLSM) [ 20 ], or poly(ethylene glycol)- b -polyglutamate- b -polylysine for cholesterol uptake by polymeric vesicles inside living cells via fluorescence lifetime imaging microscopy-Förster resonance energy transfer (FLIM-FRET) method [ 21 ]. Additionally, the monomers with RhB pendant group allowed for obtaining fluorescent poly(methyl methacrylate) latex [ 22 ].…”