Exploiting directed self-assembly and disassembly for off-to-on fluorescence responsive live cell imaging

Abstract

A bio-responsive nanoparticle was formed by the directed self-assembly (DSA) of a hydrophobic NIR-fluorophore with poloxamer P188.

Substituent directed cellular imaging in the 800–850 nm range with BF2-azadipyrromethene fluorophores

“… 37 Previously reported LD staining fluorophores include the BF 2 azadipyrromethene 1b with emission centred at 720 nm (ref. 35 ) with other classes including coumarin, statomerocyanine and naphthalimide based probes with emissions within the 600–700 nm range. 38 …”

“…32,33 It has also been previously shown to be highly effective in delivering molecular and nanoparticle uorophores to cells. 34,35 As LDs are the most concentrated lipophilic cellular regions, it was reasoned that these would be the preferred site of accumulation of 5. LDs are abundant intracellular organelles that are storage vessels for neutral lipids such as triacylglycerols and sterol esters.…”

“…37 Previously reported LD staining uorophores include the BF 2 azadipyrromethene 1b with emission centred at 720 nm (ref. 35) with other classes including coumarin, statomerocyanine and naphthalimide based probes with emissions within the 600-700 nm range. 38 Imaging experiments used epithelial breast cancer MDA-MB 231 cells which are a highly aggressive triple-negative human cell line making imaging of its subcellular features of fundamental research importance.…”

Identifying STEDable BF2-Azadipyrromethene Fluorophores

“…This solution was diluted 1/10 in cell media and incubated for 3 h with cells prior to imaging. Previous work in our group has shown that this procedure forms non-emissive nanoparticles that can deliver the fluorophore to cells [ 25 ]. All cells were imaged live with fluorophore 3 also imaged fixed.…”

“…Depending on the substituents attached to the core of the fluorophore, they can emit from the far-red to the near-infrared between 640 and 1060 nm [ 23 ]. At the concentrations used for live cell imaging, they have been demonstrated excellent photostability with no cellular toxicity [ 23 , 24 , 25 , 26 , 27 , 28 ]. These advantageous properties encouraged our goal to identify specific examples that were suitable for STED imaging.…”