Conclusions
The nanoprobe Cy5@Au NP was successfully used as a lysosomal probe for the super-resolution observation in living cells and found to overcome the limitations of commercial LysoTrackers. Our results thus confirm that nanoparticles can be useful tools for subcellular super-resolution imaging and highlight new avenues for using nanoparticles in biology.
Methods
The nanoprobe Cy5@Au NP contained three parts: a bio-inert gold core, a biocompatible polyethylene glycol spacer, and a fluorophore cyanine 5. Structured illumination microscopy (SIM) was employed to capture the fluorescence of Cy5@Au NPs in cells. The tolerance assays to changes in the lysosomal microenvironment and to LMP, the photobleaching assay, and the long-term lysosomes labelling assay of Cy5@Au NPs were compared with commercial LysoTrackers. The super-resolution observation of lysosomal dynamics with Cy5@Au NPs was performed.
Results
Cy5@Au NPs can light up lysosomes specifically under SIM. Compared with commercial lysosomal molecular probes, Cy5@Au NPs exhibited stronger tolerance in lysosomes during various treatments, and changes in the lysosomal microenvironment and LMP did not cause Cy5@Au NPs to lose track of their targets. Cy5@Au NPs demonstrated an excellent anti-photobleaching ability, and a long-term labelling assay revealed that they could label lysosomes more than 3 d. Biological events of lysosomes such as the kiss-and-run process, fusion, fission, and mitophagy were recorded with the fluorescent Cy5@Au NPs under SIM. Conclusions: The nanoprobe Cy5@Au NP was successfully used as a lysosomal probe for the super-resolution observation in living cells and found to overcome the limitations of commercial LysoTrackers. Our results thus confirm that nanoparticles can be useful tools for subcellular super-resolution imaging and highlight new avenues for using nanoparticles in biology.