Super-Resolution Microscopy Revealed the Lysosomal Expansion During Epigallocatechin Gallate-Mediated Apoptosis

Abstract

Direct visualization of the dynamic events in lysosomes during drug-mediated programmed cell death (apoptosis) is a great challenge. This is due to the lack of resolving power of a conventional microscope and also the unavailability of a suitable multimodal probe that simultaneously can carry the drug with high loading capacity and ensure its specific internalization into lysosomes. In this work, using super-resolution microscopy, we observed the lysosomal expansion during apoptosis that was treated with epigallocatechin gallate (EGCG) conjugated to bovine serum albumin (BSA). Albumin protein is known to internalize into lysosomes via endocytosis, thus helping in the specific delivery of EGCG to the lysosomal compartment. The conjugation of EGCG to BSA not only helped in increasing the killing efficiency of cancer cells but it also reduces the side effects and produces minimal reactive oxygen species. The decrease in local viscosity helped in lysosomal expansion during apoptosis.

Superparamagnetic Iron Oxide Nanoparticles with Large Magnetic Saturation and High Particle Photon Counts for Super-Resolution Imaging of Lysosomes

“…The uptake of SPION particles through endocytosis is a well-known mechanism, , and the colocalization study had to be done to further confirm the above conclusion. Recently, using the fact that bovine serum albumin (BSA) ends up in lysosomes via endocytosis, the BSA–dye conjugates were used to stain the lysosomes . Colocalization of the BSA-conjugated Cy5 dye with the commercially available lysotracker can be seen in Figure S8, suggesting that BSA–Cy5 could be used as an alternative to lysotracker.…”

“…Recently, using the fact that bovine serum albumin (BSA) ends up in lysosomes via endocytosis, 47 the BSA−dye conjugates were used to stain the lysosomes. 48 Colocalization of the BSA-conjugated Cy5 dye with the commercially available lysotracker can be seen in Figure S8, suggesting that BSA−Cy5 could be used as an alternative to lysotracker. Next, we checked the colocalization of SPIONs with the established BSA−Cy5 conjugates as the SPIONs also showed minimal emission in the red channel where Cy5 also emits.…”

Protein Conjugation Helped CdTe Quantum Dots for the Specific Labeling and Super‐Resolution Imaging of Lysosomes

“…As a result, BSA immensely helped the conjugated CdTe QDs to specifically stain the lysosomes and provide the SRM imaging. [20,[24][25][26] The standard deviation of localizations for the QDs improved substantially from ~50 nm to ~25 nm upon conjugation with BSA. This ultimately helped to achieve better resolution of lysosomes in both STORM and super-resolution radial fluctuation (SRRF) microscopy.…”

“…BSA internalize inside the lysosomes via the caveolae‐mediated endocytic pathway involving plasma membrane invagination and a bulb‐like structure formation. As a result, BSA immensely helped the conjugated CdTe QDs to specifically stain the lysosomes and provide the SRM imaging [20,24–26] . The standard deviation of localizations for the QDs improved substantially from ∼50 nm to ∼25 nm upon conjugation with BSA.…”

Mapping the time dependent DNA fragmentation caused by doxorubicin loaded on PEGylated carbogenic nanodots using fluorescence lifetime imaging and superresolution microscopy

“…28,29 The FLIM technique can provide a detailed spatial mapping of the drug in its various stages of action, as the lifetime of the probe is independent of the concentration, but an accurate depicter of the environmental forces experienced by the probe. 30,31 On the other hand, superresolution microscopy helps overcome the diffraction limit and observe many cellular components, including nuclear structures with high resolution. 32,33 In particular, the new analytical method, namely "superresolution radial fluctuation (SRRF)", has made it possible to obtain the superresolved image even when using confocal or wide-field microscopy.…”