Super-Resolution Structured Illumination Microscopy to Study Endocytosis and Cellular Nanoparticle Uptake

Engineering nanoparticles for cancer intervention requires a detailed understanding of their internalization and intracellular trafficking, as these processes ultimately determine delivery efficiency. Over the past decade, advances in labeling strategies and microscopy have significantly deepened our knowledge of these processes. Further progress is imminent, as super-resolution microscopy has shattered the diffraction limit, enabling the investigation of biological structures at scales as small as ∼10 nm. Among the various super-resolution techniques used to interrogate endocytosis, super-resolution structured illumination microscopy (SR-SIM) stands out for its ability to provide faster, gentler imaging in live specimens. In this review, we will highlight how SR-SIM has enabled in-depth investigation of intracellular processes ranging from endocytic coat formation to endosomal maturation and therapeutic targeting. With the increasing popularity of SR-SIM in the biological sciences, this review aims to serve as a practical guide to its emerging applications, particularly in elucidating the endocytosis and intracellular trafficking of therapeutic nanomedicines.