Super-resolution Microscopy for Nanomedicine Research

Abstract

Super-resolution microscopy, or nanoscopy, revolutionized the field of cell biology, enabling researchers to visualize cellular structures with nanometric resolution, single-molecule sensitivity, and in multiple colors. However, the impact of these techniques goes beyond biology as the fields of nanotechnology and nanomedicine can greatly benefit from them, as well. Nanoscopy can visualize nanostructures in vitro and in cells and can contribute to the characterization of their structures and nano-bio interactions. In this Perspective, we discuss the potential of super-resolution imaging for nanomedicine research, its technical challenges, and the future developments we envision for this technology.

Figure 1

Super-resolution microscopy. Schematic representation of super-resolution methods and their performances. Three main families can be identified: (i) structured illumination microscopy (SIM) methods and their point scanning variations where the sample is irradiated with patterned illumination and the resolution is enhanced through mathematical reconstruction; (ii) stimulated emission depletion (STED) where a de-excitation doughnut is scanned around the excitation beam, resulting in the confinement of the excitation and subsequent enhancement of resolution; and (iii) single-molecule localization microscopy (SMLM) where individual fluorophores are sequentially localized and the image reconstructed in a pointillistic fashion. Many SMLM variants are available, depending on the mechanisms of single-molecule control: stochastic optical reconstruction microscopy (STORM), photoactivated localization microscopy (PALM), ground-state depletion (GSD), and point accumulation for imaging nanotopography (PAINT). Notably, it is important to compare the techniques’ performances with the properties of the material under study (top left).

Figure 2

Opening the nanomedicine black box. Pictorial representation of the journey of a nanoparticle from the injection site to the target tissue (cancer). Several barriers have to be overcome in blood (protein corona, immune system), tissues (extravasation, matrix diffusion), and cells (membrane targeting, cell uptake, endosomal escape, and cell trafficking). Super-resolution imaging can shed light on the mechanisms of these phenomena, contributing to opening the black box of nanomedicine.