Atomic Force Microscopic Imaging of mRNA-lipid Nanoparticles in Aqueous Medium

The efficacy of mRNA-lipid nanoparticles (mRNA-LNPs) depends on several factors, including their size and morphology. This study presents a new technique to characterize mRNA-LNPs in an aqueous medium using atomic force microscopy (AFM). This method utilizes an anti-polyethylene glycol antibody to immobilize mRNA-LNPs onto a glass substrate without corruption, which cannot be avoided with conventional proce-dures using solid substrates such as mica and glass. The obtained AFM images showed spherical and bleb -like structures of mRNA-LNPs, consistent with previous observations made using cryo-transmission electron microscopy. The AFM method also revealed the predominant existence of nanoparticles with a diameter < 60 nm, which were not detectable by dynamic light scattering and nanoparticle tracking analysis. As mRNA-LNPs are usually not monodisperse, but rather polydisperse, the AFM method can provide useful comple-mentary information about mRNA-LNPs in their development and quality assessment.(c) 2022 American Pharmacists Association. Published by Elsevier Inc. All rights reserved.

Automated summary

This study presents a new technique utilizing atomic force microscopy (AFM) to characterize mRNA-lipid nanoparticles (mRNA-LNPs) in an aqueous medium. The AFM method allows for the immobilization of mRNA-LNPs on a glass substrate without corruption, providing detailed images of their spherical and bleb-like structures. Additionally, the AFM method reveals the presence of nanoparticles with a diameter < 60 nm that cannot be detected by other techniques. This method complements the development and quality assessment of polydisperse mRNA-LNPs.