Abstract
Abstract
Quality control of lipid nanoparticles (LNPs) is central to development of mRNA therapeutics, yet ensemble measurements obscure critical heterogeneity in particle morphology and mRNA cargo loading. Here we introduce PINPOINT (Profiling Individual Nanoparticles with Precise Observation of INternalized Therapeutics), a single-particle nanoscopy platform for non-destructive, multiparametric profiling of preformulated LNP samples. Super-resolution imaging with Nile Red resolves size and morphology, while an optimized permeabilization strategy provides selective access to encapsulated mRNA without compromising LNP integrity. Single-particle fluorescence measurements, including RiboGreen and sequence-specific probes, enable quantification and validation of mRNA loading and identity. Comparative analyses of bare and encapsulated mRNA reveal kinetic and structural features, exposing heterogeneity masked by bulk assays. By integrating structural and molecular readouts at the single-particle level, PINPOINT establishes a quantitative framework for assessing of LNP composition and payload distribution, offering actionable insights for improving batch consistency and guiding the rational design of next-generation mRNA delivery systems.