Dresden 2026 – scientific programme
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BP: Fachverband Biologische Physik
BP 26: Biomaterials and Biopolymers (joint session BP/CPP)
BP 26.3: Talk
Thursday, March 12, 2026, 10:00–10:15, BAR/SCHÖ
FCS-Based RNA Payload Quantification and FLIM Analysis of pH-Dependent Lipid Phase Transitions in Lipid Nanoparticless — •Bernhard Kirchmair1, Judith Müller1, Thomas Kellerer2, Ekaterina Kostyurina1, and Joachim Rädler1 — 1Ludwig-Maximilians-Universität München, Germany — 2Max Planck-Institut für Biochemie, Martinsried, Germany
Lipid nanoparticles (LNPs) emerged as one of the most promising delivery systems for transfecting mammalian cells with synthetic messenger RNA (mRNA). However, LNPs show a substantial heterogeneity both in shape and cargo and the precise mRNA payload and stoichiometric ratios in multi-component nucleic acid delivery remain poorly quantified. In this project we investigate how mRNA payload depends on LNP size and surface composition using fluorescence correlation spectroscopy (FCS) supported by dynamic light scattering, enabling estimation of particle concentration and RNA copies per LNP. Fluorescence cross-correlation spectroscopy further allows measurement of siRNA/mRNA ratios in mixed cargos. To link payload properties to endosomal escape rates and hence delivery efficiency, we probed pH-dependent lipid phase transitions using fluorescence lifetime imaging (FLIM) and fluorescence anisotropy, capturing changes both in bulk lipid phases and in intact LNPs. These measurements build a framework to monitor structural changes relevant to endosomal escape and can be applied to other LNP formulations and cargo types. Quantitative knowledge about content and ratios will ultimately support the delivery of genetic programs for regulated gene expression.
Keywords: FCS; lipid nanoparticles; FLIM; RNA; delivery