Virus-like particle (VLP) measurements via gas-phase electrophoresis (nES GEMMA instrumentation) V. U. Weiss, Vienna/AUT, S. Zoratto, Vienna/AUT, M. Marchetti-Deschmann, Vienna/AUT Assoc. Prof. Dr. Victor U. Weiss, TU Wien, Getreidemarkt 9/164, 1060 Vienna/AUT Gas-phase electrophoresis using a nano electrospray gas-phase electrophoretic mobility molecular analyzer (nES GEMMA) separates singly-charged particles based on their size at ambient pressure in a high laminar sheath flow of particle-free air and a tunable electric field. [1] In accordance with recommendations of the European Commission for nanoparticle research (updated version 2022/C 229/01, June 10th, 2022), subsequent analyte detection is particle-number based. To date, such setup has been successfully applied for several (bio-)nanoparticle containing materials and has yielded valuable insights regarding sample purity, stability, aggregation, and dry particle sizes. Also, a correlation based on molecular weight (MW) and EM diameter from well-defined standards can be set up. Thus, the MW of an analyte can be determined from its EM diameter, as already demonstrated for proteins [2] and for intact viruses and virus-like particles (VLPs). [3] VLPs resemble their parent viruses but lack the infectious genomic material. Hence, VLPs find great application in various bio-pharmaceutical fields, e.g. for vaccine development, shielded cargo delivery, gene therapy or parent virus characterization. In all those cases, detailed analysis of particle size, size distribution, sample components, particle numbers and MW yields valuable insights about VLPs. We present the applicability of gas-phase electrophoresis for the in-depth characterization of VLPs. Exemplary bionanoparticles include adeno-associated virus (AAV) VLP, and VLPs based on SARS-CoV2, the source of the recent COVID19 pandemic. For the latter case, we demonstrate for the first time that gas-phase electrophoresis on a nES GEMMA instrument is possible (manuscript in preparation). VLPs can be detected as broad, size-heterogeneous peak next to low molecular weight material, probably VLP building blocks. Hence, in addition to information on particle size, size heterogeneity, and number-concentration, the stability of bionanoparticles can also be investigated. Literature: [1] S. L. Kaufman, Anal. Chem., 1996, 68, 11. [2] G. Bacher, J .Mass Spectrom., 2001, 36, 9. [3] V. U. Weiss, Anal. Bioanal. Chem., 2019, 411, 23.