Abstract
mRNA-LNPs are unusually complex drugs. This places unique demands – and correspondingly unique importance – on analytical methods for their characterization and quality control. But which analytical methods are appropriate, and how do we choose the best ones?
In the current work, the selection, suitability and application of analytical methods – and their orthogonality and complementarity, as requested by regulatory authorities – is presented, based on comprehensive comparisons and interlaboratory studies we have performed. A tiered analytical approach is proposed, from the early screening by batch methods like dynamic light scattering (DLS) or nanoparticle tracking analysis (NTA) to more in-depth analyses with e.g. multi-detector field flow fractionation (MF-FFF), differential scanning calorimetry (DSC) and analytical ultracentrifugation (AUC). We show that the latter methods are crucial to discover more subtle differences in LNP quality that are important for biological activity.
Finally, we try to address what can be seen as something of an analytical gap – the LNP surface chemistry. We present a novel and unique chromatography method can separate intact LNPs based on their surface. This complements the existing analytical toolbox - and can be taken further to preparatively purify the same LNPs while avoiding TFF.