Adeno-associated viruses (AAVs) are used in approved gene therapies to deliver genetic cargo to target cells. Distinguishing heterogeneously filled AAV capsids is an important aspect of sample characterization when developing these therapeutics.

Here, data collected by Pharmaron Gene Therapy show that mass photometry can distinguish populations of AAV capsids with heterogeneous loading of genomic content and quantify the proportion of each population in a sample. Mass photometry measurements take only minutes, require minimal training and have very low titer requirements.