Gene therapy is based on the delivery of genetic material to treat specific diseases. Adeno-associated viruses (AAVs) have been approved for use as gene delivery vehicles directly into target organs or tissues.

 

One challege of AAV-mediated gene therapy is quality control, due to the lack of techniques that can evaluate the relative abundance of AAVs that are loaded with their genetic cargo, are empty, or disassembled. Here, we show how mass photometry can be used to control the integrity and purity of AAVs, and measure the cargo they carry.