Rapid and Noninvasive Quantification of Capsid Gene Filling Level Using Water Proton Nuclear Magnetic Resonance

The present work reports an enabling novel technology for quantifying the gene content in adeno-associated viral capsids. The method is based on the water proton nuclear magnetic resonance (wNMR) technique. Instead of analyzing the capsid directly, it utilizes water molecules to distinguish empty and full capsids, as water interacts with them differently. The transverse relaxation rate of water protons, R₂(¹H₂O), readily distinguishes empty and full capsids and is capable of quantifying the fraction of full capsids in a mixture of full and empty ones. It involves no sample preparation and no reagents. Measurement is rapid (data collection takes 1-2 min), noninvasive (the capsid sample can stay inside the original sealed and labeled container to be used in other studies or administered to a patient), and performed using a wide-bore benchtop NMR instrument. The method can be readily implemented at a production plant for product release as part of product quality control.