Virus Surface Chemistry (1 of 2) (IMAGE) Michigan Technological University Caption An isoelectric point is a common way to characterize viruses. However, it's not easy. To improve manufacturing for vaccines and gene therapy, a Michigan Tech team uses surface charge to determine the isoelectric point of different viruses. Specifically, they use a single-particle method with atomic force microscopy (AFM). Credit Jess Brassard/Michigan Tech Usage Restrictions please credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.