Easy Mass Measurement Of Viruses And Nanoparticles

A fast, simple way to find the mass of viruses and nanoparticles has been developed by researchers in Taiwan (Anal. Chem., DOI: 10.1021/ac300615v). The mass distributions of viruses and nanoparticles—which range between 1 megadalton and 1 gigadalton—are hard to measure. Most viruses and nanoparticles have 50 charges or fewer when ionized. This range lies in a detection black hole: Mass spectrometry can easily cope with small molecules with one or a few charges, and techniques exist for much larger biomolecules or cells with thousands of charges. But in between, noise from the instruments’ electronics drowns out the signal. Chung-Hsuan Chen of Academia Sinica, in Taipei, and his team used a technique they recently developed, based on laser-induced acoustic desorption spectroscopy. Unlike other techniques for large particles, Chen’s method doesn’t need a matrix, which could form aggregates with the sample and thereby distort its mass spectral signal. Chen’s team also introduced a steel shield around its charge detector to reduce electronic noise. Analyzing either spherical polystyrene nanoparticles or HIV virions took less than a minute, Chen says.