# Aerosol size determination via light scattering of viruses and protein complexes

## TL;DR

A new optical method detects and measures ultrafine aerosol particles, including viruses and proteins, as small as 16 nm, useful for health, environment, and X-ray imaging.

## Contribution

A novel light scattering technique enables size determination of sub-100 nm aerosol particles, including viruses and proteins, down to 16 nm.

## Key findings

- The method detects individual particles as small as 16 nm in diameter.
- It tracks the size and location of aerosolized viruses and protein complexes.
- The technique is primarily used for X-ray laser imaging but has broader environmental and health applications.

## Abstract

The study of ultrafine particle aerosols, those with particle diameters of 100 nm or less, is important due to their impact on our health and environment. However, given their small sizes, such particles can be difficult to measure and trace. Most common optical methods are unable to reach this size range. Other methods exist but incur other limitations, such as the need for electrically charged particles. Here we show how light scattering can be used to detect and measure the size and location of single viruses and protein complexes forming an aerosol beam, as well as trace their path. We were able to detect individual particles down to 16 nm in diameter. The primary purpose of our instrument is to monitor the delivery of single bioparticles to the focus of an X-ray laser to image those particles, but it has the potential to study any other aerosols such as those resulting from ultrafine sea spray, with important consequences for cloud formation and climate modeling, or from combustion, responsible for most air pollution and resulting health impacts.

Ultrafine particle aerosols with particle diameters <100 nm have a high impact on our health and the environment but are difficult to characterize. Here, the authors present an optical method to determine the size of small aerosolized viruses and protein complexes in vacuum mainly for characterizing samples for X-ray imaging, with particle diameters down to 16 nm.