Mass photometry

A new way of characterising biomolecules

"…the Refeyn OneMP instrument is a new and transformative technology that enables experiments that were not possible before. The results from the demonstration, and the potential benefits of the technology for our science made a compelling case to purchase a mass photometer…I think that it will rapidly become a first-choice method in our facility for the characterisation of the increasingly complex, sensitive and hard-won macromolecular samples that are studied at the frontiers of structural biology."

- Tim Sharpe, Biozentrum, University of Basel. 

Mass photometry is a revolutionary new way to analyse molecules. It enables the accurate mass measurement of single molecules in solution, in their native state and without the need for labels. This approach opens up new possibilities for bioanalytics and research into the functions of biomolecules.

How does it work?

Mass photometry builds on the principles of interference reflection microscopy (1) and interferometric scattering microscopy (2). It was developed by the research group of Prof. Kukura at Oxford University. They used carefully controlled illumination, a novel spatial-filtering strategy in the detection beam path (3) and careful image analysis to demonstrate that the minute amount of light scattered by single molecules can be reliably detected and, more importantly, correlates directly with molecular mass (Figure) (4).

Mass-photometry-explained.png

Figure: The principle of mass photometry. The light scattered by a molecule that has landed on a measurement surface interferes with light reflected by that surface. The interference signal scales linearly with mass.

A revolutionary new technology

Mass photometry is a revolutionary new method for analysing molecules. It enables the accurate mass measurement of single molecules in solution, in their native state and without the need for labels.

This approach opens up new possibilities for bioanalytics and research into the functions of biomolecules.

Fig2.PNG

The amount of light scattered by a particle scales linearly with the particle’s volume and refractive index. As the optical properties and density of biomolecules vary only by just a few percent, the scattering signal is directly proportional to the molecule’s mass – making it possible to weigh single molecules with light (Figure). The correlation of scattering signal with mass holds true for a variety of biomolecules (e.g. glycoproteins, nucleic acids and / or lipids), making mass photometry a universal analysis tool for biomolecules in solution.

Figure: Mass photometry measures the molecular mass of proteins and protein assemblies in solution. Via calibration, mass photometry enables the mass measurement of unknown biomolecules with high accuracy

(1) Verschueren, J. Cell Sci. 1985, 75, 279-301

(2) Ortega-Arroyo et al., Phys. Chem. Chem. Phys. 2012, 14, 15625-36

(3) Cole et al., ACS Photonics 2017, 4, 211-216

(4) Young et al., Science 2018, 360 (6387), 423-7

Benefits of mass photometry

Accurate mass measurement of true native behaviour

  • In solution, in a variety of buffers and compatible with membrane proteins

  • Label-free, without the need to modify samples
     

Information on all sub-populations in samples 

  • Single molecule counting 

  • Wide mass range and high dynamic range 

One assay format delivering multiple results

  • Homogeneity, structural integrity and activity

  • Quick, simple, minimal sample amounts