Analysis of Protein Complex Formation at Micromolar Concentrations by Coupling Microfluidics with Mass Photometry

Area of Science:

• Biophysics
• Biochemistry
• Analytical Chemistry

Background:

• Mass photometry is a label-free technique for studying biomolecular interactions in solution.
• Conventional mass photometry is limited to nanomolar concentration ranges, hindering the analysis of low-affinity or transient interactions.
• Studying concentrated samples is crucial for understanding complex biological systems and weak binding events.

Purpose of the Study:

• To extend the concentration range of mass photometry analysis from nanomolar to tens of micromolar.
• To investigate the formation of protein complexes in solution at micromolar concentrations.
• To enable the characterization of weak biomolecular interactions and high-order complex formation.

Main Methods:

• Integration of mass photometry with a novel microfluidics system.
• On-chip dilution of concentrated samples (micromolar range) to nanomolar range milliseconds before measurement.
• Application to study the interaction between immunoglobulin G (IgG) and the neonatal Fc receptor.

Main Results:

• Successfully expanded the measurable concentration range for mass photometry to tens of micromolar.
• Enabled the detection and quantification of high-order protein complexes not observable with static mass photometry.
• Demonstrated the ability to study interactions with weaker affinities.

Conclusions:

• The combination of mass photometry and microfluidics significantly enhances the capability to characterize biomolecular interactions at higher concentrations.
• This technique is proficient in measuring weak affinities and transient interactions, crucial for understanding biological systems.
• The developed method has broad applications in biotherapeutic development and protein-protein interaction studies.