Mass Photometry to Study Antigen-Antibody Interactions on a Single-Molecule Level

Abstract

Source: Wu, D. et. al., Rapid Determination of Antibody-Antigen Affinity by Mass Photometry. J. Vis. Exp. (2021)

In this video, we demonstrate the use of mass photometry to study antigen-antibody interactions in a flow chamber. The focused light scatters differently based on the mass of the molecules. A detector collects the scattered light and generates the interference pattern as spots of varied intensities, which correlate with the molecular masses.

Protocol

1. Prepare the flow chambers Clean the glass coverslips Using wash bottles with distilled water, ethanol, and isopropanol, rinse the 24 mm x 50 mm coverslips in the following order: water, ethanol, water, isopropanol, water. Dry the coverslips with a stream of clean nitrogen. It is important to rinse the coverslips from top to bottom, holding the bottom corner with soft-tipped forceps. Dry the coverslip in the same direction to avoid transferring contamination from the forceps (<str…

Representative Results

Figure 1: MP flow chamber preparation and loading. (A) Coverslip holding position for the cleaning procedure. (B) Alignment of the 24 x 24 mm coverslip (middle layer) and the double-sided tape (top layer) on the surface of aluminum foil (bottom layer, not shown). Blue dashed lines show the location of the cut lines. (C) Top and side view of …

Materials

AcquireMP	Refeyn		MP data collection software
Anti-human thrombin	Haematologic Technologies	AHT-5020	RRID: AB_2864302
Cotton-tipped applicators	Thorlabs	CTA10	Cotton optical swabs for lens cleaning
Coverslips 24×24 mm	Globe Scientific	1405-10
Coverslips 24×50 mm	Fisher Scientific	12-544-EP
DiscoverMP	Refeyn		MP data processing software
Forceps	Electron Microscopy Sciences	78080-CF	Soft-tipped forceps for coverslips handling
Human α-thrombin	Haematologic Technologies	HCT-0020
Immersion oil	Thorlabs	MOIL-30
Isopropanol	Alfa Aesar	36644
Microsoft Excel	Microsoft		Spreadsheet
OneMP	Refeyn		Mass Photometry instrument
Origin	OriginLab		Scientific graphing software
PBS	Corning	46-013-CM	10x stock
Syringe filter	Millipore	SLGSR33SS	Buffer and sample filtering