What is Microfluidic Diffusional Sizing (MDS)?

Published on September 10th, 2019

Microfluidic diffusional sizing MDS exploits the unique properties of flow in microfluidic channels — specifically laminar flow, where streams can flow alongside one another with no convective mixing.

The interactions of proteins with secondary molecules is of great importance across the life sciences. Understanding how proteins bind with other secondary molecules is the key to combating diseases. The Fluidity One-W and Fluidity One-W Serum both use MDS technology to determine the binding affinity between proteins and their binding partners; whether they are aptamers, lipids, DNA, small molecules or other proteins.


What is Microfluidic Diffusional Sizing (MDS)?

Watch the video below to understand how the Fluidity One-W works:


What is microfluidic diffusional sizing—in the Fluidity One-W, a stream of fluorescently labeled protein is introduced into the diffusion chamber alongside an auxiliary stream. These streams flow in parallel with no convective mixing, so the only way protein can migrate from one stream to the other is by diffusion. Small peptides and proteins diffuse rapidly. Large proteins and aggregates, slowly.

At the end of the diffusion chamber, the streams are split. The quantity of protein in each stream is determined by the fluorescence from the label. The ratio of fluorescence between the two streams gives us the protein’s hydrodynamic radius.

The Fluidity One-W can measure this with proteins in buffer and in crude solutions like cell lysates or biological fluids. Because only the labeled species is detected.

If we repeat the test using a mixture of labelled protein and unlabeled binding partner, we can observe the degree of binding due to the change in size. Only species including the labeled protein are detected and measured. Titrating the binding partner against the labeled protein gives a binding curve and automatically generates a KD value on screen. The hydrodynamic radius for the unbound protein and the protein complex are also automatically calculated and displayed.

Microfluidic diffusional sizing (MDS) in the literature:

If you would like to learn more about microfluidic diffusional sizing (MDS) you can find a summary of all the papers showing the research behind Fluidic Analytics and microfluidic diffusional sizing (MDS) here. As well as seeing where others have used our products to make amazing discoveries.