Users love mass photometry

Using mass photometry and the MassFluidix HC system gives us that control where we can track over time and see ‘now it’s this size’, ‘now it’s broken down to tetramers’, ‘now it’s dimers’. It’s more kinetic than we could be with any other technique.

The GMP software is simple, easy-to-use and all aspects of the workflow are captured in an audit trail. The automated analysis algorithm eliminates user bias and generates very repeatable data.

[Our mass photometer] has been invaluable in a number of studies, ranging from simple cases of clarifying the oligomeric states of drug targets to elucidating complex binding mechanisms of small molecules.

Our experience with the KaritroMP has been great - very easy, rapid quantification of empty/full particles in purified adenovirus samples with accuracy comparable to that of AUC.

Mass photometry is very straightforward and convenient. You just need to dilute your sample in the right concentration and then you can quickly measure your sample in solution. You can also quickly analyze your measurements.

We have several other techniques for the characterization of mass and size distributions for macromolecules, but an increasing number of precious, heterogeneous, and metastable samples test the limits of detection for all of them. By comparison, mass photometry provides a winning combination of speed of data collection, very low sample consumption, and impressive accuracy of molar mass distributions. In addition, as a single-molecule technique, mass photometry provides unique information about which discrete species are populated in a binding or oligomerization equilibrium, even when those species are in fast exchange. This is a perfect complement to other techniques where macromolecular association can be detected but the exact composition of complexes, required to constrain fitting models, cannot be measured.

Mass photometry was the method of choice for our study, since it can quickly quantify the relative abundance of all the tau oligomers and show how these populations change over time, from the beginning of the aggregation process.

The nice thing about mass photometry is that it happens in solution, without requiring labels or sample fixation. Therefore, I am sure of what to expect when I use magnetic tweezers, since I know how long my complex can remain stable at the desired temperature and conditions.

It’s a game changer in AAV characterization, for us as well as our clients. In one project, for example, we saw that the partially filled AAV capsids were way more abundant than desired. Thanks to the SamuxMP, we could identify this rapidly and went back to the plasmid design... which led to drastically lower production of partials during plasmid expression, simplifying our downstream processing and purification workflows.

The underlying physics behind how it works are very complicated, but using the instrument is very much plug-and-play. We’ve got students in the lab using the instruments with no problems… One of the routine things that we are doing now is after solubilizing the protein and purifying it we put it into the mass photometer to check if there is a single peak of the right size before we then go on to do the expensive cryo-EM experiments.

I recently ran some manual, time-resolved samples on the Refeyn TwoMP, and the data was an absolute eye-opener. It generated clear, decisive insights that gave us a level of system understanding we simply couldn't have uncovered from SPR alone.

Compared to SEC-MALS, mass photometry is fast and provides robust and reliable data… We also chose the MassFluidix HC as an add-on to the TwoMP, as some of our biophysical analyses do need to be conducted at higher concentrations.

For any biochemical experiments that I will do in the future, I will always use mass photometry as a technique that either complements other techniques or replaces them entirely. I will try to keep mass photometry as integrated in my work as possible because it is a very honest technique that gives you a direct picture of your sample.

Unlike nsEM and cryo-EM, mass photometry allows us to look at our samples at the low nanomolar concentrations we use for activity assays... The MassFluidix HC was able to detect much longer filaments than expected – it turns out they tend to dissociate rapidly upon binding to the surface. We didn’t know our protein could do that!

We use mass photometry in our lab to provide clients with fast, easily generated, and readily interpretable data to support drug development. Mass photometry is particularly useful in early-phase and formulation screening, and as an orthogonal technique to sedimentation velocity AUC for size distribution characterization.

I’ve used AUC, A260/A280 and other techniques to measure adenovirus empty/full capsid ratios. The Karitro lets me do it quickly in the lab, with the accuracy of AUC. What I like most about the Karitro is the speed and ease of us – the software is so simple and straightforward!

[With mass photometry,] we were able to characterize the monomer-to-dimer transition in a low concentration range, which would have been difficult to detect with other techniques... I see mass photometry as a valuable tool in exploring the relationship between enzymatic activity and oligomeric states.

We study many protein interactions, so the low sample and time requirements of mass photometry make it valuable to us. We use it mainly to determine the stoichiometry of protein complexes and to check if they are adequately formed before doing structural analysis. It turned out to be a very good machine!

From the first moment I saw a mass photometer, I was mind-blown by how simple the instrument was to use and by how quickly you could see individual molecules and complexes... Since mass photometry requires very little sample, it is suitable for proteins that are hard to produce in large quantities... We also use mass photometry to quickly check our samples before using optical tweezers, to make sure we are really measuring single molecules.

I feel that mass photometry is really reporting on my actual sample as I have it in my tube. That's a huge benefit. In particular, you can parse out compositional heterogeneity independent of conformational variability, which is a difficult thing to get with other techniques.

We set up our cryo-EM facility this year, and all our samples go through mass photometry screening. If they look good enough with mass photometry, they go directly to high-resolution cryo-EM – we don’t need nsEM or even preliminary cryo-EM.

We use mass photometry to rapidly characterize the aggregation state and homogeneity of proteins before cryo-EM, helping us reduce the cost of our structural analyses... Compared to analytical SEC and SEC-MALS, mass photometry requires less sample, and the analysis of a single sample is faster.

We are proud to be one of the first labs in Europe to offer mass photometry for AAV analytics within a GMP environment. We want to convince our customers that mass photometry is the preferred method for AAV analytics. It is highly valuable for final product release testing as well as during process development.

Previous gel filtration chromatography experiments indicated that one of the proteins I studied was a hexamer, according to the marker. I subsequently did the same experiment using mass photometry and I realized that my protein exists in various oligomeric forms. We are now exploring different functions that can be attributed to these forms. This revelation would not be possible without mass photometry!

We chose mass photometry for its super-fast turnaround time and minimal sample requirements – compared to methods like AUC. It allows us to rapidly quantify AAV full-to-empty ratios and determine the proportion of AAV particles during purification.

There are three primary ways in which TwoMP improves our workflows: Fast and precise QC with next-to-no sample consumption, quick estimation of success and appropriate ratios in complexation experiments, and analysis of sample homogeneity with higher precision than SEC.

We had to map the monomer-tetramer equilibrium across concentration, temperature, and time, but other methods couldn't handle the low concentrations or flexible conditions we needed. Mass photometry allowed us to generate this crucial data for the customer and their IND filing.