Can I carry out measurements at a higher concentration?
Since Mass Photometry is based on single-molecule detection, it is restricted to a specific range of working concentrations. We recommend 100 nM – 100 pM concentrations depending on the sample. If you are concerned that these concentrations might be too low to observe complete assembly of a complex with low affinity, following are two procedures that might still help you detect the intact complex:
Measure in gaskets and quickly dilute highly concentrated sample in the buffer droplet used for focus finding. If the off-rate is slow enough the intact complex should be detectable.
Cross-link the complex at high concentration and dilute it for the measurement. This could stop dissociation and allow dilution of the complex to a concentration at which single events can be measured.
Dear Nikolas, thanks a lot for sharing your protocol. I will test it in near future, as I will be interested to perform some experiments at higher concentration. Greetings, Nikolay