Diluting Samples for SPR

I am hoping to use the Biacore 8K+ within the next 6 months. This is the high throughput system that I am hoping to do library screening on. Part of my concern with designing experiments is that my samples are synthesized/prepared in DMSO which means I will be diluting 100x into HBS (1% DMSO) then possibly diluting that further to meet a certain analyte concentration that is reasonable.

How would you go about doing these dilutions and preparing the running buffer so there is no buffer mismatch? Should I use a running buffer that is 1% DMSO? If so, how would I prepare that running buffer bottle (~500 mL) to match the smaller volume analyte samples? And in preparing the analytes, would it make the most sense to first dilute to a desired concentration in DMSO only and then do a 100x dilution for everything into HBS?

What I normally do is to dilute all my samples to an intermediate dilution (e.g. 100 µM) in the same buffer as the stock (e.g. DMSO for small compounds). Then the final dilution in running buffer (e.g. to 1 µM) without DMSO which wil result in 1%DMSO in running buffer. Then make running buffer with about the same DMSO concentration.

Since it is very difficult to match the DMSO concentration between sample and running buffer exact, you should add a series of calibration solutions to compensate for these differences (excluded volume differences) because reference subtraction is not sufficient in this case. The 8K instruments have special routines for compensating the excluded buffer volume  a.k.a. solvent correction.

Some publications that may be of help:


1. Giannetti, A. M., Koch, B. D. and Browner, M. F.; Surface Plasmon Resonance Based Assay for the Detection and Characterization of Promiscuous Inhibitors. Journal of Medicinal Chemistry (51) 3: 574-580; 2008.
2. Perspicace, S., Banner, D., Benz, J., et al.; Fragment-Based Screening Using Surface Plasmon Resonance Technology. Journal of Biomolecular Screening (14) 4: 337-349; 2009.
3. Shepherd, C. A., Hopkins, A. L. and Navratilova, I.; Fragment screening by SPR and advanced application to GPCRs. Progress in Biophysics and Molecular Biology (116) 2–3: 113-123; 2014.

Arnoud