Triage a hit list for solubility and aggregation before SPR: ~15 min per 384-well plate, ~2 µL/datapoint. Catch aggregators before they foul the chip.
A few weeks ago we brought the ORYL F1 for a demo at a top ten pharma to test a single question. We were lucky to work alongside automation and biophysics team on the use-case: could the F1 act as a pre-SPR solubility and aggregation triage for an entire small-molecule hit list? The full method and the complete dataset are in our new application note; this post is the shorter story of why the question matters and what we found.
Why aggregation impacts an SPR campaign
Compounds that aggregate at assay concentration adsorb non-specifically onto the immobilized protein and occlude the binding sites, so the compounds that run next across that same surface can no longer give an interpretable signal and must be retested. The worst aggregators go further and physically block the microfluidics and the sensor chips, which forces recurring cleaning cycles and, eventually, chip replacements. The cost is rarely a single bad data point; it is the rework and the uncertainty that follow, because a fouled surface corrupts every compound run after it and stalls the whole campaign. Debugging which compound is responsible would require further retests that simply disrupt the flow with no added value. In short, it adds frustration and wastes scientists’ time.
Current methods fail
The problem is, there is no single method that reliably catches aggregation at hit-list scale. Nephelometry and turbidity miss aggregation onset below ~20 µM — right where the assay concentration is most needed — so a genuine aggregator can be flagged clean. HPLC reads solubility accurately, but it is too slow and too sample-hungry to screen an entire list. So the aggregation problem tends to be discovered downstream, on the SPR instrument itself, which is an expensive place to discover it.
A triage layer that runs before SPR
That is the gap the F1 is built to fill. It profiles the whole list at around 15 minutes per 384-well plate (24 compounds × 8 concentrations × 2 replicates), using roughly 2 µL per datapoint from 10 mM DMSO stocks, and it reads each compound at two timepoints, 1 hour and 24 hours. The second read matters: supersaturating compounds can look soluble at 1 hour and only aggregate by 24 hours, so a single read would quietly misclassify them. For every compound the method returns a safe operating concentration, an avoid-above limit, the severity of the aggregation, and a flag for the compounds that shift their profile between the two reads — all reported with confidence intervals.
What we saw on a 142-compound list in the application note
On this particular list of 142 compounds, the F1’s risk calls agreed with internal solubility issues flagged during SPR runs on 10 of 11 scored compounds. About a fifth of the panel changed behaviour between the 1-hour and 24-hour reads, which is exactly the population a single timepoint would have got wrong. Scaled to a 1,000-compound campaign, the consumables and maintenance you avoid come to roughly CHF 20k on their own, before counting the retests and the stalled time that a fouled surface creates. For more details, check this SPR ROI calculator, to answer “How much pre-screening solubility saves you?”
Before Triage, not after it. You now a choice.
The value of the F1 isn’t really the measurement; it’s the timing. Catch a fouling compound during SPR and all you can do is retest. Catch it the day before, while the shortlist is still forming, and you have choices. Because every compound comes back with a safe operating concentration and an avoid-above limit, you can leave the worst aggregators out, push them to the end of the run, or — where the assay concentration allows — hold each compound inside its safe zone so it never reaches a fouling level. That window, before SPR while the list is still open, is the only one where this data changes a decision rather than just explaining a failure.
The full method, the complete dataset, and exactly how we scored the F1’s calls against internal flags are in our new application note.