Quantifying the quality of the experiments used to grow protein crystals: the iQC suite

Millions of crystallization trials are set up each year, with no clear metrics for determining if the experiments were correctly dispensed. This article reports the development of a software tool (iQC - image Quality Control) that recognizes factors associated with suboptimal experimental control during the setting up of protein crystallization trials. In its simplest form, iQC returns a report that gives an overall rating to the quality of an experimental setup. The iQC software is able to identify many common problems observed in setting up crystallization trials - droplets that have associated splatter; droplets with air bubbles; the positional accuracy of droplet placement; elongated or otherwise `non-circular' drops - as well as detecting small and large droplets. An obvious use of this application is to track the status of the instrumentation used to set up crystallization trials in a multi-user laboratory.