Challenge of Dry Compounds
Recent progress in compound management has not, however, included the transfer of dry compounds, despite the high demand for automation of this common task.
“The physical transfer of dry compound from source to destination is still a very manual process, mainly because the industry has not developed an acceptable automated solution due to the extreme complexities of transferring dry compounds,” says Genentech’s Hascall.
“Although weighing compounds is one of the least desired tasks in the lab, it is a critical first step to preparing the sample for testing. Whether compound management is weighing a large library, or newly synthesized compounds from chemistry, it has historically required human manipulation of the compound for the transfer to occur.”
One of the challenges of automating this process is the type of solid—powders are much easier for robots to work with. Hascall’s group uses a fully automated weighing system called the Nova, from Innovate Engineering, to transfer dry, free-flowing powders.
Other solids such as dry films, oils, globular material, or chunks of crystals, still present challenges. For powder transfer, the Nova uses a stainless steel collector pin charged with static electricity, to which the powder clings.
The Nova changes the collector pin each time to avoid cross contamination, and uses powder level detection (similar to liquid level sensing) to calculate the static charge, and the right level at which to place the collector into the vial.
“Fully automated weighing holds many challenges that the Nova has been designed to handle,” says Hascall. “With a greater than 85% success rate in our study of over 4,000 compounds, the Nova can be considered to be one of the first fully automated compound transfer robots.”
It is also integrated into Titian’s Mosaic compound-management software to eliminate manual data entry.
Even though compound management is evolving quickly, new challenges are directly ahead. For example, nucleic acid reagents such as plasmids, siRNA, microRNA, and shRNA are increasingly stored and require a special kind of management.
A repository that stores plasmids, which are typically purified using RNases, and also stores siRNA must have separate, dedicated liquid-handling systems to avoid destruction of the siRNA.
“These are the strategies,” says Damoiseaux. “You have to be very careful to set up your equipment in such a way that the workflows are parallel, and the overlaps are such that you are not damaging reagents.”
Whether for nucleic acid reagents or other compounds, no doubt parallel advances in software and automated instrumentation, such as MScreen, the Plate Auditor, and the Nova, will pave the way to progress, with labs running more smoothly than ever.