Storage, retrieval, and distribution of chemical and biological libraries is a critical activity in drug discovery. Successful high throughput screening requires careful coordination and interaction of screening technology with assay / reagent preparation and availability of screening libraries. Failure of any of these to come together leads to a problem in the discovery program.
What is a library? Consider a library as a collection of chemical compounds or biological substances that should be handled or screened together. Examples include:
?Compound Collection ?all the compounds/substances a pharmaceutical company can put their hands on.
?Related compounds by activity in a class of assay ?such as a kinase or protease library.
?Related by structure or synthesis ?combinatorial libraries
?Purchased collections
How are libraries received, stored and exchanged? There are four major ways to handle libraries:
?Solubilized in plates
?Solubilized in tubes or microtubes
?Neat substances in vials
?Neat substances in tubes or plates
Neat substances are generally quite stable and are generally stored at room temperature. Sometimes neat substances must be stored cold, in an inert atmosphere, or protected from light. Solubilized substances are generally stored in 100% DMSO. Most organizations store these solutions cold, near the freezing point of DMSO. Source plates or tubes generally contain a fairly high concentration, usually in the range of 3 to 20 mM. Collections are generally distributed to screening laboratories at much lower concentrations, usually less than 1 mM and often in the mM range.
Handling issues to consider:
?Automation of processes to prepare and distribute libraries
?Vendor and equipment reliability
?Sealing tubes and plates to protect solutions from evaporation or water absorption
?Unsealing or piercing plate seals to allow sampling by screening robots
?Stability of substances in solution over long periods of time and conditions
This paper will conclude with a survey of equipment and techniques to make the handling of libraries easier and more reliable. Products from several vendors in the following categories will be mentioned:
?Storage and retrieval systems
?Sealing and piercing devices
?Replication systems
?Robotic systems

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?2002 Laboratory Robotics Interest Group