title: Achieving accurate compound concentration in cell-based screening: validation of acoustic droplet ejection technology.
abstract: Compound handling is a fundamental and critical step in compound screening throughout the drug discovery process. Although most compound-handling processes within compound management facilities use 100% DMSO solvent, conventional methods of manual or robotic liquid-handling systems in screening workflows often perform dilutions in aqueous solutions to maintain solvent tolerance of the biological assay. However, the use of aqueous media in these applications can lead to suboptimal data quality due to compound carryover or precipitation during the dilution steps. In cell-based assays, this effect is worsened by the unpredictable physical characteristics of compounds and the low DMSO tolerance within the assay. In some cases, the conventional approaches using manual or automated liquid handling resulted in variable IC(50) dose responses. This study examines the cause of this variability and evaluates the accuracy of screening data in these case studies. A number of liquid-handling options have been explored to address the issues and establish a generic compound-handling workflow to support cell-based screening across our screening functions. The authors discuss the validation of the Labcyte Echo reformatter as an effective noncontact solution for generic compound-handling applications against diverse compound classes using triple-quad liquid chromatography/mass spectrometry. The successful validation and implementation challenges of this technology for direct dosing onto cells in cell-based screening is discussed.
authors.affiliation: AstraZeneca, Macclesfield, Cheshire, UK. richard.grant@astrazeneca.com
authors.forename: Richard John
authors.initials: RJ
authors.lastname: Grant
authors.forename: Karen
authors.initials: K
authors.lastname: Roberts
authors.forename: Carly
authors.initials: C
authors.lastname: Pointon
authors.forename: Clare
authors.initials: C
authors.lastname: Hodgson
authors.forename: Lynsey
authors.initials: L
authors.lastname: Womersley
authors.forename: Darren Craig
authors.initials: DC
authors.lastname: Jones
authors.forename: Eric
authors.initials: E
authors.lastname: Tang
mesh_terms: D001681:Biological Assay / Q000295:instrumentation / Q000379:methods; D002460:Cell Line; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D055808:Drug Discovery / Q000295:instrumentation / Q000379:methods; D006801:Humans; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015203:Reproducibility of Results; D012997:Solvents / Q000737:chemistry; D013016:Sound; D013678:Technology, Pharmaceutical / Q000295:instrumentation / Q000379:methods
chemical_list: D012997:Solvents; D051057:Proto-Oncogene Proteins c-akt; D004121:Dimethyl Sulfoxide