• No calibration
  • No clogged needles
  • Reproducible residual volumes <0.3µl/ well

What is z' (z-prime, z-factor) and why does it matter?

z' is a catch-all parameter that grades how well a screen separates active from inactive compounds. z' maps %CVs of known active and inactive reference compounds plus the assay's signal to noise ratio into a value between 0 and 1; z'=0.5 being the minimum acceptable value, z'=1 being "perfect".  Blue® Washer users typically improve z' vs. aspiration washers by 0.1-0.3.  E.g., AstraZenca report boosting a reference assay's z' from 0.5 to 0.7, another user from 0.6 to 0.9.  The corresponding increase in the size of the "window" that separates inactive from active compounds gives medicinal chemists additional confidence that they are pursuing the most promising hits from discovery.

Blue® Washer dramatically shortens wash time for intracellular drug distribution at AZ

Bomi Jung et. al. (AZ, Gothenburg SWE) in their ELRIG poster "High density assessment of drug distribution profiles in cultured cells" reduced wash time from 20-30 minutes to <1min using the Blue® Washer.

Better data from cell-based assays with Blue® Washer's centrifugal evacuation

-  Screening and assay development in 96, 384, and 1536w plates  -

2019 paper

High-throughput screening (HTS), High-Content Screening (HCS), 3D cell screens, FLIPR®, expression assays

Better Data

FLIPR® is a registered trademark of Molecular Devices, LLC

Blue® Washer helped generate great, conclusive data with 1536w screen, incredibly fast

Katie Heiser, Peter F. McLean, et al (Recursion, SLC, UT) in their paper "Identification of potential treatments for COVID-19 through AI-enabled phenomic analysis of human cells infected with SARS-CoV-2" used their Blue® Washer for all staining and imaging washes and reagent additions achieving z' of >0.8.

2017 paper

Blue® Washer enabling 1536w HTS, improving z'

Helen Plant (AstraZeneca, Alderley Park, UK) shows how the Blue® Washer enabled 384w to 1536w conversion of complex, high-content phenotypic high-throughput screens, and in-house fibronectin coating of 1536w plates, resulting in up to a 25% reduction in cells needed, ~4x time reduction, economical screening of expensive assays.

Blue® Washer removing medium from iNs cells

Banu Priya Sridharan et. al. (The Scripps Research Molecular Screening Center, Juniper, FL) in their paper "A Simple Procedure for Creating Scalable Phenotypic Screeing Assays in Human Neurons" describe using Blue® Washer's GentleSpin cycle to remove growth medium from IPSC-derived human neurons (iNs) in a 384w format for subsequent HCS imaging.

2017 paper

2020 paper

  • <20sec to evacuate plate
  • 40cm x 70cm footprint
  • No compressed air or vacuum

Stand-alone & Automated

2020 paper

100% identical results across sites/ operators

 2018 poster

SLAS2019 presentation


Blue® Washer used for cell wash at BMS

Tao Wang et. al. (BMS, Hopewell, NJ) in their paper "Measurement of beta-Arrestin Recruitment for GPCR Targets" use the Blue®Washer to wash cells in their Sample Protocol for Antagonist Assays. This paper has been included in the 2018 edition of the Assay Guidance Manual (Eli Lilly & Company and the National Center for Advancing Translational Sciences, Bethesda, MD)

Helen Plant (AZ, Alderley Park, UK) disusses how the Blue® Washerintegrates centrifugal emptying with the individual addition of up to four separate solutions for complex phenotypic assays. "Successful conversion of complex phenotypic assays to 1536w results in up to a 50 percent reduction in cells needed & 4x time reduction for full HTS screening campaign".

SLAS2017 presentation

Blue® Washer enabling efficient 3D cell culture assays in high throughput format

Haim Barr et. al. (Weizmann Institute of Science, Rehovat, Israel) show how the Blue® Washer streamlines sample preparation of spheroid cultures in a high throughput workflow using 1536w plates.

AstraZeneca and BlueCatBio collaborate on Blue® Washer assay optimization

Helen Plant (AstraZeneca, Alderley Park, UK) and BlueCatBio collaborated to develop a see-through  rotor cover, allowing observation of washes in progress to optimize Blue® Washer assay protocols.

Bristol-Myers Squibb


More Reproducible Screens

2016 paper

Blue® Washer enabling 1536w High Throughput (HT) cell based screening

Sinead Knight et. al. (AZ, Cambridge, UK) describes how the Blue® Washer allowed miniaturizing a range of cell assays into 1536w format. Improved data quality and reduced number of wash steps in 384w assays shown. Cell assays currently limited in throughput due to cost and complex protocols may be enabled.

Fast, compact, quiet

Simply automate "dump and tap"

Avoid false negatives

  • Fewer wash steps
  • Simpler assay automation
  • Simpler transition to 1536

2019 poster

Weizmann Institute

 2017 SLAS Webinar

Cell-Based In Vitro Assay Automation:  Avoid false negatives with Blue® Washer

Adam Weinglass and Mary Jo Wildey (Merck & Co, Kenilworth, NJ) show how Blue® Washer  improves data consistency and decreases rate of false negatives.  Historically inactive compounds aligned when Blue® Washer was used for media removal.

2017 paper

Simpler Assay Design

SLAS2016 presentation

Highly reproducible, low residual volumes < 0.3 µl/ well raise z' by 0.1-0.3 for typical cellular assays.

Higher z' means more reliable compound profiles - fewer truly active compounds missed AND fewer false positives to re-screen.


SLAS2017 presentation


Blue® Washer integrated into AstraZeneca's fully automated 1536w HCS platform

Paul Harper (AstraZeneca, Alderley Park, UK) integrated Blue® Washers into their fully automated HighRes Cellario and Agilent VWorks platforms, replacing Tecan PW384 and Biotek 405 aspiration based washers.

Blue® Washer reduces "false negatives", improves GPCR assay performance& reproducibility

Brande Thomas-Fowlkes et. al. (Merck & Co, Kenilworth, NJ) in their paper "Cell-Based In Vitro Automation: Balancing Technology and Data Reproducibility/ Predictability" show how Blue® Washer reduces "false negatives",improves assay quality and reduces the replicates in SAR assay support for Merck HTRF and IP-I cell-based, functional adherent 384w assays.

  • z' lift: 0.1-0.3 due to better %CV and Signal to Noise
  • Lower background due to residual volumes <0.3µl/ well
  • No contact, no "donuts"
Blue® is a registered trademark of BlueCatBio, registered in the EU, Switzerland and Japan. US registration pending.

Blue® Washer used for media removal at Merck Kenilworth

Corin Miller et. al. (Merck & Co, Kenilworth, NJ) in their paper "GPR40 partial agonist MK-2305 lower fasting glucose in the Goto Kakizaki rat via suppression of endogenous glucose production" use Blue® Washer to remove growth media in in-vitro receptor potency assay.

Astra Zeneca

(for literature on 3D cellular screens, go to Magnetic Assays)

Blue® Washer delivering high z' for 1536w drug library screen

Shurong Hou et. al. (Dept of Molecular Therapeutics, Scripps Research Institute, Juniper, FL) in their paper "Drug Library Screening for the Identification of Ionophores That Correct the Mistrafficking Disorder Associated with Oxalosis Kidney Disease" use Blue® Washer for 4 cell wash steps in a 1536w HCS, reporting Z′ 0.70 ± 0.07.