The Thermo Scientific Pierce RED Device for Rapid Equilibrium Dialysis provides the easiest, fastest and most reliable system for performing plasma protein-binding assays, a critical step in drug development.
The Pierce Device for rapid equilibrium dialysis (RED) was developed in association with the pharmaceutical industry to provide the easiest, fastest and most reliable system for performing plasma protein-binding assays. The RED Device is an apparatus for performing equilibrium dialysis experiments in a high throughput, automation-compatible format. The RED device consists of disposable inserts and a base plate formatted to a standard microplate footprint. The RED Device has been extensively validated for plasma-binding assays and produces results consistent with those reported in the literature. The RED Device offers significant improvements in automation, time requirements, versatility and product reliability compared to other commercially available equilibrium dialysis systems.
- Easy and ready to use – disposable tubes require no presoaking, assembly or specialized equipment
- Designed for speed – the high surface-to-volume ratio of the insert design enables equilibrium to be reached in as few as 100 minutes with vigorous agitation or in three to four hours with 200rpm agitation
- Automation-compatible – designed on a standard 96-well plate template suitable for automated liquid handlers
- Flexible and scalable – perform any number of assays (1 to 48 assays per plate) without wasting the entire plate
- Robust – compartmentalized design eliminates potential for cross talk or leakage
- Reproducible and accurate – validated for plasma binding assays, producing results consistent with those reported in literature
- Quality-tested – each lot of inserts is functionally tested in a protein-binding assay for guaranteed performance
Features of the RED Device Inserts:
Each single-use, disposable insert is made of two side-by-side chambers separated by a vertical cylinder of dialysis membrane (in 8K or 12K MWCO) validated for minimal nonspecific binding. This format requires no extensive assembly steps or specialized equipment, and each chamber or well is easily accessible from the top of the insert after insertion in the base plate. Additionally, the high surface-to-volume ratio of the membrane compartment allows rapid dialysis, where equilibrium can be reached in 4 hours with high levels of reproducibility and accuracy. In many cases, experiments can be completed in less than 100 minutes.
- Disposable: require no presoaking, assembly, or specialized equipment
- Short incubation time: large dialysis surface area accelerates equilibrium
- 8K MWCO membrane: ideal molecular-weight cutoff for protein-drug binding studies
- 12K MWCO membrane also available for larger drug molecules
- Membrane composition: regenerated cellulose with low glycerol content as a humectant
Features of the RED Device Base Plates:
RED Device Inserts are designed to be used with either the reusable PTFE or disposable high-density polypropylene base plates. Each RED Device Base Plate holds up to 48 RED Device Inserts and has a standard 96-well plate footprint with 9mm x 9mm well spacing to provide compatibility with automated liquid handling systems. In addition, the disposable RED Device Base Plates are available pre-loaded, providing operation convenience for scientists conducting protein-binding applications. No pre-conditioning of the membrane inserts is needed. When using radioactive materials, this single-use plate is easily disposed of to avoid contamination and cleaning. RED Device Inserts and Base Plates are also available separately.
Base Plate Features:
- Microplate footprint: compatible with automated systems for 96-well plates
- Compartmentalized: eliminates potential for crosstalk or leakage
- PTFE construction: eliminates nonspecific binding and risk of contamination
- Accepts 1 to 48 inserts: run exactly the number of assays needed without waste
- Determination of free vs. drug bound to plasma proteins
- Pharmacokinetics studies
- Formulation of drug dosage for in vivo studies
- Drug-drug interaction studies
- Selection criteria during drug lead optimization
- Drug partition between plasma and whole blood
- Solubility study
- Dissociation constant determination (Kd)
- Tissue-binding study using tissue homogenate
Determining the extent to which a molecule binds to plasma proteins is a critical phase of pharmaceutical development because it influences compound dosing, drug efficacy, clearance rate and potential for drug interactions. This determination is enabled by equilibrium dialysis, an accepted standard method for reliable estimation of the nonbound drug fraction in plasma. Although it is the preferred method, equilibrium dialysis is generally labor-intensive, time-consuming, cost-prohibitive and difficult to automate. The RED Device for rapid equilibrium dialysis was developed in close association with the pharmaceutical industry to specifically address these issues, accelerating lead optimization and reducing the attrition rate. In addition to plasma protein binding, the device is used for determining drug partition between red blood cell and plasma, protein binding of liver microsomes to improve the correlation between in vitro and in vivo intrinsic clearance, the competition between tissue protein binding against plasma proteins and dissociation constant determination (Kd).
The RED Device has been extensively validated for plasma-binding assays producing results consistent with those reported in the literature. For example, when used to measure warfarin binding to plasma (human and rat) proteins at two concentrations of 1µM and 10µM, the RED Device produced results with minimal intra-experimental variability. The Rapid Equilibrium Dialysis (RED) Device offers significant improvements in automation, time requirements, versatility and product reliability compared to other commercially available systems.
||Use the RED Device for increased productivity. Each RED Device Base Plate sits in a 96-well plate footprint withe 9 x 9mm well spacing making it compatible with automated liquid handling systems. Single-Use RED Base Plates are available with inserts preloaded mimimizing setup time.
The RED Device reproduces results found in the literature. Performance of pre-loaded Single-Use RED Device Base Plates (Part No. 90006) using high, medium and low protein-binding compounds tested at 1µM on human plasma.
||Human plasma (% bound)
||Other Devices †
||95 to 98
||80 to 92
||88 to 92
|† Values reported in the literature (Cited References 2-6).
The RED Device for comparison of plasma and microsome samples. Comparison of protein bindings between human plasma and human microsome at 1µM concentration as determined using the Single-Use RED Device. Microsomal protein concentration of 1.0mg/mL was used in the study.
||Human Plasma, % free
||Human Microsome, % free
The RED Device had many advantages to other methods. The RED Device System offers significant improvements in the ease of use, time requirements, versatility and product reliability compared to other methods. Equilibrium can be reached in as little as 100 minutes with mild agitation or 3-4 hours with no agitation.
||Time to reach Equilibrium
|RED (Rapid Equilibrium Dialysis) Device
|96 - well Micro Equilibrium Dialysis block (HTDDialysis, LLC)
|24-Multiwell Dialysis (BD Biosciences)
|Data are from the following authors: Shelley Li1, Bob Xiong2, Tainang Huang2, Lily Li2, John Donovan3, Frank Lee1, Shaoxia Yu1, Gerald Miwa1, Hua Yang1 (Institutions: 1DMPK/Drug Safety & Disposition, and 3Process Technology, Millennium Pharmaceuticals, Inc. 40 Landsdowne Street, Cambridge, MA 02139 USA; and 2Linden Bioscience, 35A Cabot Road, Woburn, MA 01801, USA).
- Waters, N.J., et al. (2008). Validation of a rapid equilibrium dialysis approach for the measurement of plasma protein binding. J Pharm Sci 97(10): 4586-95.
- Brouwer, E.J., et al. (2000). Measurement of fraction unbound paclitaxel in human plasma. Drug Metab Disposition 28(10): 1141-5.
- Brunton, L., et al. Goodman and Gilman's Pharmacological Basis of Therapeutics. McGraw Hill Publishing: New York, 2005.
- Clausen, J. and Bickel, M. (1993). Prediction of drug distribution in distribution dialysis and in vivo from binding to tissue and blood. J Pharm Sci 82: 345-9.
- Sonnichsen, D. and Relling, M. (1994). Clinical pharmacokinetics of paclitaxel. Clin Pharmacokinet 27: 256-69.
- Steele, W., et al. (1983). The protein binding of vinblastrine in the serum of normal subjects and patients with Hodgkin's disease. Eur J Clin Pharmacol 24: 683-7.
Rapid Equilibrium Dialysis Device FAQs
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Sealing Tape for Microplates
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LC/MS Grade Acetonitrile