Fluidity One-W


Fluidity One-W

Investigate protein interactions in solution

Fluidity One systems offer a novel approach to determine affinity (KD), size, concentration, and stoichiometric information when a labeled protein interacts with DNA, lipids, antigens or other proteins

Analyze protein interactions in aqueous buffer solutions

Eliminate risk of artefacts. No surface attachment

Determine affinity KD and concentration

Control for off-target binding and false positives

Verify the identity of a complex

Confirm interaction partners via absolute size (hydrodynamic radius, Rh) measurements Infer stoichiometry of interaction

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Data in agreement with reported literature

PD-1/PD-L1 interaction – critical in control of autoimmune response


KD (µM) Technique Reference
4.0 Fluidity One-W
2.2 ITC Cheng et al., JBC (2013)
3.9 SPR equilibrium Zhang et al., Immunity (2004)
0.7 SPR equilibrium Latchman et al., Nat. Imm. (2001)
7.2 MST Magnez et al., Sci. Rep. (2017)

A comparison of binding affinity values for PD-1/PD-L1 from a range of biophysical techniques

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Protein-DNA interactions

KD of aptamer-protein interactions

  • No calibration or specialist preparation required
  • KD successfully calculated for each aptamer binding
  • KD values in agreement with reported literature values

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Reveal changes in molecular conformation

Follow changes in hydrodynamic radius in solution: Protein A:IgG interaction

  • Determine size of SpA:IgG complex in solution
  • Microfluidic diffusion sizing confirmed SpA:IgG 1:3
  • Experimental data in agreement with hypothetical Rh values from molecular modelling (PyMOL*)

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Take a closer look

Fluidity One-W highlights

  • Generate data in close to physiologically-relevant conditions
  • Reduce or eliminate need for time-consuming purification
  • Determine KD and concentration directly in solution
  • Minimize sample consumption – typically 60 – 100 μL per KD
  • Reveal changes in molecular conformation

Fluidity One-W specifications

  • System

    • Application

      Determine size, KD and stoichiometry in aqueous buffer systems

    • Technology

      Microfluidic Diffusional Sizing (MDS)

    Interaction analysis

    • Run time

      Typically 8 – 14 min per datapoint

    • Size range: hydrodynamic radius, Rh

      1 – 20 nm

    • Accuracy of size determination

      ± 10%

    • Reproducibility of size determination

      CV < 10%

    • Working range molecular weight

      1.4 kDa – 14 MDa

    • Sensitivity range (labeled HSA in PBS)

      1 nM – 1 μM Alexa Fluor™ 488

    • Typical sample consumption to determine protein KD

      60 – 100 μL

    • Sample volume per datapoint

      5 μL

    • Compatibility

      Compatible with aqueous buffer systems

    • Fluorescent labels

      Alexa Fluor 488 and equivalents | GFP and FITC | Fluidiphore labeling kit (fluidiphore rapid amine 503)

    • Data export

      USB Mass Storage Device | Fluidity Cloud

    • Exported data file formats

      CSV and JSON formats

    • Data output from Fluidity Cloud

      Result tables, binding curves and affinity (KD), size (Rh) of complex and labeled species


    • Consumables

      Kits containing chips and cartridges sufficient for 96 or 288 datapoints


    • Temperature control


    • Operating environment

      5 °C to 40 °C

    • Power requirements

      100 – 240 V AC, 50 – 60 Hz

    • Safety and EMC standards

      Designed to comply with all relevant safety and EMC standards


    • Dimensions (D x W x H; mm)

      400 x 400 x 430

    • Weight (kg)

      15 kg

Fluidic Analytics is changing how proteins are characterised

We're doing this with novel, cutting edge technology and a fantastic, committed team

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