Wyatt Technology




The finest, most versatile light scattering instrument for reliable electrophoretic mobility and size measurements of proteins, polymers, and all types of nanoparticles.

Wyatt Technology's Mobius is the first and only light scattering instrument that makes reliable, reproducible, and non-destructive electrophoretic mobility measurements of macromolecules as small as 2 nm in radius (as well as micron-size nanoparticles) in most aqueous buffers. It is also Wyatt's best-performing detector for nanoparticle size analysis by means of batch dynamic light scattering.

The Mobius is accompanied by DYNAMICS, our powerful software package for analyzing batch dynamic light scattering and electrophoretic mobility measurements. The Security Pack (DYNAMICS SP) option provides 21 CFR (11) compliance for GMP/GLP use.

  • Key benefits

    The Mobius offers a unique suite of capabilities for mobility and size measurements of proteins, polymers and nanoparticles:

    • Non-destructive analysis of fragile biomolecules
    • Repeatable and accurate measurements in conductive buffers such as physiological saline
    • Simultaneous measurements of size and mobility
    • Automated sample handling or manual measurements
    • Fluorescence blocking filter for sizing of fluorescing nanoparticles such as quantum dots

    The Mobius characterizes the mobility of proteins and other biomolecules non-destructively and robustly, thanks to an innovative design enabling some unprecedented capabilities described more fully in the Advanced Technology tab.

    Productivity, you say?

    The Mobius features a novel, 170 µL flow cell providing advanced benefits, such as automated sample handling with a standard autosampler, to measure dozens of samples or conditions per day and maximize productivity. The high-pressure flow cell also affords connection to the Atlas pressurization system for robust and reproducible analysis of biomolecular mobility, net charge and zeta potential in solvents with conductivity up to 100 mS/cm - about 6x physiological saline.

    The combination of mobility + size results in a calculation of the nanoparticle's zeta potential or the protein's net charge. Thanks to simultaneous dynamic light scattering analysis of molecular/nanoparticle size alongside the mobility measurement, you can monitor changes to the sample in real time and adjust measurement parameters as necessary.

    The closed, PEEK flow cell also means compatibility with a wide range of volatile organic solvents.

  • Massively parallel phase analysis light scattering

    The Mobius characterizes the mobility of proteins and other biomolecules non-destructively, thanks to an innovative design that incorporates 32 parallel detectors denoted as 'massively parallel phase analysis light scattering', or MP-PALS.

    MP-PALS is a true enabler for maximum sensitivity and short acquisition times. The combination of a powerful solid-state laser, precision optics and real parallel-plate electrodes near the optical path that do not distort electric field lines, permits application of low voltages with low current. Low voltage and current minimize perturbation of the sample, even in conductive solvents such as physiological saline, since exposure to high voltage may denature the sample and high currents produce heating and convection of the solvent, degrading the measurement.

    Parallel, optimized optical channels

    The combination of hydrodynamic radius and electrophoretic mobility are necessary to compute zeta potential, or net molecular charge. Most zeta potential detectors use a single avalanche photodiode for both size and mobility. This compromise means that dynamic light scattering (DLS) measurements, performed with light scattered into a high angle, may not be taken concurrently with mobility measurements that are performed with light scattered into a low angle.

    The Mobius incorporates parallel optical channels that measure simultaneously - MP-PALS measurements of mobility at low angles utilize a completely separate detector than the DLS measurement of size via high angles. Both, of course, make use of the same high-quality laser beam originating in a single-longitudinal-mode solid-state laser.

    Some samples are subject to degradation upon application of electric voltage and current, even at the very low values typically applied in the Mobius. Simultaneous monitoring of DLS and MP-PALS means that you can track changes to the sample, and modify measurement conditions accordingly to minimize degradation.

    What about low-conductivity solvents?

    Conversely, when high ionic strength is not an issue, you want to maximize mobility signals for the fastest and most accurate results. In addition to very low voltages, the Mobius can apply electric fields of hundreds of V/cm to extract robust signals in the presence of poorly conducting samples. The advanced technology incorporated into this instrument makes it the most versatile ELS detector available.

  • Autosampler operation

    The Mobius flow cell enables automated sample handling with a standard autosampler. An Agilent autosampler and HPLC pump are controlled directly by DYNAMICS software to flush the system, inject sample, perform the measurement, and repeat with the next sample.

    When measuring samples in high-ionic-strength buffers, an Atlas pressurization system should be incorporated in order to suppress bubbles formed by electrolysis in the cell, since these bubbles scatter light and corrupt the ELS signal. The Atlas is also controlled by DYNAMICS, making the entire sequence seamless.

    Automating buffer conditions

    Do you need to measure zeta potential or net molecular charge as a function of concentration, pH, ionic strength or excipient? The autosampler may even be programmed to automatically prepare samples at a series of buffer conditions. The Mobius measures conductivity directly in its flow cell, and pH by means of a Wyatt in-line pH detector. These data are recorded simultaneously with the size and mobility results.

    Automation not for you?

    If automation is not required, several convenient options are available for manual operation: samples may be injected directly into the flow cell (with or without the Atlas) or measured by means of cuvettes and dip electrodes.

  • Möbius Dip Cell

    Atlas - Pressurizes the Mobius cell to allow mobility measurements of samples in high-salt buffers. Controlled by DYNAMICS, the Atlas may be used in conjunction with an autosampler or with manual sample injections.

    Mobius Dip Cell - A convenient alternative to the high-pressure flow cell when making non-automated measurements in low-salt buffer, the Mobius Dip Cell requires only 65 µL of solution under typical conditions. It uses a quartz cuvette for the highest optical quality and compatibility with aqueous buffers and select polar organic solvents

    DLS-only Cuvette - If only DLS measurements are needed, they made be made in the flow cell or with this quartz cuvette. The cuvette is compatible with most solvents and requires only 45 µL of sample.

    DLS-only Disposable Cuvette - an adapter permits use of standard plastic, 100 µL cuvettes for DLS when the low sample volume and maximum sensitivity are not needed for aqueous samples.

    NanoFilter Kit - Makes it easy to filter, recover and re-filter precious sample. This is especially useful when your total sample volumes are below 300 µL.

  • DYNAMICS 7, software

    DYNAMICS - Software for MP-PALS and DLS measurements in the Mobius. Calculates electrophoretic mobility, size and size distributions, and derives zeta potential, Debye-Hückel-Henry and effective net charge. 

    DYNAMICS also controls Agilent autosamplers and pumps for hands-off analyses of dozens of samples per day.

  • Mobility Measurements  
       Conductivity Range 0 to 7 mS/cm; 0 to 100 mS/cm with Atlas pressurization system *
       Mobility Range No practical limit
       Mobility Size Range (Radius) 1 nm to 50 µm
       Mobility Sensitivity 1 mg/mL lysozyme (flow cell); 5 mg/mL BSA (dip cell)
    DLS Size Measurements  
       Size Range (Radius) 0.2 to 5000 nm (flow cell); 0.2 to 200 nm (dip cell, quartz cuvette);
    0.2 to 250 nm (disposable cuvette)
       Size Sensitivity 0.1 mg/mL lysozyme
       Detection Angle 163.5°
       Attenuation Maximum Detector Auto-attenuation 3000x
    Sample Cells  
       Flow Cell (PALS + DLS) 170 µL PEEK flow cell for aqueous and most organic solvents. Required for autosampler and/or Atlas operation.
       Dip Cell (PALS + DLS) Quartz cuvette + PEEK & platinum dip probe. For manual sample introduction; cannot be pressurized. Requires 65 µL of solution for PALS  or 45 µL for DLS measurements.
       Quartz Cuvette (DLS Only) 45 µL quartz cuvette. 
       Disposable Cuvette (DLS Only) 100 µL polystyrene cuvette.
    Sample Temperature Control 4 to 70°C
       Laser Power Control Selectable 10% or 100%
       Laser Wavelength 532 nm. Please inquire regarding other wavelengths.
       Laser Lifetime > 10,000 hours
       Detectors 32 detector channels for multi-angle PALS detection
    Wetted Materials 316 stainless steel, PEEK, quartz or glass, platinum, Kalrez
    Instrument Options Fluorescence blocking filter
       Auxiliary I/O Alarm In, Alarm Retransmit, Auto Inject contact closure, 2 Analog Inputs (16 bits, ± 10 V)
    Onboard Computer  
       Communications Ethernet interface to DYNAMICS software on host computer; USB to Atlas
       Front Panel Display 162.5 mm, 16-bit, high resolution LCD touch screen display
    Dimensions 60 cm (L) x 36 cm (W) x 21 cm (H)

    * Wyatt Atlas is required for conductivity above 8 mS/cm.

     Solvent is Tris-Glycine buffer containing 25 mM Tris and 192 mM Glycine at pH 8.0. The standard deviation over ten thirty-second measurements is 10% of the mean value.

    Host PC requirements may be found in Computer Requirements.

    Specifications subject to change without notice.


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Wyatt Technology is the recognized leader in light scattering instrumentation and software for determining the absolute molar mass, size, charge and interactions of macromolecules and nanoparticles in solution.

Wyatt's line of multi-angle static light scattering products couple to size exclusion chromatography (SEC-MALS), field-flow fractionation (FFF-MALS), and stop-flow composition-gradient systems (CG-MALS). Our dynamic light scattering (DLS) products operate in traditional cuvette as well as on-line and automated, high-throughput modes. We also offer unique instruments for electrophoretic light scattering (MP-PALS), differential refractometry, and differential viscosity.

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