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Ulf Nobbmann
Ulf Nobbmann received his PhD in colloidal physics from Oklahoma State University (USA) and has since focused on light scattering from biological molecules and nanoparticles. He joined Malvern Instruments in 2003, has held various positions involved in support. training, development of application knowledge & expertise within the Nanometrics group, and is currently Zetasizer Product Manager - Americas.

Customer experience, Zetasizer »

[14 Dec 2017 | ]

… and receiving a Zetasizer
 
In North America, this time of the year is the busiest period for shipping companies like DHL, Federal Express or the US Postal Service. Malvern Panalytical does not rest either, in fact, our systems are part of the global shipping growth in this busy season. As a global company certified in ISO 14001 we are conscious of our role and take measures to minimize the use of resources. One of these efforts resulted in the design of a new reusable shipping box for the Zetasizer. An …

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Differential Scanning Calorimetry, Dynamic Light Scattering, MicroCal, Molecular size, Molecular structure, Particle size, Protein Aggregation, Tech Talk, Zetasizer »

[16 Nov 2017 | ]

Measuring aggregation temperature using the Zetasizer

In dynamic light scattering (DLS), the hydrodynamic size and size distribution of particles in solution can be obtained.  It may be of interest to examine this measurement as a function of time and temperature, or as a ‘trend’, as it is called in the Malvern Zetasizer software.  For biological protein samples, this temperature trend is particularly interesting: although at low temperatures a protein may be stable and show repeatable size (and scattering intensity) measurements, typically at some elevated temperature (Tagg), protein molecules will show a tendency …

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Dynamic Light Scattering, Molecular size, Molecular weight, Static Light Scattering, Zetasizer »

[2 Nov 2017 | ]

Molecular weight measurements with the Zetasizer software?
First a few words of caution: molecular weight or Mw measurements in general are not easy, require time, good sample preparation skills as well as patience. If you are new to the Malvern Zetasizer it might be best to familiarize yourself first with the rapid, user-friendly, and quite forgiving technique of dynamic light scattering (DLS).
OK, with that out of the way, the software can handle static light scattering with the relatively simple concentration series method. All that’s required is

a scattering standard (which is usually …

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Dynamic Light Scattering, Particle size, Tech Talk, Zetasizer »

[26 Sep 2017 | ]

Is there a maximum viscosity for DLS measurements?
 
The Malvern Zetasizer can determine particle size by dynamic light scattering (DLS). In this technique, the intensity fluctuations are analyzed to find the corresponding diffusion coefficient that led to the fluctuations. The translational diffusion coefficient Dt of a particle is inversely related to its size and the viscosity of the dispersant (or more accurately the hydrodynamic radius rH and viscosity η).

This relationship can be used to predict detectability limits of the technique in general, and this is how we explore the idea of …

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Electrophoretic light scattering, Tech Talk, Zeta potential, Zetasizer »

[5 Sep 2017 | ]

Zetasizer: What is the zeta potential deviation?
 
The Malvern Zetasizer software report for zeta potential shows a parameter that is called Zeta deviation. This parameter is shown directly below the mean Zeta potential.

The mean zeta potential is derived from the fast field reversal (FFR) phase analysis light scattering (PALS) technique.
The fast field reversal provides a single number from the analysis. This single number is the mean zeta potential. The slow field reversal [also known as SFR] can be used to determine the zeta distribution, a distribution of different charge values from …

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Customer experience, Dynamic Light Scattering, Particle size, Zeta potential, Zetasizer »

[22 Aug 2017 | ]

Zetasizer: 21CFR? Electronic Record/Electronic Signature? Test Schedule?
 

The Malvern Zetasizer is an extremely versatile measurement system. By far the most systems are used in academic and industry research laboratories, for example in fundamental research, drug discovery, or formulation optimization. However, a significant number of installations are in operation in “controlled” environments, such as for quality control in pharmaceutical companies. Here documentation and compliance with good manufacturing standards GMP is critically important, and a specific version of the operating software exist that locks down standard operating procedures (SOP) with limited ability (based …

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Dynamic Light Scattering, Electrophoretic light scattering, Laser Diffraction, Particle size, Zeta potential, Zetasizer »

[3 Aug 2017 | ]

Intralipid-Lipid emulsions

Lipid emulsions are administered intravenously for a variety of purposes:

To help feed patients with temporary difficulty in ingesting food orally
For better transport of lipophilic drugs (fat-friendly active ingredient (API) which is not soluble in water)
For controlled release of drugs (size related to uptake and retention)
To decreasing adverse reactions to drugs
To improve targeting of drugs
In emerging gene therapies for cellular and gene delivery, and personalized medicine

Control and understanding of colloidal properties – such as droplet size and zeta potential – enable the design and optimization of appropriately stable emulsions. The …

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Electrophoretic light scattering, Meet the Experts, Protein Mobility, Zeta potential, Zetasizer »

[27 Jul 2017 | ]

Nanomaterial isoelectric points IEPs
 
In a recent webinar presented by Ana Morfesis titled “Characterizing the zeta potential & Isoelectric Point of Nanomaterials” we got such a good turnout that we were not able to address the numerous questions asked during the event.
Thank you for the participation!
Since there was such strong interest, we have provided the following list of questions and answers to benefit all who are interested.  We have also provided a table of common metal oxide IEPs, as shown to the left.
 
 
For those who were not able to attend the live event, the session was recorded and is …

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Differential Scanning Calorimetry, Dynamic Light Scattering, Meet the Experts, MicroCal, Molecular size, Molecular weight, OMNISEC, Particle concentration, Protein Aggregation, Size Exclusion Chromatography, Taylor Dispersion Analysis, Zetasizer »

[18 Jul 2017 | ]

Monoclonal Antibodies – or mAbs for short

Since many of these mAbs require refrigeration we had used dynamic light scattering (with a Zetasizer) to show the formation of aggregates after freeze-thaw cycles (for details see application note “Effect of storage conditions on Immunoglobulin“). These could be seen both in the increased polydispersity index (PDI) and the appearance of a large-size aggregate peak in the intensity size distribution as shown to the right. The area under the peak gives an indication of the presence of the large aggregates but is not suited for …

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Customer experience, Dynamic Light Scattering, Meet the Experts, Particle size, Zetasizer »

[20 Jun 2017 | ]

Three methods to verify dynamic light scattering systems
If you are a meticulous researcher you may want to test your new Zetasizer. Is it really providing the correct size? One of the advantages of dynamic light scattering is that there are no tweakable adjustments, it is all physics: laser wave length, scattering angle, refractive index of the dispersant are all known in advance and are given parameters for the optical setup and sample. Nevertheless, it is a good idea to check and verify the performance of the system. One of the …

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Customer experience, Dynamic Light Scattering, Electrophoretic light scattering, Molecular size, Particle size, Zeta potential, Zetasizer »

[25 May 2017 | ]

A challenge to all new Zetasizers!
 
The Zetasizer is so simple to use that the majority of Zetasizer (user)s just “dive in” and find out how to operate the system.
By design it is (almost) indestructable, so what can go wrong? Not much – nevertheless, you might be able to get even more use and benefit from your system with a little preparation.
 
Free eLearning video – really!
If you are relatively new to the Zetasizer then take a look at our free eLearning introductory course. It was meant as a teaser for the …

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Customer experience, Dynamic Light Scattering, Molecular size, Particle size, Zeta potential, Zetasizer »

[4 May 2017 | ]

3 stumbling blocks for Report Designer (Zetasizer) – the rule of two
The three most common holdups encountered in the report designer feature are listed here.
Not everyone delves into the depth of the Zetasizer software, but of those who do want to take advantage of the report customization features in the ‘report designer’ nearly everyone runs into at least one of these three common mistakes:

1. Folder locations – there are two!
The Zetasizer software is typically installed in a (hidden) Windows directory like  C:\Program Files\Malvern Instruments\Zetasizer Software and that’s good. However, if …

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Corporate, Customer experience, Dynamic Light Scattering, Inside Malvern Panalytical, Zetasizer »

[25 Apr 2017 | ]

Exposition at scientific meetings:
How useful are they and can they help me to get a job?
A brief insight from the ACS meeting
If you follow my writings, you’d probably expect more detail about Dynamic Light Scattering (DLS)… However, today I’d like to report on a recent conference we went to, the national meeting of the American Chemical Society, otherwise known as ACS. It is the world’s largest scientific society by number with close to 160k members.  There were over 17k registrants at the San Francisco meeting earlier this month, quite a turnout. With the constant …

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[26 Mar 2017 | ]

What are Polyolefin Polymers?
Polyolefins are macromolecules formed by the polymerization of olefin monomer units. The IUPAC nomenclature term is poly(alkene). The most common polyolefins are polypropylene (PP) and polyethylene (PE). These polymers are prevalent in a wide array of applications depending on the material characteristics of the polymer, most notably consumer plastic. Molecular properties like molecular weight (MW) distribution and branching are fundamental and related to parameters such as material fatigue, impact strength, and resistance to degradation. These properties are therefore routinely assessed as part of research and development (R&D) …

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Dynamic Light Scattering, Molecular size, Particle concentration, Particle size, Protein Aggregation, Tech Talk, Zetasizer »

[7 Mar 2017 | ]

How can I use DLS for sample xyz?
What sample concentration / refractive index is needed for reliable DLS size measurements?

Has it been done before?
In Dynamic Light Scattering (DLS) intensity fluctuations in the sample are analyzed to obtain size information on the sample. The technique is applicable to a wide size range from sub-nanometer up to a few microns. In order to obtain a meaningful result, a minimum scattering signal strength must be present. Malvern’s Zetasizer Nano software contains a calculator to help estimate the required minimum concentration.
If anyone else has …

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Dynamic Light Scattering, Particle size, Zetasizer »

[23 Jan 2017 | ]

Over the years one of the frequently asked questions that stands out in the data analysis of dynamic light scattering results is the issue about which size one should report.
 
 
 
Here is an example of just such an email I received this month:
“We have several data sets with low PDI (<0.1), single exponential decay, low cumulant fit error(~10^(-4)).  The intensity-distribution size and the cumulant fit size are similar.  But the number-distribution size (d=33 nm)and size obtained by cumulant fit(d=47 nm) are very different.  In this case, should we trust the number-distribution size …

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Electrophoretic light scattering, Protein Mobility, Tech Talk, Zetasizer »

[12 Jan 2017 | ]

Electrophoretic mobility measurements from proteins: How to protect proteins in an electric field
 
What is the protein mobility mode?
When applying an electric field to a sample containing protein molecules, there are a few considerations to take into account to avoid “over-stressing” delicate biomolecules. The force a charged object experiences in an electric field is proportional to its charge times the electric field. Therefore the electric field strength (defined by the applied voltage divided by the distance between the electrodes, in V/cm) is more relevant than the absolute value of the applied …

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Dynamic Light Scattering, Molecular size, Molecular structure, Particle size, Tech Talk, Zetasizer »

[27 Dec 2016 | ]

How to measure it with DLS?
What virus concentration is needed for reliable DLS size measurements?
 
What is a virus?
In cell biology, a virus is a self assembly of organic molecules (mainly proteins) in the size range 20 nm – 300 nm (diameter). Viruses hold great interest for human gene therapy researchers, and the AAV-2  virus shown to the left is an example.
How to size a virus in solution?

One of the techniques available to size viruses (as well as other biological nanoparticles) is Dynamic Light Scattering (DLS), where intensity fluctuations in a small …

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Dynamic Light Scattering, Molecular size, Protein Aggregation, Tech Talk, Zetasizer »

[1 Nov 2016 | ]

α-synuclein promotes vesicle assembly – when size can support theory
 

What is a vesicle?
In cell biology, a vesicle is an (often spherical) assembly of amphiphilic molecules (usually proteins and phospholipids), and is typically sized between 30 nm – 100 nm in diameter. Vesicles are often classified by the type of interaction they are involved with. For extracellular vesicles (or exosomes), this is usually intercellular signal transmission. A particular example of exosomes is synaptic vesicles, which transmit signals between neurons (average size: 40 nm).
In a paper entitled “Structural basis of synaptic vesicle assembly promoted …

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Customer experience, Dynamic Light Scattering, Electrophoretic light scattering, Molecular size, Molecular weight, Particle size, Zeta potential, Zetasizer »

[20 Oct 2016 | ]

How can I save paper and print a Zetasizer report as a PDF?
 
Why print?
The Zetasizer software includes several popular report options. The most frequently used of these is probably the Intensity PSD (M), which gives a compact overview of the results. It lists the z-average and up to three peaks by intensity with their respective mean size, the area under the peak in % intensity and the standard deviation of the peak. In addition, several relevant sample identifiers and measurement conditions, like the sample name,  file name, refractive index of …

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