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Differential Scanning Calorimetry, Isothermal Titration Calorimetry, MicroCal, Microcalorimetry, Molecular weight, Tech Talk »

[23 May 2017 | ]

A professional and personal view
If your newsfeed from scientific and mainstream media sources is anything like mine, you have seen numerous articles and blogs about the ‘reproducibility crisis’ in the life sciences.
Well-established cornerstones of scientific inquiry and research are the publication of findings in peer-reviewed journals, along with the opportunity for others to reproduce and verify published data.  This advancement and consolidation of knowledge leads to further understanding on how biological systems work, and provides the basis for the discovery and development of new drugs which benefit all of us.
However, there …

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Dynamic Light Scattering, Meet the Experts, Taylor Dispersion Analysis, Tech Talk, Viscosizer TD, Zetasizer »

[18 May 2017 | ]

Matt McGann and I will be representing Malvern at the upcoming annual UD Biophysical Characterization Workshop, sponsored by CBST (Center for Biomanufacturing Science & Technology), BITC (Biomolecular Interaction Technologies Center), and the University of Delaware, on June 6, 2017, hosted by Professor Christopher Roberts.
This year’s workshop will consist of three days of short courses and small-group demonstrations of the principles and commercial technologies for characterization of protein solutions and related colloidal systems, focusing specifically on static and dynamic light scattering, electrophoresis (DLS, ELS), and Taylor Dispersion Analysis (TDA).
Matt has been …

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Image Analysis, Laser Diffraction, Mastersizer, Morphologi G3, Tech Talk »

[13 Apr 2017 | ]

The prevalence of chocolate eggs and chocolate bunnies in the supermarkets here in the UK can only signal one thing: Easter is upon us.  With the emergence of daffodils, buds appearing on trees, lambs frolicking in the fields and warmth seeping back into the northern hemisphere, the cold winter months are over.  Of course, it is not just in the western world that the arrival of spring, new life and new beginnings are celebrated.
In Japan, a country I had the pleasure of living in for a year and a half …

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Customer experience, Insitec, Kinexus, Mastersizer, Morphologi G3-ID, Tech Talk »

[30 Mar 2017 | ]

The recently announced merger of Malvern Instruments and PANalytical could not be better timed from the Cement industry’s perspective. Both companies are market leaders in their respective technology fields – Malvern in particle characterization and PANalytical in elemental and mineralogical analysis – and both having strong teams of application experts with a lot of experience in cement production and characterization.
The synergy between the teams and product offerings was described in a recent webinar by Harald van Weeren of PANalytical and myself. The live event was attended by over one hundred participants and …

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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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Gel permeation chromatography, Molecular weight, OMNISEC, Size Exclusion Chromatography, Tech Talk »

[23 Feb 2017 | ]

Recently, I’ve presented a new webinar focusing on the protein characterization using the OMNISEC, the highest quality Gel Permeation Chromatography (GPC) / Size Exclusion Chromatography (SEC) system for the measurement of absolute molecular weight, molecular size, intrinsic viscosity, branching and other parameters. Thank you to all participants for your interest and attention during the webinar.
In this webinar, I highlighted the key features and benefits of the OMNISEC system. How to run samples and analyze data and how to access repeatability of multiple sample measurements.

As usual, after the live section of …

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Differential Scanning Calorimetry, Malvern Events, MicroCal, Tech Talk »

[14 Feb 2017 | ]

My introduction to Differential Scanning Calorimetry (DSC) was a postdoctoral fellow in the late 1980s.  I was producing mutant forms of the enzyme thymidylate synthase, and I needed to characterize the effects amino acid changes had on the overall stability of the protein.  Using a DSC instrument at our facility, I compared the thermal stability of the different mutants to wild-type protein by ranking the thermal transition temperature (TM). As I recall, I needed about 2 mg -4 mg protein per DSC experiment, which was a lot of protein at …

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Meet the Experts, Molecular weight, OMNISEC, Particle size, Tech Talk, Zeta potential, Zetasizer »

[30 Jan 2017 | ]

Malvern Instruments takes part at the 8th International Symposium on the Separation and Characterization of Natural and Synthetic Macromolecules (SCM-8) at Rhone Events & Congrescenter. The main interest of the conference is the separation and characterization of large molecules. The target audience includes specialists from analytical chemistry, polymer science, and life-science communities.
Malvern is a sponsor of the conference so keep an eye out for us at our booth. In addition, I will give a talk on Thursday February, 2nd about ‘Combining Multi-Detector GPC Measurements with Ultra-High Performance GPC Separations’. The …

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Kinexus, Rheological and Viscosity, Tech Talk »

[17 Jan 2017 | ]

Why measure a viscosity flow curve, rather than just give a number?
 

Very often chemists are asked to provide a single viscosity value for a product or formulation without much information about the required conditions of the measurement.  For an oil or low viscosity liquid which is Newtonian this is pretty straightforward, so long as your viscometer is properly calibrated and the measurement temperature is provided. However, most industrially interesting or complex fluids such as polymer solutions, suspensions and emulsions are non-Newtonian, meaning that their viscosity varies with shear rate – …

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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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Particle size, Tech Talk »

[15 Dec 2016 | ]

Paul Kippax alerted me to an interesting piece in Chemical Watch (Global Risk and Regulation News). It’s based on a comment by the European Commission Joint Research Council (JRC) that:
‘The term “particle size” does not sufficiently describe the exact quantity that is measured, across different nanomaterial particle size analysis (PSA) methods’.
‘Our findings show that the equivalent diameter values of some measurement methods do not agree and that the results of some others only agree, due to their relatively large uncertainties,” the study authors say.
“For a reliable comparison of particle size, …

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Customer experience, Differential Scanning Calorimetry, Dynamic Light Scattering, Français, Isothermal Titration Calorimetry, Meet the Experts, Nanoparticle Tracking Analysis, Tech Talk »

[14 Dec 2016 | ]

Journée d’information APGI/MALVERN – “Nouvelles méthodes de caractérisations des biomolécules”

Mercredi 11 janvier 2017 au CNAM
Co-organisé avec APGI et le CNAM
Avec le développement rapide de biomolécules dans les nouvelles thérapies, des techniques de caractérisation innovantes se développent en parallèle des techniques classiques (comme par exemple la chromatographie d’exclusion couplées à de la triple ou tetra détection, ou la technique NTA, très adaptée à la mesure des exosomes, des particules subvisibles et tout autre type de contaminant, etc).
C’est pourquoi l’APGI (Association de Pharmacie Galénique Industrielle) et Malvern vous invitent à une journée …

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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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Insitec, Meet the Experts, Tech Talk »

[10 Oct 2016 | ]

ISO16332 – Oil / Water separators
 
A while ago, I wrote a blog “Characterizing filter efficiency in diesel engines – ISO16332” about a cell we were designing to meet the challenges of new filters in filter efficiency testing. This has now been successfully launched and has quite a few installs at different customer sites.
The key features were a straight pass through system (no bends which could cause shearing) and a unique design which couples a narrow path length with optimization of the flow within the cell to meet the high concentrations …

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

[20 Sep 2016 | ]

Washing dishes with DLS

How does dish washing work?
Surfactants have seemingly magical properties: combine greasy plates with dish washing liquid and hot water and the dishes become squeaky clean again.
So, how does that actually work?
Detergents are often amphiphilic molecules which means that have both a hydrophilic and a hydrophobic end. If the detergent concentration is high enough (that is above the cmc or critical micelle concentration) the fat friendly ends self-assemble into micelles with the water-friendly ends sticking out into the surrounding water.
When the micelles comes in contact with a …

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Dynamic Light Scattering, Nanoparticle Tracking Analysis, Nanosight, Particle concentration, Particle size, Protein Aggregation, Tech Talk, Zetasizer »

[15 Sep 2016 | ]

Nanoparticle Tracking Analysis or Dynamic Light Scattering ?
After a recent joint NanoSight and Zetasizer demonstration, I received this set of questions that helps illustrate the core of the issue of these two techniques:

Since the Nanosight gives me particle concentration, it’s somewhat straightforward to calculate what % of my Nanoparticles are aggregated. Can I calculate % aggregated particles in the DLS as well?  Or does the varying amount of intensity, and the protein+nanoparticle mixture in the sample confound that calculation?

If I wanted to measure non-spherical particles (for example nanorods), which system …

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Gel permeation chromatography, Malvern Events, Meet the Experts, Molecular weight, OMNISEC, Size Exclusion Chromatography, Tech Talk, Viscotek »

[13 Sep 2016 | ]

Together with Sysmex, our distributor in Benelux, we are proud to be Gold Sponsors of the International Symposium on GPC/SEC and Related Techniques, taking place from 26-29th September in Amsterdam.
One of our technical experts, John Stenson, is looking forward to presenting some exciting new data in his talk “Combining multi-detector GPC measurements with ultra-high pressure GPC separations” at 3:30 pm on Wednesday 28th September, and says:
“This presentation will discuss the issues related to dispersion and how these can be minimized. We will then show the first high quality data from a combined multi-detector/ UPLC™ …

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Dynamic Light Scattering, Laser Diffraction, Mastersizer, Particle size, Tech Talk, Zetasizer »

[25 Aug 2016 | ]

Size distributions are a description of the fact that not every component in the sample has the same size.  There is a range of sizes present, as mathematically described by a distribution.
There are different ways to represent this distribution in terms of:

Intensity – How much light comes from the different components?
Volume or mass – How much volume is present in the different components?
Number – How many particles are present in the different components?

This often causes confusion, and the intensity volume number issue is one of the most popular blogs.
Intuitively most …

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

[16 Aug 2016 | ]

Why are my particles measuring too small?
The technique of  Dynamic Light Scattering (DLS) has become quite standard in many biophysical characterization labs, often alongside common tools like UV-Vis, SEC, AUC, Fluorescence, NMR, AFM, SAXS, or Mass Spec.  As DLS systems (like the Malvern Zetasizer Nano) have become ever easier to use we see an increasing range of applications and research. By observing and analyzing intensity fluctuations in a sample, we can find the diffusion coefficient and, with known viscosity, the corresponding size. Inevitably, at some point the size measured will not …

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