Spotlight Particle Characterisation Papers and Posters on Powder Characterisation
At the World Congress on Particle Technology (WCPT6), which this year took place from 26-29 April alongside POWTECH and TechnoPharm at the NürnbergMesse in Germany, members of the Freeman Technology team presented a series of papers and posters covering various aspects of powder characterisation. The company also exhibited as part of the Powtech show where the FT4 Powder Rheometer will be on display.
The FT4 is a universal powder tester that uses patented dynamic methodology, fully automated shear cells and several bulk property tests, including density, compressibility and permeability to quantify powder properties in terms of flow and processability. Correlating this data with processing performance enables users to optimise powder processes.
Podium presentations from the Freeman team at WCPT6 will discuss: ‘The application of advanced powder characterisation techniques to pharmaceutical Quality by Design protocols’ and ‘Evaluation of dry powder blending using Positron Emission Tomography and the relationship between powder bulk properties and process parameters’. In addition, Dr David Morton of Monash University, Australia, will speak about work that involves the use of the FT4 Powder Rheometer to investigate ‘The influence of dry powder coating methods, including mechanofusion, on the flow properties of inhalable grades of lactose monohydrate’. In the poster sessions, Freeman Technology’s contributions will include ‘The quantification of particle shape and size using image analysis and its effect on the flow properties of various forms of lactose’ and ‘The characterisation of the physical properties of wet masses’. Freeman Technology specialises in providing systems for measuring powder flow properties and has over a decade of experience in powder flow and characterisation.
Circle no. 369
Researchers Optimise Nanolatex Production
Professor Steven Armes and his research team in the Department of Chemistry, at The University of Sheffield in the UK, are using a Zetasizer Nano from Malvern Instruments to monitor the rapid and efficient production of nanolatexes. This single instrument can determine both the particle size distribution and also monitor the zeta potential, making it an ideal characterisation tool for following the in situ synthesis of many types of polymer colloids, such as latexes, microgels or colloidal nanocomposite particles.
“The Zetasizer Nano is so easy to use,” explained Professor Armes. “All my students can familiarise themselves with it very quickly. As a result, we are purchasing a second instrument to ensure we have enough capacity for our expanding research programme in this area. We are making block copolymer nanolatexes directly in water using a very versatile and efficient aqueous dispersion polymerisation formulation,“ said Prof Armes. “By targeting an appropriate block composition, we can prepare spherical nanoparticles of
pre-determined diameter within the technologically important 25 to 100nm size range at relatively high particle concentrations. Recently, we have extended our formulation to prepare worm-like polymer particles and hollow particles known as vesicles.”
Additionally, the elecrophoretic behaviour of the Sheffield team’s nanolatexes strongly depends on the chemical nature of the polymeric stabiliser that is selected. If cationic or anionic polyelectrolytes are used, this has a profound effect on the zeta potential of the nanolatex, as confirmed using the Zetasizer Nano instrument. Professor Armes’ research group at Sheffield University also study colloidal nanocomposites, conducting polymer particles, stimulus-responsive microgels, Pickering emulsions and block copolymer self-assembly in aqueous solution. Zetasizer Nano particle characterisation systems from Malvern Instruments measure particle size, zeta potential and molecular weight. Applications range from characterizing high concentration colloids and nanoparticles, through to measurement of dilute proteins and macromolecules in their native state, requiring as little as 12 microlitres of sample.
Circle no. 370
University of St Andrews Selects NTA System for Exosomes Characterisation
NanoSight reports that the School of Medicine at the University of St Andrews is using nanoparticle tracking analysis, NTA, to characterise exosome behaviour.
Dr Simon Powis and his colleagues at the University of St Andrews are working to understand how a set of molecules involved in the immune system's defence against intracellular pathogens function. These molecules are called major histocompatibility complex (MHC) class I molecules, and they are expressed on almost every cell in the body. Their relevance to medicine is most commonly known because they are one of the key sets of genes that have to be closely matched when an organ transplant is made, otherwise the transplant can be rejected. It is now known that their precise role in the normal immune system is to bind small fragments of degraded viral proteins, which they display to T lymphocytes of the immune system. This allows the specific detection of 'foreign' proteins, for example from potential pathogens, and allows the immune system to specifically detect and kill infected cells, whilst leaving a neighbouring uninfected cell alone. In addition, there is one fascinating autoimmu ne disease closely associated with a particular type of MHC class I molecule. Over 90% of patients with a type of inflammatory arthritis called ankylosing spondylitis which affects the spine, expresses one specific type of MHC class I molecule called HLA-B27. The link between this arthritic condition and HLA- B27 has been known for almost 40 years, but the disease mechanism and how HLA-B27 is involved is yet to be understood.
Whilst the Powis group were studying MHC class I molecules expressed on exosomes, it was discovered that they can express a novel type of structure. The tail region of the MHC class I molecule, which sits inside the exosome, can frequently form a disulfide-bond linkage to another MHC class I molecule, thus bringing two molecules closely together in a dimeric structure. This normally does not happen on cells because the cytoplasm has a reducing environment, preventing disulfide bonds from forming. However, in exosomes the capacity to maintain a reducing environment seems to have been lost. The group is now studying whether cells of the immune system see these MHC class I dimers structures on exosomes and respond to them. Another key question is what peptides are found bound to MHC class I molecules on exosomes. The exosome production pathway is not the normal route for MHC class I molecules to get to the cell surface, so the possibility that different peptides are found in thi s subset of exosomal MHC class I molecules is a real possibility. To be able to study these exosomes from a variety of immune cells, it is necessary to detect their presence and size in cultures. This is the reason for the team choosing the NanoSight NTA approach with the LM10 system.
Circle no. 371
With a total measuring range of 0.01 – 2000 µm in a single instrument, the Laser Particle Sizer ANALYSETTE 22 NanoTec plus is
the ideal, universally applicable Laser Particle Sizer for the effective and reliable determination of particle size distributions in production and quality control as well as in research and development. Innovative Fritsch laser technology makes it possible to separately select 5 different measuring ranges. For elegant measurements with maximum flexibility, highest resolution, outstanding sensitivity - and perfect results down to the nano range. Five measuring ranges without optical conversion- with the ANALYSETTE 22 NanoTec plus, users can choose between three measurement positions of the measuring cell, allowing measurements in five different measuring ranges without modification.
Highest measurement precision with all detectors - the elegant Fritsch measuring solution: regardless of the measurement position you select, the ANALYSETTE 22 NanoTec plus always uses all 57 measuring channels of the detector. By combining the various measurement positions, it is possible to perform measurements with up to 165 effective channels.
A third laser for measuring nano-particles - to extend the particle size determination down to the nano range, it is necessary to detect the light that scatters backward. And the Fritsch solution for this is simply brilliant: a third laser beam utilises backward scattering for the measurement. This beam irradiates the sample positioned directly in front of the detector through a micro-hole in the centre of the detector. Perfectly conceived dispersion units - any particle size measurement is only as good as its dispersion. For this reason, we have developed the ANALYSETTE 22 NanoTec plus as an especially practical modular system with perfectly conceived units for dry and wet dispersion. When switching between wet and dry measurement, the measuring cell, which is located in a practical cartridge, can be easily exchanged – without changing any hoses or modifying the instrument! The cartridge you are not using now, can be easily stored within the dispersion unit. Advantages include: measurement of even nano-particles in
an extremely wide measuring range of 0.01 – 2000µm; triple- laser technology for forward and backward scattering; especially high measurement precision through the analysis of 165 channels; fast, automatic particle size analysis; practical modular system; quick change between wet and dry measurement; and fast and simple cleaning.
Circle no. 372
Laser Particle Sizer
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