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Nanoparticle Measuring System Used for Vaccine Characterisation at Lomonosov Moscow State University
The MSU Department of Virology headed by Professor Joseph Atabekov is studying the in vitro assembly of compositions, consisting of artificial plant virus particles and antigens, potentially attractive for vaccines development. Artificial plant virus particles are spherical particles (SPs) generated by thermal denaturation and structural remodelling of helical plant tobacco mosaic virus, a rod-shaped virus with a diameter of 18nm and a modal length of 300nm. It has been found that upon thermal denaturation of TMV, viral RNA is released and becomes degraded whereas viral coated protein is assembled into spherical particles. The size of SPs depends on the initial TMV concentration and particles from 50 to 800nm may be obtained. The group of Professor Olga Karpova has shown that SPs based on TMV are stable and may adsorb a diversity of proteins. Thus, SPs represent a new type of biogenic nanoplatform attractive for binding antigens and antigenic determinants of different pathogens.
Describing the choice of NTA from NanoSight for this work, Dr Nikitin said "It permits us to analyse and control the size, state of aggregation and concentration of artificial plant virus particles and small spherical plant and animal viruses. Furthermore, NTA allows us to see the formation of immunogenic complexes by using the indirect immunofluorescence or immunogold staining methods. The technique provides us with the opportunity to obtain simultaneous information concerning nanoparticle size, state of aggregation, concentration and antigenic specificity in liquid. This is particularly important for vaccine characterisation and standardisation.
"Previously, we had used transmission electron microscopy (TEM) and dynamic light scattering (DLS) for sizing SPs, isometric viruses and virus- like particles. To detect the formation of immunogenic complexes we use immunogold TEM and immunofluorescence microscopy. For us, the main advantage of NTA over these microscopic methods is that there is no need to fix and dry the object on a supporting film which could lead to morphological deformations and aggregation of nanoparticles. NTA provides the means for analysis of samples in liquid in real-time and makes measurements particle by particle.”
MORE INFO. 169
Vivid Scientific Research at the University of Silesia
Birefringence, a property of a crystalline material describes how within the material there are two distinct indices of refraction. Birefringent materials are used to create polarising filters or interference colours.
1,000th Coater Sold 32 Months after Launch
Quorum Technologies market-leading Q150 series coaters recently achieved yet another notable milestone when the 1,000th model was dispatched from its Ashford UK factory.
“This significant landmark was achieved in only 32 months from the launch of the Q series and is a reflection of just how well the products has been received within the electron microscopy (EM) specimen preparation and thin film coating markets,” explained David Barnbrook, Managing Director at Quorum Technologies.
“We are also pleased that our customers can currently benefit from fast delivery times, with the Q150 series typically available for dispatch within only one week of acceptance of purchase orders.”
The Q150 can be tailored to suit the needs of most EM coating applications. It is available with rotary or turbo pumping and in three formats: sputter coating, carbon evaporation or both combined in a single space-saving bench-top design.
Built with intuitive touch-screen control, the Q150 series allows quick access to both stored and customer-entered coating ‘recipes’. The performance and flexibility of the system is further enhanced by a wide range of ‘drop-in’ specimen stages and coating head inserts. Other optional accessories include film thickness measurement and glow discharge.
Like all Quorum Technologies products, the Q150 comes with a generous three-year warranty. MORE INFO. 170
Krystian Roleder, the Regional Editor for the Central and Eastern Europe edition of the multinational journal ‘Phase Transitions’ and Researcher at the Institute of Physics, University of Silesia, Poland, has been studying birefringence measurements for a number of years. Mr Roleder has been using the THMSG600 stage to study birefringence in several materials, including BaTiO3. He commented: “This Linkam stage is indispensable for my scientific work."
In this research, Roleder and his colleagues have focused on the materials properties above crystallisation temperature. BaTiO3 has been the focus of many research projects since its first recognition in the 1940s. Extensive studies have looked at the phase transitions and domain structure along with the optical, electrical and mechanical properties.
The cubic to tetragonal phase change is described as the order-disorder type and is displacive in nature. It is widely accepted that the Ti ion becomes displaced from its position within the oxygen octahedron, and this is the cause of the polar region formation within the crystal. It was found that the BaTiO3 crystals were birefringent over a broad temperature range but disappeared over 160-170°C.
Launch of Next Generation Turnkey Optical Tweezers System
JPK unveiled the new NanoTracker 2 optical tweezers system at the 2013 Biophysics Annual Meeting held in Philadelphia. Visitors to the conference and exhibition had a first impression about the new system first hand.
JPK, with a reputation as the ‘force tool shop’ for researchers in techniques such as Bio AFM and force spectroscopy, decided to develop a system to meet the needs of the practising applications scientist. These are people who work in the areas that include biophysics, biochemistry, polymer science, biology, single molecule mechanics groups, cell sorting and manipulation. In total, this means all people who are working with small particles interacting with their environment - and measuring their forces. This optical tweezers platform provides force and interaction measurement in parallel with optical microscopy using complementary spectroscopic techniques.
By talking with users of optical tweezers systems, both the home-builders and of their first-generation system, JPK has come up with a system which minimises user interactions on a platform which has been built with increased stability and lower noise to improve detection. With force measurements being so important to users, JPK has enabled new open routines for the user to design their own enhanced measurements. It also provides new force clamp and signal multiplexing and de-multiplexing capabilities by utilising acousto-optic deflectors which spatially control the optical beams.
As CTO, Torsten Jähnke, described the system, "We have developed a more integrated-design approach than before. For example, it makes single molecule experiments such as DNA stretching or cell/particle experiments much more straightforward. This saves time for the user who now has the full control of all parameters in one control and analysis software package."
The new system comes with an overall improved performance especially for the beam steering through highly accurate pivot-point piezo mirrors and the detection system which benefits from a complete redesign of the optical pathway. The resulting better linearity and diminished crosstalk improve all sensitive force measurements. New functions are also implemented for a more precise trap calibration which allows the extraction of additional material properties. The full capabilities of the system are described in detail in a new eight page product brochure which is available free at JPK's web site.
MORE INFO. 171
The group has demonstrated the temperature dependence of the birefringence above crystallisation temperature and the behaviour of anomalous birefringence can be attributed to the existence of polar clusters. These polar clusters originate due to the interdependence of the structural and polar soft modes. These polar clusters interrupt the cubic symmetry of the crystal and about crystallisation temperature the crystal become birefringent. These polar regions are connected to the movement of the Ti molecule within the oxygen cage.
Samples were tested using the THMSG600 stage on an Oxford Cryosystems Metripol Birefringence Imaging System and heated at a constant 0.2°C/min.
The THMS600 is one of the most widely used heating and freezing microscope stages on the market. With its excellent 0.1°C accuracy and stability, the THMS600 is used in many applications including birefringence research. The stage gives researchers the option to characterise their sample quickly by heating to within a few degrees of the required temperature at a rate of up to 150°C/min with no overshoot.
MORE INFO. 172
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INTERNATIONAL LABMATE - MARCH 2013
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