Ulf Nobbmann

Malvern Panalytical · Nanometrics

A key step in the development of novel messenger RNA drugs is the ability to deliver genetic material into host cells. One such potential route is via Adeno Associated Virus (AAV) capsids. In order to develop vaccine materials and optimize their efficacy, knowing the concentration of these AAV vectors is important. To date, a gold standard has been...

Some Covid-19 vaccines involve the introduction of messenger RNA (mRNA) to trigger an immune response to the spike proteins of the SARS-CoV-2 coronavirus. One potential gene transfer vector to deliver this mRNA payload are Adeno-Associated Viruses (AAVs). Access to biophysical techniques present in many core facilities can provide fundamental insig...

Dynamic light scattering (DLS) is well established for rapid size, polydispersity, and size distribution determination of colloidal samples. While there are limitations in size range, resolution, and concentration, the technique has found ubiquitous applications from molecules to particles. With the ease of use of today’s commercial DLS instrumenta...

Jar testing simulates the coagulation / flocculation process in a water treatment plant. In a set of beakers (typically 6) a defined amount of water is mixed with varying amounts of coagulant. Each beaker receives a slightly different dose of the coagulant, and then stirred for a set amount of time to mimic plant operation. The formation of floc ha...

As Nanotechnology continues to gain importance in both fundamental and applied sciences, the need to measure size has grown with it. Of the various techniques available to characterize nanoparticle size (such as atomic force AFM, transmission electron TEM, or scanning electron microscopy SEM, and also small angle X-ray scattering SAXS), we concentr...

Liposomes have been used in drug discovery and drug delivery, and the biophysical characterization of these systems and their payloads is critical to understanding and optimizing their fabrication and function. We describe optimal conditions for extruding liposomes as well as their stability under different conditions.

A main concern for exosome purification methods is the elimination of non-vesicular debris, including free protein and lipoprotein aggregates, membrane blebs, smaller nanoparticles, inorganic particles. Degree of purity from large debris can be ascertained with number-based sizing techniques such as nanoparticle tracking analysis (NTA) and ensemble...

Nanoparticle zeta-potentials are relatively easy to measure, and have consistently been proposed in guidance documents as a particle property that must be included for complete nanoparticle characterization. There is also an increasing interest in integrating data collected on nanomaterial properties and behavior measured in different systems (e.g....

The ability to precisely detect the onset of protein aggregation to draw insights into microstructural characteristics plays a critical role in a variety of biotechnological applications such as therapeutic protein stability. ootnotetextA Saluja et al., "Ultrasonic rheology of a monoclonal antibody (IgG2) solution: implication for physical stabilit...

Drinking water is typically treated to remove contamination, both mineral and organic. Zeta potential provides a measurable value to monitor optimal water clarification capabilities. Optimal conditions for water production can be obtained by monitoring zeta potential, turbidity, and flocculating agent concentration.

Measurement of the rotational diffusion coefficient is an important tool for the characterisation of anisotropic particles. Traditionally, Depolarised Dynamic Light Scattering (DDLS) has been used to measure rotational diffusion of small particles, such as proteins. We present a different approach, and show an application to colloidal silver partic...

Metal oxide nanoparticles are finding increasing application in the preparation of new nanocrystalline materials, with metal oxide composites being used to confer new electronic, magnetic and optical properties into material structures. Often these materials are formulated and processed as slurries or aqueous suspensions. One key parameter in contr...

Obtaining good quality protein crystals still remains a bottleneck in structural determination by X-ray crystallography. This book is written for biochemists, crystallographers, graduate students, technicians, undergraduates or anyone else working with proteins with the intention of crystallizing them. The approach is a practical one and no previou...

Dynamic light scattering (DLS) probes the diffusion of particles and molecules on sub-micrometer length scales. Static light scattering (SLS) uses the mean scattering intensity to obtain an average molar mass of all components in solution. While the two techniques may be employed simultaneously in one optical configuration, they provide independent...

Metal oxide nanoparticles are increasingly being used to prepare new nanocrystaline materials. By controlling formulations of multicomponent metal oxides; crystal shape, structure and surface properties important in the design of new materials are gaining acceptance for many applications. Metal oxide composites are being used to design new electron...

Dynamic Light Scattering (DLS) is an established metrology for the characterization of colloids, nanoparticles, polymers and biomolecules. Typically, sub-micron sizes are quickly and easily assessed by this technique, analyzing the intensity fluctuations of scattered light from a sample suspension. Advances in electronics and optics now allow acces...

Dynamic light scattering (DLS) measures time-dependent fluctuations in the scattering intensity arising from particles undergoing random Brownian motion. Diffusion coefficient and particle size information can be obtained from the analysis of these fluctuations. This paper discusses the factors which will influence the lower size limit of DLS and r...

Size exclusion chromatography (SEC) and dynamic light scattering (DLS) are common technologies in protein laboratories. SEC is used routinely for the purification, identification, and quantification of protein mixtures, while batch DLS is used for pre-column size and poly-dispersity measurements, along with aggregate quanti-fication. Until now, cou...

In today’s high performance liquid chromatography (HPLC) systems common detectors typically measure ultraviolet (UV) light absorption or refractive index (RI) changes. Dynamic light scattering can measure the size of molecules directly, and can be combined with chromatography. As different peaks elute, the diffusion coefficient and size of the mole...

Solution molar masses and conformations of glycogens from different sources (rabbit, oyster, mussel and bovine) were analysed using sedimentation velocity in the analytical ultracentrifuge, size-exclusion chromatography coupled to multi-angle laser light scattering (SEC-MALLS), size-exclusion chromatography coupled to a differential pressure viscom...

Dynamic light scattering (DLS) is a technique used for measuring the size of molecules and particles undergoing Brownian motion by observing time-dependent fluctuations in the intensity of scattered light. The measurement of samples using conventional DLS instrumentation is limited to low concentrations due to the onset of a phenomenon called multi...

Recent progress in structure determination of proteins allows us to reveal the interactions of protein molecules at molecular level. NMR and X-ray crystallography are widely used for the determination of the three-dimensional structure of the proteins in detail. In both techniques, preparation of good samples is now the most difficult and important...

The two analytical techniques of analytical ultracentrifugation and dynamic light scattering are used to find the %mass of monomer in antibody samples in the presence of other oligomeric species. The results are then compared to show the degree of accuracy one can expect from each technique.

Prokaryotic DNA segregation most commonly involves members of the Walker-type ParA superfamily. Here we show that the ParF partition protein specified by the TP228 plasmid is a ParA ATPase that assembles into extensive filaments in vitro. Polymerization is potentiated by ATP binding and does not require nucleotide hydrolysis. Analysis of mutations...

The visible light wavelength ranges from similar to400nm to similar to700nm, just slightly larger than the main topic of this book: Mesoscale phenomena, roughly defined as 1 - 100nm. Nevertheless, light is an ideal probe to determine the size, shape, structure, or aggregation state of mesoscale phenomena in complex fluids. A brief overview of the t...

Multiple light scattering can be suppressed by slightly tilting two single-mode fibers viewing the same sample volume. The cross-correlation function of the two signals shows more or less contributions from single scattering, depending on the tilt angle. We show experimental results for polystyrene spheres at a scattering angle of 90°. The measured...

The derivation of a correlation transfer equation Is outlined, This correlation transfer equation comes from multiple-scattering theory for the electric field fluctuations of light propagating through suspensions of diffusing particles, The correlation equation is very similar to the radiative intensity equation, Thus, radiative solution techniques...

Scope and method of study. The scattering of light from a NdYAG laser was used to investigate several colloidal samples of spheres of polystyrene (PST). The spheres were dispersed into water in such concentrations that multiple scattering resulted. Data for intensity and correlation functions are presented for various particle parameters and geomet...

Light scattering can be used to investigate colloidal samples. In concentrated suspensions the scattering can be interpreted under the assumption that the photons undergo a random walk (Diffusing Wave Spectroscopy, DWS). Another approach balances incoming and outgoing photons (Correlation Transfer, CT). Using the same approximations the two theorie...

A correlation transfer equation for multiple scattering of light through suspensions of diffusing particles is derived from multiple scattering theory. Because of the formal similarity between the correlation equation and the radiative transfer equation, radiative transport solution techniques are applied to obtain solutions for the field correlati...

In previous work, correlation transfer (CT) theory has been developed, potentially to handle dynamic light scattering measurements from single scattering to highly multiple scattering. Through the preliminary experimental results presented herein, correlation function measurements are compared to CT predictions for a variety of parametrical effects...

The correlation of the temporal fluctuations of an electric field in multiple scattering media is shown to be governed by an integral equation similar to the radiative transport equation. Some approximate methods utilized in the RT area are applied to obtain approximate solutions for the field correlation function in isotropic 1D media. Initial res...

A correlation transfer equation is developed for multiple scattering applications, and is solved for the field correlation function that is measured by photon correlation experiments. Radiative transport solution techniques are applied, because there is a formal similarity between the two theories. Small correlation delay time, isotropic scattering...

A method of extending the interpretation of photon-correlation measurements from the restrictions of a single scattering regime to the high orders of multiple scattering is formulated. The method involves the development of a correlation transfer (CT) equation based on the intuition underlying the diffusive wave spectroscopy (DWS) approach. Because...