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Purpose: A comparative assessment was performed to evaluate the potential of particle sizing by an ensemble based conventional dynamic light scattering (DLS) technique and an emerging technology based on tunable resistive pulse sensing (TRPS) using particle by particle approach by evaluating three different types of vaccine formulations representing three case studies and showing the limitation of each technique, instrument variability, sensitivity, and the resolution in mixed population. Methods: Three types of in-house vaccine formulations- a protein antigen, an outer membrane vesicle and viral particles were simultaneously evaluated by TRPS based Exoid and two DLS instruments-Zetatrac and Zetasizer for particle size distribution, aggregates, and resolution of polydisperse species. Results: The data from first case study show the risk of possible size overestimation and size averaging in polydisperse samples in DLS measurements which can be addressed by the TRPS analysis. It also shows how TRPS may be utilized only to large size antigens due to its limited size range. The second case study highlights the difference in the sensitivities of two DLS instruments working on the same principle. The third case study show that how TRPS can better resolve the large aggregate species compare to DLS in polydisperse samples. Conclusion: This analysis shows that TRPS can be used as an orthogonal technique in addition to conventional DLS based methods for more precise and in-depth characterization. Both techniques are efficient in size characterization and produce comparable results, however the choice will depend on the type of formulation and size range to be evaluated. [ABSTRACT FROM AUTHOR]

There is a critical need to generate environmentally relevant microplastics (MPs) and nanoplastics (NPs) to better investigate their behavior in laboratory settings. Environmental MPs are heterogenous in size and shape, unlike monodisperse and uniform microspheres commonly used as surrogates. Cryogenic grinding, or cryomilling, was successfully utilized to transform polystyrene (PS) bulk material into heterogenous micro and nano fragments. Fourier-Transform Infrared (FTIR) spectroscopy confirmed that this approach did not alter polymer surface chemistry. The number of milling cycles (time of milling) and frequency of grinding (intensity of milling) were varied to investigate the role cryomilling parameters had on generated MP characteristics. The resulting particle size distributions of cryomilled samples were measured and compared. Coulter Counter and Nanoparticle Tracking Analysis (NTA) were used to measure the particle size distributions at the micro and nanoparticle size ranges, respectively. Microspheres were used to determine what camera settings yielded more accurate sizing and to reduce bias in the NTA analysis. Increasing milling cycles generally increased the number of smaller particles. The evolution of the measured size distributions indicated that small nanosized fragments broke off from larger MPs during cryomilling, steadily eroding larger MP fragments. The number of milling cycles was observed to more consistently impact the size distributions of fragments compared to the frequency of milling. This study offers both analysis of the cryomilling process and recommendations for generating more realistic PS MP/NPs for examining environmental fate and effects. [ABSTRACT FROM AUTHOR]

Extracts with emulsifying capacity have been extracted from split peas (Pisum sativum). At pH 7 and extract concentrations above 0.75 g L−1 s, stable emulsions were produced, with droplets of tens μm. At higher concentrations (2 g L−1 s) bridging flocculation occurs, with the flocs breaking up into μm-sized particles upon SDS addition, reaching sizes comparable to those obtained by oilve compost emulsifiers. At even higher concentrations, depletion flocculation is observed due to unadsorbed extracts. The extract cannot emulsify at pH 3. In all cases, the interfacial tension is quickly reduced (at a higher degree at pH 7) due to the fast adsorption of small-molecular surfactants. Within 10 s further reductions are observed, as macromolecules are adsorbed, forming steric layers at the oil – water interface at pH 7. At pH 3 the adsorption of the macromolecules reduces the interfacial tension to a smaller extent, and is followed by a slower (over 100 s) rearrangement at the interface. Coupled with a change in zeta potential from 10.8 ± 0.6 mV at pH 7 down to 4.1 ± 2.2 mV at pH 3, these phenomena render the interfacial layer at pH 3 unable to stabilize against coalescence. Size exclusion chromatography of the extract, the emulsion serum and the cream layer highlight the preferential adsorption of specific biopolymers at the interface and confirm the hypothesis of the sequential adsorption and interfacial rearrangements. Fourier transform infrared spectra show that proteins are preferably adsorbed at the interface, while polysaccharides remain at the bulk phase. [ABSTRACT FROM AUTHOR]

"Surgical smoke" is an airborne by-product of electrosurgery comprised of vapour and suspended particles. Although concerns exist that exposure may be harmful, there is a poor understanding of the smoke in terms of particle size, morphology, composition and biological viability. Notably, it is not known how the biological tissue source and cutting method influence the smoke. The objective of this study was to develop a collection method for airborne by-product from surgical cutting. This would enable comprehensive analyses of the particulate burden, composition and biological viability. The method was applied to compare the electrosurgical smoke generated (in the absence of any evacuation mechanism) with the aerosolized/airborne by-products generated by ultrasonic and high-speed cutting, from bone and liver tissue cutting. We report a wide range of particle sizes (0.93–806.31 μm for bone, 0.05–1040.43 μm for liver) with 50% of the particles being <2.72 μm (~PM2.5) and 90% being <10 μm (PM10). EDX and biochemical analysis reveal components of biological cells and cellular metabolic activity in particulate from liver tissue cut by electrosurgery and ultrasonic cutting. We show for the first time however that bone saws and ultrasonic cutting do not liberate viable cells from bone. [ABSTRACT FROM AUTHOR]

During the past two decades the nanomedicine field has experienced significant progress. To date, over sixty nanoparticle (NP) formulations have been approved in the US and EU while many others are in clinical or preclinical development, indicating a concerted effort to translate promising bench research to commercially viable pharmaceutical products. The use of NPs as novel drug delivery systems, for example, can improve drug safety and efficacy profiles and enable access to intracellular domains of diseased cells, thus paving the way to previously intractable biological targets. However, the measurement of their physicochemical properties presents substantial challenges relative to conventional injectable formulations. In this perspective, we focus exclusively on particle size, a core property and critical quality attribute of nanomedicines. We present an overview of relevant state-of-the-art technologies for particle sizing, highlighting the main parameters that can influence the selection of techniques suitable for a specific size range or material. We consider the increasing need, and associated challenge, to measure size in physiologically relevant media. We detail the importance of standards, key to validate any measurement, and the need for suitable reference materials for processes used to characterize novel and complex NPs. This perspective highlights issues critical to achieve compliance with regulatory guidelines and to support research and manufacturing quality control. [ABSTRACT FROM AUTHOR]

Lucy–Richardson (LR) is a classical iterative regularization method largely used for the restoration of nonnegative solutions. LR finds applications in many physical problems, such as for the inversion of light scattering data. In these problems, there is often additional information on the true solution that is usually ignored by many restoration methods because the related measurable quantities are likely to be affected by non-negligible noise. In this article we propose a novel Weakly Constrained Lucy–Richardson (WCLR) method which adds a weak constraint to the classical LR by introducing a penalization term, whose strength can be varied over a very large range. The WCLR method is simple and robust as the standard LR, but offers the great advantage of widely stretching the domain range over which the solution can be reliably recovered. Some selected numerical examples prove the performances of the proposed algorithm. [ABSTRACT FROM AUTHOR]

THz extinction spectroscopy extends UV-Vis and NIR-spectroscopy to characterize particles from fine powders and dust to sand, grains and granulated materials. We extract particle sizes from the spectral position of the first peak of the interference structure and size distributions from the visibility of the fine ripple structure in the measured extinction spectra. As such, we can demonstrate a route for a quick determination of these parameters from single measurements. [ABSTRACT FROM AUTHOR]

The effects of local interaction of light with a particle used for diagnostics of the dispersed phase of flows are usually well described by the laws of geometrical optics. For forward scattering, geometrical optics is complemented by Fraunhofer diffraction by an opaque disk. Accurate calculations using Mie theory reveal an additional intensity of the radiation scattered in a direction close to the the direction of illumination. This additional contribution is attributed to the edge wave. The components of forward scattered light, namely, diffraction, reflection, and edge wave are studies in order to refine the contribution to the scattered intensity and locality of the interaction with the particle. It is shown that localization of the interaction with the particle occurs for all of these components. The distributions of the intensity of the individual components in forward scattering are obtained. [ABSTRACT FROM AUTHOR]

Hydrodynamic chromatography (HDC) is a liquid chromatographic technique that separates analytes on the basis of their size in solution. Separation can be conducted either in an open tube or in a column packed with inert, nonporous beads. In HDC, larger analytes elute first and smaller ones later, due to preferential sampling of the streamlines of flow in the open tube or in the interstitial medium of the packed column. Because of the low shear rates experienced in HDC, coupled with the wealth of information obtained when employing a multiplicity of detection methods, the technique has experienced a resurgence in recent years in both the particle sizing and macromolecular arenas, where it can provide information on the mutual interdependence of molar mass, size, shape, and compactness. Additionally, microcapillary HDC is also gaining popularity amongst the bioanalytical community, who have employed the technique, inter alia, to separate DNA fragments over a base pair range spanning four orders in magnitude. Here, examples from the literature are used to show how HDC has been applied in each of the aforementioned areas, explaining the information that can be obtained from various detector combinations, and opining on the future of the technique. [ABSTRACT FROM AUTHOR]

The biological application of nanoparticles has resulted in an increased need for the development of robust, accurate, and precise methods for quality control analysis and characterization. Parameters such as particle size, particle shape, and their distributions affect end-use properties such as chemical reactivity, diffusivity, permeability, and transport. Introduced here is a hydrodynamic chromatography (HDC) method utilizing multi-angle static light scattering, quasi-elastic light scattering, differential viscometry, and differential refractometry detection for characterizing nanoscale vesicles. Quadruple-detector HDC was used to determine multiple sizing parameters and their statistical moments and distributions. Molar mass and molar mass averages were determined in a calibrant-independent fashion. Both the sizing parameters and the molar mass were measured across the HDC elution profile. The shape and structure of the nanoparticle were monitored as a function of HDC elution volume through the dimensionless ratio ρ ≡ R/ R. The HDC results were comparable to those obtained by transmission electron microscopy, but more extensive characterization was possible by HDC, which provided distributions of both particle size and particle shape. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The need to monitor, measure, and control sub-visible proteinaceous particulates in biopharmaceutical formulations has been emphasized in recent publications and commentaries. Some of these particulates can be highly transparent, fragile, and unstable. In addition, for much of the size range of concern, no practical measurement method with adequate sensitivity and repeatability has been available. A complication in measuring protein particulates in many formulations is the simultaneous presence of other particle types such as silicone micro-droplets, air bubbles, and extrinsic contaminants. The need has therefore been identified for new analytical methods which can accurately measure and characterize sub-visible particulates in formulations. Micro-flow imaging has been shown to provide high sensitivity in detecting and imaging transparent protein particles and a unique capability to independently analyze such populations even when other particle types are present. [ABSTRACT FROM AUTHOR]

Knowledge of the effects of different product and process variability on microparticle characterization is essential for the successful development, optimization, and scale-up of an encapsulation process. In the current research, the qualitative application of the Lasentec focused beam reflectance (FBRM) system for online monitoring of microparticle size distribution was demonstrated. lasentec particle vision and measurement (PVM) images were also employed to follow up the steps of microparticle formation and ripening. The drug entrapment efficiency and drug release characteristics were found to be dependent on the polymer, drug, and surfactant concentrations. DSC, FTIR, and XRD data revealed that the drug was compatible with the matrix forming polymer in the solid state. As indicated from the chord count data, FBRM was sensitive to the amount of the solid materials and the number of microparticles formed. Linear relationships with good correlations were obtained between polymer, drug, and surfactant levels and the disappearance rate of 5 to 36.8, 18.4 to 135.9, and 63 to 398 µm chord length fractions. Upon organic solvent evaporation, PVM imaging detected various stages of microemulsion droplets, sheath formation, and solidification with subsequent microparticle hardening. This study illustrated the utility of FBRM and PVM in monitoring the progress of particle formation during drug encapsulation. [ABSTRACT FROM AUTHOR]

Size and size distribution of particles in particulate two-phase flow play an important role in a wide variety of industrial areas, while their measurement still remains a hard task till now. Ultrasonic wave as a mechanical vibration contains plenty of information about medium when it passes through. Thus the size distribution could be extracted from the measured ultrasonic attenuation and velocity spectra by means of well established models and data processing techniques. This paper contributes to the extraction of information of droplet size of a two-phase fat emulsion simultaneously from signals of broad-band ultrasonic attenuation and velocity spectra. According to the formulated single particle scattering model, the relationship between particle size distribution and ultrasonic spectrum is established. The sensitivities of ultrasonic spectra to the variation of particle size are illustrated. Distinguishing features for attenuation and velocity spectra are summarized. Demonstration calculations of inversion by optimum regularization factor method are carried out to yield the typical numerical results for discussion. Based on the proposed inversion algorithm and theoretical model, a fat emulsion sample with a volume fraction up to 20% is measured and analyzed. To validate the proposed ultrasonic spectrum particle sizing method, the results are compared to those obtained from optical measurement. [ABSTRACT FROM AUTHOR]

This paper reviews recent developments in dynamic light scattering and their application to the study of particle sizes, structures and interactions in food materials. Results obtained in concentrated and highly turbid suspensions via the recently developed technique of diffusing wave spectroscopy (DWS) are described. Problems in the detailed analysis of the information contained in DWS are described, and the possible future uses of the techniques are discussed. [ABSTRACT FROM AUTHOR]

In multiphase flow research and many industrial applications it is important to determine the bubble size and velocity. To achieve this, one of approaches is to utilize laser phase-Doppler anemometry. However, it was found that the second order refraction has great impact on PDA sizing method when the relative refractive index of media is less than one. In this paper, the problem of second order refraction is investigated and a model of phase-size correlation to eliminate the measurement errors is introduced for bubble sizing. As a result, the model relaxes the assumption of single scattering mechanism in conventional phase-Doppler anemometry. The results of simulations based on this new model by using Generalized Lorenz Mie Theory (GLMT) are compared with those based on the conventional method. An optimization method for accurately sizing air-bubble in water has been suggested. [ABSTRACT FROM AUTHOR]

Conventional phase Doppler systems are useful for sizing particles in the order of microns, but sensitive to the Gaussian beam defect which can cause sizing errors. The defect can be significant when a large size is measured. In this paper, we present a new phase Doppler system using a planar optical layout which permits large particles to be measured in a forward scattering scheme without the Gaussian beam errors. The optical system design is discussed by numerical simulation based on the Mie theory. [ABSTRACT FROM AUTHOR]

Measurement of the diameter of the fuel aerosol droplet is very important in the design of new type burners and in diagnostic process. Diffraction method is one of the most useful measuring procedures in this case. An investigation setup is presented enabling the determination of the substituting drop diameter in fuel aerosol stream created by aeroengine injectors. The results obtained for K 108-767, K 108-012, 37.03.9595, 16.83.0310 types are presented. [ABSTRACT FROM AUTHOR]