Nanoplastic is an emerging topic of relevance in environmental science. The analytical methods for microplastic have a particle size limit of a few micrometers so that new methods have to be ...developed to cover the nanometer range. This contribution reviews the progress in environmental nanoplastic analysis and critically evaluates which techniques from nanomaterial analysis may potentially be adapted to close the methodological gap. A roadmap is brought forward for the whole analytical process from sample treatment to particle characterization. This includes a critical review of (i) methods for analyte extraction and preconcentration from various environmental matrices; (ii) methods for the separation of the nanoplastic into specific size fractions; (iii) light scattering techniques and various types of microscopy to characterize the particle fractions; (iv) chemical identification of particles to validate the obtained data. For these methods, we will discuss prospects and limitations to develop analytical protocols for specific sampling scenarios.
•Analytical methods for submicrometer- and nanoplastic face a methodological gap.•Methods for nanomaterial characterization that may be applicable for submicrometer- and nanoplastic are presented.•A roadmap for the whole analytical process of submicrometer- and nanoplastic is discussed.
Cell identification and analysis play a crucial role in many biology- and health-related applications. The internal and surface structures of a cell are complex and many of the features are ...sub-micron in scale. Well-resolved images of these features cannot be obtained using optical microscopy. Previous studies have reported that the single-cell angular laser-light scattering patterns (ALSP) can be used for label-free cell identification and analysis. The ALSP can be affected by cell properties and the wavelength of the probing laser. Two cell properties, cell surface roughness and the number of mitochondria, are investigated in this study. The effects of probing laser wavelengths (blue, green, and red) and the directions of scattered light collection (forward, side, and backward) are studied to determine the optimum conditions for distinguishing the two cell properties. Machine learning (ML) analysis has been applied to ALSP obtained from numerical simulations. The results of ML analysis show that the backward scattering is the best direction for characterizing the surface roughness, while the forward scattering is the best direction for differentiating the number of mitochondria. The laser light having red or green wavelength is found to perform better than that having the blue wavelength in differentiating the surface roughness and the number of mitochondria. This study provides important insights into the effects of probing laser wavelength on gaining information about cells from their ALSP. This article is protected by copyright. All rights reserved.
•AFM, SEM; TEM and DLS all compared.•Silica, gold, and polymer nanoparticles characterised.•AFM and TEM shown to be most appropriate for small particles.•SEM just as accurate as AFM and TEM for ...larger particles.•DLS shows dynamic behaviour but cannot characterise mixtures.
Nanoparticles have properties that depend critically on their dimensions. There are a large number of methods that are commonly used to characterize these dimensions, but there is no clear consensus on which method is most appropriate for different types of nanoparticles.
In this work four different characterization methods that are commonly applied to characterize the dimensions of nanoparticles either in solution or dried from solution are critically compared. Namely, transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and dynamic light scattering (DLS) are compared with one another. The accuracy and precision of the four methods applied nanoparticles of different sizes composed of three different core materials, namely gold, silica, and polystyrene are determined. The suitability of the techniques to discriminate different populations of these nanoparticles in mixtures are also studied.
The results indicate that in general, scanning electron microscopy is suitable for large nanoparticles (above 50 nm in diameter), while AFM and TEM can also give accurate results with smaller nanoparticles. DLS reveals details about the particles’ solution dynamics, but is inappropriate for polydisperse samples, or mixtures of differently sized samples. SEM was also found to be more suitable to metallic particles, compared to oxide-based and polymeric nanoparticles. The conclusions drawn from the data in this paper can help nanoparticle researchers choose the most appropriate technique to characterize the dimensions of nanoparticle samples.
We consider light scattering off a two-dimensional (2D) dipolar array and show how it can be tailored by properly choosing the lattice constant of the order of the incident wavelength. In particular, ...we demonstrate that such arrays can operate as a nearly perfect mirror for a wide range of incident angles and frequencies, and shape the emission pattern from an individual quantum emitter into a well-defined, collimated beam. These results can be understood in terms of the cooperative resonances of the surface modes supported by the 2D array. Experimental realizations are discussed, using ultracold arrays of trapped atoms and excitons in 2D semiconductor materials, as well as potential applications ranging from atomically thin metasurfaces to single photon nonlinear optics and nanomechanics.
Liposome development is of great interest owing to increasing requirements for efficient drug carriers. The structural features and thermal stability of such liposomes are crucial in drug transport ...and delivery. Reported here are the results of the structural characterization of PEGylated liposomes via small‐ and wide‐angle X‐ray scattering and an asymmetric flow field‐flow fractionation (AF4) system coupled with differential refractive‐index detection, multi‐angle light scattering (MALS) and dynamic light scattering. This integrated analysis of the exemplar PEGylated liposome formed from hydrogenated soy phosphatidylcholine (HSPC) with the addition of cholesterol reveals an average hydrodynamic radius (Rh) of 52 nm with 10% polydispersity, a comparable radius of gyration (Rg) and a major liposome particle mass of 118 kDa. The local bilayer structure of the liposome is found to have asymmetric electronic density profiles in the inner and outer leaflets, sandwiched by two PEGylated outer layers ca 5 nm thick. Cholesterol was found to effectively intervene in lipid chain packing, resulting in the thickening of the liposome bilayer, an increase in the area per lipid and an increase in liposome size, especially in the fluid phase of the liposome. These cholesterol effects show signs of saturation at cholesterol concentrations above ca 1:5 cholesterol:lipid molar ratio.
Small‐ and wide‐angle X‐ray scattering and asymmetric flow field‐flow fractionation integrated with multi‐angle light scattering (AF4–MALS) are used to characterize PEGylated liposomes of hydrogenated soy phosphatidylcholine (HSPC) that have potential for drug delivery. Observed local and global structural changes of the phospholipid bilayers reveal the effects of cholesterol on PEGylated HSPC liposomes.
Ion-exchange chromatography coupled to light scattering detectors represents a fast and simple analytical method for the assessment of multiple critical quality attributes (CQA) in one single ...measurement. The determination of CQAs play a crucial role in Adeno-Associated Virus (AAV)-based gene therapies and their applications in humans. Today, several different analytical techniques, including size-exclusion chromatography (SEC), analytical ultracentrifugation (AUC), qPCR or ELISA, are commonly used to characterize the gene therapy product regarding capsid titer, packaging efficiency, vector genome integrity, aggregation content and other process-related impurities. However, no universal method for the simultaneous determination of multiple CQAs is currently available. Here, we present a novel robust ion-exchange chromatography method coupled to multi-angle light scattering detectors (IEC-MALS) for the comprehensive characterization of empty and filled AAVs concerning capsid titer, full-to-total ratio, absolute molar mass of the protein and nucleic acid, and the size and polydispersity without baseline-separation of both species prior to data analysis. We demonstrate that the developed IEC-MALS assay is applicable to different serotypes and can be used as an orthogonal method to other established analytical techniques.
Abstract The paper describes simulating light scattering of an electromagnetic field on a deformed gas bubble suspended in a liquid. The field intensity distributions around the deformed bubble were ...obtained. It turned out that field scattering increases with bubble deformation up to a certain limit of the deformation coefficient A (relative deformation amplitude). At A = 0.7 and higher, the scattering remains independent of the magnitude of the deformation.
PDF
