In this study, two saponins-rich plant extracts, viz.
and
, were used as surfactants in an oil-in-water (O/W) emulsion based on hempseed oil (HSO). This study focused on a low oil phase content of 2%
.../
HSO to investigate stable emulsion systems under minimum oil phase conditions. Emulsion stability was characterized by the emulsification index (EI), centrifugation tests, droplet size distribution as well as microscopic imaging. The smallest droplets recorded by dynamic light scattering (droplets size v. number), one day after the preparation of the emulsion, were around 50-120 nm depending the on use of
and
as a surfactant and corresponding to critical micelle concentration (CMC) in the range 0-2 g/L. The surface and interfacial tension of the emulsion components were studied as well. The effect of emulsions on environmental bacteria strains was also investigated. It was observed that emulsions with
extract exhibited slight toxic activity (the cell metabolic activity reduced to 80%), in contrast to
emulsion, which induced
growth. The highest-stability samples were those with doubled CMC concentration. The presented results demonstrate a possible use of oil emulsions based on plant extract rich in saponins for the food industry, biomedical and cosmetics applications, and nanoemulsion preparations.
•Micro/nanobubbles (MNB) promote the photocatalytic disinfection of microbial spores.•H2O2 and •OH are the primary active species responsible for the spore inactivation.•MNB induced light scattering ...significantly increases the bactericidal efficiency.•Sustainable O2 supply from MNBs can accelerate the hole oxidation of the catalyst.•MNB triggered interfacial photoelectric effect plays a key role in the enhancement.
Microbial contamination of water in the form of highly-resistant bacterial spores can cause a long-term risk of waterborne disease. Advanced photocatalysis has become an effective approach to inactivate bacterial spores due to its potential for efficient solar energy conversion alongside reduced formation of disinfection by-products. However, the overall efficiency of the process still requires significant improvements. Here, we proposed and evaluated a novel visible light photocatalytic water disinfection technology by its close coupling with micro/nano bubbles (MNBs). The inactivation rate constant of Bacillus subtilis spores reached 1.28 h−1, which was 5.6 times higher than that observed for treatment without MNBs. The superior performance for the progressive destruction of spores’ cells during the treatment was confirmed by transmission electron microscopy (TEM) and excitation-emission matrix (EEM) spectra determination. Experiments using scavengers of reactive oxygen species (ROSs) revealed that H2O2 and •OH were the primary active species responsible for the inactivation of spores. The effective supply of oxygen from air MNBs helped accelerate the hole oxidation of H2O2 on the photocatalyst (i.e. Ag/TiO2). In addition, the interfacial photoelectric effect from the MNBs was also confirmed to contribute to the spore inactivation. Specifically, MNBs induced strong light scattering, consequently increasing the optical path length in the photocatalysis medium by 54.8% at 700nm and enhancing light adsorption of the photocatalyst. The non-uniformities in dielectricity led to a high-degree of heterogeneity of the electric field, which triggered the formation of a region of enhanced light intensity which ultimately promoted the photocatalytic reaction. Overall, this study provided new insights on the mechanisms of photocatalysis coupled with MNB technology for advanced water treatment.
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Prion diseases are transmissible neurodegenerative disorders that affect mammals, including humans. The central molecular event is the conversion of cellular prion glycoprotein, PrPC, into a plethora ...of assemblies, PrPSc, associated with disease. Distinct phenotypes of disease led to the concept of prion strains, which are associated with distinct PrPSc structures. However, the degree to which intra- and inter-strain PrPSc heterogeneity contributes to disease pathogenesis remains unclear. Addressing this question requires the precise isolation and characterization of all PrPSc subpopulations from the prion-infected brains. Until now, this has been challenging. We used asymmetric-flow field-flow fractionation (AF4) to isolate all PrPSc subpopulations from brains of hamsters infected with three prion strains: Hyper (HY) and 263K, which produce almost identical phenotypes, and Drowsy (DY), a strain with a distinct presentation. In-line dynamic and multi-angle light scattering (DLS/MALS) data provided accurate measurements of particle sizes and estimation of the shape and number of PrPSc particles. We found that each strain had a continuum of PrPSc assemblies, with strong correlation between PrPSc quaternary structure and phenotype. HY and 263K were enriched with large, protease-resistant PrPSc aggregates, whereas DY consisted primarily of smaller, more protease-sensitive aggregates. For all strains, a transition from protease-sensitive to protease-resistant PrPSc took place at a hydrodynamic radius (Rh) of 15 nm and was accompanied by a change in glycosylation and seeding activity. Our results show that the combination of AF4 with in-line MALS/DLS is a powerful tool for analyzing PrPSc subpopulations and demonstrate that while PrPSc quaternary structure is a major contributor to PrPSc structural heterogeneity, a fundamental change, likely in secondary/tertiary structure, prevents PrPSc particles from maintaining proteinase K resistance below an Rh of 15 nm, regardless of strain. This results in two biochemically distinctive subpopulations, the proportion, seeding activity, and stability of which correlate with prion strain phenotype.
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•Critical CO2 is considered as fluid randomized optically by density fluctuations.•Poynting's vector is estimated for laser light single Rayleigh scattering by CO2 molecules.•Optic ...path is used instead of geometric one to evaluate the scattered light phases.•Small-angle distribution of scattered light intensity we got fits well with experimental data.•Statistical properties for large-scale critical fluctuations are obtained from experiment.
In this paper we propose a new theoretical model for critical opalescence describing the observed peculiarities of small angle scattering of laser radiation by critical CO2 well enough. Comparing the theoretical and experimental angular distributions of scattered light intensity we get reliable information about correlation length ~10−5 m and relative density variance ~2·10−4 for CO2 large-scale critical fluctuations.
Tungsten carbide cobalt nanoparticles (WC/Co NPs) are extensively employed to fabricate wear-resistant parts, cutting tools, and rock drills. The colloidal stability of the WC/Co NP suspension plays ...a vital role in determining the mechanical properties of WC/Co-based products. In this work, dispersion of WC/Co NPs in aqueous media was conducted using surfactants (cationic, anionic, nonionic) with different concentration conditions. The z-average hydrodynamic diameters measured using dynamic light scattering (DLS) revealed the optimal surfactant for WC/Co NP dispersion: cationic hexadecyltrimethylammonium bromide (CTAB) which induces interparticle electrostatic repulsion forces at a concentration of 2 g/L. The capping behavior of CTAB was demonstrated using Zeta-potential analysis, Fourier transform infrared spectroscopy, and X-ray diffraction measurements. The mean size measurement of immobilized WC/Co NPs was also conducted using atomic force microscopy (AFM). We demonstrate a comparative protocol between number-weighted mean sizes measured using AFM (dAFM) and DLS (dDLS) in relation to the relative standard deviation (RSD) from AFM measurements. A highly linear correlation was demonstrated between dDLS/dAFM and RSD. We indicate that for polydisperse (RSD > 0.1) and non-spherical NPs, the highest correlation between dDLS and dAFM exists when the RSD is 0.37, where dDLS/dAFM is close to 1.
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•Dispersion of WC/Co nanoparticles is important in industry to enhance the wear and corrosion resistance performance of cutting tools.•We found that CTAB (cationic surfactant) is most effective in dispersing WC/Co nanoparticles in aqueous media.•A highly linear correlation exists in mean size measurements between AFM and DLS for polydisperse and non-spherical nanoparticles.
(1) Background: Several properties of silver nanoparticles (AgNPs), such as cytotoxic, anticancer, and antimicrobial activities, have been subjects of intense research; however, important aspects ...such as nanoparticle aggregation are generally neglected, although a decline in colloidal stability leads to a loss of the desired biological activities. Colloidal stability is affected by pH, ionic strength, or a plethora of biomolecules that interact with AgNPs under biorelevant conditions. (2) Methods: As only a few studies have focused on the relationship between aggregation behavior and the biological properties of AgNPs, here, we have systematically evaluated this issue by completing a thorough analysis of sterically (via polyvinyl-pyrrolidone (PVP)) stabilized AgNPs that were subjected to different circumstances. We assessed ultraviolet-visible light absorption, dynamic light scattering, zeta potential measurements, in vitro cell viability, and microdilution assays to screen both colloidal stability as well as bioactivity. (3) Results: The results revealed that although PVP provided outstanding biorelevant colloidal stability, the chemical stability of AgNPs could not be maintained completely with this capping material. (4) Conclusion: These unexpected findings led to the realization that stabilizing materials have more profound importance in association with biorelevant applications of nanomaterials than just being simple colloidal stabilizers.
Material losses in metals are a central bottleneck in plasmonics for many applications. Here we propose and theoretically demonstrate that metal losses can be successfully mitigated with dielectric ...particles on metallic films, giving rise to hybrid dielectric–metal resonances. In the far field, they yield strong and efficient scattering, beyond even the theoretical limits of all-metal and all-dielectric structures. In the near field, they offer high Purcell factor (>5000), high quantum efficiency (>90%), and highly directional emission at visible and infrared wavelengths. Their quality factors can be readily tailored from plasmonic-like (∼10) to dielectric-like (∼103), with wide control over the individual resonant coupling to photon, plasmon, and dissipative channels. Compared with conventional plasmonic nanostructures, such resonances show robustness against detrimental nonlocal effects and provide higher field enhancement at extreme nanoscopic sizes and spacings. These hybrid resonances equip plasmonics with high efficiency, which has been the predominant goal since the field’s inception.
Cervical cancer is a high‐risk disease that threatens women's health globally. In this study, we developed the multi‐modal static cytometry that adopted different features to classify the typical ...human cervical epithelial cells (H8) and cervical cancer cells (HeLa). With the light‐sheet static cytometry, we obtain brightfield (BF) images, fluorescence (FL) images and two‐dimensional (2D) light scattering (LS) patterns of single cervical cells. Three feature extraction methods are used to extract multi‐modal features based on different data characteristics. Analysis and classification of morphological and textural features demonstrate the potential of intracellular mitochondria in cervical cancer cell classification. The deep learning method is used to automatically extract deep features of label‐free LS patterns, and an accuracy of 76.16% for the classification of the above two kinds of cervical cells is obtained, which is higher than the other two single modes (BF and FL). Our multi‐modal static cytometry uses a variety of feature extraction and analysis methods to provide the mitochondria as promising internal biomarkers for cervical cancer diagnosis, and to show the promise of label‐free, automatic classification of early cervical cancer with deep learning‐based 2D light scattering.
Exposure of eukaryotic cells to ionizing radiation or clastogenic chemicals leads to formation of DNA double-strand breaks (DSBs). These lesions are also generated internally by chemicals and ...enzymes, in the absence of exogenous agents, though the sources and consequences of such endogenously generated DSBs remain poorly understood. In the current study, we have investigated the impact of reduced recombinational repair of endogenous DSBs on stress responses, cell morphology and other physical properties of S. cerevisiae (budding yeast) cells. Use of phase contrast and DAPI-based fluorescence microscopy combined with FACS analysis confirmed that recombination-deficient rad52 cell cultures exhibit chronically high levels of G2 phase cells. Cell cycle phase transit times during G1, S and M were similar in WT and rad52 cells, but the length of G2 phase was increased by three-fold in the mutants. rad52 cells were larger than WT in all phases of the cycle and displayed other quantifiable changes in physical characteristics. The high G2 cell phenotype was abolished when DNA damage checkpoint genes, but not spindle assembly checkpoint genes, were co-inactivated with RAD52. Several other RAD52 group mutants (rad51, rad54, rad55, rad57 and rad59) also exhibited the high G2 cell phenotype. The results indicate that recombination deficiency leads to accumulation of unrepaired DSBs during normal mitotic growth that activate a major stress response and produce distinct changes in cellular physiology and morphology.
In order to develop soot models that include effects due to particle aggregation, data must be obtained from flames containing all of the relevant chemical and physical processes that affect the ...evolution of a soot particle. In this study, the effective radius of gyration of aggregated soot is experimentally determined in nitrogen-diluted ethylene coflow diffusion flames using 2-D multi-angle light scattering (2D-MALS). High spatial resolution is achieved by minimizing signal blur that results from imaging light scattering from the probe volume at oblique angles. The results are validated at six locations in the flame through comparison to an effective radius of gyration derived from transmission electron microscope (TEM) analysis of thermophoretically-sampled soot. Simulations are used to model the path taken by a soot particle to reach the TEM grid to ensure the sampling measurements have the spatial resolution necessary to differentiate between aggregate properties at different radial locations in the flame. A radial distance δ is determined from which the front face of the probe is offset from the desired sample location. The ability of the probe to separately capture wing and centerline soot morphology is confirmed by comparison to a previous time-resolved laser-induced incandescence (TiRe-LII) measurement of primary particle diameter. The observed increase in polydispersity and maximum diameter of primary particles along the flame wing compared to the centerline is thought to be a result of surface growth. Excellent agreement is found between the effective radius of gyration derived from 2D-MALS and TEM analysis. The TEM results not only confirm the optical measurement but also elucidate the effective radius of gyration, which depends on aggregate size and polydispersity.
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