Visualisation of microalgal lipid bodies through electron microscopy

In this study, transmission electron microscopy (TEM) and cryo-scanning electron microscopy (cryo-SEM) were evaluated for their ability to detect lipid bodies in microalgae. To do so, Phaeodactylum tricornutum and Nannochloropsis oculata cells were harvested in both the mid-exponential and early stationary growth phase. Two different cryo-SEM cutting methods were compared: cryo-planing and freeze-fracturing. The results showed that, despite the longer preparation time, TEM visualisation preceded by cryo-immobilisation allows a clear detection of lipid bodies and is preferable to cryo-SEM. Using freeze-fracturing, lipid bodies were rarely detected. This was only feasible if crystalline layers in the internal structure, most likely related to sterol esters or di-saturated triacylglycerols, were revealed. Furthermore, lipid bodies could not be detected using cryo-planing. Cryo-SEM is also not the preferred technique to recognise other organelles besides lipid bodies, yet it did reveal chloroplasts in both species and filament-containing organelles in cryo-planed Nannochloropsis oculata samples.

Flower shaped Bi2O2.33/Bi2WO6 composite: An efficient photocatalyst for degradation of methylene blue from aqueous solution in direct solar light

Herein, we synthesized a Bi2O2.33/Bi2WO6 heterostructure as a platform for the degradation of methylene blue (MB) dye in an aqueous phase. The heterostructure was synthesized by facile ultrasonicated assisted solvothermal method. Various structural, morphological and other techniques such as XRD, FTIR, PL, EIS, UV-DRS, FESEM, HRTEM, XPS, EPR, TGA, BET surface area were used to analyze the characteristics of as-synthesized Bi2O2.33/Bi2WO6. The morphological studies revealed the deposition of Bi2O2.33 flowers in high density on Bi2WO6. Under solar irradiation, 98.6% degradation of MB was achieved in 190 min at optimal conditions (pH = 5, catalyst dose = 0.35 gL-1 and MB concentration = 10 mgL-1). The improved photocatalytic ability of composite in contrast to Bi2O2.33 and Bi2WO6 could be usually ascribed to the interface created between them, assisting the charge transfer. Based on the findings of radical trapping experiments, the charge transfer process over the photocatalyst was completely studied. Additionally, the present heterostructure demonstrated good recyclability over five runs. In nutshell, this study provided a facile approach for synthesizing solar light driven photocatalyst for degradation of methylene blue in aqueous phase and can further explored to be utilized for varied environmental remediation.

Antivesiculation and Complete Unbinding of Tail-Tethered Lipids

We report the effect of tail-tethering on vesiculation and complete unbinding of bilayered membranes. Amphiphilic molecules of a bolalipid, resembling the tail-tethered molecular structure of archaeal lipids, with two identical zwitterionic phosphatidylcholine headgroups self-assemble into a large flat lamellar membrane, in contrast to the multilamellar vesicles (MLVs) observed in its counterpart, monopolar nontethered zwitterionic lipids. The antivesiculation is confirmed by small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cyro-TEM). With the net charge of zero and higher bending rigidity of the membrane (confirmed by neutron spin echo (NSE) spectroscopy), the current membrane theory would predict that membranes should stack with each other (aka "bind") due to dominant van der Waals attraction, while the outcome of the nonstacking ("unbinding") membrane suggests that the theory needs to include entropic contribution for the nonvesicular structures. This report pioneers an understanding of how the tail-tethering of amphiphiles affects the structure, enabling better control over the final nanoscale morphology.

Immunophenotype profile by flow cytometry reveals different subtypes of extracellular vesicles in porcine seminal plasma

BACKGROUND

Porcine seminal plasma (SP) is endowed with a heterogeneous population of extracellular vesicles (sEVs). This study evaluated the immunophenotypic profile by high-sensitivity flow cytometry of eight sEV subpopulations isolated according to their size (small [S-sEVs] and large [L-sEVs]) from four different SP sources, namely three ejaculate fractions (the first 10 mL of the sperm rich fraction [SRF-P1], the remaining SRF [SRF-P2], and the post-SRF [PSRF]) and entire ejaculate (EE).

METHODS

Seminal EVs were isolated using a size exclusion chromatography-based protocol from six SP pools (five ejaculates/pool) of each SP source and characterized using complementary approaches including total protein (BCA™assay), particle size distribution (dynamic light scattering), morphology (transmission electron microscopy), and purity (albumin by Western blot). Expression of CD9, CD63, CD81, CD44 and HSP90β was analyzed in all sEV subpopulations by high-sensitivity flow cytometry according to MIFlowCyt-EV guidelines, including an accurate calibration, controls, and discrimination by CFSE-labelling.

RESULTS

Each sEV subpopulation exhibited a specific immunophenotypic profile. The percentage of sEVs positive for CD9, CD63, CD81 and HSP90β differed between S- and L-sEVs (P < 0.0001). Specifically, the percentage of sEVs positive for CD9 and CD63 was higher and that for CD81 was lower in S- than L-sEVs in the four SP sources. However, the percentage of HSP90β-positive sEVs was lower in S-sEVs than L-sEVs in the SRF-P1 and EE samples. The percentage of sEVs positive for CD9, CD63, and CD44 also differed among the four SP sources (P < 0.0001), being highest in PSRF samples. Notably, virtually all sEV subpopulations expressed CD44 (range: 88.04-98.50%).

CONCLUSIONS

This study demonstrated the utility of high-sensitivity flow cytometry for sEV immunophenotyping, allowing the identification of distinct sEV subpopulations that may have different cellular origin, cargo, functions, and target cells.

Meteora sporadica, a protist with incredible cell architecture, is related to Hemimastigophora

"Kingdom-level" branches are being added to the tree of eukaryotes at a rate approaching one per year, with no signs of slowing down.1,2,3,4 Some are completely new discoveries, whereas others are morphologically unusual protists that were previously described but lacked molecular data. For example, Hemimastigophora are predatory protists with two rows of flagella that were known since the 19th century but proved to represent a new deep-branching eukaryote lineage when phylogenomic analyses were conducted.2Meteora sporadica5 is a protist with a unique morphology; cells glide over substrates along a long axis of anterior and posterior projections while a pair of lateral "arms" swing back and forth, a motility system without any obvious parallels. Originally, Meteora was described by light microscopy only, from a short-term enrichment of deep-sea sediment. A small subunit ribosomal RNA (SSU rRNA) sequence was reported recently, but the phylogenetic placement of Meteora remained unresolved.6 Here, we investigated two cultivated Meteora sporadica isolates in detail. Transmission electron microscopy showed that both the anterior-posterior projections and the arms are supported by microtubules originating from a cluster of subnuclear microtubule organizing centers (MTOCs). Neither have a flagellar axoneme-like structure. Sequencing the mitochondrial genome showed this to be among the most gene-rich known, outside jakobids. Remarkably, phylogenomic analyses of 254 nuclear protein-coding genes robustly support a close relationship with Hemimastigophora. Our study suggests that Meteora and Hemimastigophora together represent a morphologically diverse "supergroup" and thus are important for resolving the tree of eukaryote life and early eukaryote evolution.

Modified toxic potential of multi-walled carbon nanotubes to zebrafish (Danio rerio) following a two-year incubation in water

Multi-walled carbon nanotubes (MWCNTs), widely used in several industrial fields, are not readily degradable thus, persist in environmental matrices, serving as a source of environmental toxicity to organisms. However, the effects of environmental weathering on nanomaterial toxicity remain unclear. Herein, we prepared aged-MWCNTs (a-CNTs) by incubating commercial pristine-MWCNTs (p-CNTs) for two years and compared their changes in physicochemical properties and toxic effects on zebrafish. The characterization of a-CNTs by transmission electron microscopy, X-ray photoelectron spectra, Raman spectroscopy, and Fourier-transform infrared spectroscopy showed an increased surface area, pore size, structural defects, and surface oxidation than those of p-CNTs. Zebrafish were exposed to 100 mg/L p-CNT and a-CNT for four days. Subsequently, the mRNA expression of antioxidant enzymes, including cat, gst, and sod, in a-CNT group increased by 1.5- to 1.7-fold, consistent with increased expression of genes associated with inflammation (interleukin-8) and apoptosis (p53) compared to control. The higher toxicity of a-CNTs to zebrafish than p-CNT might be due to the increased oxidative potential by altered physicochemical properties. These findings provide new insights into the risk assessment and environmental management of MWCNTs in the aquatic environment. However, further testing at environmentally relevant doses, different exposure durations, and diverse weathering parameters is warranted.

EMDB-the Electron Microscopy Data Bank

The Electron Microscopy Data Bank (EMDB) is the global public archive of three-dimensional electron microscopy (3DEM) maps of biological specimens derived from transmission electron microscopy experiments. As of 2021, EMDB is managed by the Worldwide Protein Data Bank consortium (wwPDB; wwpdb.org) as a wwPDB Core Archive, and the EMDB team is a core member of the consortium. Today, EMDB houses over 30 000 entries with maps containing macromolecules, complexes, viruses, organelles and cells. Herein, we provide an overview of the rapidly growing EMDB archive, including its current holdings, recent updates, and future plans.

Recombinant Full-Length TDP-43 Oligomers Retain Their Ability to Bind RNAs, Are Not Toxic, and Do Not Seed TDP-43 Aggregation in Vitro

TAR DNA-binding protein with 43 kD (TDP-43) is a partially disordered protein that misfolds and accumulates in the brains of patients affected by several neurodegenerative diseases. TDP-43 oligomers have been reported to form due to aberrant misfolding or self-assembly of TDP-43 monomers. However, very little is known about the molecular and structural basis of TDP-43 oligomerization and the toxic properties of TDP-43 oligomers due to several reasons, including the lack of conditions available for isolating native TDP-43 oligomers or producing pure TDP-43 oligomers in sufficient quantities for biophysical, cellular, and in vivo studies. To address these challenges, we developed new protocols to generate different stable forms of unmodified and small-molecule-induced TDP-43 oligomers. Our results showed that co-incubation of TDP-43 with small molecules, such as epigallocatechin gallate (EGCG), dopamine, and 4-hydroxynonenal (4-HNE), increased the production yield of TDP-43 stable oligomers, which could be purified by size-exclusion chromatography. Interestingly, despite significant differences in the morphology and size distribution of the TDP-43 oligomer preparations revealed by transmission electron microscopy (TEM) and dynamic light scattering (DLS), they all retained the ability to bind to nucleotide DNA. Besides, circular dichroism (CD) analysis of these oligomers did not show much difference in the secondary structure composition. Surprisingly, none of these oligomer preparations could seed the aggregation of TDP-43 core peptide 279-360. Finally, we showed that all four types of TDP-43 oligomers exert very mild cytotoxicity to primary neurons. Collectively, our results suggest that functional TDP-43 oligomers can be selectively stabilized by small-molecule compounds. This strategy may offer a new approach to halt TDP-43 aggregation in various proteinopathies.

Myxoinflammatory fibroblastic sarcoma: ultrastructural study of 7 cases

Since first described, several studies about Myxoinflammatory fibroblastic sarcomas (MIFS) have been published stating the clinicopathological, morphological and immunohistochemical features. However, the ultrastructural findings of these MIFS are limited. Thus, the objective of the present paper is to describe the ultrastructural characteristics of these type of tumors by utilizing tissue that was embedded in paraffin and submitted for immunohistochemistry.The tissue of seven different cases was obtained for ultrastructural study with automatized staining devices, that were later observed by using transmission electron microscopy. Histologically all cases displayed conventional structures of Myxoinflammatory fibroblastic sarcoma (Reed-Sternberg like cells, pseudolipoblasts and emperipolesis). Conversely, two of them exhibited high-grade components, one rich in osteoclastic type giant cells and hypercellular areas, and another one rich in inflammation (Hodgkin-like).After immunohistochemistry, all the samples revealed positivity for CD68 with six cases CD163 and five being positive to CD34, Cyclin-D1, and D2-40. Ultrastructural findings indicated rough endoplasmic reticulum with dilatation of the cisterns that indented the nuclei ("soccer ball" cells), abundant lysosomes, phagolysosomes, and intermediate filaments evidencing this entity as a morphologic continuum that exhibited modified fibroblastic phenotype and variable proportion of macrophagic differentiation.

Functional morphology and ultrastructure of the mouth apparatus in the freshwater mite larvae Limnochares aquatica (L., 1758) (Acariformes, Limnocharidae)

The mouth apparatus in larvae of the freshwater mite Limnochares aquatica (L., 1758) (Acariformes, Limnocharidae), belonging to the lower Hydrachnidia, was studied with light microscopy, scanning (SEM) and transmission (TEM) electron microscopy, as well as with confocal laser scanning microscopy (CLSM) to reveal its main morphological and functional characteristics. The gnathosoma, functioning as a mouth organ takes a prognathous position, and inclines to the body axial line at the angle of around 30°. The gnathosoma is composed of segments of the two pairs of anterior appendages and their derivatives - two-segmented chelicerae lying above the infracapitulum - the compound medial portion of the palpal coxae, and five-segmented palps, articulated with the infracapitulum laterally. The palp tibia bears the bifid palpal claw facing downward nearly at right angle. The basal cheliceral segments are free, i.e., are not covered with the integumental fold posteriorly, and do not fuse with each other. Apically, they articulate with the relatively short movable digits composed of the basal portion (lever) and the distal portion (the cheliceral blades) curved upward by their ends. The flexible fixed digits protrude forward from the distal parts of the basal cheliceral segments. The ventral wall of the gnathosoma (mentum) transforms into a very specific papillary area (velum). A papillary area with long slim papillae is formed of a light cuticle and likely acts as a sucker but does not have contractile elements. The hypostome possesses the well developed lateral lips (galea) tightly embracing the distal portions of the chelicerae and hiding the movable digits. The roof of the infracapitulum (the cervix, or epistome) lying beneath the chelicerae, shows a compound structure. Anteriorly it connects with the inner hypostomal walls forming a particular pharyngeal ring framing the narrow mouth opening. We saw no evidence of a labrum. A characteristic valve projects forward from the dorsal surface of the cervix. A crescent-shaped pharynx runs along the bottom of the infracapitulum and is attached but not fused with the cuticle of the papillary area. The dorsal pharyngeal dilators originate on the cervix, sigmoid pieces and the lateral walls of the infracapitulum at their junction with the dorsal walls of the basal cheliceral segments. A pair of sigmoid pieces having small cavities inside serves for termination of the cheliceral elevators originated on the posterior portions of the dorsal walls of the basal cheliceral segments. The organizational pattern of the gnathosoma in larvae of L. aquatica is rather specific and is quite different from those of other aquatic or terrestrial parasitengonin larvae.

Expression dynamics of the aplysia abyssovirus

Two recent studies documented the genome of a novel, extremely large (35.9 kb), nidovirus in RNA sequence databases from the marine neural model Aplysia californica. The goal of the present study was to document the distribution and transcriptional dynamics of this virus, Aplysia abyssovirus 1 (AAbV), in maricultured and wild animals. We confirmed previous findings that AAbV RNA is widespread and reaches extraordinary levels in apparently healthy animals. Transmission electron microscopy identified viral replication factories in ciliated gill epithelial cells but not in neurons where viral RNA is most highly expressed. Viral transcripts do not exhibit evidence of discontinuous RNA synthesis as in coronaviruses but are consistent with production of a single leaderless subgenomic RNA, as in the Gill-associated virus of Penaeus monodon. Splicing patterns in chronically infected adults suggested high levels of defective genomes, possibly explaining the lack of obvious disease signs in high viral load animals.

Characterization of Drug Delivery Systems by Transmission Electron Microscopy

The contribution of electron microscopy, and here, in particular transmission electron microscopy (TEM), to the formulation and understanding of the biological action of drug delivery systems has led to a better insight into the design principles of drug delivery systems. TEM can be applied for particle characterization, for the visualization of the uptake and intracellular pathways of drug vehicles in cells and tissues and more recently can be also applied for the high-resolution investigation of drug-receptor interactions with near-atomic resolution. This chapter introduces basic techniques to optimize imaging quality of soft matter samples, highlights possibilities to study certain aspects of drug delivery applications, and finally provides a short introduction to high-resolution characterization possibilities which recently emerged.

Structural insights and aggregation propensity of a super-stable monellin mutant: A new potential building block for protein-based nanostructured materials

Protein fibrillation is commonly associated with pathologic amyloidosis. However, under appropriate conditions several proteins form fibrillar structures in vitro that can be used for biotechnological applications. MNEI and its variants, firstly designed as single chain derivatives of the sweet protein monellin, are also useful models for protein fibrillary aggregation studies. In this work, we have drawn attention to a protein dubbed Mut9, already characterized as a "super stable" MNEI variant. Comparative analysis of the respective X-ray structures revealed how the substitutions present in Mut9 eliminate several unfavorable interactions and stabilize the global structure. Molecular dynamic predictions confirmed the presence of a hydrogen-bonds network in Mut9 which increases its stability, especially at neutral pH. Thioflavin-T (ThT) binding assays and Fourier transform infrared (FTIR) spectroscopy indicated that the aggregation process occurs both at acidic and neutral pH, with and without addition of NaCl, even if with a different kinetics. Accordingly, Transmission Electron Microscopy (TEM) showed a fibrillar organization of the aggregates in all the tested conditions, albeit with some differences in the quantity and in the morphology of the fibrils. Our data underline the great potential of Mut9, which combines great stability in solution with the versatile conversion into nanostructured biomaterials.

Mass Spectrometry-Based Characterization of Protein Aggregates in Tissues and Biofluids

Protein aggregation is a common mechanism in multiple neurodegenerative and heart diseases and the accumulation of proteins in aggregates is toxic to cells, causing injury and death. The degree of protein aggregation directly correlates with the severity of the disease. Misfolded proteins present thermodynamic barriers that culminate in the loss of structure and function and the exposure of hydrophobic residues. The exposure of hydrophobic residues is the driving force behind protein aggregation, as it reduces surface free energy and increases the propensity for the formation of large insoluble aggregates. Exploring the protein content of aggregates is fundamental to understanding their formation mechanism and pathophysiological effects. We demonstrate here a method for isolating aggregated protein content in human plasma and mouse brain samples. The samples were characterized by mass spectrometry analysis, transmission electron microscopy, and western blotting. We report the identification of proteins associated with neurodegenerative diseases in the isolated pellets. The western blotting analyses of the isolated pellet showed the positivity for CD89 and CD63, consolidated markers of exosomes, confirming the presence of exosomes within the pellet but not in the supernatant in human plasma. Notably, the concomitant isolation of exosomes together with the protein aggregates was feasible starting from 200 μL of human plasma. Moreover, the presented methodology separated albumin from the aggregated pellet, allowing identification of larger diversity of proteins through mass spectrometry analysis.

Synergistic effect in the structural, optical, and electrical properties of harnessing NiFe2O4/CuO nanocomposite for enhanced environmental remediation

This study presents the synthesis and characterization of composite material comprised of NiFe2O4 and CuO. The preparation of this composites involves a facile and cost-effective co-precipitation method, followed by heat treatment. The aim of this study is to explore the potential of this composite material for various catalytic applications. The synthesized NiFe2O4/CuO composites were extensively characterized using various analytical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), impedance analyzer, UV-Visible spectroscopy (UV-Vis.), Brunner-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). These characterizations revealed the successful formation of a nanocomposite material with a well-defined structure and identified the oxygen vacancies/defects in the samples which might result in enhanced photocatalytic efficiency. Photocatalytic activity of 0.5NiFe2O4/0.5CuO composite showed degradation of methylene blue dye by 96.15% in 120 min. This work is not only to understand the photocatalytic mechanism but also to develop effective catalysts for the degradation of harmful organic pollutants.

Observation of Bacteriophage Ultrastructure by Cryo-Electron Microscopy

Transmission electron microscopy (TEM) is an ideal method to observe and determine the structure of bacteriophages. From early studies by negative staining to the present atomic structure models derived from cryo-TEM, bacteriophage detection, classification, and structure determination have been mostly done by electron microscopy. Although embedding in metal salts has been a routine method for virus observation for many years, the preservation of bacteriophages in a thin layer of fast frozen buffer has proven to be the most convenient preparation method for obtaining images using cryo-electron microscopy (cryo-EM). In this technique, frozen samples are observed at liquid nitrogen temperature, and the images are acquired using different recording media. The incorporation of direct electron detectors has been a fundamental step in achieving atomic resolution images of a number of viruses. These projection images can be numerically combined using different approaches to render a three-dimensional model of the virus. For those viral components exhibiting any symmetry, averaging can nowadays achieve atomic structures in most cases. Image processing methods have also evolved to improve the resolution in asymmetric viral components or regions showing different types of symmetries (symmetry mismatch).

Visualization of Engineered M13 Phages Bound to Bacterial Targets by Transmission Electron Microscopy

The filamentous phage M13 is one of the most well-studied and characterized phages, particularly since it was introduced as a scaffold for phage display, a technique to express and evolve fusion proteins on the M13 phage's coat to study protein or peptide binding interactions. Since phages can be engineered or evolved to specifically bind to a variety of targets, engineered M13 phages have been explored for applications such as drug delivery, biosensing, and cancer therapy, among others. Specifically, with the rising challenge of antimicrobial resistance among bacteria, chimeric M13 phages have been explored both as detection and therapeutic agents due to the flexibility in tuning target specificity. Transmission electron microscopy (TEM) is a powerful tool enabling researchers to directly visualize and characterize binding of phages to bacterial surfaces. However, the filamentous phage structure poses a challenge for this technique, as the phages have similar morphology to bacterial structures such as pili. In order to differentiate between bacterial structures and the filamentous phages, here we describe a protocol to prepare TEM samples of engineered M13 phages bound to bacterial cells, in which the phage virions have been specifically labeled by decoration of the major capsid proteins with gold nanoparticles. This protocol enables clear visualization and unambiguous identification of attached filamentous phages within the context of bacterial cells expressing numerous pili.

Unveiling the multifaceted applications of magnetically responsive chitosan capped ZnS QDs for sensing and annihilation of pharmaceutical drugs

The persistence of active pharmaceutical ingredients in water bodies has lead to detrimental impacts on public health as well as deteriorated aquatic resources at breakneck pace. To address this, highly fluorescent chitosan capped ZnS QDs (CZS QDs) were integrated with nickel ferrite nanoparticles (NF NPs) through ultrasonic assisted method to yield a series of magnetically responsive CZS-xNF nanohybrids (x = 5, 10, 15 and 20 wt% of NF). The successful fabrication of nanohybrids were affirmed through various techniques such as Fourier transform infra-red spectroscopy (FT-IR), powder X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS), high resolution transmission electron microscopy (HRTEM), vibrating sample magnetometer (VSM) and diffused reflectance spectroscopy (DRS). The dual applicability of CZS-xNF nanohybrid was witnessed for the detection of pharmaceutical waste by fluorescence sensing and their concomitant annihilation via visible light driven photodegradation reactions. The developed nanohybrid showed exceptional selectivity towards tetracycline antibiotics, with ultra-low limit of detection of 0.53 μM for tetracycline (TC) and 0.30 μM for minocycline (MC), respectively. The fluorescent sensor was also analysed for trace level detection of tetracyclines in real water samples that showed satisfactory recoveries of 90-106%, depicting practical applicability of sensor. Additionally, the excellent photocatalytic features of synthesized nanohybrid prompted their use in photodegradation of TC and MC and a superior photocatalytic performance was achieved in comparison to CZS QDs. The enhanced photocatalytic performance of CZS-xNF nanohybrid can be attributed to type-I charge transfer mechanism, which resulted in efficient charge separation and reduced photo-induced recombination rate of charge carriers. The nanohybrids were recyclable up to four cycles after being utilized in sensing and photocatalysis, thus offering a promising strategy for environmental remediation through synchronized sensing and extirpation of pharmaceutical waste.

Combining Step-Growth and Chain-Growth Polymerizations in One Pot: Light-Induced Fabrication of Conductive Nanoporous PEDOT-PCL Scaffold

A novel method based on light-induced fabrication of a poly (3,4-ethylenedioxythiophene)-polycaprolactone (PEDOT-PCL) scaffold using phenacyl bromide (PAB) as a single-component photoinitiator is presented. HBr released from the step-growth polymerization of EDOT is utilized as an in situ catalyst for the chain-growth polymerization of ε-caprolactone. Detailed investigations disclose the formation of a self-assembled nanoporous electroconductive scaffold (1.2 mS cm-1 ). Fluorescence emission spectra of the fabricated scaffold exhibit a mixed solvatochromic behavior, indicating specific interactions between the self-assembled scaffold and solvents with varying polarities, as evidenced by transmission electron microscopy (TEM). Moreover, the same light-induced technique can also be applied for bulk photopolymerization showcasing the versatility and wide-ranging scope of the originated method. In brief, this study introduces a novel approach for light-induced polymerization reactions that is merging step-growth and chain-growth mechanisms. This innovative approach is promising to facilitate in situ polymerization of monomers possessing diverse functionalities.

Rapid Intrafibrillar Mineralization Strategy Enhances Adhesive-Dentin Interface

Biomimetic mineralization of dentin collagen appears to be a promising strategy to optimize dentin bonding durability. However, traditional postbonding mineralization strategies based on Ca/P ion release still have some drawbacks, such as being time-consuming, having a spatiotemporal mismatch, and having limited intrafibrillar minerals. To tackle these problems, a prebonding rapid intrafibrillar mineralization strategy was developed in the present study. Specifically, polyacrylic acid-stabilized amorphous calcium fluoride (PAA-ACF) was found to induce rapid intrafibrillar mineralization of the single-layer collagen model and dentin collagen at just 1 min and 10 min, as identified by transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. This strategy has also been identified to strengthen the mechanical properties of demineralized dentin within a clinically acceptable timeframe. Significantly, the bonding strength of the PAA-ACF-treated groups outperformed the control group irrespective of aging modes. In addition, the endogenous matrix metalloproteinases as well as exogenous bacterial erosion were inhibited, thus reducing the degradation of dentin collagen. High-quality integration of the hybrid layer and the underlying dentin was also demonstrated. On the basis of the present results, the concept of "prebonding rapid intrafibrillar mineralization" was proposed. This user-friendly scheme introduced PAA-ACF-based intrafibrillar mineralization into dentin bonding for the first time. As multifunctional primers, PAA-ACF precursors have the potential to shed new light on prolonging the service life of adhesive restorations, with promising significance.

Preparation and Imaging of Specialized ER Using Super-Resolution and TEM Techniques

The plant endoplasmic reticulum (ER) forms several specialized structures. These include the sieve element reticulum (SER) and the desmotubule formed as the ER passes through plasmodesmata. Imaging both of these structures has been inhibited by the resolution limits of light microscopy and their relatively inaccessible locations, combined with the fragile nature of the ER. Here we describe methods to view desmotubules in live cells under 3D-structured illumination microscopy (3D-SIM) and methods to fix and prepare phloem tissue for both 3D-SIM and transmission electron microscopy (TEM), which preserve the fragile structure and allow the detailed imaging of the SER.

Trichite features contribute to the revision of the genus Strombidium (Alveolata, Ciliophora, Spirotricha)

Strombidium is a species-rich genus of oligotrichid ciliates mainly inhabiting the marine pelagial. In molecular phylogenies, the genus emerged as non-monophyletic, and cladistic analyses suggest that it is largely characterized by plesiomorphies. A reliable split of the genus and the establishment of new genera necessitate, however, support by novel morphological and/or ultrastructural features. In the present study, the arrangement and ultrastructure of trichites are proposed as taxonomically relevant characters. Strombidium biarmatum Agatha et al., 2005 differs in the trichite pattern from the type species Strombidium sulcatum and most congeners. Aside from the trichites inserting anteriorly to the girdle kinety and generating the typical funnel-shaped complex in the posterior cell portion, the species displays additional trichites between the adoral membranelles even visible in live cells. Here, this exceptional trichite arrangement is detailed based on transmission electron microscopic investigations. In molecular phylogenies, S. biarmatum forms a monophylum with two congeners sharing its trichite arrangement. Therefore, the strombidiid genus Heteropilum nov. gen. is established with S. biarmatum as type species to also include H. paracapitatum (Song et al., 2015) nov. comb. and H. basimorphum (Martin & Montagnes, 1993) nov. comb. Further differences discovered in the trichite ultrastructure support the organelles' taxonomic significance.

Formation, structure and functional characteristics of amyloid fibrils formed based on soy protein isolates

Food protein-derived amyloid fibrils possess great untapped potential applications in food and other biomaterials. The objective of this report was to investigate the formation mechanism, structure and functional characterization of soy protein amyloid fibrils (SPF) through hydrolysis and heating (pH 2.0, 85 °C, 0-24 h) of soy protein isolate (SPI). Fibrillation growth analysis indicated polypeptide hydrolysis upon hydrolytic heating, and the amyloid fibrils were basically formed 8 h later. The microstructure of SPF was monitored by transmission electron microscopy and scanning electron microscopy, exhibiting change from an irregular spherical structure to a coiled, intertwined thread-like polymer. The secondary structures of SPI all changed drastically during the fibrillation process was characterized by Fourier transform infrared spectroscopy, which the α-helical and β-turned content decreasing by 12.67 % and 5.07 %, respectively, and the content of ordered β-folded structures increasing with heating time, finally increasing to 53.61 % at 24 h. The fluorescence intensity of the endogenous fluorescence spectra decreased and the maximum emission wavelength was red-shifted, suggesting that the fibrillation unfolded the protein structure, hydrolyzed and self-assembled into amyloid fibrils aggregates obscuring the aromatic amino acid residues. The emulsification activity, emulsion stability and viscosity of SPF improved with the increase in protein fibrillation.

The sperm structure of the Scraptiidae (Coleoptera; Tenebrionoidea)

The sperm ultrastructure of two members of the Scraptiidae Anaspis pulicaria and A. lurida was studied. The results confirm the general organization of the sperm in the superfamily Tenebrionoidea. The sperm bundles at the end of the spermiogenesis show the same peculiar antiparallel distribution at the two opposite poles of the germ cyst, observed in other Tenebrionoidea. The sperm have a bi-layered acrosome, a long cylindrical nucleus with two infoldings at its basal region, two elliptical equal mitochondrial derivatives and two triangular accessory bodies. The flagellar axoneme has the common 9 + 9 + 2 microtubular pattern that at the tail end results disorganized. All these sperm characteristics are quite similar to those found in Pythidae, a closely related family, according to molecular data.

Ice Isn't the Only Crystal in Town: Structure Determination of Ice-Binding Proteins via X-Ray Crystallography

Ice-binding proteins (IBPs) are proteins that have the remarkable ability to bind to ice, and their study has intrigued researchers for decades. This chapter explores the importance of structural biology in understanding IBPs and highlights the significant contributions of IBPs to the field of structural biology. The structures of various IBPs from different organisms have been elucidated, revealing key elements involved in ice binding. Structural biology techniques, including nuclear magnetic resonance (NMR) spectroscopy, transmission electron cryo-microscopy (cryo-EM), and X-ray crystallography, play crucial roles in solving protein structures. This article focuses on X-ray crystallography as a tool for investigating IBP structures, providing insights into its theoretical and practical aspects, experimental workflows, and common pitfalls to avoid.

Sedimentation and Laser Light Scattering Methods for Quantifying Synthetic Tau Aggregation Propensity

Tau aggregation assays detect and quantify the conversion of soluble tau monomers into species having filamentous or oligomeric structure. Assays for filamentous aggregates in cross-β-sheet conformation leverage optical, biochemical, or biophysical methods, each with their own advantages and throughput capacity. Here we provide protocols for two medium-throughput assays based on sedimentation and laser light scattering and compare their performance, their utility for characterizing tau aggregation dynamics, and their limitations relative to other approaches. Additionally, a protocol for transmission electron microscopy analysis is updated so as to be compatible with the truncated tau variants that have emerged as powerful tools for interrogating the structural basis of tau polymorphism. Together these methods contribute to a rich tool kit for interrogating tau aggregation kinetics and propensity over a wide range of experimental conditions.

Both incompatible and compatible rhizobia inhabit the intercellular spaces of leguminous root nodules

In addition to rhizobia, many types of co-existent bacteria are found in leguminous root nodules, but their habitats are unclear. To investigate this phenomenon, we labeled Bradyrhizobium diazoefficiens USDA122 and Bradyrhizobium sp. SSBR45 with Discosoma sp. red fluorescent protein (DsRed) or enhanced green fluorescent protein (eGFP). USDA122 enhances soybean growth by forming effective root nodules, but SSBR45 does not form any nodules. Using low-magnification laser scanning confocal microscopy, we found that infected cells in the central zone of soybean nodules appeared to be occupied by USDA122. Notably, high-magnification microscopy after co-inoculation of non-fluorescent USDA122 and fluorescence-labeled SSBR45 also revealed that SSBR45 inhabits the intercellular spaces of healthy nodules. More unexpectedly, co-inoculation of eGFP-labeled USDA122 and DsRed-labeled SSBR45 (and vice versa) revealed the presence of USDA122 bacteria in both the symbiosomes of infected cells and in the apoplasts of healthy nodules. We then next inspected nodules formed after a mixed inoculation of differently-labeled USDA122, without SSBR45, and confirmed the inhabitation of the both populations of USDA122 in the intercellular spaces. In contrast, infected cells were occupied by single-labeled USDA122. We also observed Mesorhizobium loti in the intercellular spaces of active wild-type nodules of Lotus japonicus using transmission electron microscopy. Compatible intercellular rhizobia have been described during nodule formation of several legume species and in some mutants, but our evidence suggests that this type of colonization may occur much more commonly in leguminous root nodules.

A Fast, Robust Method for Quantitative Assessment of Collagen Fibril Architecture from Transmission Electron Micrographs

Collagen is the most abundant protein in mammals; it exhibits a hierarchical organization and provides structural support to a wide range of soft tissues, including blood vessels. The architecture of collagen fibrils dictates vascular stiffness and strength, and changes therein can contribute to disease progression. While transmission electron microscopy (TEM) is routinely used to examine collagen fibrils under normal and pathological conditions, computational tools that enable fast and minimally subjective quantitative assessment remain lacking. In the present study, we describe a novel semi-automated image processing and statistical modeling pipeline for segmenting individual collagen fibrils from TEM images and quantifying key metrics of interest, including fibril cross-sectional area and aspect ratio. For validation, we show first-of-their-kind illustrative results for adventitial collagen in the thoracic aorta from three different mouse models.

Optimizing Exosome Preparation Based on Size and Morphology: Insights From Electron Microscopy

Extracellular vesicles (EVs), including exosomes, are crucial in intercellular communication, but differentiating between exosomes and microvesicles is challenging due to their similar morphology and size. This study focuses on multivesicular bodies (MVBs), where exosomes mature, and optimizes exosome isolation using transmission electron microscopy (TEM) for size information. Considering that EVs are nanocolloidal particles, a salt-free Bis-Tris buffer is found to maintain EV integrity better than phosphate-buffered saline (PBS). Dynamic light scattering (DLS) and TEM analysis confirm that intact exosome fractions under the salt-free Bis-Tris buffer condition exhibit polydispersity, including a unique population of <50 nm vesicles resembling intraluminal membrane vesicles (ILVs) in MVBs, alongside larger populations. This <50 nm population disappears in PBS or Bis-Tris buffer with 140 mM NaCl, transforming into a monodisperse population >100 nm. Immunoelectron microscopy also validates the presence of CD63, an exosome biomarker, on approximately 50 nm EVs. These findings provide valuable insights into exosome characterization and isolation, essential for future biomedical applications in diagnostics and drug delivery.

Photoinduced force microscopy as a novel method for the study of microbial nanostructures

A detailed comparison of the capabilities of electron microscopy and nano-infrared (IR) microscopy for imaging microbial nanostructures has been carried out for the first time. The surface sensitivity, chemical specificity, and non-destructive nature of spectroscopic mapping is shown to offer significant advantages over transmission electron microscopy (TEM) for the study of biological samples. As well as yielding important topographical information, the distribution of amides, lipids, and carbohydrates across cross-sections of bacterial (Escherichia coli, Staphylococcus aureus) and fungal (Candida albicans) cells was demonstrated using PiFM. The unique information derived from this new mode of spectroscopic mapping of the surface chemistry and biology of microbial cell walls and membranes, may provide new insights into fungal/bacterial cell function as well as having potential use in determining mechanisms of antimicrobial resistance, especially those targeting the cell wall.

Unveiling Cellular Diversity in the Buffalo Corneal Stroma: Insights into Telocytes and Keratocytes Using Light Microscope, Transmission Electron Microscope, and Immunofluorescence Analysis

Telocytes and keratocytes are important cells that maintain the structure and function of the cornea. The buffalo cornea, known for its resilience in harsh conditions, has not been extensively studied regarding the presence and role of telocytes and keratocytes. We used light microscopy, transmission electron microscopy (TEM), and immunofluorescence assays with platelet-derived growth factor receptor alpha (PDGFRα), CD34, and Vimentin markers to investigate their expression and localization in the cornea. TEM analysis confirmed the presence of spindle-shaped keratocytes with intercellular connections, while telocytes exhibited small spindle-shaped bodies with long, thin branches connecting to corneal keratocytes. Immunofluorescence findings showed that CD34 was more abundant near the endothelium, Vimentin was prominently expressed near the epithelium, and PDGFRα was uniformly distributed throughout the corneal stroma. Co-expression of CD34 and Vimentin, PDGFRα and Vimentin, as well as CD34 and PDGFRα, was observed in keratocytes and telocytes within the stroma, indicating the potential presence of mesenchymal cells. These results suggest the involvement of telocytes and keratocytes in corneal wound healing, transparency maintenance, and homeostasis. The co-expression of these markers highlights the critical role of telocytes and keratocytes in regulating corneal physiological functions, further enhancing our understanding of corneal biology in the buffalo model.

Nano-biochar uptake and translocation by plants: Assessing environmental fate and food chain risk

Nano-biochar (N-BC) is an emerging nanomaterial with potential applications in various fields. Understanding its behavior in the environment and its interaction with plants is crucial for assessing its ecological implications and potential risks to the food chain. In this study, we investigated the absorption and transportation of N-BC by wheat and Chinese cabbage plants using microscopy techniques and stable isotope analysis. Our results revealed that N-BC particles were readily absorbed by the plants through their root systems and transported to the aboveground tissues. Scanning electron microscopy and transmission electron microscopy provided visual evidence of N-BC particles inside the plants, predominantly located in the xylem and cell walls of the cortical tissue. Stable isotope analysis confirmed the uptake and transportation of N-BC, with elevated isotopic values observed in the plant tissues exposed to 13C-N-BC. Our results demonstrated that around 50.2 %-52.4 % of the absorbed N-BC by plants was accumulated in the roots of wheat and Chinese cabbage, and the remaining fraction was transferred to the shoots including steam (31.0 %-32.1 %) and leaf (16.5 %-17.6 %). Importantly, we observed significant accumulation of N-BC in the edible parts of Chinese cabbage, raising concerns about its potential entry into the food chain and associated health risks. These findings highlight the need for further research to explore the specific pathways and modes of N-BC uptake and transport in plants. Monitoring the presence of N-BC in the environment and its potential impact on the food chain is crucial for ensuring food security and safeguarding human health.

Cryo-TEM Reveals the Influence of Multivalent Charge and PEGylation on Shape Transitions in Fluid Lipid Assemblies: From Vesicles to Discs, Rods, and Spheres

Lipids, and cationic lipids in particular are of interest as delivery vectors for hydrophobic drugs such as the cancer therapeutic paclitaxel, and the structures of lipid assemblies affect their efficacy. We investigated the effect of incorporating the multivalent cationic lipid MVL5 (+5e) and poly(ethylene glycol)-lipids (PEG-lipids), alone and in combination, on the structure of fluid-phase lipid assemblies of the charge-neutral lipid 1,2-dioleoyl-sn-glycero-phosphocholine (DOPC). This allowed us to elucidate lipid-assembly structure correlations in sonicated formulations with high charge density, which are not accessible with univalent lipids such as the well-studied DOTAP (+1e). Cryogenic transmission electron microscopy (cryo-TEM) allowed us to determine the structure of the lipid assemblies, revealing diverse combinations of vesicles and disc-shaped, worm-like, and spherical micelles. Remarkably, MVL5 forms an essentially pure phase of disc micelles at 50 mol % MVL5. At a higher (75 mol %) content of MVL5, short- and intermediate-length worm-like micellar rods were observed, and in ternary mixtures with PEG-lipid, longer and highly flexible worm-like micelles formed. Independent of their length, the worm-like micelles coexisted with spherical micelles. In stark contrast, DOTAP forms mixtures of vesicles, disc micelles, and spherical micelles at all studied compositions, even when combined with PEG-lipids. The observed similarities and differences in the effects of charge (multivalent versus univalent) and high curvature (multivalent charge versus PEG-lipid) on the assembly structure provide insights into parameters that control the size of fluid lipid nanodiscs, relevant for future applications.

Protocol to visualize glycan-mediated binding between virus and human blood mononuclear cells using thin-section transmission electron microscopy

Glycan-glycan interactions between viral particles and host cells may lengthen the dwell time of the virus on the cell surface to facilitate cellular receptor engagement. Here, we present a protocol for visualizing glycan-mediated binding between virus or virus-like-particles (VLPs) and human peripheral blood mononuclear cells using transmission electron microscopy (TEM). We describe steps for virus and VLP production, isolation of human peripheral blood mononuclear cells, and sample preparation. We then detail procedures for thin-section TEM. For complete details on the use and execution of this protocol, please refer to Spillings et al.1.

CuO nanoparticles mixed with activated BC extracted from algae as promising material for supercapacitor electrodes

The present analysis aims to use existing resources to lower the cost of electrodes and reduce environmental pollution by utilizing waste materials like green algae. In the present research, the hydrothermal carbonization technique was utilized to synthesize a nano sized CuO mixed with activated biochar (CuO@BC) extracted from red sea algae (Chlorophyta). The CuO@BC sample was extensively examined using several advanced physical techniques, such as UV/Visible spectroscopy, FTIR, XED, HRTEM, SEM, EDX, BET, and TGA. The HRTEM indicated that the size of the particles is 32 nm with a larger surface area and without aggregations. The BET analysis of CuO@BC indicates that the material contains pores of a relatively large size and with a pore diameter of about 42.56 A°. The electrochemical analysis of CuO@BC modified glassy carbon electrode CuO@BC/GCE has been investigated using CV, GCD, and EIS techniques. This CuO@BC/GCE shows excellent electrochemical features that are significant for energy storage applications. The CuO@BC/GCE showed a specific capacitance of approximately 353 Fg-1 which is higher compared to individual materials. Overall, the research outcomes suggest that the CuO@BC/GCE shows potential for use in high-performance supercapacitors as energy storage systems that are eco-friendly and sustainable.

Nanodot zirconium trisulfide modified conducting thread: A smart substrate for fabrication of next generation biosensor

In present work, we report an eco-friendly, flexible and highly conducting cotton thread (CT) as a smart substrate for the development of biosensing platform towards ultrasensitive detection of swine flu serum amyloid A (SAA) biomarker. The biosensor was fabricated by optimized coating of CT with poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) conductive ink followed by incorporation of nanodot zirconium trisulfide (nZrS3) which helped in enhancing the electrochemical properties and improving stability of PEDOT:PSS polymeric film. The fabricated nZrS3/PEDOT:PSS/CT electrode was then used for sequential immobilization of monoclonal antibodies of SAA (anti-SAA) and bovine serum albumin (BSA). The synthesized nanomaterials and fabricated electrodes were characterized through X-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy and contact angle analyser techniques. The electrochemical response of the fabricated smart thread based biosensor (BSA/anti-SAA/ZrS3/PEDOT:PSS/CT) was recorded against SAA using chronoamperometry technique which revealed superior sensitivity {30.2 μA [log (μg mL-1)]-1 cm-2}, excellent lower detection limit (0.72 ng mL-1) and prolonged shelf life up to 48 days. The response of the biosensor was also validated by analysing the electrochemical response of SAA spiked serum samples and the obtained results showed good correlation with that of standard samples.

The armoured cuticle of the black soldier fly Hermetia illucens

We characterise in detail the larval and pupal cuticle of the black soldier fly Hermetia illucens L. (Diptera: Stratiomyidae), a key insect species in circular economy. In particular, we focus on ultrastructure using scanning and transmission electron microscopy, material characterization and composition (elements and minerals) with confocal laser scanning microscope, energy dispersive X-ray microanalysis, powder X-ray diffraction and mechanical properties with nanoindentation measurements. Calcium carbonate crystallizes on the epicuticle as blocks of calcite in the pupal cuticle. Calcium carbonate granules are stored in two specialised Malpighian tubules. CaCO3 is already present in the cuticle of young larval instars, but it is mainly in the form of amorphous calcium carbonate while the amount of calcite increases during larval development. The presence of calcite leads to cuticle hardening. Larval and pupal cuticles contain large amounts of resilin which guarantee cuticle flexibility.

Structure and Chemical Composition of Soil C-Rich Al-Si-Fe Coprecipitates at Nanometer Scale

Soil carbon stabilization is mainly driven by organo-mineral interactions. Coprecipitates, of organic matter with short-range order minerals, detected through indirect chemical extraction methods, are increasingly recognized as key carbon sequestration phases. Yet the atomic structure of these coprecipitates is still rather conceptual. We used transmission electron microscopy imaging combined with energy-dispersive X-ray and electron energy loss spectroscopy chemical mappings, which enabled direct nanoscale characterization of coprecipitates from Andosols. A comparison with reference synthetic coprecipitates showed that the natural coprecipitates were structured by an amorphous Al, Si, and Fe inorganic skeleton associated with C and were therefore even less organized than short-range order minerals usually described. These amorphous types of coprecipitates resembled previously conceptualized nanosized coprecipitates of inorganic oligomers with organics (nanoCLICs) with heterogeneous elemental proportions (of C, Al, Si, and Fe) at nanoscale. These results mark a new step in the high-resolution imaging of organo-mineral associations, while shedding further light on the mechanisms that control carbon stabilization in soil and more broadly in aquatic colloid, sediment, and extraterrestrial samples.

Scaling up cryo-EM for biology and chemistry: The journey from niche technology to mainstream method

Cryoelectron microscopy (cryo-EM) methods have made meaningful contributions in a wide variety of scientific research fields. In structural biology, cryo-EM routinely elucidates molecular structure from isolated biological macromolecular complexes or in a cellular context by harnessing the high-resolution power of the electron in order to image samples in a frozen, hydrated environment. For structural chemistry, the cryo-EM method popularly known as microcrystal electron diffraction (MicroED) has facilitated atomic structure generation of peptides and small molecules from their three-dimensional crystal forms. As cryo-EM has grown from an emerging technology, it has undergone modernization to enable multimodal transmission electron microscopy (TEM) techniques becoming more routine, reproducible, and accessible to accelerate research across multiple disciplines. We review recent advances in modern cryo-EM and assess how they are contributing to the future of the field with an eye to the past.

Electron counting with direct electron detectors in MicroED

The combination of high sensitivity and rapid readout makes it possible for electron-counting detectors to record cryogenic electron microscopy data faster and more accurately without increasing the number of electrons used for data collection. This is especially useful for MicroED of macromolecular crystals where the strength of the diffracted signal at high resolution is comparable to the surrounding background. The ability to decrease fluence also alleviates concerns about radiation damage which limits the information that can be recovered from a diffraction measurement. The major concern with electron-counting direct detectors lies at the low end of the resolution spectrum: their limited linear range makes strong low-resolution reflections susceptible to coincidence loss and careful data collection is required to avoid compromising data quality. Nevertheless, these cameras are increasingly deployed in cryo-EM facilities, and several have been successfully used for MicroED. Provided coincidence loss can be minimized, electron-counting detectors bring high potential rewards.

Call to action to properly utilize electron microscopy to measure organelles to monitor disease

This review provides an overview of the current methods for quantifying mitochondrial ultrastructure, including cristae morphology, mitochondrial contact sites, and recycling machinery and a guide to utilizing electron microscopy to effectively measure these organelles. Quantitative analysis of mitochondrial ultrastructure is essential for understanding mitochondrial biology and developing therapeutic strategies for mitochondrial-related diseases. Techniques such as transmission electron microscopy (TEM) and serial block face-scanning electron microscopy, as well as how they can be combined with other techniques including confocal microscopy, super-resolution microscopy, and correlative light and electron microscopy are discussed. Beyond their limitations and challenges, we also offer specific magnifications that may be best suited for TEM analysis of mitochondrial, endoplasmic reticulum, and recycling machinery. Finally, perspectives on future quantification methods are offered.

[Establishment of a method for separating macrophage migrasomes]

Objective To establish an efficient method for isolating migrasomes from RAW264.7 macrophages and identifying these isolated migrasomes. Methods Scanning electron microscopy was used to observe the morphological characteristics of migrasomes produced by RAW264.7 cells. A 0.45 μm filter was employed for reverse filtration and elution to isolate the migrasomes. The morphological characteristics of the migrasomes were then observed using transmission electron microscopy. Western blot analysis was performed to determine the expression of characteristic markers of the migrasomes. The RNA carried by the migrasomes was analysed by using LabChip bioanalyzer. Results Scanning electron microscopy revealed that the migrasomes, with membranous structures, were attached to the tip or bifurcation of the retraction fiber formed in the tail of RAW264.7 cells. Transmission electron microscopy showed that the isolated migrasomes had a typical oval vesicle-like structure with wrinkled membrane surfaces. Western blot analysis confirmed the expression of the characteristic markers phosphatidylinositol glycan anchor biosynthesis class K (PIGK), epidermal growth factor domain-specific O-linked N-acetylglucosamine transferase (EOGT) and tetraspanin 4 (TSPAN4) in the migrasomes, while the EV (extracellular vesicle) markers tumor susceptibility gene 101 (TSG101) and Arabidopsis homolog of apoptosis-linked gene 2-interacting protein X (ALIX) were not detected. Furthermore, the isolated migrasomes were found to be rich in small RNA, which were approximately 25-200 nt in length. Conclusion A method for the extraction of well-structured and high quality migrasomes from macrophages is established.

Enhancement in photocatalytic selectivity of TiO2-based nano-catalyst through molecular imprinting technology

Improvement in the photocatalytic selectivity is imperative for the effective and efficient utilization of catalysts. In this study, a molecularly imprinted polymer-coated iron-doped titanium dioxide (Fe-TiO2@MIP) nanocomposite was successfully synthesized by precipitation polymerization while using RB-19 as a template. The synthesized nanocomposites (Fe-TiO2@MIP and Fe-TiO2@NIP) were characterized by Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) with energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-EMMETT-Teller (BET), and UV-visible spectrophotometry. The optimized binding experiments revealed a high imprinting factor of 5.0 for RB-19. The catalytic degradation efficiency and selectivity of Fe-TiO2@MIP enhanced to almost complete degradation of RB-19 from 70% for the parent Fe-TiO2 and 76% for Fe-TiO2@NIP. An outstanding degradation selectivity of RB-19 was achieved compared to other competitive dyes. Finally, the analysis of the non-degraded and degraded RB-19 by ESI-MS revealed the presence of different intermediates that fits well with the proposed degradation mechanism. The study opens new possibilities of selective photo-degradation of targeted contaminants that may ultimately lead to efficient use of photocatalysts.

A method for extraction of exosomes from breast tumour cells and characterisation by transmission electron microscopy

Exosomes can not only be used as markers of tumour metastasis but also be used for noninvasive diagnosis of clinical diseases, which holds significant medical research value. Observing the morphology and distribution of exosomes using transmission electron microscopy (TEM) is highly significant. In this study, we use breast tumour cell (MDA-MB-231) exosomes as a representative sample and focus on the extraction and purification of exosomes, as well as the investigation of optimal conditions for the observation of exosomes using TEM. Through comparative tests, we obtained the optimal dilution concentration and staining method for TEM of exosomes, the best dilution concentration is 100 times, the best negative staining time is 1.5 min. Western blotting and scanning electron microscopy (SEM) confirmed the presence of exosome. The particle size experiment shows that the size of exosomes is mainly distributed between 60 nm and 150 nm. This method provides a reference for TEM sample preparation of subcellular structures and small molecular biomaterials other than exosomes.

Photocatalytic degradation of chlorpyrifos using Ag nanoparticles-doped g-C3N5 decorated with dendritic CdS

In this work, g-C3N5/CdS dendrite/AgNPs nanocomposite was synthesized using a mixed method consisting of hydrothermal, ultrasonic and chemistry reduction with sodium borohydride. The characterization of the as-prepared nanocomposite was done using infrared spectroscopy, X-ray, scanning electron microscopy, transmission electron microscopy, BET, and DRS methods was performed. The DRS results showed that the g-C3N5/CdS dendrite/AgNPs nanocomposite nanocomposite has a band gap of 1.08 eV. This band gap indicates the good capability of this nanocomposite as a photocatalyst. Accordingly, the photocatalytic degradation of chlorpyrifos (CPS) in was performed in an aqueous solution of the synthesized nanocomposite. The results showed that almost 95.3% of this poison, a concentration of 50 mg L-1 was degraded in the presence of 0.05 g L-1 of nanocomposite at pH = 5 in a 60 min. Hydroxide radicals and holes play a significant role in the photocatalytic process. The reusability of the nanocomposite with excellent performance in the degradation of photocatalytic toxins caused by the reduction in the electron-hole recombination and the high surface area of the nanocomposite are among the unique features of this work.

Isolation and characterization of the morphology, size and particle number of rainbow trout (Oncorhynchus mykiss) and zebrafish (Danio rerio) cell line derived large and small extracellular vesicles

Extracellular vesicles (EVs) are 50-1,000 nm lipid bilayer-bound vesicles, released into the extracellular environment by various cell types for intercellular communication purposes. The quantitative and qualitative characteristics of EVs can be affected by stress and pathological conditions. The majority of extracellular vesicle (EV) studies have been performed on mammalian cell lines or bodily fluids. EVs have been previously described from bodily fluids like plasma, serum or mucus in different fish species, however the available knowledge of fish cell line derived EVs is limited and in the vast majority of studies, the overall focus is on small EVs (< 200 nm). We isolated large and small extracellular vesicles from zebrafish (Danio rerio) liver (ZFL), rainbow trout (Oncorhynchus mykiss) liver (RTL-W1), gill (RTgill-W1) and intestinal epithelial (RTgutGC) cell lines using stepwise centrifugation and characterized the size and morphology of EVs. Here we demonstrated that large and small extracellular vesicles can be successfully isolated using stepwise centrifugation from the serum-free medium of the selected piscine cell lines after a 24-h incubation period. The size distribution of large and small EVs isolated from the piscine cell lines suggest that large and small EV groups show high diversity in size ranges, containing heterogenous subpopulations in sizes, and the results highly depend on the applied method and whether filtration steps were included following the isolation. The spherical morphology of EVs was verified by transmission electron microscopy.

Three-dimensional reconstruction of interstitial extracellular vesicles in human liver as determined by electron tomography

Extracellular vesicles (EVs) are lipid bilayer nanoparticles involved in cell-cell communication that are released into the extracellular space by all cell types. The cargo of EVs includes proteins, lipids, nucleic acids, and metabolites reflecting their cell of origin. EVs have recently been isolated directly from solid tissues, and this may provide insights into how EVs mediate communication between cells in vivo. Even though EVs have been isolated from tissues, their point of origin when they are in the interstitial space has been uncertain. In this study, we performed three-dimensional (3D) reconstruction using transmission electron tomography of metastatic and normal liver tissues with a focus on the presence of EVs in the interstitium. After chemical fixation of the samples and subsequent embedding of tissue pieces in resin, ultrathin slices (300 nm) were cut and imaged on a 120 ekV transmission electron microscopy as a tilt series (a series of subsequent images tilted at different angles). These were then computationally illustrated in a 3D manner to reconstruct the imaged tissue volume. We identified the cells delimiting the interstitial space in both types of tissues, and small distinct spherical structures with a diameter of 30-200 nm were identified between the cells. These round structures appeared to be more abundant in metastatic tissue compared to normal tissue. We suggest that the observed spherical structures in the interstitium of the metastatic and non-metastatic liver represent EVs. This work thus provides the first 3D visualization of EVs in human tissue.

Design and advanced characterization of quercetin-loaded nano-liposomes prepared by high-pressure homogenization

Quercetin-loaded nano-liposomes were prepared by high-pressure homogenization (HPH) at different pressures (up to 150 MPa) and number of passes (up to 3) to define the best processing conditions allowing the lowest particle size and the highest encapsulation efficiency (EE). The process at 150 MPa for 1 pass was the best, producing quercetin-loaded liposomes with the lowest particle size and 42% EE. Advanced techniques (multi-detector asymmetrical-flow field flow fractionation and analytical ultracentrifugation combined with transmission electron microscopy) were further used for the characterization of the liposomes which were oblong in shape (ca. 30 nm). Results highlight the need for several techniques to study nano-sized, polydisperse samples. The potential of quercetin-loaded liposomes against colon cancer cells was demonstrated. Results prove that HPH is an efficient and sustainable method for liposome preparation and highlight the remarkable role of process optimisation as well as the powerfulness of advanced methodologies for the characterisation of nano-structures.

Bi-coloured enhanced luminescence imaging by targeted switch on/off laser MEF coupling for synthetic biosensing of nanostructured human serum albumin

In this communication luminescent bioconjugated human serum albumin nanostructures (HSA NPs) with tiny ultraluminescent gold core-shell silica nanoparticles (Au@SiO2-Fl) were designed with enhanced bi-coloured luminescence properties. The HSA NPs were obtained from Human Serum Albumin free (HSA free) through the desolvation method, and Au@SiO2-Fl, through modified Turkevich and Störber methods. In this manner, porous HSA Nanostructures of 150.0-200 nm and Au@SiO2-Fl 45.0 nm final diameters were obtained. Both methodologies and structures were conjugated to obtain modified Nanocomposites based on tiny gold cores of 15 nm surrounded with well spatial Nanostructured architectures of HSA (d15 Au@SiO2-Fl-HSA) that generated variable nanopatterns depending on the modified methodology of synthesis applied within colloidal dispersions. Therefore, three methodologies of non-covalent conjugation were developed. In optimal conditions, through Transmission Electronic Microscopy (TEM), well resolved multilayered nano-architectures with a size 190.0-200 nm in average with variable contrast depending of the focused nanomaterial within the nanocomposite were shown. Optimized nanoarchitecture was based on a template tiny gold core-shell surrounded by nanostructured HSA NPs (d15 Au@SiO2-Fl-HSA). In this manner, the NanoImaging generated by laser fluorescence microscopy permitted to record improved optical properties and functionalities, such as: (i) enhanced ultraluminescent d15 Au@SiO2-Fl-HSA composites in comparison to individual components based on Metal Enhanced Fluorescence (MEF); (ii) diminished photobleaching; (iii) higher dispersibility; (iv) higher resolution of single bright nano-emitters of 210.0 nm sizes; and (v) enhanced bi-coloured Bio-MEF coupling with potential non-classical light delivery towards other non-optical active biostructures for varied applications. The characterization of these nanocomposites allowed the comparison, evaluation and discussion focused on new properties generated and functionalities based on the incorporation of different types of tuneable materials. In this context, the biocompatibility, Cargo confined spaces, protein-based materials, optical transparent could be highlighted, as well as optical active materials. Thus, the potential applications of nanotechnology to both nanomedicine and nano-pharmaceutics were discussed.

Detection of protamine based on competitive adsorption onto the surface of functionalized multi-walled carbon nanotubes

This study developed an adsorption-based determination system for protamine. A multi-walled carbon nanotube (MWCNT), which is a strong adsorbent, was used. The competitive adsorption process between dyes and protamine formed the basis of the sensor system. The adsorption process was followed over the dyes by UV-Vis. absorption spectroscopy. This sensor system was developed using the thermodynamic parameters. Transmission electron microscopy and Fourier-transform infrared spectroscopy techniques were used for the characterization of the sensor system. It was determined that the sensor system remained stable at physiological temperature and pH range. Limit of detection values of PyB-COO-MWCNT and PyY-COO-MWCNT systems were found to be 1.32 and 1.12 ng mL-1 , respectively. The applicability of the sensor systems was demonstrated using bovine serum solutions.