Search Results (871)

Transmission electron microscopy (TEM) is an essential technique for characterizing nanomaterials. However, specimen preparation, which is a critical factor affecting image quality, remains a practical challenge. Focusing on nanopowders used in materials and chemical science, this article employs case studies to analyze the key steps in TEM specimen preparation. Carbon support films (CSFs) are essential tools for specimen preparation, and this study introduces several commonly used, cost-effective options, including conventional CSFs, conventional holey CSFs, ultrathin holey CSFs, and double-grid support films. We characterize their structural and morphological characteristics and evaluate their suitability for different types of samples. Several representative case studies of nanopowders, spanning from zero-dimensional (0D) to one-dimensional (1D) and two-dimensional (2D) materials, are used to illustrate tailored specimen preparation approaches, which serve as practical references for researchers conducting TEM characterization. These findings facilitate higher image reliability and experimental efficiency, thereby providing critical support for advancing fundamental exploration and frontier innovation in nanomaterial science. Full article

Background/Objectives: Cisplatin is a potent chemotherapeutic agent whose clinical utility is limited by severe side effects, including neurotoxicity affecting the ocular system. The pathophysiology involves oxidative stress and mitochondrial dysfunction, to which the retina is particularly vulnerable. Selenium (Se), an essential trace element and component of antioxidant enzymes, has shown potential in mitigating cisplatin toxicity, although its efficacy with respect to retinal structure and the influence of administration routes remain underexplored. This study aimed to evaluate the protective efficacy of selenium against cisplatin-induced retinal toxicity and compare the effects of intraperitoneal and oral selenium administration. Methods: Forty adult male Wistar rats were randomized into four groups (n = 10 each): Group A (Cisplatin Monotherapy, 3.5 mg/kg IP for 5 days; cumulative dose 17.5 mg/kg); Group B (Cisplatin + Intraperitoneal Selenium, 2.73 mg/kg; cumulative dose 60 mg/kg); Group C (Control); and Group D (Cisplatin + Oral Selenium). Selenium prophylaxis, administered as sodium selenite (Na₂SeO₃), began two days prior to cisplatin administration and continued for 15 days post-treatment. Retinal evaluation two weeks after cisplatin cessation included light microscopy, semi-quantitative immunohistochemical (IHC) analysis for inflammatory (IL-6) and fibrotic (TGF-β2) markers, and Transmission Electron Microscopy (TEM) for ultrastructural analysis, which were the primary endpoints. Statistical differences in the IHC scores were analyzed via the Kruskal-Wallis H test with Dunn’s post hoc comparisons. Results: Cisplatin monotherapy (Group A) caused severe disruption of the retinal architecture, including edema, reactive gliosis, and significant upregulation of IL-6 and TGF-β2. Ultrastructural analysis revealed mitochondrial swelling (cristolysis) and photoreceptor disk fragmentation. Intraperitoneal selenium (Group B) was associated with significant structural preservation and intact mitochondria, with TGF-β2 levels comparable to those of the controls, although the IL-6 level remained moderately elevated. Conversely, oral selenium (Group D) suppressed both IL-6 and TGF-β2 expression to near-negative levels but provided less ultrastructural protection, resulting in persistent mitochondrial swelling and focal photoreceptor disruption. Conclusions: Systemic cisplatin induces severe subcellular retinal toxicity characterized by mitochondrial damage and photoreceptor degeneration. Selenium supplementation attenuates these effects; however, outcome patterns differ by administration route. Intraperitoneal selenium was associated with greater morphological and ultrastructural preservation despite persistent IL-6 elevation, whereas oral selenium normalized immunohistochemical marker expression to near-control levels but was associated with more pronounced residual subcellular damage on qualitative TEM assessment. These preliminary morphological and immunohistochemical findings suggest that the route of selenium delivery may influence its neuroprotective profile; however, pharmacokinetic measurements and functional retinal assessments, such as electroretinography, are warranted before its clinical translation. Full article

Small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) are emerging as potent acellular therapeutics; however, their rapid clearance hinders their clinical translation. To address this issue, 3D-bioprinted genipin-crosslinked gelatin (GECL) was engineered for human health. GECL hydrogels were functionalised with human umbilical cord MSC-derived sEVs (hUCMSC-sEVs) to create a bioactive wound-healing platform. These hydrogels demonstrated favourable physicochemical, mechanical, and biodegradable properties while providing an extracellular matrix (ECM)-mimetic environment conducive to tissue regeneration. MSCs were isolated from the umbilical cords, and their small extracellular vesicles (sEVs) were extracted and incorporated into gelatin-based hydrogels via 3D bioprinting. These sEV-loaded scaffolds were embedded in full-thickness wounds in mice, and healing was evaluated through macroscopic observation, histological analysis, collagen deposition, and angiogenesis assessment. Compared with the untreated controls, both the hydrogel-only (B) and sEV-loaded hydrogel (BE) groups significantly accelerated in vivo wound healing. Notably, the BE group achieved complete wound closure within 14 days, restoring the skin architecture, which closely resembled the native tissue with well-organised epidermal and dermal layers, optimal thickness, and skin appendages. Histological and ultrastructural assessments revealed an increased collagen type I deposition, a reduced α-smooth muscle actin (α-SMA) expression, and a robust neovascularisation. The TEM revealed tight junctions and active cellular infiltration, indicating scaffold integration and functional remodelling. Immunohistochemistry further revealed an upregulated CD31 expression with a balanced α-smooth muscle actin (α-SMA) expression, reflecting coordinated angiogenesis and myofibroblast regulation. These results highlight sEV-functionalised GECL hydrogels as robust and clinically translatable acellular therapeutic green products for accelerated wound closure and functional skin regeneration, advancing the fields of regenerative medicine and life expectancy. Full article

This study presents the post-synthetic functionalization of Ni-Co bimetallic nanoparticles (NPs) with a β-cyclodextrin (β-CD) framework using a green synthesis approach with Illicium verum (Star anise) extract. The synthesized nanocomposite was verified using physicochemical characterization techniques such as FTIR, XRD, Zeta potential, DLS, SEM, and TEM. This surface modification successfully yielded a stable core–shell architecture with a reduced crystallite size of 29.5 nm, compared to 41.2 nm for bare Ni-Co NPs. The β-CD coating shifted the Zeta potential from −33.07 mV to −27.65 mV, establishing an electro-steric stabilization mechanism. Sensing performance toward Cd²⁺ ions was evaluated via the QCM-D technique. The Ni-Co/β-CD nanocomposite demonstrated a superior sensitivity of 34.72 Hz/mM and a remarkably low limit of detection (LOD) of 17.3 µM, representing a 27-fold enhancement over the bare Ni-Co NPs (LOD: 472.2 µM). The mechanical signature, characterized by negative dissipation shifts and a high acoustic ratio (ΔD/Δf = 79.410 × 10⁻⁶), confirms an analyte-induced conformational rigidification driven by a host–guest interaction mechanism. These findings establish a robust method of producing bio-based, “smart” nanocomposites for high-precision environmental sensing. Full article

The activation of molecular oxygen driven by solar energy presents a cost-effective and environmentally friendly approach in the area of environmental purification. Carbon quantum dots and semiconductor nanocomposite photocatalysts serve as an effective strategy for enhancing the separation and transport of photogenerated carriers, thereby boosting the activation of molecular oxygen. In this study, we prepared 0D tea biomass quantum dots (T-BCDs) coupled with 2D PbBiO₂Br nanosheets, which demonstrate enhanced molecular oxygen activation under visible light irradiation and were synthesized using a solvothermal method. Transmission electron microscopy (TEM) analysis reveals that T-BCDs, with diameters of approximately 5 nm, are uniformly distributed on the surface of PbBiO₂Br. Notably, experimental results indicate a strong covalent interaction between PbBiO₂Br and T-BCDs, which enhances the absorbance of visible light, facilitates the transfer and separation of interfacial photogenerated carriers, and promotes the conversion of molecular oxygen into superoxide radicals. The degradation rate constant of ciprofloxacin achieved with 5 mL T-BCDs/PbBiO₂Br is 3.3 times greater than that obtained with pure PbBiO₂Br. This research offers a promising strategy for the development of efficient 0D/2D photocatalysts aimed at sustainable environmental remediation. Full article

Exosomes, a major subpopulation of small extracellular vesicles (sEV), are conserved mediators of intercellular communication, yet the properties of their endosomal precursors, intraluminal vesicles (ILV), have not been systematically quantified across species or imaging modalities. This study systematically evaluates ILV sizes across diverse eukaryotic species and modalities while assessing their relationship to secreted sEV sizes. We carried out two complementary meta-analyses of ILV sizes based on transmission electron microscopy (TEM) and cryogenic electron microscopy (cryo-EM) data across species. This was followed by in situ assessment of sEVs secreted by HEK293T cells with TEM, nanoparticle tracking analysis and super-resolution microscopy characterization. Across species, imaging modalities, and cellular contexts, ILV sizes were under approximately 200 nm, with a mean diameter of 100.5 nm, overlapping with the size range of sEVs. This study addresses an existing knowledge gap by systematically evaluating ILV size across species and revealing an upper size limit of approximately 200 nm. Full article

The rational design of supported ruthenium catalysts for sustainable energy applications requires precise control over metal nanoparticle size, dispersion, and metal–support interactions. This study investigates the influence of mesoporous silica support topology—SBA-15 (2D hexagonal, cylindrical pores), SBA-12 (3D hexagonal structure), and SBA-3 (2D hexagonal)—on the structure and catalytic performance of 1 wt% ruthenium catalysts in CO₂ methanation and gas-phase toluene hydrogenation. Comprehensive characterization by nitrogen physisorption, low- and high-angle X-ray diffraction (XRD), H₂ temperature-programmed reduction (H₂-TPR), CO chemisorption, and transmission electron microscopy (TEM) revealed that support pore architecture dictates ruthenium particle size (1.2 nm for Ru/SBA-15, 2.8 nm for Ru/SBA-3, 4.3 nm for Ru/SBA-12) and dispersion (80%, 35%, 23%, respectively) through geometric confinement effects. Catalytic testing demonstrated contrasting structure–activity relationships: CO₂ methanation exhibited strong structure sensitivity with turnover frequency (TOF) increasing with particle size (Pearson’s r = 0.96), favoring Ru/SBA-3 and Ru/SBA-12 with near-optimal 3–4 nm particles, while toluene hydrogenation showed weaker structure sensitivity, with Ru/SBA-12 achieving the highest TOF owing to its larger particle size and higher crystallinity. These findings underscore the critical importance of tailoring mesoporous support topology to match reaction-specific structure sensitivity, providing fundamental insights for the design of bifunctional catalysts for hydrogenation reactions. Full article

The development of biomimetic scaffolds requires balancing structural integrity with biological signaling. This study evaluates kefiran, a microbial exopolysaccharide, as a bioactive component in establishing printing feasibility of 3D composite constructs. Kefiran from Romanian artisanal cultures was characterized via ¹H-NMR, HPLC, and SEM/TEM, confirming a high-quality hexasaccharide repeating unit. Three composite inks (K100, K70, and K50) were developed by integrating kefiran, chondroitin sulfate, and Si-substituted hydroxyapatite into an alginate matrix and processed using a Bio X 3D-printer. Results showed that higher kefiran concentrations improved printing feasibility, providing enhanced structural fidelity and stability during the layer-by-layer deposition process. All bioprinted scaffolds demonstrated high cytocompatibility with L929 fibroblasts, maintaining viability above 70%. Notably, kefiran exhibited dual-functional therapeutic potential: concentrations above 500 mg/L showed a concentration-dependent antiproliferative effect against HT-29 cells at 72 h while remaining safe for normal cells. These findings establish kefiran-based biomaterial inks as robust, bioactive platforms for regenerative medicine. By enhancing both the mechanical printability of alginate composites and the biological response of cultured cells, kefiran proves to be a versatile component for advanced tissue engineering and potential biological activity applications. Full article

Hafnium carbide (HfC) ceramics are of growing interest due to their exceptional mechanical properties and ultra-high melting points, making them ideal for extreme environmental applications. In this study, we present a synthesis route for HfC nanoparticles via carbothermal reduction of an organic–inorganic hybrid precursor derived from hafnium tetrachloride (HfCl₄) and pectin, followed by thermal treatment at 1500 °C for 1.5 h under an argon atmosphere. According to TGA/DSC analysis of the hybrid precursor, hafnia phases initially formed during pyrolysis and were subsequently converted into HfC at 1500 °C, with the endothermic carbothermal reduction reaction initiating near 1200 °C. Comprehensive characterization using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), X-ray diffraction (XRD) with Rietveld refinement, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) confirmed the synthesis of hafnium carbide (HfC) exhibiting predominantly cubic morphology. XRD analysis determined a lattice parameter of a = 4.63 Å and an interplanar spacing of d = 2.68 Å. Rietveld refinement revealed a phase composition of 98.08% HfC and 1.92% monoclinic hafnium dioxide (m-HfO₂). Debye–Scherrer analysis indicated an average crystallite size of 67.6 nm. SEM and TEM images showed uniformly distributed nanoparticles with an average particle size of approximately 65–70 nm. Full article

Spring vegetation phenology is highly sensitive to climate change; however, climate drivers and their threshold responses at the urban scale remain insufficiently and systematically quantified. Focusing on 31 provincial capitals and municipalities in mainland China, this study integrated MODIS MCD12Q2-derived start-of-season (SOS) for spring green-up and TerraClimate climate data (2001–2023) at a 500 m grid resolution. SOS trends were characterized using the Mann–Kendall test and the Theil–Sen slope estimator. Building on these trend metrics, we developed an XGBoost–SHAP framework using the interannual rate of temperature change (tem_slope) and the interannual rate of precipitation change (pre_slope) as input features, to quantify the nonlinear contributions of climate-change rates to SOS trends and to identify key thresholds. Results indicate that the multi-year mean SOS across China’s provincial capitals and municipalities is primarily distributed between approximately DOY 74 and 138, exhibiting a clear spatial pattern of earlier green-up in the south, later green-up in the north, and delayed green-up on plateaus, with pronounced shifts in distribution centers and dispersion among climatic zones and cities. At the city level, the mean SOS trend shows an overall advancing rate of 0.81 d·year⁻¹ (i.e., the average of city-mean Sen slopes across the 31 cities). Pixel-level trend analyses show that advancing and delaying trends commonly coexist within most cities; among pixels with significant or marginally significant SOS trends identified by the Mann–Kendall test (MK p < 0.10) across all cities, advancing and delaying SOS pixels account for 75.02% and 24.98%, respectively. At the city scale, the proportions of advancing versus delaying pixels vary markedly among cities, forming directional structures characterized by advance-dominant, delay-dominant, or bidirectional coexistence patterns. SHAP dependence relationships further reveal that the effects of tem_slope and pre_slope on SOS trends are generally nonlinear and piecewise, with substantial heterogeneity across climate zones and cities. The identified tipping points and associated sensitive ranges collectively delineate spatially differentiated climate-sensitive intervals, which define the nonlinear response boundaries of spring SOS to sustained warming and precipitation changes. This study provides quantitative evidence for regional differences in urban spring phenological responses to climate change across major Chinese cities and offers a methodological reference for identifying actionable climate thresholds in urban greening design and climate-adaptive management. Full article

Collagen is a major extracellular-matrix protein widely used in regenerative medicine, yet conventional terrestrial sources raise biosafety and acceptability concerns, motivating the search for marine alternatives. This study evaluates the jellyfish Rhizostoma pulmo (R. pulmo) from the Azov Sea as a sustainable collagen source and assesses its suitability for biomedical materials. Acid-soluble collagen was extracted using 0.5 M acetic acid and purified by salt precipitation and dialysis, followed by physicochemical/structural characterization (sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), Limulus amebocyte lysate (LAL) endotoxin testing, transmission electron microscopy (TEM), and immunofluorescence with type I collagen antibodies) and biological evaluation in vitro (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity on MRC5 fibroblasts; adhesion and proliferation assays on HeLa cells). The extracted collagen showed a high yield (~26.2%), a type I-like electrophoretic profile with α-, β-, and γ-components, fibrillar ultrastructure by TEM, and positive type I collagen immunoreactivity; endotoxin levels were low (0.461 EU/µL), and no cytotoxicity was detected under the tested conditions. Porous collagen sponges/scaffolds were fabricated by lyophilization, displaying interconnected pores with an average size of ~80 µm and pH-dependent swelling, and they supported 3D cell growth and tumor-cell dissemination in an in vitro breast carcinoma scaffold model. Overall, Azov Sea R. pulmo collagen demonstrates promising structural quality, low endotoxin burden, and cytocompatibility, supporting its potential as a marine biomaterial for sponge/scaffold-based tissue engineering and wound-related applications. Full article

Acidic mine drainage (AMD) poses a severe global environmental threat due to its high acidity and elevated levels of toxic hexavalent chromium (Cr(VI)), for which biogenic iron sulfide (FeS) nanoparticles have emerged as a promising remediation agent; however, their practical application is hindered by aggregation and oxidative deactivation. This research synthesized biogenic FeS nanoparticles via sulfate-reducing bacteria (SRB) and employed humic acid (HA) as a stabilizing agent to enhance Cr(VI) removal performance in simulated AMD conditions. Single-factor experiments combined with response surface methodology identified the optimal biosynthetic conditions for FeS: yeast extract powder dosage of 2.2 g/L, Fe/S molar ratio of 0.8, and NH₄Cl dosage of 3.1 g/L. Under these conditions, the material achieved 84.25% Cr(VI) removal, with the Fe/S molar ratio identified as the most influential parameter governing synthesis and performance. Introducing HA at an optimal dosage of 2 mg/L drove marked improvements in both nanoparticle yield and reactivity: FeS yield increased to 1096.26 mg/L, Cr(VI) removal efficiency reached 99.62%, and residual Cr(VI) dropped from 15.75 mg/L to just 0.38 mg/L. Kinetic and isotherm analyses, paired with SEM/TEM imaging and zeta potential measurements, revealed that HA stabilization improved particle dispersion and reduced lamellar stacking, resulting in a surface-controlled Cr(VI) removal process. FTIR and 2D-COS analyses demonstrated that HA-derived oxygen-containing functional groups, including O–H/N–H, C=O, and C–O moieties, played a central role in interfacial interactions during Cr(VI) sequestration. XRD results confirmed that Cr(VI) was reduced to Cr(III) and primarily immobilized as low-solubility CrOOH and Cr₂S₃, while the formation of Fe–Cr spinel-like phases remains tentative without X-ray Photoelectron Spectroscopy (XPS) validation. Further investigation via surface-sensitive spectroscopy and dynamic leaching tests is needed to fully assess the long-term stability of the reaction products. Full article

Background: Inflammatory bowel disease (IBD) involves chronic intestinal inflammation, epithelial barrier disruption, and dysbiosis, with environmental factors playing a significant role in its pathogenesis. Previous work revealed that cold exposure alleviates colitis in mice; this study extends that finding by demonstrating that cold exposure enhances intestinal regeneration even in healthy mice, upregulating proliferation markers (Mki67, PCNA, Cyclin D1). Methods: Applying this pro-regenerative effect to a colitis model, we investigated the underlying mechanisms through multi-omics analysis, transmission electron microscopy (TEM), immunofluorescence, and pathological staining as well as 16S rRNA sequencing. Results: We found that cold exposure activates intestinal epithelial proliferation pathways. Further analysis indicated that cold exposure induces colonic stem cell regeneration, upregulating stem cell markers Lgr5 and Ascl2. Notably, colonic transcriptomic profiling revealed the emergence of a Paneth-like cell phenotype, characterized by altered expression of specific lineage genes. Furthermore, cold exposure simultaneously promoted the accumulation of secretory granules and upregulated the expression of antimicrobial peptide genes (such as Lysozyme and Defa) in ileal Paneth cells. This enhanced ileal antimicrobial defense effectively reshaped the gut microbiota in inflamed intestines. Conclusions: This research elucidates a mechanism whereby cold adaptation promotes mucosal repair by integrating localized colonic epithelial regeneration with enhanced ileal Paneth cell-mediated antimicrobial defense. This offers compelling new perspectives on how environmental factors, such as cold exposure, could influence the pathophysiology of IBD and contribute to intestinal regeneration, which may provide foundational theoretical support for the future diagnosis and treatment of IBD. Full article

Background: Danhong injection (DHI), a standardized traditional Chinese medicine formulation, has shown clinical benefits in treating cerebrovascular diseases. Blood–brain barrier (BBB) disruption is a key pathological feature of ischemic stroke, but its modulation by DHI under hyperlipidemic conditions remains unclear. This study aimed to investigate the protective effects and mechanisms of DHI in cerebral ischemia/reperfusion injury (CI/RI) under hyperlipidemia, focusing on BBB integrity and the Wnt/β-catenin signaling pathway. Methods: Rats were divided into control, ischemic, hyperlipidemic, and treatment subgroups to evaluate DHI’s dose-dependent effects and pathway specificity using DKK1 inhibition. Assessments included neurological scores, TTC and Nissl staining, TEM, and molecular analyses (qRT-PCR/Western blot/immunofluorescence/immunohistochemistry). Results: DHI significantly improved neurological function, reduced cerebral infarct size, and alleviated cortical damage. DHI treatment upregulated the expression of tight junction proteins (Claudin-5, Occludin, ZO-1) and downregulated MMP-9 expression. Mechanistically, DHI promoted the nuclear translocation of β-catenin and increased the expression of Wnt3α, p-GSK-3β, and Cyclin D1, thereby activating the Wnt/β-catenin pathway. Additionally, DHI treatment increased the count of NeuN-positive neurons, suppressed astrocyte activation, and markedly reduced IgG infiltration in the ischemic cerebral cortex. These effects were reversed by DKK1. Conclusions: The results indicate that DHI protects BBB integrity and alleviates CI/RI in hyperlipidemic rats independently of direct lipid-lowering activity. Specifically, DHI activates the Wnt/β-catenin pathway by enhancing β-catenin nuclear translocation, which in turn mediates the upregulation of tight junction proteins and suppression of MMP-9, ultimately preserving BBB integrity. These findings support its therapeutic potential in ischemic stroke with comorbid hyperlipidemia. Full article

Bovine mastitis threatens the dairy industry with limited effective therapies. The selenoprotein family offers potential anti-inflammatory interventions, yet the role of Selenoprotein F (SELENOF) remains unclear. This study investigated SELENOF in mitochondrial damage and pyroptosis using clinical mammary biopsies and a Staphylococcus aureus-induced Mammary alveolar cell-type T (MAC-T) cell model. Histology, TEM, immunofluorescence, Western blot, qPCR, RNA-seq, and mitochondrial staining (MitoTracker Red and JC-1) were employed. Mastitic mammary tissue exhibited severe architectural disruption, including focal necrosis with coalescing vacuoles of variable size, extensive epithelial denudation, and interstitial thickening with dense inflammatory infiltrates. At the ultrastructural level, mitochondrial swelling, cristae loss, and plasma membrane rupture were evident. Additionally, these tissue specimens exhibited marked upregulation of inflammatory mediator transcripts, notably IL-1β, IL-6, and TNF-α, alongside heightened abundance of pyroptosis-associated proteins including NOD-like receptor family pyrin domain containing 3 (NLRP3), cleaved caspase-1, and GSDMD-N (Gasdermin D N-terminal domain). RNA-seq identified SELENOF as significantly downregulated. The MAC-T model recapitulated the mitochondrial dysfunction, inflammatory response, and pyroptosis observed in mastitic tissue. SELENOF overexpression restored mitochondrial membrane potential, dampened the output of inflammatory signaling molecules, and suppressed NLRP3-mediated pyroptosis via attenuation of caspase-1/GSDMD-N pathway activation. These findings establish SELENOF as a novel target that mitigates bovine mastitis by preserving mitochondrial homeostasis and suppressing NLRP3-mediated pyroptosis. Full article