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Nanometer-scale local structural study of the paraelectric cubic phase of KNbO <sub/>3</sub> by convergent-beam electron diffraction
摘要： Nanometer-scale local structures of the paraelectric cubic phase of potassium niobate (KNbO3) are examined by convergent-beam electron diffraction (CBED) using a nanometer-size electron probe. The breaking of the cubic symmetry has been directly observed in the nanometer-scale areas of the cubic phase of KNbO3. This indicates the existence of local polarization clusters in the cubic phase. Symmetry breaking index maps for the fourfold rotation symmetry are given at different temperatures with the combined use of scanning transmission electron microscopy (STEM) and CBED (STEM–CBED). ? 2017 The Japan Society of Applied Physics
关键词： local polarization clusters,CBED,convergent-beam electron diffraction,STEM,KNbO3,symmetry breaking
更新于2025-09-09 09:28:46
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Exploring the Capability of HAADF-STEM Techniques to Characterize Graphene Distribution in Nanocomposites by Simulations
摘要： This paper explores the capability of scanning transmission electron microscopy (STEM) techniques in determining the dispersion degree of graphene layers within the carbon matrix by using simulated high-angle annular dark-field (HAADF) images. Results ensure that unmarked graphene layers are only detectable if their orientation is parallel to the microscope beam. Additionally, gold-marked graphene layers allow evaluating the dispersion degree in structural composites. Moreover, electron tomography has been demonstrated to provide truthfully 3D distribution of the graphene sheets inside the matrix when an appropriate reconstruction algorithm and 2D projections including channelling effect are used.
关键词： HAADF-STEM,electron tomography,nanocomposites,dispersion degree,graphene
更新于2025-09-08 09:54:54
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Intelligent Photosensitive Mesenchymal Stem Cells and Cell-Derived Microvesicles for Photothermal Therapy of Prostate Cancer
摘要： Targeted delivery of nanomedicines into the tumor site and improving the intratumoral distribution remain challenging in cancer treatment. Here, we report an effective transportation system utilizing both of mesenchymal stem cells (MSCs) and their secreted microvesicles containing assembled gold nanostars (GNS) for targeted photothermal therapy of prostate cancer. The stem cells act as a cell carrier to actively load and assemble GNS into the lysosomes. Accumulation of GNS in the lysosomes facilitates the close interaction of nanoparticles, which could result in a 20 nm red-shift of surface plasmon resonance of GNS with a broad absorption in the near infrared region. Moreover, the MSCs can behave like an engineering factory to pack and release the GNS clusters into microvesicles. The secretion of GNS can be stimulated via light irradiation, providing an external trigger-assisted approach to encapsulate nanoparticles into cell derived microvesicles. In vivo studies demonstrate that GNS-loaded MSCs have an extensive intratumoral distribution, as monitored via photoacoustic imaging, and efficient antitumor effect under light exposure in a prostate-cancer subcutaneous model by intratumoral and intravenous injection. Our work presents a light-responsive transportation approach for GNS in combination of MSCs and their extracellular microvesicles and holds the promise as an effective strategy for targeted cancer therapy including prostate cancer.
关键词： mesenchymal stem cells,photothermal therapy,targeted transportation,microvesicles,gold nanostars
更新于2025-09-04 15:30:14
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Improvement in infected wound healing in type 1 diabetic rat by the synergistic effect of photobiomodulation therapy and conditioned medium
摘要： We investigated the effects of photobiomodulation therapy (PBMT) and conditioned medium (CM) of human bone marrow mesenchymal stem cells (hBM‐MSC) individually and/or in combination on the stereological parameters and the expression of basic fibroblast growth factor (bFGF), hypoxia‐inducible factor (HIF‐1α), and stromal cell–derived factor‐1α (SDF‐1α) in a wound model infected with methicillin‐resistant Staphylococcus aureus (MRSA) in diabetic rats. CM was provided by culturing hBM‐MSCs. Type 1 diabetes mellitus (T1DM) was induced in 72 rats, divided into four groups, harboring 18 rats each: group 1 served as a control group, group 2 received PBMT, group 3 received CM, and group 4 received CM + PBMT. On days 4, 7, and 15, six animals from each group were euthanized and the skin samples were separated for stereology examination and gene expression analysis by real‐time polymerase chain reaction. In the CM + PBMT, CM, and PBMT groups, significant decreases were induced in the number of neutrophils (1460 ± 93, 1854 ± 138, 1719 ± 248) and macrophages (539 ± 69, 804 ± 63, 912 ± 41), and significant increases in the number of fibroblasts (1073 ± 116, 836 ± 75, 912 ± 41) and angiogenesis (15 230 ± 516, 13 318 ± 1116, 14 041 ± 867), compared with those of the control group (2690 ± 371, 1139 ± 145, 566 ± 90, 12 585 ± 1219). Interestingly, the findings of the stereological examination in the CM + PBMT group were statistically more significant than those in the other groups. In the PBMT group, in most cases, the expression of bFGF, HIF‐1α, and SDF‐1α, on day 4 (27.7 ± 0.14, 28.8 ± 0.52, 27.5 ± 0.54) and day 7 (26.8 ± 1.4, 29.6 ± 1.4, 28.3 ± 1.2) were more significant than those in the control (day 4, 19.3 ± 0.42, 25.5 ± 0.08, 22.6 ± 0.04; day 7, 22.3 ± 0.22, 28.3 ± 0.59, 24.3 ± 0.19) and other treatment groups. The application of PBMT + CM induced anti-inflammatory and angiogenic activities, and hastened wound healing process in a T1 DM model of MRSA infected wound.
关键词： stereology,diabetes mellitus,diabetic foot ulcer,methicillin‐resistant staphylococcal aureus,low‐level laser therapy,phobiomodulation therapy,human bone marrow mesenchymal stem cell‐conditioned medium,real‐time PCR,rat
更新于2025-09-04 15:30:14
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AIEgen Nanoparticles of Arylamino Fumaronitrile Derivative with High Near-infrared emission for Two-photon Imaging and in vivo Cell Tracking
摘要： Developing of two-photon materials for live-cell imaging and in vivo analysis in-deep have been received great attention, and it is still urgent so that such microscopy technique could be promoted and advanced into new progress using the powerful probs. Herein, a new arylamino fumaronitrile derivative NPAPF was synthesized and transferred as aggregation-induced emission luminogen (AIEgen) fluorescent nanoparticles (AF-NPs) via assembly technique. This AF-NPs exhibited two-photon absorption cross-section at 2.6×106 GM with 19.5% of fluorescence quantum yield. Moreover, utilizing the great potential of AF-NPs, two-photon imaging of live cells with good cytocompatibility is realized upon two-photon microscopy. By in vivo long-term tracing studies of mesenchymal stem cells, we demonstrated the tremendous advantage of AF-NPs tracer in monitoring the stem cells transplant. Therefore, our unique AF-NPs provided an efficient two-photon-absorbing probe for investigating biological mechanism and behavior, and also opened a new avenue for spatiotemporal visualization of transplanted stem cells.
关键词： organic nanoparticles,aggregation-induced emission,two-photon,in vivo imaging,mesenchymal stem cell
更新于2025-09-04 15:30:14
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An X-ray TES Detector Head Assembly for a STEM–EDS System and Its Performance
摘要： A detector head for an energy-dispersive X-ray spectroscopy (EDS) for a scanning transmission electron microscope (STEM) was designed, fabricated, and tested. A 64-pixel TES X-ray microcalorimeter and 64 SQUID array amplifiers (SAAs) are mounted on a detector head which is cooled to about 100 mK. The body of the detector head is a copper rod of about 1 cm2 cross section and 10 cm length with 3 cm cubic structure at the bottom. The TES microcalorimeter is mounted at the top of the rod while the SAAs are mounted on the four side surfaces of the cubic structure. In order to reduce the number of wire bondings, we adopted a flip-chip bonding for the SAAs. In order to reduce the stress imposed on the flip-chip bondings due to the difference in the linear thermal expansion of the SAA chip and the mounting surfaces, we mounted the SAAs and connectors to the room-temperature electronics on sapphire circuit board and mounted the SAAs and connectors using a superconducting flip-chip bonding technology. Then, both the TES and the sapphire circuit board were mounted on the rod and are connected to the print circuit like superconducting wires, which are created on the multiple surfaces of the rod, with Al wire bondings. We reduced the number of wire bondings from 768 to 256. The yield of the flip-chip bonding was not perfect but relatively high. We installed the detector head in the STEM EDS system, confirmed that the energy resolution and counting requirements, (cid:2)E < 10 eV with 5 kcps were fulfilled.
关键词： EDS,TES,Superconducting flip-chip bonding,STEM
更新于2025-09-04 15:30:14
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Characterization of neurite dystrophy after trauma by high speed structured illumination microscopy and lattice light sheet microscopy
摘要： Background: Unbiased screening studies have repeatedly identified actin-related proteins as one of the families of proteins most influenced by neurotrauma. Nevertheless, the status quo model of cytoskeletal reorganization after neurotrauma excludes actin and incorporates only changes in microtubules and intermediate filaments. Actin is excluded in part because it is difficult to image with conventional techniques. However, recent innovations in fluorescent microscopy provide an opportunity to image the actin cytoskeleton at super-resolution resolution in living cells. This study applied these innovations to an in vitro model of neurotrauma. New method: New methods are introduced for traumatizing neurons before imaging them with high speed structured illumination microscopy or lattice light sheet microscopy. Also, methods for analyzing structured illumination microscopy images to quantify post-traumatic neurite dystrophy are presented. Results: Human induced pluripotent stem cell-derived neurons exhibited actin organization typical of immature neurons. Neurite dystrophy increased after trauma but was not influenced by jasplakinolide treatment. The F-actin content of dystrophies varied greatly from one dystrophy to another. Comparison with existing methods: In contrast to fixation dependent methods, these methods capture the evolution of the actin cytoskeleton over time in a living cell. In contrast to prior methods based on counting dystrophies, this quantification scheme parameterizes the severity of a given dystrophy as it evolves from a local swelling to an almost-perfect spheroid that threatens to transect the neurite. Conclusions: These methods can be used to investigate genetic factors and therapeutic interventions that modulate the course of neurite dystrophy after trauma.
关键词： Traumatic brain injury,Dystrophy,Structured illumination microscopy,Human induced pluripotent stem cell derived neurons,Lattice light sheet microscopy
更新于2025-09-04 15:30:14
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<i>In vitro</i> and <i>in vivo</i> Proteomic Comparison of Human Neural Progenitor Cell-Induced Photoreceptor Survival
摘要： Retinal degenerative diseases are some of the leading causes of blindness with few treatments. Various cell-based therapies have aimed to slow the progression of vision loss by preserving light-sensing photoreceptor cells. A subretinal injection of human neural progenitor cells (hNPCs) into the Royal College of Surgeons (RCS) rat model of retinal degeneration has aided in photoreceptor survival, though the mechanisms are mainly unknown. Identifying the retinal proteomic changes that occur following hNPC treatment will lead to better understanding of neuroprotection. To mimic the retinal environment following hNPC injection, a co-culture system of retinas and hNPCs was developed. Less cell death occurred in RCS retinal tissue co-cultured with hNPCs than in retinas cultured alone, suggesting that hNPCs provide retinal protection in vitro. Comparison of ex vivo and in vivo retinas identified NRF2-mediated oxidative response signaling as an hNPC-induced pathway. This is the first study to compare proteomic changes following treatment with hNPCs in both an ex vivo and in vivo environment, further allowing the use of ex vivo modeling for mechanisms of retinal preservation. Elucidation of the protein changes in the retina following hNPC treatment may lead to the discovery of mechanisms of photoreceptor survival and its therapeutic for clinical applications.
关键词： retinal degeneration,stem cells,transplantation,Human neural progenitor cells,neuroprotection
更新于2025-09-04 15:30:14
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Gadolinium Doping Enhances the Photoacoustic Signal of Synthetic Melanin Nanoparticles: A Dual Modality Contrast Agent for Stem Cell Imaging.
摘要： In this paper we show that gadolinium-loaded synthetic melanin nanoparticles (Gd(III)-SMNPs) exhibit up to a 40-fold enhanced photoacoustic signal intensity relative to synthetic melanin alone and higher than other metal-chelated SMNPs. This property makes these materials useful as dual labelling agents because Gd(III)-SMNPs also behave as magnetic resonance imaging (MRI) contrast agents. As a proof-of-concept, we used these nanoparticles to label human mesenchymal stem cells (hMSCs). Cellular uptake was confirmed with bright field optical and transmission electron microscopy. The Gd(III)-SMNP labeled stem cells continued to express the stem cell surface markers CD73, CD90, and CD105 and proliferate. The labeled stem cells were subsequently injected intramyocardially in mice, and the tissue was observed by photoacoustic and MR imaging. We found the photoacoustic signal increased as cell number increased (R2 = 0.96) indicating that such an approach could be employed to discriminate between stem cells populations with a limit of detection of 2.3 x 104 cells in in vitro tests. This multimodal photoacoustic/MRI approach combines the excellent temporal resolution of photoacoustics with the anatomic resolution of MRI.
关键词： Photoacoustic Signal,Stem Cell Imaging,Gadolinium,Dual Modality Contrast Agent,Synthetic Melanin Nanoparticles
更新于2025-09-04 15:30:14
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Transplantation of retinal progenitor cells from optic cup-like structures differentiated from human embryonic stem cells in vitro and in vivo generation of retinal ganglion-like cells
摘要： Human embryonic stem cells (hESCs) have the potential to differentiate along the retinal lineage. We have efficiently differentiated human pluripotent stem cells (hPSCs) into optic cup-like structures by using a novel retinal differentiation medium (RDM).The purpose of this study was to determine whether the retinal progenitor cells (RPCs) derived from hESCs can integrate into the host retina and differentiate into retinal ganglion cells (RGCs) in vivo. In the present study, hESCs (H9-GFP) were induced to differentiate into optic cup-like structures by using our novel differentiation system. The RPCs extracted from the optic cup-like structures were transplanted into the vitreous cavity of N-Methyl-D-aspartic acid (NMDA)-treated mice. Sham-treated eyes received the same amount of retinal differentiation medium (RDM). The host retinas were analyzed by triple immunofluorescence on the 4th and 5th weeks after transplantation. The optic cup-like structures were efficiently differentiated from hESCs by using our novel differentiation system in vitro for 6-8 weeks. The RPCs extracted from the optic cup-like structures migrated and integrated into the GCL of the host retina. Furthermore, the remaining transplanted cells were spread over the GCL and had a complementary distribution with host residual RGCs in the GCL of the mouse retina. Surprisingly, some of the transplanted cells expressed the RGC-specific marker Brn3a. These findings demonstrated that the RPCs derived from hESCs could integrate into the host GCL and differentiate into retinal ganglion-like cells in vivo, suggesting that RPCs can be used as an ideal source in supplying countless RGC and ESC-based replacement therapies may be a promising treatment to restore vision in patients with degenerative retinal diseases.
关键词： retinal ganglion cells,human embryonic stem cells,transplantation,optic cup-like structures,retinal progenitor cells
更新于2025-09-04 15:30:14