- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Electron microscopic observation of photoreceptor cells in directly inserted anesthetized <i>Drosophila</i> into a high-pressure freezing unit
摘要： The high-pressure freezing (HPF) technique is known to cryofix water-containing materials with little ice-crystal formation in deep depths compared with other freezing techniques. In this study, HPF for anesthetized living Drosophila was performed by placing them directly on the carrier of the HPF unit and exposing them to light. Frozen Drosophila were freeze substituted, and their compound eyes were examined by transmission electron microscopy. The ultrastructures of ommatidia composed of photoreceptor cells were well preserved. The location of the cytoplasmic organelles inside the photoreceptor cells was observed. In some photoreceptor cells in ommatidia of the light-exposed Drosphila, the cytoplasmic small granules were localized nearer the base of rhabdomeres, compared with those of the nonlight-exposed Drosophila. Thus, HPF with the direct insertion of living Drosophila under light exposure into the HPF machine enabled us to examine changes to functional structures of photoreceptor cells that occur within seconds.
关键词： photoreceptor cell,high-pressure freezing,Drosophila
更新于2025-09-23 15:23:52
-
Freezing Induced Turn-on Modality for Real-time Imaging in Cryosurgery
摘要： Cryosurgery has attracted great attention for the treatment of tumors due to its obvious advantages. However, it still remains a challenge to determine the volume of frozen tissues in real-time, which greatly lowers the therapeutic efficacy of cryosurgery and hinders its broad application for the treatment of cancers. Herein, we report a freezing induced turn-on strategy for selective real-time imaging of frozen cancer cells. As a type of aggregation induced emission (AIE) fluorogen, TABD-Py molecules interact specifically with ice crystals and form aggregates at the ice/water interface. Consequently, bright fluorescent emission appears upon freezing. Note that TABD-Py molecules are enriched only in the cancer cells and exhibit high biocompatibility as well as low cytotoxicity, therefore a freezing induced turn-on imaging modality for cryosurgery is developed, which will certainly maximize therapeutic efficacy of cryosurgery in treating tumors.
关键词： aggregation induced emission,cancer cells,real-time imaging,freezing,cryosurgery
更新于2025-09-23 15:23:52
-
[IEEE 2018 International Conference on Intelligent Informatics and Biomedical Sciences (ICIIBMS) - Bangkok (2018.10.21-2018.10.24)] 2018 International Conference on Intelligent Informatics and Biomedical Sciences (ICIIBMS) - Computational Study of Frozen Tissue Melanoma Imagining at Terahertz Frequencies
摘要： Terahertz radiation is highly absorbed by liquid water, with less than 0.0001% of the signal surviving to a depth of 1.0 millimeter at 0.45 terahertz, limiting the potential for imaging of human tissues. On the other hand, 90% of the terahertz signal survives in ice in the 0.1 to 1.0 terahertz band, opening the possibility of in-vivo imaging of skin lesions, particularly melanomas, to a depth of 5.0 millimeters by first freezing the skin in situ. Computational modelling of THz-frozen skin imaging indicates that contrast exists to differentiate melanomas from normal frozen skin on the basis of water content alone. If the melanin content of melanomas is a significant absorber of terahertz radiation, then melanin becomes the main contrast element. The modelling results justify the further exploration of the imaging technique with the study of ex-vivo frozen melanoma samples before progressing to in-vivo clinical trials.
关键词： terahertz,melanoma,skin,freezing,imaging
更新于2025-09-23 15:22:29
-
[Methods in Molecular Biology] Autophagy Volume 1880 (Methods and Protocols) || Correlative Light and Electron Microscopy to Analyze LC3 Proteins in Caenorhabditis elegans Embryo
摘要： In this chapter, we present a protocol to perform correlative light and electron microscopy (CLEM) on Caenorhabditis elegans embryos. We use a specific fixation method which preserves both the GFP fluorescence and the structural integrity of the samples. Thin sections are first analyzed by light microscopy to detect GFP-tagged proteins, then by transmission electron microscopy (TEM) to characterize the ultrastructural anatomy of cells. The superimposition of light and electron images allows to determine the subcellular localization of the fluorescent protein. We have used this method to characterize the roles of autophagy in the phagocytosis of apoptotic cells in C. elegans embryos. We analyzed in apoptotic cell and phagocytic cell the localization of the two homologs of LC3/GABARAP proteins, namely, LGG-1 and LGG-2.
关键词： LC3-associated phagocytosis,High-pressure freezing,Freeze substitution,LGG-2,Green fluorescent protein,GMA resin,LGG-1
更新于2025-09-23 15:22:29
-
Fabrication and photoluminescent properties of Tb3+ doped carbon nanodots
摘要： Carbon nanodots (CNDs) doped with Tb ions were synthesized using different synthetic routes: hydrothermal treatment of a solution containing carbon source (sodium dextran sulfate) and TbCl3; mixing of CNDs and TbCl3 solutions; freezing-induced loading of Tb and carbon-containing source into pores of CaCO3 microparticles followed by hydrothermal treatment. Binding of Tb ions to CNDs (Tb-CND coupling) was confirmed using size-exclusion chromatography and manifested itself through a decrease of the Tb photoluminescence lifetime signal. The shortest Tb photoluminescence lifetime was observed for samples obtained by hydrothermal synthesis of CaCO3 microparticles where Tb and carbon source were loaded into pores via the freezing-induced process. The same system displays an increase of Tb photoluminescence via energy transfer with excitation at 320–340 nm. Based on the obtained results, freezing-induced loading of cations into CNDs using porous CaCO3 microparticles as reactors is proposed to be a versatile route for the introduction of active components into CNDs. The obtained CNDs with long-lived emission may be used for time-resolved imaging and visualization in living biological samples where time-resolved and long-lived luminescence microscopy is required.
关键词： freezing-induced loading,Tb3+ doping,photoluminescence,hydrothermal treatment,Carbon nanodots,CaCO3 microparticles
更新于2025-09-23 15:21:01
-
Metallopolymer Organohydrogels with Photoa??Controlled Coordination Crosslinks Work Properly Below 0 ?°C
摘要： Controlling the structures and functions of gels is important for both fundamental research and technological applications. Introducing photoresponsive units into gels enables remote control of their properties with light. However, existing gels show photoresponsiveness only at room temperature or elevated temperatures. The development of photoresponsive gels that work below 0 °C can expand their usage in cold environments. Here, photoresponsive metallopolymer organohydrogels that function even at ?20 °C are reported. The organohydrogels are prepared using photoresponsive Ru–thioether coordination bonds as reversible crosslinks to form polymer networks. A water/glycerol mixture is used as an anti-freezing solvent. At ?20 °C, the Ru–thioether coordination bonds are dissociated under light irradiation and reformed reversibly in the dark, which result in alternating crosslinking densities in the polymer networks. This process enables inducing reversible gel-to-sol transitions, healing damaged gels, controlling the mechanical properties and volumes of the gels, and rewriting microstructures on the gels below 0 °C.
关键词： photoresponsive materials,gels,crosslinks,anti-freezing,metallopolymers
更新于2025-09-23 15:19:57
-
Computational phantom study of frozen melanoma imaging at 0.45 terahertz
摘要： Terahertz radiation (THz) is highly absorbed by liquid water. This creates the possibility of medical imaging on the basis of the water content difference between normal and diseased tissue. The effective penetration of THz is limited, however, to a tissue depth of 0.2–0.3 mm at body temperature. A unique feature of the 0.1–2.0 THz frequency is that there is a high disparity between liquid water absorption and ice absorption, with ice being 100 times more permeable to the radiation than liquid water. This results in 90% of the radiation surviving to 1.0 mm in ice, permitting the imaging of frozen tissues to a depth of 5.0 mm. This method is practical as an in vivo procedure before or during surgical excision. Finite difference time domain (FDTD) computational modeling of frozen normal skin and frozen melanoma was undertaken using tissue phantoms. The study suggests that sufficient contrast exists to differentiate normal frozen skin and melanoma on the basis of the difference of water content alone. When the melanin pigment in melanomas is modeled as a significant absorber of THz, the contrast changes. Based on the modeling, further exploration of the “THz-skin freeze” imaging technique is justified. In the modeling, the boundary between the frozen tissue and non-frozen tissue is shown to be strongly reflective. If the reflective properties of the boundary are substantiated, the “THz-skin freeze” technique will have applications in other areas of skin diagnostics and therapeutics.
关键词： imaging,freezing,melanoma,skin,terahertz
更新于2025-09-19 17:15:36
-
Effects of freezing on mesenchymal stem cells labeled with gold nanoparticles
摘要： Stem cell therapies are a promising treatment for many patients suffering from diseases with poor prognosis. However, clinical translation is inhibited by a lack of in vivo monitoring techniques to track stem cells throughout the course of treatment. Ultrasound-guided photoacoustic imaging of nanoparticle-labeled stem cells may be a solution. To allow photoacoustic tracking, stem cells must be labeled with an optically absorbing contrast agent. Gold nanoparticles are one option due to their cytocompatibility and strong optical absorption in the near-infrared region. However, stem cell labeling can require up to 24-hour incubation with nanoparticles in culture prior to use. Although stem cell monitoring is critically needed, the additional preparation time may not be feasible – it is cost prohibitive and stem cell treatments should be readily available in emergency situations as well as scheduled procedures. To remedy this, stem cells can be labeled prior to freezing and long-term storage. While it is well known that stem cells retain their cellular function after freezing, storage, and thawing, the impact of gold nanoparticles on this process has yet to be investigated. Therefore, we assessed the viability, multipotency, and photoacoustic activity of gold nanosphere-labeled mesenchymal stem cells after freezing, storage, and thawing for one week, one month, or two months and compared to unlabeled, na?ve mesenchymal stem cells which were frozen, stored, and thawed at the same time points. Results indicated no substantial change in viability as assessed by the MTT assay. Differentiation, observed through adipogenesis and osteogenesis, was also comparable to controls. Lastly, strong photoacoustic signals and similar photoacoustic spectral signatures remained. Further studies involving more diverse stem cell types and nanoparticles are required, but our data suggests that function and imaging properties of nanoparticle-labeled stem cells are maintained after freezing and storage, which improves translation of stem cell monitoring techniques by simplifying integration with clinical protocols.
关键词： photoacoustic imaging,cell tracking,freezing,Gold nanospheres,ultrasound,stem cells
更新于2025-09-16 10:30:52
-
Protocol for Producing Three-Dimensional Infrared Video of Freezing in Plants
摘要： Freezing in plants can be monitored using infrared (IR) thermography, because when water freezes, it gives off heat. However, problems with color contrast make 2-dimensions (2D) infrared images somewhat difficult to interpret. Viewing an IR image or the video of plants freezing in 3 dimensions (3D) would allow a more accurate identification of sites for ice nucleation as well as the progression of freezing. In this paper, we demonstrate a relatively simple means to produce a 3D infrared video of a strawberry plant freezing. Strawberry is an economically important crop that is subjected to unexpected spring freeze events in many areas of the world. An accurate understanding of the freezing in strawberry will provide both breeders and growers with more economical ways to prevent any damage to plants during freezing conditions. The technique involves a positioning of two IR cameras at slightly different angles to film the strawberry freezing. The two video streams will be precisely synchronized using a screen capture software that records both cameras simultaneously. The recordings will then be imported into the imaging software and processed using an anaglyph technique. Using red-blue glasses, the 3D video will make it easier to determine the precise site of ice nucleation on leaf surfaces.
关键词： Infrared thermography,plant freezing,anaglyph,3-dimensional video,convergence,strawberry
更新于2025-09-10 09:29:36
-
THERMOLUMINESCENCE OF NEWLY DEVELOPED HIGHLY SENSITIVE α-Al2O3:C BY THE VERTICAL GRADIENT FREEZING METHOD
摘要： A highly sensitive α-Al2O3:C crystal was directly grown by the vertical gradient freezing (VGF) method using Al2O3 and graphite powder as the raw materials. The main thermoluminescence (TL) characteristics of α-Al2O3:C detectors grown by the VGF method and TLD-500K detectors were compared. The α-Al2O3:C grown by the VGF method shows good dosimetric properties, such as high TL sensitivity (152 times higher than that of the TLD-100 at heating rate of 1°C/s), an extremely low residual signal of 0.03%, a minimum measurable dose of 0.12 μGy and an excellent linear response within the dose range studied from 1 μGy to 10 Gy. The α-Al2O3:C detectors grown by the VGF method have a higher sensitivity and a better linear response compared to the TLD-500K detectors. Both kinds of α-Al2O3:C can be used in an unannealed form and to measure the very low dose in environmental monitoring and personnel dosimetry.
关键词： α-Al2O3:C,personnel dosimetry,dosimetric properties,vertical gradient freezing method,thermoluminescence,environmental monitoring
更新于2025-09-09 09:28:46