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<i>In vivo</i> blood viscosity characterization based on frequency-resolved photoacoustic measurement
摘要： In this letter, we proposed a photoacoustic (PA) method for noninvasively detecting blood viscosity in subcutaneous microvasculature with the frequency-resolved measurement. The influence of viscosity on PA generation was investigated theoretically, and a negative correlation was shown between the viscosity and the full width at half maximum (FWHM) of the PA frequency spectrum, which can be utilized to reflect the viscosity distribution. To test the feasibility and accuracy of this method, water mixed with different concentrations of glycerol was measured. FWHM of the PA frequency spectrum was also obtained in vivo in the mouse ear to characterize the blood viscosity from different vessel bifurcations, and the metabolism-induced viscosity changes were dynamically monitored in the microvasculature. Experimental results demonstrate that this technique has future potential clinical applications for real-time monitoring the viscosity changes in subcutaneous microvasculature.
关键词： in vivo,microvasculature,frequency-resolved measurement,photoacoustic,blood viscosity
更新于2025-09-23 15:21:01
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Probing Cell Mechanics with Bead-Free Optical Tweezers in the <em>Drosophila</em> Embryo
摘要： Morphogenesis requires coordination between genetic patterning and mechanical forces to robustly shape the cells and tissues. Hence, a challenge to understand morphogenetic processes is to directly measure cellular forces and mechanical properties in vivo during embryogenesis. Here, we present a setup of optical tweezers coupled to a light sheet microscope, which allows to directly apply forces on cell-cell contacts of the early Drosophila embryo, while imaging at a speed of several frames per second. This technique has the advantage that it does not require the injection of beads into the embryo, usually used as intermediate probes on which optical forces are exerted. We detail step by step the implementation of the setup, and propose tools to extract mechanical information from the experiments. By monitoring the displacements of cell-cell contacts in real time, one can perform tension measurements and investigate cell contacts' rheology.
关键词： Drosophila embryo,Developmental Biology,in vivo imaging,optical tweezers,Light sheet microscopy,force measurements,Issue 141,cell mechanics
更新于2025-09-23 15:21:01
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Unraveling the Safety Profile of Nanoscale Particles and Materials - From Biomedical to Environmental Applications || Applications of Fluorescent Quantum Dots for Reproductive Medicine and Disease Detection
摘要： Understanding the mechanisms associated with fertility and disease management in animals remains challenging. Continuing advances in nanotechnology provide new tools and alternative approaches for the investigation of these mechanisms. Fluorescent quantum dot nanoparticles, for example, have unique physicochemical properties, which allow for in vivo and in vitro imaging in various areas of life sciences. Traditional quantum dots contain heavy metal semiconductor cores, which have raised concern over their potential for toxicity. The majority of available quantum dots today prevent heavy metal release with additional chemical and polymer layers for safe water solubility. In this chapter, the most widely used quantum dots made of cadmium selenide, which possess great potential for real-time imaging in disease detection and reproductive medicine, are discussed.
关键词： real-time imaging,spermatozoa,quantum dots,in vivo imaging,fertility,luminescence
更新于2025-09-23 15:21:01
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High dynamic range fluorescence imaging
摘要： Fluorescence acquisition and image display over a high dynamic range is highly desirable. However, the limited dynamic range of current photodetectors and imaging CCDs impose a limit on the fluorescence intensities that can be simultaneously captured during a single image acquisition. This is particularly troublesome when imaging biological samples, where protein expression fluctuates considerably. As a result, biological images will often contain regions with signal that is either saturated or hidden within background noise, causing information loss. In this manuscript we summarize recent work from our group and others, to extended conventional to high dynamic range fluorescence imaging. These strategies have many biological applications, such as mapping of neural connections, vascular imaging, bio-distribution studies or pharmacologic imaging at the single cell and organ level.
关键词： optical imaging,Intravital microscopy,drug imaging,in vivo imaging,high dynamic range
更新于2025-09-23 15:21:01
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<em>In Vivo</em> Two-photon Imaging of Cortical Neurons in Neonatal Mice
摘要： Two-photon imaging is a powerful tool for the in vivo analysis of neuronal circuits in the mammalian brain. However, a limited number of in vivo imaging methods exist for examining the brain tissue of live newborn mammals. Herein we summarize a protocol for imaging individual cortical neurons in living neonatal mice. This protocol includes the following two methodologies: (1) the Supernova system for sparse and bright labeling of cortical neurons in the developing brain, and (2) a surgical procedure for the fragile neonatal skull. This protocol allows the observation of temporal changes of individual cortical neurites during neonatal stages with a high signal-to-noise ratio. Labeled cell-specific gene silencing and knockout can also be achieved by combining the Supernova with RNA interference and CRISPR/Cas9 gene editing systems. This protocol can, thus, be used for analyzing the developmental dynamics of cortical neurons, molecular mechanisms that control the neuronal dynamics, and changes in neuronal dynamics in disease models.
关键词： Neuroscience,in vivo imaging,single-cell labeling,mouse,cerebral cortex,Newborn,two-photon
更新于2025-09-23 15:21:01
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Ultrahigh Resolution Mouse Optical Coherence Tomography to Aid Intraocular Injection in Retinal Gene Therapy Research
摘要： HR-SD-OCT is utilized to monitor the progression of photoreceptor degeneration in live mouse models, assess the delivery of therapeutic agents into the subretinal space, and to evaluate toxicity and efficacy in vivo. HR-SD-OCT uses near infrared light (800-880 nm) and has optics specifically designed for the unique optics of the mouse eye with sub-2-micron axial resolution. Transgenic mouse models of outer retinal (photoreceptor) degeneration and controls were imaged to assess the disease progression. Pulled glass microneedles were used to deliver sub retinal injections of adeno-associated virus (AAV) or nanoparticles (NP) via a trans-scleral and trans-choroidal approach. Careful positioning of the needle into the subretinal space was required prior to a calibrated pressure injection, which delivers fluid into the sub retinal space. Real time subretinal surgery was conducted on our retinal imaging system (RIS). HR-SD-OCT demonstrated progressive uniform retinal degeneration due to expression of a toxic mutant human mutant rhodopsin (P347S) (RHOP347S) transgene in mice. HR-SD-OCT allows rigorous quantification of all the retinal layers. Outer nuclear layer (ONL) thickness and photoreceptor outer segment length (OSL) measurements correlate with photoreceptor vitality, degeneration, or rescue. The RIS delivery system allows real-time visualization of subretinal injections in neonatal (~P10-14) or adult mice, and HR-SD-OCT immediately determines success of delivery and maps areal extent. HR-SD-OCT is a powerful tool that can evaluate the success of subretinal surgery in mice, in addition to measuring vitality of photoreceptors in vivo. HR-SD-OCT can also be used to identify uniform animal cohorts to evaluate the extent of retinal degeneration, toxicity, and therapeutic rescue in preclinical gene therapy research studies.
关键词： Optical Coherence Tomography,Retinal Degeneration,Imaging,Real-time,Retina,Microscope,Intraocular Injection,Preclinical,In Vivo,Photoreceptors,Greenough Stereo Microscopy,Sub-retinal
更新于2025-09-23 15:21:01
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Influence of Axial Length on Thickness Measurements Using Spectral-Domain Optical Coherence Tomography
摘要： The purpose of this study was to assess the in?uence of axial length on spectral-domain optical coherence tomography (SD-OCT) thickness measurements in patients with subretinal visual implants. Data from eight emmetropic pseudophakic eyes of eight patients with subretinal visual implants were analyzed retrospectively. These patients participated in the monocentric part of a multicenter trial. The axial length was measured in three short (<22.5 mm), three medium (22.51–25.50 mm), and two long (>25.52 mm) eyes. Using Heidelberg Spectralis, the known thickness of a subretinal implant microchip (70 lm) was measured on 15 images per eye with SD-OCT, using the software calipers. The mean axial length was 20.8 6 0.8 mm in short eyes, 23.3 6 0.4 mm in medium eyes, and 26.3 6 0.5 mm in long eyes. We found in short eyes, in medium eyes, and in long eyes a mean value of microchip thickness measurements from SD-OCT of 82.9 6 1.4 lm, 70.5 6 1.3 lm, and 64.2 6 1.3 lm, respectively. The thickness measurements decreased in SD-OCT measurements with longer axial lengths signi?cantly (P < 0.0001). Axial length in?uences SD-OCT thickness measurements. Our ?ndings demonstrate accuracy of the scaling in SD-OCT thickness measurements in emmetropic medium eyes. Caution is recommended when comparing the measured values of short and long eyes with the normative database of the instrument. There is a need for larger sample-size studies to con?rm our results.
关键词： subretinal visual implant,spectral-domain optical coherence tomography (SD-OCT),axial length,Heidelberg Spectralis,in vivo measurement
更新于2025-09-23 15:21:01
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A minimally invasive technique for serial intraosseous perfusion measurements in the murine tibia using laser Doppler flowmetry
摘要： In biomedical and preclinical research, the current standard method for measuring blood perfusion inside murine bone, radiolabeled microspheres, is a terminal procedure that cannot be used to monitor longitudinal perfusion changes. Laser Doppler ?owmetry (LDF) can assess perfusion within the proximal tibial metaphysis of mice in vivo but requires a surgical procedure to place the measurement probe directly onto the bone surface. Sustained in?ammation for over a month following this technique was previously reported, and previous studies have used LDF as an endpoint-only procedure. We developed a modi?ed, minimally invasive LDF procedure to measure intraosseous perfusion in the murine tibia without stimulating local or systemic in?ammation or inducing gait abnormalities. This modi?ed technique can be used to measure perfusion weekly for up to at least a month in the murine tibia.
关键词： Vascular supply,In vivo,Bone blood ?ow
更新于2025-09-23 15:19:57
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Facile Synthesis of Noncytotoxic PEGylated Dendrimer Encapsulated Silver Sulfide Quantum Dots for NIR-II Biological Imaging
摘要： Near-Infrared-II (NIR-II, 1000-1700 nm) bioimaging features high penetration depth and high spatio-temporal resolution compared to traditional fluorescence imaging, but the key is to develop stable and biocompatible NIR-II fluorophores suitable for in vivo applications. Silver sulfide quantum dots (Ag2S QDs) have been demonstrated excellent for in vivo NIR-II imaging with unique optical properties and decent biocompatibility, but they often require complex post modifications for in vivo applications. Herein we demonstrate a facile one-pot strategy to synthesize the PEGylated dendrimer-encapsulated Ag2S QDs useful for in vivo NIR-II imaging. Silver ions were first loaded into the core of acylthiourea-functionalized dendrimer (PEG-PATU) through the coordination between silver ions and acylthiourea groups, followed by the addition of sodium sulfide to form Ag2S QDs in situ. The resulting PEG-PATU Ag2S QDs hold excellent NIR-II fluorescence signal, and thus could be executed for high efficiency labelling and tracking of A549 cancer cells mobility in vivo and real time visualization of vast circulatory network of a mouse.
关键词： in vivo imaging,PEGylated dendrimer,one-pot synthesis,Ag2S QDs,NIR-II bioimaging
更新于2025-09-23 15:19:57
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ZF-AutoML: An Easy Machine-Learning-Based Method to Detect Anomalies in Fluorescent-Labelled Zebrafish
摘要： Background: Zebra?sh are e?cient animal models for conducting whole organism drug testing and toxicological evaluation of chemicals. They are frequently used for high-throughput screening owing to their high fecundity. Peripheral experimental equipment and analytical software are required for zebra?sh screening, which need to be further developed. Machine learning has emerged as a powerful tool for large-scale image analysis and has been applied in zebra?sh research as well. However, its use by individual researchers is restricted due to the cost and the procedure of machine learning for speci?c research purposes. Methods: We developed a simple and easy method for zebra?sh image analysis, particularly ?uorescent labelled ones, using the free machine learning program Google AutoML. We performed machine learning using vascular- and macrophage-Enhanced Green Fluorescent Protein (EGFP) ?shes under normal and abnormal conditions (treated with anti-angiogenesis drugs or by wounding the caudal ?n). Then, we tested the system using a new set of zebra?sh images. Results: While machine learning can detect abnormalities in the ?sh in both strains with more than 95% accuracy, the learning procedure needs image pre-processing for the images of the macrophage-EGFP ?shes. In addition, we developed a batch uploading software, ZF-ImageR, for Windows (.exe) and MacOS (.app) to enable high-throughput analysis using AutoML. Conclusions: We established a protocol to utilize conventional machine learning platforms for analyzing zebra?sh phenotypes, which enables ?uorescence-based, phenotype-driven zebra?sh screening.
关键词： ?uorophores,in vivo screening,arti?cial intelligence
更新于2025-09-23 15:19:57