High Penetration Depth Research Articles

NIR-I fluorescence imaging tumorous methylglyoxal by an activatable nanoprobe based on peptide nanotubes by FRET process

Methylglyoxal (MGO), a glycolysis metabolite with high reactivity, can nonenzymatically modify proteins, lipids and nucleic acids etc., and it is closely related to the development of tumors. The accurate detection and high-performance optical imaging of MGO from deep tumor issues is of great significance for understanding their roles in tumor initiation and progression. Herein, we have presented a nanoprobe D/I-PNTs with emission in the first near infrared (NIR-I) region by employing a fluorescence resonance energy transfer (FRET) process between a far-red emission MGO probe and IR783 based on peptide nanotubes. The nanoplatform extended the emission range of MGO probe through FRET process and avoided complex molecular design and synthesis. The biocompatible peptide nanotubes improved the water solubility of MGO probe. D/I-PNTs was sensitive to MGO with a detection limit of 272 nM and enabled high-resolution NIR-I fluorescence imaging of MGO induced by glyoxalase I (GLO1) inhibitor in tumor with higher penetration depth (∼4 mm) than that in visible (Vis) region (∼3 mm). Most importantly, the FRET process based on the structure characteristics of peptide nanotubes can be a universal approach to realize the extension of emission wavelength and ratio detection of target analytes, which will be a promising strategy for bioimaging in deep tissue with high contrast.

Self-quenched liposomal probes for tumor imaging based on cellular on/off system

Near-infrared fluorophores have been widely used in tumor imaging due to superior resolution and sensitivity, high penetration depth and low auto-fluorescence. However, the tumor imaging efficacy of fluorophores in vivo is impeded by the background signals and the delivery efficiency of the fluorophores. To realize sensitive tumor imaging, we developed self-quenched liposomal probes DiR-LP-C and DiR-LP-B as tumor-specific imaging probes with cellular on/off system. To prepare DiR-LP-C probes, hydrophobic DiR was solubilized in DMSO and actively loaded into the aqueous interior of liposomes. Based on the structure, DiR-LP-C showed high self-quenching (46-fold at 1.0% loading ratio) that is ‘off’ state with weak fluorescence signal but recovered fluorescence after cellular uptake. DiR-LP-B was prepared where the hydrophobic DiR molecules were dispersed in the hydrophobic lipid bilayer of liposomes and showed weaker self-quenching (5.4-fold at 1.0% loading ratio). Importantly, DiR-LP-C showed brighter cell imaging than DiR-LP-B. For in vivo imaging, both probes showed excellent tumor targeting with signal to background ratio around 5 at 24 h post-injection, with DiR-LP-C had much lower background. These results proved that the tumor-homing cellular ‘on/off’ nanoparticle system of DiR-LP-C has a great potential for tumor imaging and phototherapeutics.

Love Wave Sensor with High Penetration Depth for Potential Application in Cell Monitoring.

Love wave (L-SAW) sensors have been used to probe cell monolayers, but their application to detect changes beyond the focal adhesion points on cell monolayers, as viscosity changes on the cytoskeleton, has not been explored. In this work we present for the first time a Love wave sensor with tuned penetration depth and sensitivity to potentially detect mechanical changes beyond focal adhesion points of cell monolayers. We designed and fabricated a Love wave sensor operating at 30 MHz with sensitivity to detect viscous changes between 0.89 and 3.3 cP. The Love wave sensor was modeled using an acoustic transmission line model, whereas the response of interdigital transducers (IDTs) was modeled with the Campbell’s cross-field circuit model. Our design uses a substrate with a high electromechanical coupling coefficient (LiNbO3 36Y-X), and an 8-µm polymeric guiding layer (SU-8). The design aims to overcome the high insertion losses of viscous liquid environments, and the loss of sensitivity due to the low frequency. The fabricated sensor was tested in a fluidic chamber glued directly to the SU-8 guiding layer. Our experiments with liquids of viscosity similar to those expected in cell monolayers showed a measurable sensor response. In addition, experimentation with SaOs-2 cells within a culture medium showed measurable responses. These results can be of interest for the development of novel cell-based biosensors, and novel characterization tools for cell monolayers.

Enhancing Penetration Ability of Semiconducting Polymer Nanoparticles for Sonodynamic Therapy of Large Solid Tumor.

Sonodynamic therapy (SDT) holds growing promise in deep‐seated or large solid tumor treatment owing to its high tissue penetration depth ability; however, its therapeutic efficacy is often compromised due to the hypopermeable and hypoxic characteristics in the tumor milieu. Herein, a semiconducting polymer nanoparticle (SPNC) that synergistically enhances tumor penetration and alleviates tumor hypoxia is reported for sonodynamic therapy of large solid tumors. SPNC comprises a semiconducting polymer nanoparticle core as a sonodynamic converter coated with a poly (ethylene glycol) corona. An oxygen‐modulating enzyme, catalase, is efficiently conjugated to the surface of nanoparticles via the coupling reaction. Superior to its counterpart SPNCs (SPNC2 (84 nm) and SPNC3 (134 nm)), SPNC with the smallest size (SPNC1 (35 nm)) can efficiently penetrate throughout the tumor interstitium to alleviate whole tumor hypoxia in a large solid tumor model. Upon ultrasound (US) irradiation, SPNC1 can remotely generate sufficient singlet oxygen to eradicate tumor cells at a deep‐tissue depth. Such a single treatment of SPNC1‐medicated sonodynamic therapy effectively inhibits tumor growth in a large solid tumor mouse model. Therefore, this study provides a generalized strategy to synergistically overcome both poor penetration and hypoxia of large tumors for enhanced cancer treatment.

Value addition property of a cationic surfactant on endodontic irrigant: A confocal laser scanning microscope study.

Introduction:Chlorhexidine (CHX) is a commonly used root canal irrigant with high surface tension which prevents its penetration into the isthmus and fins of the root canal. Surfactants have known to reduce the surface tension of the liquid. Cetylpyridinium chloride (CPC) is a cationic surfactant. The aim of this study is to assess the contact angle formed and depth of penetration of the endodontic irrigant with and without the addition of surfactant.Methods:Contact angle analysis – Ninety-nine freshly extracted and cleaned single-rooted mandibular premolars were obtained. Thirty-three teeth were sectioned longitudinally and then transversely. The sections were mounted on an acrylic block, polished to obtain a flat dentin surface. Five microliter of Group 1: 2% CHX as control, Group 2: 2% CHX + 0.1% CPC, and Group 3: 2% CHX + 0.2% CPC were placed on the dentin surface and subjected to contact angle analysis. Depth of penetration – Access cavity was prepared in sixty-six teeth and instrumented to working length till Protaper Gold F2. The samples were assigned to Groups 1, 2, and 3 and irrigated accordingly, and subjected to a confocal laser scanning Microscopy. Data were analyzed using one-way ANOVA and Tukey multiple comparison test. Karl Pearson's correlation test was performed to analyze the correlation between the two.Results:Group 3 had the lowest contact angle (12.82°) and the highest depth of penetration (222.74 μm) when compared to Group 1 and Group 2. Karl Pearson's correlation showed no correlation between the contact angle and the depth of penetration.Conclusion:Higher the concentration of CPC, lower is the contact angle formed with the dentin and higher is the depth of penetration into the dentinal tubule.

Response characteristics of impinging shock wave/turbulent boundary layer interaction disturbed by arc plasma energy deposition

Experiments and numerical simulations of shock wave/turbulent boundary layer interaction (STBLI) disturbed by arc plasma energy deposition (APED) were carried out in this paper. The experiments were conducted in a M = 2.497 wind tunnel. Both the flow structures and the evolution process of impinging STBLI disturbed by APED were captured by time-resolved schlieren imaging. The disturbance effects of APED on supersonic flow without STBLI were studied with different capacitor stored energies. Furthermore, under the same capacitor stored energy, the impinging STBLI control with APED were explored in different flow deflection angles. The experimental results indicated that thermal bubbles induced by APED had a high penetration depth and impacted the STBLI seriously. Compared to the incident shock wave, the separation shock wave was more sensitive to the influence of APED and showed significant instability. With equivalent energy deposited into the flow, the ability of APED to disturb the impinging STBLI was decreased as the flow deflection angle increased, and the separation shock wave had a smaller position change and shorter recovery time. The direct numerical simulation results showed that the APED added in a flow field can hinder the velocity development of the turbulent boundary layer. The unsteadiness of separation shock waves was induced by both thermal bubbles and blast waves, and the thermal bubbles' effects were dominant. They would modify the compressibility of the boundary layer and enlarge the separation zone, which contributed to the separation shock wave's dispersion and movement.

Back-projection method with fast time-delay correction for photoacoustic tomography reconstruction based on a focused sound field model

Photoacoustic tomography is a rapidly developing imaging technology, which can provide structural and functional information of biological tissues. It can integrate the advantage of high optical contrast from optical imaging with those from high penetration depth from ultrasound imaging. However, the existing back-projection algorithm in photoacoustic tomography equates the ultrasonic transducer scanning around the target to a point detector, which leads to a notable tangential blur in the eccentric imaging regions, and thus seriously degrading the image quality. In this paper, we propose a novel photoacoustic tomography reconstruction algorithm, which employs a focused sound field equivalent model to overcome the sound field distortion caused by the transducer’ finite aperture effect and can quickly and effectively restore the elongated tangential resolution in the eccentric imaging regions. Simulation results show that for the target with a diameter of 5 mm and a distance of 6 mm from the rotation center, the tangential resolution is improved by at least twice. Experimental results show that this method can effectively restore the image tangential blur in the off-center regions, where the tiny structures of complex targets can be detected. This new method provides a valuable alternative to the conventional back-projection method and plays an important guiding role in the design of photoacoustic tomography systems based on circle/sphere scanning.

On possible new methods for δ-layer synthesis of the diamond transistor

An upper estimate of the activation barrier Ea, overcome by boron atom during its adsorption on singular face of unalloyed diamond, has been obtained using quantum chemistry methods. This process is connected with the formation of boron-doped δ-layer in the unalloyed diamond, which is an integral part of the diamond transistor. The estimate of Ea was found to be approximately 6–7 eV. It is correspondent by the order of magnitude with floating electrode potential drop relative to stationary low-temperature plasma at electronic temperature above ~ 1 eV. Meanwhile, in the existing high-frequency plasma-enhanced CVD (MWCVD) technology used to create boron-doped δ-layers, the source of the δ-layer growth is high-energy boron ions with energies of hundreds of eV (and even units of keV) which enter the substrate from MW plasma. This energy that the ions acquire at the near-electrode voltage drop is clearly excessive and leads both to excessively high depth of ion penetration into the diamond and to large dispersion of this depth. This reduces the quality of the δ-layer and the transistor efficiency as a whole. At the same time, specificity of high-frequency plasma, created in the MW-resonator for the diamond growth, allows plasma modes and diamond growth both with large (units of keV) and small (units of eV) near-electrode voltage drops. This paper considers the possibility of switching between these two modes. The high-drop mode realizes the rapid growth of unalloyed diamond and the low-drop mode – high quality δ-layer.

Neuronal responses to focused ultrasound are gated by pre-stimulation brain rhythms

BackgroundOwing to its high spatial resolution and penetration depth, transcranial focused ultrasound stimulation (tFUS) is one of the most promising approaches to non-invasive neuromodulation. Identifying the impact of endogenous neural activity on neuromodulation outcome is critical to harnessing the potential of tFUS. ObjectiveHere we sought to identify the relationship between pre-stimulation neural activity and the neuronal response to tFUS. MethodsWe applied 3 min of continuous-wave tFUS to the hippocampal region of the rat while recording local field potentials (LFP) and multi-unit activity (MUA) from the target. We also tested the application of tFUS but with an air gap separating the transducer and the skull, as well as active stimulation of the contralateral olfactory bulb. ResultsWe observed a modest but significant increase in firing rate during hippocampal tFUS, but not during stimulation of the olfactory bulb or when an air gap was present. Importantly, the observed firing rate increase was significantly modulated by the power of baseline oscillations in the LFP, with low levels of delta (1–3 Hz) and high levels of theta (4–10 Hz) and gamma (30–250 Hz) power producing significantly larger firing rate increases. Firing rate increases were also amplified by a factor of 7× when stimulation was applied during periods of frequent sharp-wave ripple (SWR) activity. ConclusionOur findings suggest that baseline brain rhythms may effectively “gate” the response to tFUS.

Ultrasound imaging of liquid fraction in foam

Flotation is an important process in liquid-solid and solid-solid separation, whereby desired solids in suspensions are recovered by their attachment to gas bubbles. Monitoring the process is essential for an increased grade and reduced water consumption. However, in situ measurements of the froth’s phases (liquid, air, particles) and / or volume flow that would be easily integrable in industrial processes are not available. The constant alternation of phases remains challenging for measurement instrumentations. In this paper, we report on pilot tests of novel instrumentation that allows for measurement of low liquid fraction based on electrodes and ultrasound transducers measurements. It offers high milliscale spatial and temporal resolution in the low liquid fraction range of foam (≤ 0.83∙10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ). Improving the accuracy of prospective volume flow estimations, a high penetration depth of 9.2 cm was achieved. The measurement system was calibrated using homogeneous, steady foam and an integral conductivity measurement. A backscatter model was applied to reduce the effect of ultrasound shadowing and enhance quantitative liquid fraction estimates. Additionally, six cases of inhomogeneous and dynamic liquid fraction distributions were investigated qualitatively. The quantitative and qualitative validation was conducted with a reference neutron radiography measurement, showing good correspondence. This investigation distinguished between two of the three froth phases within the analyzed range. Whereby a first step towards in situ monitoring of foam parameters in industrial applications was achieved, which is especially relevant to widely used froth flotation processes.

Supramolecular Polymerization Powered by Escherichia coli : Fabricating a Near-Infrared Photothermal Antibacterial Agent in Situ

Supramolecular Polymerization Powered by <i>Escherichia coli</i> : Fabricating a Near-Infrared Photothermal Antibacterial Agent in Situ

Quantum dots assisted in vivo two-photon microscopy with NIR-II emission

With the advantages of high resolution and deep penetration depth, two-photon excited NIR-II (900–1880 nm) fluorescence (2PF) microscopic bioimaging is promising. However, due to the lack of imaging systems and suitable probes, few such works, to our best knowledge, were demonstrated utilizing NIR-II excitation and NIR-II fluorescence simultaneously. Herein, we used aqueously dispersible PbS/CdS quantum dots with bright NIR-II fluorescence as the contrast agents. Under the excitation of a 1550 nm femtosecond (fs) laser, they emitted bright 2PF in the NIR-II region. Moreover, a 2PF lifetime imaging microscopic (2PFLIM) system was implemented, and in vivo 2PFLIM images of mouse brain blood vessels were obtained for the first time to our best knowledge. To improve imaging speed, an in vivo two-photon fluorescence microscopy (2PFM) system based on an InGaAs camera was implemented, and in vivo 2PFM images of QDs-stained mouse brain blood vessels were obtained.

Au/Si Bilayer Nanodisks with Tunable Localized Surface Plasmon Resonance for Optical Coherence Tomography in the Second Near‐Infrared Window

Bioimaging in the second near‐infrared (NIR‐II) window can help to obtain high‐resolution images and a high penetration depth. This study proposes an Au/Si bilayer plasmonic nanodisk (Au/Si ND) that has a resonance wavelength in the NIR‐II window caused by Si ND stacking on top of the Au ND with a resonance wavelength in the first near‐infrared window; the Si ND has a high refractive index. Au/Si NDs are physically synthesized using nanoimprint lithography and vacuum deposition. Optical coherence tomography (OCT) imaging is performed using synthesized Au/Si NDs as OCT contrast agents in the NIR‐II window. Due to the 2D circular shape and its remarkable response to random incident light, the Au/Si NDs exhibit approximately 250‐fold greater OCT signal intensity than do commercial 1D Au nanorods, as well as fourfold greater penetration depth and improved OCT image contrast.

Enhancing the Upconversion Luminescence and Sensitivity of Nanothermometry through Advanced Design of Dumbbell-Shaped Structured Nanoparticles.

The core-shell engineering of lanthanide-doped nanoparticles has captured considerable attention because it can safeguard the luminescence intensity of the core by reducing surface defects. However, the limited surface area of the traditional spherical core-shell structure hinders the further breakthrough of the brightness. Herein, a unique NaYF4:Yb3+/RE3+@NaYF4:Yb3+/RE3+@NaNdF4:Yb3+ (RE3+ = Ho3+ or Er3+) dumbbell-shaped multilayer nanoparticle featuring a high surface area is reported. Its upconversion luminescence intensity is higher than that of the conventional spherical core-shell structure. A thorough investigation is performed on the luminescence and thermometric mechanisms of Ho3+/Er3+ distributed in the core and the first shell. Remarkably, when Ho3+/Er3+ ions are distributed in the first shell, the relative sensitivity of the biological luminescence nanothermometer composed of downshifting near-infrared emissions is increased to 2.543% K-1 (328 K), which considerably exceeds most reported values. The increased value is attributed to the more thermal-sensitive phonon-assisted energy transfer. For potential biological applications, dumbbell-shaped nanoparticles (DSNPs) with hydrophilic modification show excellent thermometric performance and high tissue penetration depth. Overall, the insights provided by this work will broaden the scope of novel DSNPs in the fields of luminescence and nanothermometry.

Ultrasound-controlled drug release and drug activation for cancer therapy.

Traditional chemotherapy suffers from severe toxicity and side effects that limit its maximum application in cancer therapy. To overcome this challenge, an ideal treatment strategy would be to selectively control the release or regulate the activity of drugs to minimize the undesirable toxicity. Recently, ultrasound (US)-responsive drug delivery systems (DDSs) have attracted significant attention due to the non-invasiveness, high tissue penetration depth, and spatiotemporal controllability of US. Moreover, the US-induced mechanical force has been proven to be a robust method to site-selectively rearrange or cleave bonds in mechanochemistry. This review describes the US-activated DDSs from the fundamental basics and aims to present a comprehensive summary of the current understanding of US-responsive DDSs for controlled drug release and drug activation. First, we summarize the typical mechanisms for US-responsive drug release and drug activation. Second, the main factors affecting the ultrasonic responsiveness of drug carriers are outlined. Furthermore, representative examples of US-controlled drug release and drug activation are discussed, emphasizing their novelty and design principles. Finally, the challenges and an outlook on this promising therapeutic strategy are discussed.

Bottom layer absorption coefficients extraction from two-layer phantoms based on crossover point in diffuse reflectance.

.Significance: Numerous optical imaging and spectroscopy techniques are used to study the tissue-optical properties; the majority of them are limited in information regarding the penetration depth. A simple, safe, easily applicable diagnostic technique is required to get deeper tissue information in a multilayer structure.Aim: A fiber-based diffuse reflectance (DR) technique is used to extract and quantify the bottom layer absorption coefficients in two-layer (2L) tissue-mimicking solid phantoms. We determine the Indian black ink concentrations in a deep-hidden layer that is sandwiched between agar and silicone-based phantom layers.Approach: A fiber-based DR experiment was performed to study the optical properties of the tissue at higher penetration depth, with different fiber core diameters and a constant numerical aperture (0.5 NA). The optimal core diameter of the fiber was chosen by measuring solid phantoms. In 2L phantoms, the thickness of the top layer was kept 5.5 mm with a constant absorption and reduced scattering coefficients ( and ), whereas the absorption coefficients of the bottom layers were varied from 0.014 to keeping the the same as the top layer. A unique crossover point (Cp) was found in the DR intensity profile against distance. We examined the slope before and after the Cp. These two slopes indicate the difference between the optical properties of the top and bottom layers. Our technique got further verification, as we successfully determined the Cp with different Indian black ink concentrations, placed at the junction between the agar and silicone-based phantom layers.Results: The DR measurements were applied to 2L phantoms. Two different slopes were found in 2L phantoms compared to the one-layer (optical properties equal to the top layer of 2L). We extracted the slopes before and after the Cp in the 2L phantoms. The calculated absorption coefficients before the Cp were , , , and , and the absorption coefficients after the Cp were , , , and , respectively. The calculated absorption coefficients before the Cp were in good agreement with the optical properties of the bottom layer. The calculated absorption coefficients after the Cp were not the same as the top layer. Our DR system successfully determines the crossover points and for 70% and 100% ink concentrations placed at the junction of the agar and silicone layers.Conclusions: In a 2L tissue structure, the Cp depends on the absorption coefficients of top and bottom layers and the thickness of the top layer. With the help of the Cp and the absorption coefficients, one can determine the thickness of the top layer or vice versa. The slope value before the Cp in the DR profile allowed us to determine the absorption properties of the bottom layer instead of having the average behavior of the 2L phantom in the far detection range (11.0 to 17.0 mm).

Photosynthetic Oxygenation-Augmented Sonodynamic Nanotherapy of Hypoxic Tumors.

Reactive oxygen species (ROS) has been employed as a powerful therapeutic agent for eradicating tumor via oxidative stress. As an emerging ROS-involving noninvasive anticancer therapeutic modality, sonodynamic therapy (SDT) with high tissue penetration depth and benign remote spatiotemporal selectivity has been progressively utilized as the distinct alternative for ROS-based tumor treatment. However, the hypoxic tumor microenvironment substantially restricts the sonodynamic effect. In this work, an oxygen self-sufficient hybrid sonosensitizer on the basis of photosynthetic microorganisms cyanobacteria (Cyan) integrated with ultrasmall oxygen-deficient bimetallic oxide Mn1.4 WOx nanosonosensitizers, termed as M@C, is designed and engineered to overcome the critical issue of hypoxia-induced tumor resistance and strengthen the SDT effect. The sustained photosynthetic oxygen production by Cyan under light illumination can promote Mn1.4 WOx nanosonosensitizers to produce more ROS against cancer cells both in vitro and in vivo under ultrasound (US) irradiation. Especially, the sustained oxygen evolution for suppressing the gene expression of hypoxia-inducible factor 1alpha (HIF-1α) further boosts and augments the SDT efficiency. Thus, this work provides the paradigm that the rationally engineered biohybrid microorganism-based multifunctional sonosensitizers can serve as an effective bioplatform for augmenting the therapeutic efficiency of SDT, particularly for the treatment of hypoxic tumors.

Indentation Size Effect in CoCrFeMnNi HEA Prepared by Various Techniques.

High entropy alloys (HEAs) are materials of great application potential and which have been extensively studied during the last two decades. As the number of possible element combinations is enormous, model materials representing certain groups of HEAs are used for the description of microstructure, properties, and deformation mechanisms. In this study, the microstructure and mechanical properties of the so-called Cantor alloy composed of Co, Cr, Fe, Mn, and Ni in equiatomic ratios prepared by various techniques (casting, melt-spinning, spark plasma sintering) were examined. The research focused on the indentation measurements, namely, the indentation size effect describing the evolution of the hardness with penetration depth. It was found that the standard Nix–Gao model can be used for this type of alloy at higher penetration depths and its parameters correlate well with microstructural observations. The Nix–Gao model deviates from the measured data at the submicrometer range and the applied modification affords additional information on the deformation mechanism.

Endocavity ultrasound and photoacoustic system for fetal and maternal imaging: design, implementation, and ex-vivo validation.

Purpose: Transvaginal ultrasound (TVUS) is a widely used real-time and non-invasive imaging technique for fetal and maternal care. It can provide structural and functional measurements about the fetal brain, such as blood vessel diameter and blood flow. However, it lacks certain biochemical estimations, such as hemoglobin oxygen saturation ( ), which limits its ability to indicate a fetus at risk of birth asphyxia. Photoacoustic (PA) imaging has been steadily growing in recognition as a complement to ultrasound (US). Studies have shown PA imaging is capable of providing such biochemical estimations as at relatively high penetration depth (up to 30mm). Approach: In this study, we have designed and developed a multi-modal (US, PA, and Doppler) endocavity imaging system (ECUSPA) around a commercialized TVUS probe (Philips ATL C9-5). Results: The integrated system was evaluated through a set of in-vitro, ex-vivo, and in-vivo studies. Imaging of excised sheep brain tissue demonstrated the system's utility and penetration depth in transfontanelle imaging conditions. The accuracy of using the spectroscopic PA imaging (sPA) method to estimate was validated by comparing sPA oximetry results with the gold standard measurements indicated by a blood gas analyzer. The ability of US and Doppler to measure moving blood volume was evaluated in-vivo. Spectral unmixing capabilities were tested using fluorophores within sheep brains. Conclusion: The developed system is a high resolution (about at 30mm depth), real-time (at 30Hz), and quantitative ( estimation error ) imaging tool with a total diameter less than 30mm, making it suitable for intrapartum applications such as fetal and maternal diagnostics.

A near-infrared AIE fluorescent probe for myelin imaging: From sciatic nerve to the optically cleared brain tissue in 3D

Myelin, the structure that surrounds and insulates neuronal axons, is an important component of the central nervous system. The visualization of the myelinated fibers in brain tissues can largely facilitate the diagnosis of myelin-related diseases and understand how the brain functions. However, the most widely used fluorescent probes for myelin visualization, such as Vybrant DiD and FluoroMyelin, have strong background staining, low-staining contrast, and low brightness. These drawbacks may originate from their self-quenching properties and greatly limit their applications in three-dimensional (3D) imaging and myelin tracing. Chemical probes for the fluorescence imaging of myelin in 3D, especially in optically cleared tissue, are highly desirable but rarely reported. We herein developed a near-infrared aggregation-induced emission (AIE)-active probe, PM-ML, for high-performance myelin imaging. PM-ML is plasma membrane targeting with good photostability. It could specifically label myelinated fibers in teased sciatic nerves and mouse brain tissues with a high-signal-to-background ratio. PM-ML could be used for 3D visualization of myelin sheaths, myelinated fibers, and fascicles with high-penetration depth. The staining is compatible with different brain tissue-clearing methods, such as ClearT and ClearT2 The utility of PM-ML staining in demyelinating disease studies was demonstrated using the mouse model of multiple sclerosis. Together, this work provides an important tool for high-quality myelin visualization across scales, which may greatly contribute to the study of myelin-related diseases.