Chengzhi Shi

Genetically encoded imaging reporters are critical tools for tracking cell fate and function in regenerative medicine. Gas vesicles (GVs), air-filled protein nanostructures derived from bacteria, offer unique advantages for noninvasive imaging due to their acoustic and optical properties. In this study, we engineered human pluripotent stem cells (hPSCs) to express GVs using a doxycycline (Dox)-inducible system. Stable GV expression was achieved by TALEN-mediated knock-in of the GvpNtoV cassette at the GAPDH locus together with PiggyBac GvpA integration driven by transposase, followed by antibiotic selection to isolate correctly modified clones. Upon Dox treatment, GVs formed intracellularly and enabled enhanced contrast in both ultrasound and optical coherence tomography (OCT) imaging. Dynamic ultrasound imaging revealed pressure-dependent GV buckling and harmonic signal generation, while OCT imaging confirmed high sensitivity and depth-resolved detection in both in vitro and ex vivo retinal models. Our work establishes a multimodal GV-based reporter platform compatible with human stem cells and clinically relevant imaging modalities. This approach offers a powerful and versatile tool for noninvasively visualizing and tracking therapeutic cells in real time, advancing the development and monitoring of cell-based therapies.

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Abstract Genetically encoded imaging reporters are critical tools for tracking cell fate and function in regenerative medicine. Gas vesicles (GVs), air-filled protein nanostructures derived from bacteria, offer unique advantages for noninvasive imaging due to their acoustic and optical properties. In this study, we engineered human pluripotent stem cells (hPSCs) to express GVs using a doxycycline (Dox)-inducible system. Stable GV expression was achieved by TALEN-mediated knock-in of the GvpNtoV cassette at the GAPDH locus together with PiggyBac GvpA integration driven by transposase, followed by antibiotic selection to isolate correctly modified clones. Upon Dox treatment, GVs formed intracellularly and enabled enhanced contrast in both ultrasound and optical coherence tomography (OCT) imaging. Dynamic ultrasound imaging revealed pressure-dependent GV buckling and harmonic signal generation, while OCT imaging confirmed high sensitivity and depth-resolved detection in both in vitro and ex vivo retinal models. Our work establishes a multimodal GV-based reporter platform compatible with human stem cells and clinically relevant imaging modalities. This approach offers a powerful and versatile tool for noninvasively visualizing and tracking therapeutic cells in real time, advancing the development and monitoring of cell-based therapies.

Abstract Genetically encoded imaging reporters are critical tools for tracking cell fate and function in regenerative medicine. Gas vesicles (GVs), air-filled protein nanostructures derived from bacteria, offer unique advantages for noninvasive imaging due to their acoustic and optical properties. In this study, we engineered human pluripotent stem cells (hPSCs) to express GVs using a doxycycline (Dox)-inducible system. Stable GV expression was achieved by TALEN-mediated knock-in of the GvpNtoV cassette at the GAPDH locus together with PiggyBac GvpA integration driven by transposase, followed by antibiotic selection to isolate correctly modified clones. Upon Dox treatment, GVs formed intracellularly and enabled enhanced contrast in both ultrasound and optical coherence tomography (OCT) imaging. Dynamic ultrasound imaging revealed pressure-dependent GV buckling and harmonic signal generation, while OCT imaging confirmed high sensitivity and depth-resolved detection in both in vitro and ex vivo retinal models. Our work establishes a multimodal GV-based reporter platform compatible with human stem cells and clinically relevant imaging modalities. This approach offers a powerful and versatile tool for noninvasively visualizing and tracking therapeutic cells in real time, advancing the development and monitoring of cell-based therapies.

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We introduce H-SPLID, a novel algorithm for learning salient feature representations through the explicit decomposition of salient and non-salient features into separate spaces. We show that H-SPLID promotes learning low-dimensional, task-relevant features. We prove that the expected prediction deviation under input perturbations is upper-bounded by the dimension of the salient subspace and the Hilbert-Schmidt Independence Criterion (HSIC) between inputs and representations. This establishes a link between robustness and latent representation compression in terms of the dimensionality and information preserved. Empirical evaluations on image classification tasks show that models trained with H-SPLID primarily rely on salient input components, as indicated by reduced sensitivity to perturbations affecting non-salient features, such as image backgrounds. Our code is available at https://github.com/neu-spiral/H-SPLID.

Miniaturized ultrasound systems are central to emerging biomedical applications such as targeted therapy, drug delivery, and wearable diagnostics. However, intensifying acoustic emission at small scales remains a key challenge, constrained by limits in conventional transducer designs and MEMS technologies. In this work, we demonstrate a novel approach to enhancing ultrasound emission by leveraging the acoustic Purcell effect, enabled by perfluorocarbon nanodroplets (PFCnDs). These nanoscale droplets are engineered to structure the surrounding acoustic environment and modulate the local acoustic density of states, thereby amplifying emission efficiency. We present a theoretical model of nanodroplet-enhanced Purcell emission and validate it through ultrasound measurements in soft-tissue-mimicking media. Our results show an acoustic Purcell factor normalized by droplet diameter (APF/D) of 1.6×105 ± 2.6×102 m−1, exceeding existing acoustic Purcell platforms by over two orders of magnitude. The emission intensity is tuneable via droplet size and concentration, providing precise acoustic output control within biologically safe exposure limits. When applied to B-mode ultrasound imaging, the enhanced emission leads to a 42 ± 1.4 dB contrast increase compared to conventional imaging. This study establishes a new framework for nanoscale acoustic emission enhancement, with implications for low-power, high-contrast ultrasound systems and the integration of nanostructured materials into next-generation acoustic devices.

Magnetic resonance imaging (MRI) and computed tomography (CT) are widely used for detecting brain tumors, but their clinical use is often limited by high cost, radiation exposure, and inadequate support for real-time imaging. In this study, we present active acoustic metamaterials designed for brain imaging applications. The system integrates piezoelectric elements within a compliant soft matrix to address acoustic impedance mismatches at biological interfaces. The metamaterials function as gain media and are specifically engineered to exhibit complex acoustic properties that oppose those of the skull in both their real and imaginary components. By introducing negative imaginary components, the metamaterials compensate for the intrinsic attenuation of cranial bone, enabling full acoustic transmission through the skull and minimal reflection at the interface. One-dimensional imaging was performed through an ex vivo human skull to localize the depth of a simulated tumor using acoustic echo profiles. Subsequently, two-dimensional imaging was carried out through a three-dimensional printed skull phantom to reconstruct the spatial morphology of the simulated tumor. This work demonstrates a portable, noninvasive, and real-time acoustic imaging strategy with strong potential to complement and enhance existing brain imaging technologies.

Survival analysis is widely deployed in a diverse set of fields, including healthcare, business, ecology, etc. The Cox Proportional Hazard (CoxPH) model is a semi-parametric model often encountered in the literature. Despite its popularity, wide deployment, and numerous variants, scaling CoxPH to large datasets and deep architectures poses a challenge, especially in the high-dimensional regime. We identify a fundamental connection between rank regression and the CoxPH model: this allows us to adapt and extend the so-called spectral method for rank regression to survival analysis. Our approach is versatile, naturally generalizing to several CoxPH variants, including deep models. We empirically verify our method's scalability on multiple real-world high-dimensional datasets; our method outperforms legacy methods w.r.t. predictive performance and efficiency.

A recent work introduces the problem of learning set functions from data generated by a so-called optimal subset oracle. Their approach approximates the underlying utility function with an energy-based model, whose parameters are estimated via mean-field variational inference. This approximation reduces to fixed point iterations; however, as the number of iterations increases, automatic differentiation quickly becomes computationally prohibitive due to the size of the Jacobians that are stacked during backpropagation. We address this challenge with implicit differentiation and examine the convergence conditions for the fixed-point iterations. We empirically demonstrate the efficiency of our method on synthetic and real-world subset selection applications including product recommendation, set anomaly detection and compound selection tasks.

Summary Genetically encoded imaging reporters are critical tools for tracking cell fate and function in regenerative medicine. Gas vesicles (GVs), air-filled protein nanostructures derived from bacteria, offer unique advantages for noninvasive imaging due to their acoustic and optical properties. In this study, we engineered human pluripotent stem cells (hPSCs) to express GVs using a doxycycline-inducible system. Upon doxycycline (Dox) treatment, GVs formed intracellularly and enabled enhanced contrast in both ultrasound and optical coherence tomography (OCT) imaging. Dynamic ultrasound imaging revealed pressure-dependent GV buckling and harmonic signal generation, while OCT imaging confirmed high sensitivity and depth-resolved detection in both in vitro and ex vivo retinal models. Our work establishes a multimodal GV-based reporter platform compatible with human stem cells and clinically relevant imaging modalities. This approach offers a powerful and versatile tool for noninvasively visualizing and tracking therapeutic cells in real time, advancing the development and monitoring of cell-based therapies.

Cavitation means rapid transformation of liquid to vapor phase due to a sudden and violent pressure drop. The evolutions of vaporization of the vapor phase have been investigated since the early 19th century. Recently, people have realized that it might be possible to control and utilize cavitation energy. Various approaches have been implemented to trigger cavitation intentionally at specific locations and at specific times. The energy from the collapsed bubble will blast the designated area. The challenge is to provide as much as cavitation energy will keep the pressure low. Here, we introduce acoustic vortex beams in cavitation, demonstrating how they enable the release of more energy while maintaining controlled negative pressure. These acoustic vortices bring in additional in-plane momentum, facilitating bubble evolution. This process leads to the twisting, convergence, and thus the shaping of bubble clouds. Compared to conventional ultrasound-induced cavitation, our vortex-induced cavitation releases significantly more energy into the surroundings through the collapse of gigantic bubble clusters. This makes it a promising technique for enhancing current industrial processing methods and enabling innovative bio-clinical applications.

Abstract This article studies the nonreciprocity of a system that consists of a bistable element coupled to a monostable element through a contactless magnetic interaction. To illustrate the concept, the bistable element is physically realized using a pendulum that interacts with a stationary magnet and the monostable element is a classical pendulum. A numerical model is implemented to simulate the nonlinear dynamics of the system. Both simulations and experiments show that the system exhibits a strong amplitude-dependent nonreciprocity in response to initial excitations. At small input amplitudes, the system has an intrawell response with minimal transmission of energy whether the excitation is exerted on the side of the bistable pendulum or on the other side. However, at high input amplitude, a strong nonreciprocal behavior is observed: excitation of the bistable pendulum causes an interwell response which considerably reduces the distance between the two pendulums and allows energy to be efficiently transmitted through the contactless magnetic interaction; excitation of the monostable pendulum does not cause any interwell response and results in limited energy transmission. The combination of bistability and contactless nonlinear interactions allows the system to exhibit very strong amplitude-dependent nonreciprocity, which may be useful in a wide range of applications.

Vortex ultrasound has attracted increasing research interest in biomedical engineering such as complex particle manipulation, communication speed improvement, ultrasound imaging edge enhancement, targeted drug delivery, noninvasive therapies, fast blood clot lysis, and tissue ablation. This work presents a way to generate vortex ultrasound waves by integrating a spiral phase structure with a miniaturized transducer. The assembly overcomes the drawbacks of existing transducer arrays such as complicated fabrication, costly multichannel amplifiers, and pricey feedback circuits by providing precise control over topological charges and continuous phase modulation. To assess the design, numerical simulations, analytical calculations, and experimental validation were performed. Transducer prototypes with a central frequency of 5 MHz showed transmitting sensitivity of 12.31 kPa/V peak to peak (Vpp) and 6.15 kPa/Vpp for the peak-to-peak pressure and peak negative pressure, respectively. An acoustic intensity of 0.22 W/cm 2 was measured at 13-Vpp input to the device, which agrees with simulation results. In summary, this work offers a promising path for vortex ultrasound generation with minimal complexity, affordable manufacturing, and compatibility with different transducers compared to traditional arrays.

Ou et al. (2022) introduce the problem of learning set functions from data generated by a so-called optimal subset oracle. Their approach approximates the underlying utility function with an energy-based model, whose parameters are estimated via mean-field variational inference. Ou et al. (2022) show this reduces to fixed point iterations; however, as the number of iterations increases, automatic differentiation quickly becomes computationally prohibitive due to the size of the Jacobians that are stacked during backpropagation. We address this challenge with implicit differentiation and examine the convergence conditions for the fixed-point iterations. We empirically demonstrate the efficiency of our method on synthetic and real-world subset selection applications including product recommendation, set anomaly detection and compound selection tasks.

Introduction Psoriasis is a chronic skin condition characterized by immune-mediated inflammation. Recent research suggests a possible interaction between Helicobacter pylori infection and the immunopathogenesis of psoriasis. However, over the past 5 years, no significant new evidence has clarified the relationship between H. pylori and skin diseases. This study aimed to determine the relationship between H. pylori infection and psoriasis through a systematic review and meta-analysis. Methods We searched for articles published in databases including PubMed, Embase, the China National Knowledge Infrastructure, and Web of Science up to January 1, 2024. Statistical analyses were conducted using Review Manager 5.3 and Stata 12.0 software. Results Our search yielded 271 papers. After rigorous screening by multiple reviewers, 15 studies involving 2,427 individuals were included. The odds ratio for H. pylori infection was significantly higher in the psoriasis group than in the control group (odds ratio = 1.94, 95% confidence interval: 1.40–2.68, p < 0.0001). Subgroup analysis revealed no significant differences in H. pylori infection rates between Asia and Europe. The type of study also did not significantly affect infection rates. The enzyme-linked immunosorbent assay detected H. pylori infection at a significantly higher rate than the breath test. Furthermore, the prevalence of H. pylori infection differed significantly between patients with moderate-to-severe psoriasis and those with mild psoriasis. Conclusion Our findings suggest a relationship between psoriasis and H. pylori infection, with variations observed based on geography, testing methods, and disease severity. These findings hold significant potential for guiding clinical practice. Systematic review registration http://www.crd.york.ac.uk/ , identifier CRD42022359427.

Acoustic vortex beams have garnered recent interest as an avenue to improve underwater acoustic communication bandwidth and speed. Design and deployment of these systems in ocean environments and at operational ranges has yet to be demonstrated due to the challenging and dynamic nature of the underwater acoustic environment. This manuscript presents methods to model the time series of vortex-based communication signals in ocean environments using ray tracing algorithms. The methods are used to assess the effects of Doppler, ocean turbulence, positional error, and range-dependent environmental parameters on the inner product demultiplexing of the communication signals encoded in the acoustic orbital angular momentum.

The ultrasound vortex beam showed the potential for applications including biomedical imaging, therapeutic ultrasound, acoustic trapping, and manipulations, etc. However, most existing vortex ultrasound generation are based on theory with integer topological numbers and highly relied on transducer arrays, which have limited control over orbital angular momentum. Meanwhile, the fractional vortex beam has a gapped donut distribution of acoustic pressure and is composed of complex phase chain, which provides detailed modulation of orbital angular momentum. Thus, in this work, we demonstrated the design and fabrication of the transducer integrated with a spiral phase plate to generate vortex waves with fractional topological charge (FTC) and validated the stability of fractional vortex ultrasound within 10 mm, which may serve as a new platform for diagnostic and therapeutic ultrasound applications. Diffraction, media nonlocality, and Gouy phase will be analyzed in this work during propagation. The transducer is expected to have an overall dimension of 2.0 × 2.0 × 5.4 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and 0.05 MPa acoustic pressure under 13 Vpp voltage. The generated fractional vortex maintains its phase pattern of FTC and gapped toroidal amplitude distribution.

Background: Psoriasis represents a multifaceted and debilitating immune-mediated systemic ailment afflicting millions globally. Despite the continuous discovery of biomarkers associated with psoriasis, identifying lysosomal biomarkers, pivotal as cellular metabolic hubs, remains elusive. Methods: We employed a combination of differential expression analysis and weighted gene co-expression network analysis (WGCNA) to initially identify lysosomal genes. Subsequently, to mitigate overfitting and eliminate collinear genes, we applied 12 machine learning algorithms to screen robust lysosomal genes. These genes underwent further refinement through random forest (RF) and Lasso algorithms to ascertain the final hub lysosomal genes. To assess their predictive efficacy, we conducted receiver operating characteristic (ROC) analysis and verified the expression of diagnostic biomarkers at both bulk and single-cell levels. Furthermore, we utilized single-sample gene set enrichment analysis (ssGSEA), CIBERSORT, and Pearson's correlation analysis to elucidate the association between immune phenotypes and hub lysosomal genes in psoriatic samples. Finally, employing the Cellchat algorithm, we explored potential mechanisms underlying the participation of these hub lysosomal genes in cell-cell communication. Results: Functional enrichment analyses revealed a close association between psoriasis and lysosomal functions. Subsequent intersection analysis identified 19 key lysosomal genes, derived from DEGs, phenotypic genes of WGCNA, and lysosomal gene sets. Following the exclusion of collinear genes, we identified 11 robust genes, further refined through RF and Lasso, yielding 3 hub lysosomal genes (S100A7, SERPINB13, and PLBD1) closely linked to disease occurrence, with high predictive capability for disease diagnosis. Concurrently, we validated their relative expression in separate bulk datasets and single-cell datasets. A nomogram based on these hub genes may offer clinical advantages for patients. Notably, these three hub genes facilitated patient classification into two subtypes, namely metabolic-immune subtype 1 and signaling subtype 2. CMap analysis suggested butein and arachidonic fasudil as preferred treatment agents for subtype 1 and subtype 2, respectively. Finally, through Cellchat and correlation analysis, we identified PRSS3-F2R as potentially promoting the expression of hub genes in the psoriasis group, thereby enhancing keratinocyte-fibroblast interaction, ultimately driving psoriasis occurrence and progression. Conclusion: Our study identifies S100A7, SERPINB13, and PLBD1 as potential diagnostic biomarkers, offering promising prospects for more precisely tailored psoriatic immunotherapy designs.

High-frequency ultrasound has long been a safe and effective tool for medical imaging, diagnosis, and noninvasive treatments. However, the presence of the porous skull poses a challenge, impeding wave transmission and limiting noninvasive ultrasonic brain imaging due to a significant impedance mismatch and energy attenuation. In this study, we propose an innovative approach by introducing an active non-Hermitian complementary metamaterial (NHCMM) to enhance transcranial imaging. The NHCMM integrates piezoelectric elements, hydrogel materials, and a feedback control circuit. This actively modulates the effective acoustic properties of the metamaterial, ensuring precise tuning to match the impedance of the skull, thereby reducing energy loss and enhancing transmission. This design not only creates a transparent window for high-frequency ultrasound but also significantly improves brain imaging quality. The presented work establishes a foundational framework for non-invasive ultrasound-based brain imaging and high-precision ultrasonic therapies, preserving the structural integrity of the cranial barrier. We anticipate that this research holds immense potential for advancing the fields of brain imaging and ultrasonic treatments, paving the way for future innovations in medical diagnostics and therapeutic interventions.

The emerging area of genetically engineered ultrasound contrast agents, like gas vesicles, has the potential to broaden the applications of medical ultrasound imaging by enabling targeted and deep tissue imaging at the cellular level. Nevertheless, the existing gene construct/encoding relies on significant cell processing to ensure sufficient gas vesicles are formed within the cell to produce ultrasound contrast. Here, we describe a drug-inducible and drug-selectable acoustic reporter gene construct that can enable gas vesicle expression in mammalian cell lines, which we demonstrate in wild type HEK293T cells. Fluorescence microscopy was employed to validate the integration of the plasmid, while the creation of single-cell clones was achieved through the utilization of flow cytometry. The expression for gas vesicle was optically and ultrasonically verified, achieving 80% improved signal to noise ratio in cells expressing gas vesicles compared to negative controls. This technology introduces a novel paradigm for reporter genes, utilizing ultrasound to visually identify particular cell types both in vitro and in vivo, serving diverse purposes such as cellular reporting and applications in cell therapies.

Orbital angular momentum (OAM) based acoustic communications are a promising method of increasing bandwidth in underwater acoustic communications networks as their unique phase patterns form an orthogonal basis set on which communications protocols may be based. The underwater acoustic environment, however, is highly complex and dynamic. These complexities make developing systems capable of long-range communications challenging. Methods for using BELLHOP’s ray tracing software to simulate the time series of vortex-wave based communications signals are presented. Additionally, this study explores the robustness of the inner product deconvolution method of decoding OAM-based communications against various operating conditions, considering both environmental and platform variations. The effects on channel cross-talk are assessed against sound speed profile uncertainty, position errors, Doppler Effect, and turbulence in the water column. These analyses shed light on the operational implementation of OAM-based communications systems.

The use of vortex waves in multiple environments is of increasing interest for numerous applications including underwater acoustic communications, particle manipulations, and sonothrombolysis. Finite element methods are limited in the range for which the propagation of these vortex beams may be simulated. On the other hand, ray tracing programs simulate well over long ranges, though are generally limited in their ability to resolve the features of a propagating vortex. Methods for overcoming these difficulties in simulating the long-range propagation of such waves in inhomogeneous environments have been developed and employed, though their specific implementation has not been thoroughly discussed. This manuscript provides the methods by which existing ray tracing programs may be used to approximate the long-range propagation of acoustic vortex beams in complex environments.

Endovascular sonothrombolysis has gained significant attention due to its benefits, including direct targeting of the thrombus with sonication and reduced side effects. However, the small aperture of endovascular transducers restricts the improvement of their potential clinical efficiency due to inefficient acoustic radiation. Hence, in an earlier study, we used vortex ultrasound with an endovascular ultrasound transducer to induce shear stress and enhance the clot lysis. In this study, the vortex acoustic transduction mechanism was investigated using numerical simulations and hydrophone tests. Following this characterization, we demonstrated the performance of the vortex ultrasound transducer in thrombolysis of retracted clots in in vitro tests. The test results indicated that the maximum lysis rates were 79.0% and 32.2% with the vortex ultrasound for unretracted and retracted clots, respectively. The vortex ultrasound enhanced the efficiency of the thrombolysis by approximately 49%, both for retracted and unretracted clots, compared with the typical non-vortex ultrasound technique. Therefore, the use of endovascular vortex ultrasound holds promise as a potential clinical option for the thrombolysis of retracted clots.

A promising new field of genetically encoded ultrasound contrast agents in the form of gas vesicles has recently emerged, which could extend the specificity of medical ultrasound imaging. However, given the delicate genetic nature of how these genes are integrated and expressed, current methods of producing gas vesicle-expressing mammalian cell lines requires significant cell processing time to establish a clonal/polyclonal line that robustly expresses the gas vesicles sufficiently enough for ultrasound contrast. Here, we describe an inducible and drug-selectable acoustic reporter gene system that can enable gas vesicle expression in mammalian cell lines, which we demonstrate using HEK293T cells. Our drug-selectable construct design increases the stability and proportion of cells that successfully integrate all plasmids into their genome, thus reducing the amount of cell processing time required. Additionally, we demonstrate that our drug-selectable strategy forgoes the need for single-cell cloning and fluorescence-activated cell sorting, and that a drug-selected mixed population is sufficient to generate robust ultrasound contrast. Successful gas vesicle expression was optically and ultrasonically verified, with cells expressing gas vesicles exhibiting an 80% greater signal-to-noise ratio compared to negative controls and a 500% greater signal-to-noise ratio compared to wild-type HEK293T cells. This technology presents a new reporter gene paradigm by which ultrasound can be harnessed to visualize specific cell types for applications including cellular reporting and cell therapies.

The formation and propagation of acoustic vortex waves have been of increasing interest for multiple applications, namely, underwater acoustic communications. Several methods have been presented to form these vortices in underwater environments; however, their performance and propagation over long distances is largely unstudied. Understanding the long-distance propagation of these waves is vital to enhancing their usefulness as an added degree of freedom in underwater acoustic communications systems. In this work, the ray tracing algorithm of bellhop is used to investigate the design parameters of vortex wave transducer and receiver arrays consisting of multiple rings of independently controlled transducers and simulate their performance.

Ultrasound localization microscopy (ULM) had made it possible to differentiate microbubble contrast agents that are separated only by a few micrometers and, thus, opening the path for super-resolution imaging. However, due to the innate limits of acoustic waves and microbubble imaging, similar levels of resolution to optical imaging (i.e., submicron resolution) are still very challenging. In this paper, we utilize ULM to achieve cellular imaging by using phase-change perfluorocarbon nanodroplets (PFCnDs) as a contrast agent that were fabricated with spontaneous nucleation method. To identify the point spread function (PSF) of a single nanodroplet, gaussian fit function was applied for reconstruction. Nanodroplets were injected into cells through patch clamping and later captured with two transducers: a single element transducer for focused ultrasound and linear array transducer for imaging. Nonlinear imaging (NLO) was used to maximize the sound to noise ratio (SNR), which enables optimal amplitude. With the PSF of a phase-transitioned nanodroplet known, stochastic activation of multiple nanodroplets within a cell was accumulated to image a full cell morphology. These findings can lead researchers to develop effective ultrasound imaging paradigms that can visualize intracellular level of organs in deep tissue invivo.

One treatment challenge for cerebral venous sinus thrombosis (CVST) is to achieve recanalization within a short period of time (e.g., 30 min) for significant clinical outcomes. Ultrasound-mediated thrombolysis (sonothrombolysis) presents a promising treatment for venous embolism. In this paper, a miniature vortex ultrasound transducer with frequency of 1.8 MHz was developed for sonothrombolysis. A composite transducer with 2-by-2 sub-aperture piezoelectric elements was assembled into a 9-French catheter to generate a physical helical wavefront. The prototyped vortex ultrasound catheter was characterized by measuring the acoustic pressure amplitude and phases, followed by in-vitro- sonothrombolysis tests. It was found that a vortex ultrasound field can be successfully generated by the prototype. The vortex lytic rate was increased by more than 50% compared with the nonvortex lysis with the same acoustic power input. A long (∼7.5 cm), completely occluded in-vitro- 3D model of acute CVST was fully recanalized within 8 min. The unprecedented sonothrombolysis rate was likely attributed to the vortex ultrasound-induced shear stress, which can effectively disrupt acute blood clots. Furthermore, no vessel wall damage over ex-vivo bovine veins was found after the vortex sonothrombolysis treatment.

The newly established field of genetically encoded ultrasound contrast agents in the form of gas vesicles could expand the uses of medical ultrasound imaging for cell specific deep tissue imaging. However, current gene constructs encoding for these gas vesicles require significant cell processing to ensure sufficient gas vesicles are formed within the cell to produce ultrasound contrast. Here, we describe a drug-inducible and drug-selectable acoustic reporter gene construct that can enable gas vesicle expression in mammalian cell lines, which we demonstrate in wild type HEK293T cells. Plasmid integration was validated using fluorescence microscopy, and flow cytometry was used to establish single cell clones of the cells. Gas vesicle expression was optically and ultrasonically verified, with an 80% improved signal to noise ratio in cells expressing gas vesicles compared to negative controls. This technology presents a new reporter gene paradigm by which ultrasound can be harnessed to visualize specific cell types in vitro and invivo for various applications, including cellular reporting and cell therapies.

The underwater acoustic communications environment is severely band-limited, which leads to a bottleneck in data transfer. Existing methods of data transfer in underwater acoustic communications applications typically rely primarily on conventional temporal and frequency modulation techniques and achieve bit rates peaking at approximately 40 kb/s. One method of easing the bottleneck and increasing the data rate is to explore further potential degrees of freedom which may be utilized. Acoustic orbital angular momentum (OAM) is a physical quantity that characterizes the rotation in a propagating helical pressure wavefront. The unique phase patterns of OAM carrying vortex waves form an orthogonal basis which may be useful as an additional degree of freedom in acoustics communications applications; however, the long-distance propagation of these waves is largely unstudied. By employing BELLHOP’s ray tracing algorithm, the dominant features of a propagating OAM carrying vortex wave are tracked over long ranges (to and beyond 1 km) under various environmental conditions. This provides essential guidance in the design of the sending and receiving arrays of high-speed underwater communications systems, which rely on multiplexing acoustic OAMs.

This research aims to demonstrate a novel vortex ultrasound enabled endovascular thrombolysis method designed for treating cerebral venous sinus thrombosis (CVST). This is a topic of substantial importance since current treatment modalities for CVST still fail in as many as 20% to 40% of the cases, and the incidence of CVST has increased since the outbreak of the coronavirus disease 2019 pandemic. Compared with conventional anticoagulant or thrombolytic drugs, sonothrombolysis has the potential to remarkably shorten the required treatment time owing to the direct clot targeting with acoustic waves. However, previously reported strategies for sonothrombolysis have not demonstrated clinically meaningful outcomes (e.g., recanalization within 30 min) in treating large, completely occluded veins or arteries. Here, we demonstrated a new vortex ultrasound technique for endovascular sonothrombolysis utilizing wave-matter interaction-induced shear stress to enhance the lytic rate substantially. Our in vitro experiment showed that the lytic rate was increased by at least 64.3% compared with the nonvortex endovascular ultrasound treatment. A 3.1-g, 7.5-cm-long, completely occluded in vitro 3-dimensional model of acute CVST was fully recanalized within 8 min with a record-high lytic rate of 237.5 mg/min for acute bovine clot in vitro. Furthermore, we confirmed that the vortex ultrasound causes no vessel wall damage over ex vivo canine veins. This vortex ultrasound thrombolysis technique potentially presents a new life-saving tool for severe CVST cases that cannot be efficaciously treated using existing therapies.