Microbubbles Research Articles

In Vivo Performance of Airway and Lung Ultrasound Enhanced via Inhalable Contrast Agents.

Sparse aperture ultrasound-guided acoustic vortex tweezers for real-time microbubble aggregation in peripheral vasculature.

Microbial contamination is the main safety concern of sprouts and seeds are the major source. High concentrations of sanitizers (>10,000 mg/kg) are recommended for effective sanitation. Microbubble (MB) was reported to elevate sanitizer efficacy. Hence, MBs combined with disinfectants, chlorine dioxide (ClO2, 500 ppm), and slightly acidic electrolyzed water (SAEW, 250 ppm), were used to inactivate Salmonella Typhimurium on alfalfa seeds. After fulfilling MBs for 10 min, alfalfa seeds were washed in 10 L of water for 10, 20, or 30 min. Compared with untreated seeds, S. Typhimurium reductions obtained by SAEW-MBs (SMBs) and ClO2-MBs (CMBs) for 20 min were 3.8 and 3.3 log CFU/g, respectively. Conversely, the 20 min treatments of SAEW and ClO2 only obtained reductions of 0.9 and 1.1 log CFU/g, respectively. More surface ruptures on the seeds treated with CMBs were observed under a scanning electron microscope compared with the ones treated by water and ClO2 only. No adverse effects on the seed germination rate and the weight yield of sprouts were observed when treated with CMBs for 20 min. An MB device with capacity of 100 L was assembled and achieved reductions of 3.9 and 3.2 log CFU/g of natural microbes and S. Typhimurium, respectively, after 20 min CMB washing. Additionally, an MB device at 250 L was assembled and achieved 3.0 log CFU/g reduction in natural microbes. This study demonstrated that MBs enhanced the efficacy of disinfectants and could be applied in industrial-scale operations.

Focused ultrasound (FUS) combined with microbubbles (MBs) represents a noninvasive, targeted approach for transiently opening the blood–brain barrier (BBB). While higher MB concentrations can enhance BBB permeability, they also raise the risk of adverse effects such as erythrocyte extravasation. In this study, acoustic vortex (AV) manipulation of MBs was integrated with FUS-mediated BBB opening. The results demonstrated that dispersed MBs could be effectively clustered by an AV tweezer in multi-well plates. Compared with FUS applied to dispersed MBs, the combination of AV, FUS, and MBs required lower acoustic pressure, achieved higher BBB opening efficiency, and elicited significantly stronger stable cavitation. In addition, both pore density and size on cell membranes were greater in the AV + FUS + MB group relative to the FUS + MB group. Importantly, temperature elevation was minimal and cell viability was preserved. These findings suggest that combining FUS with MB clusters trapped by an AV tweezer offers a promising and efficient strategy for BBB opening.

Gas-filled microbubbles (MBs) are widely used as contrast agents for ultrasound (US) imaging and are increasingly being explored for US-mediated drug delivery. Polymeric poly(butyl cyanoacrylate) (PBCA) MBs are particularly well-suited for these applications due to their relatively narrow size distribution, strong acoustic responsiveness, and high drug-loading capacity. While past studies have focused on enhancing the performance of MBs through polymer chemistry, the impact of reagent sourcing has received little attention. The butyl cyanoacrylate monomer, being highly reactive, is commercialized in the presence of chemicals that prevent self-polymerization. As a result, monomers from different suppliers may vary in additives and polymerization characteristics. This study demonstrates that the choice of monomer source strongly affects the size distribution, acoustic response, and payload capability of PBCA MBs. Optimized reagent selection improved the monodispersity of the samples, reducing the half-width at half-maximum of their size distributions from 30 to 16% relative to their diameters. Furthermore, differences in polymer chain length and shell thickness, driven by the monomer source, lead to 180% increases in both drug loading capacity and acoustic responsiveness. These results highlight reagent sourcing as a critical (and previously underappreciated) factor in improving the characteristics and performance of polymeric MBs.

Microbubble (MB) technology is uniquely suited for integration into microphysiological systems (MPS) for high throughput three-dimensional (3D) tissue culture, drug screening and toxicity testing. MBs are spherical compartments with nanoliter volumes produced in an array format. Here, we present a novel hybrid MB-fluidic MPS that combines 3D tissue culture with controlled fluid flow to improve nutrient delivery, waste removal, and physiological relevance. Computational fluid dynamics (CFD) simulations were used to model velocity and solute diffusion profiles as a function of MB aspect ratio (AR), with validation by fluorescent polystyrene microsphere optical tracking. Simulations reveal pronounced velocity decoupling and shear dampening effects with intra-MB flow velocities over 200-fold lower than the main channel-allowing high channel flow rates for efficient exchange while preserving low-shear microenvironments, optimal for tissue culture. Additionally, tissues spatially compartmentalized in individual MBs are not dislodged under high flow conditions. This allowance for high channel flow rates, decoupled from the MB microenvironment, enables the use of millifluidic devices which are less difficult to manufacture and control than microfluidic devices. Simulations also showed that MBs with AR values between 2 and 3 offered a balance between nutrient transport and retention of cell-secreted factors. In contrast, rectilinear wells exhibited flow splitting and lactate accumulation at AR > 2, highlighting a key advantage of the spherical MB geometry. We fabricated a millifluidic MB device using fused deposition modeling (FDM) 3D printing and a novel molding strategy to create optically clear, leak-free flow channels. Murine salivary gland tissues cultured under flow in this device showed preserved acinar cell marker gene expression and reduced ductal markers, supporting the hypothesis that dynamic flow enhances tissue fidelity. This MB-fluidic platform enables scalable, high-content 3D culture systems suitable for organoid, tumor spheroid, and tissue mimetic applications in drug discovery and toxicology.

Enhancing thrombolysis efficiency using acoustic vortex tweezers and microbubbles: a microscale mechanistic study with experimental validation.

Abstract Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest malignances with a 5-year survival rate at around 13%. This dismal prognosis is, in part, due to the dense desmoplastic stroma and low vascularity of PDAC tumors, leading to inefficient uptake of therapeutics. The combination of FDA-approved ultrasound contrast agents called microbubbles (MBs), and focused ultrasound (FUS) has the potential to increase drug uptake in PDAC tumors. Our team has developed a novel therapeutic that loads antisense oligonucleotides (ASOs) onto MBs for targeted drug delivery in vivo. The ASOs have been designed to target the pre-mRNA transcript of Negative Elongation Factor E (NELFE), a protein that is upregulated in multiple tumor types, including PDAC. In vitro ASO-only treatment was sufficient in significantly reducing cell proliferation, cell migration, and colony formation in three PDAC cell lines. To investigate the effects of ASO+MBs+FUS treatment in vivo, we performed intrapancreatic orthotopic injections of KPC-4662 cells derived from the KPC mouse model (LSL-Kras G12D/+ ;LSL-Trp53 R172H/+ ;Pdx-1-Cre) into C57BL/6 mice and recorded tumor growth over time using bioluminescence imaging. Once tumors were established, we performed 6 rounds of ASO+MBs+FUS treatment across a 2-week timespan. Mice treated with ASO+MBs+FUS had a significant reduction in tumor burden and increased overall survival compared to mice treated with MBs+FUS alone. In conclusion, targeting NELFE using ASO+MBs+FUS can be a potential therapeutic strategy for PDAC patients. Citation Format: Brittany N. Ruiz, Alvaro Lucci, Laura M. Reynolds, Pongsakorn Choochuen, Corinne Wessner, Christine Wiktor, Sarah Hynd, Christoph Eckert, Meghan Grim, Avinoam Nevler, Harish Lavu, Charles Yeo, Matthias M. Gaida, Elda Grabocka, John Eisenbrey, Hien Dang. Targeting NELFE using antisense oligonucelotides reduces tumor burden and increases overall survival in vivo [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research—Emerging Science Driving Transformative Solutions; Boston, MA; 2025 Sep 28-Oct 1; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl_3):Abstract nr B033.

Influence of Microbubble Properties and Carrier Frequency on Ultrasound Cavitation-Induced Flow Augmentation.

Aging impairs cerebrovascular structure and function, contributing to cognitive decline and dementia. Here, a novel, high-resolution, intravital imaging platform is presented that combines functional ultrasound (fUS) and ultrasound localization microscopy (ULM) through a chronically implanted, polymethylpentene (TPX) cranial window, a transparent implant that enables ultrasound imaging through the skull. This approach enables intravital, longitudinal, minimally invasive assessment of cerebrovascular structure and function across cortical and deep brain regions. Leveraging this platform, a new method is developed to estimate resting cerebral blood flow (CBF) by integrating microbubble (MB) velocity data from fUS with microvascular geometry derived from ULM. Notably, a significant age-related decline in the cortical arteriole-to-venule ratio (AVR) is discovered, introducing a novel biomarker of structural cerebrovascular remodeling. It is also validated that fUS can reliably assess neurovascular coupling (NVC) responses in aged mice. This study establishes a powerful, non-invasive, and repeatable investigative tool for future preclinical studies aimed at evaluating the efficacy of therapeutic interventions targeting vascular contributions to cognitive impairment and neurodegeneration.

The mouse motor cortex stimulation via non-invasive temporal interference transcranial focused ultrasound with microbubbles☆

Characterization of microbubble cavitation in theranostic ultrasound-mediated blood-brain barrier opening for gene delivery.

Direct insights into synthesis, protein integrity, and blood microrheology of albumin microbubbles.

Disrupting Cdc42 activation-driven filopodia formation with low-intensity ultrasound and microbubbles: A novel strategy to block ovarian cancer metastasis.

Functional neuroimaging with ultrafast ultrasound is an emerging neuroimaging tool for studying neural activities in the rodent brain. Existing methods, however, are challenged by the compromise between functional imaging sensitivity (i.e., sensitivity in detecting neural responses) and spatial resolution. For example, functional ultrasound (fUS) uses native red blood cells (RBCs) as imaging targets, which offers high functional imaging sensitivity but limited spatial resolution that is confined by the diffraction limit of ultrasound. On the other hand, functional ultrasound localization microscopy (fULM) employs intravenously injected microbubble (MB) as contrast agent to achieve super-resolved spatial resolution but at the cost of functional imaging sensitivity. This study aims to address this challenge by developing a novel, MB track-based hemodynamic activity estimation method to enhance the functional imaging sensitivity of fULM. Our approach involves conducting functional correlation analysis using the MB signals acquired from the entire MB movement track rather than individual MB centroid locations, which overcomes the signal sparsity issue in fULM. To further boost the functional sensitivity of fULM, we developed a novel approach based on indwelling jugular vein catheters to achieve fULM imaging in awake mice. The in vivo imaging results demonstrate that the proposed techniques successfully enhanced the functional imaging sensitivity of fULM without compromising its high spatial resolution. In the whisker stimulation experiments, the proposed technique enabled detection of significantly activated brain regions within fewer than five stimulation cycles (5 minutes of acquisition), reducing the required time by over 50% compared to conventional fULM.

Objective.Non-invasive imaging of the brain vascular system is key for the understanding and monitoring of cerebral small vessel disease and neurological disorders. ultrasound localization microscopy (ULM) is emerging as a powerful modality for the cerebral angiographic and hemodynamic imaging up to the microscopic scale in preclinical and clinical settings. However, the skull bone induces aberrations during ultrasonic propagation leading to distortions and shadowed regions.Approach.Here, we introduce an aberration correction method for ULM data able to extract the phase aberration from the singular value decomposition (SVD) of signals backscattered by microbubbles (MBs). Without anya prioriknowledge, SVD processing extracts several correction time delays laws associated with different isoplanetic patches. To highlight the efficiency of this correction method, we first simulated the full ULM data pipeline numerically to characterize the impact of transcranial propagation on acoustic image reconstruction and then validated it onin vivorodent data. The simulation generates synthetic backscattered signals from a rat vasculature mimicking model using real ULM position and velocity data acquired on a trepanned rat and virtually aberrated by 'ground truth' aberrators.Main results.The correction algorithm correctly retrieves this virtual aberration law in simulation. Then, applied toin vivodata, it improves image quality and enhance the number of detected MB for ULM imaging by up to 15%.Significance.This simple and fast correction method may open the way for a more widespread use of transcranial ULM in rodents and could be further extended to humans.

Focused ultrasound combined with drug-loaded microbubbles suppresses ictal spikes in kainic acid-induced epileptic animals

As a crucial medical imaging modality, ultrasonography has emerged as a pivotal tool for tumor diagnosis and treatment owing to its non-invasive nature, real-time imaging capability, and superior resolution. Recent technological advancements have demonstrated unique advantages in early tumor screening, staging, and localization. Contrast-enhanced ultrasound (CEUS), utilizing microbubbles (MBs) and nanobubbles (NBs) to target vascular biomarkers, significantly enhances tumor visualization and demonstrates high sensitivity in molecular imaging. Multimodal ultrasound (MU), incorporating techniques such as elastography and automated breast volume scanning (ABVS), achieves improved diagnostic accuracy when combined with MRI/CT. The applications of ultrasound in localized and systemic tumor therapy have expanded considerably. High-intensity focused ultrasound (HIFU) enables thermal ablation of solid tumors, while low-intensity focused ultrasound (LIFU) facilitates sonodynamic therapy (SDT) through reactive oxygen species (ROS) generation mediated by sonosensitizers. Ultrasound-assisted drug delivery systems (US-DDS) leverage MB/NB cavitation effects to enhance chemotherapeutic agent delivery efficiency, overcome biological barriers, including the blood-brain barrier, and modulate immune responses. These technological breakthroughs have provided novel therapeutic options for cancer patients, garnering significant clinical interest. This review systematically examines current applications of ultrasound imaging and therapy in oncology, evaluates its potential clinical value, analyzes existing technical limitations, and discusses future development prospects. The article aims to provide innovative perspectives for tumor diagnosis and treatment while offering references for clinical practice.

Ultrasound molecular imaging (UMI) uses targeted microbubbles (MBs) to detect disease-associated biomarkers. For UMI, distinguishing the acoustic signals produced by bound MBs from those by free MBs and tissue is critical. Currently, the main approach, known as differential targeted enhancement (DTE), is time-intensive and requires MB destruction. Here, we introduce a novel, rapid, and nondestructive UMI technique utilizing higher order singular value decomposition (HOSVD). HOSVD decomposes the signals of an acoustic contrast sequence, separating them owing to their nonlinear content and temporal coherence. The nonlinear separation enables distinction between tissue and MBs, while the temporal separation enables distinction between free and bound MBs. From the HOSVD output, we defined a bound MB indicator $\chi $ , which indicates the presence of bound MBs. In our in vitro experiments, $\chi $ was lower for free MBs and tissue ( $0.04~\pm ~0.03$ ) compared to bound MBs ( $0.31~\pm ~0.11$ without free MBs, decreasing with concentration down to $0.11~\pm ~0.07$ at $20\times 10^{{3}}$ free MBs/mL). In addition, the molecular signal determined from $\chi $ correlated well with a DTE ground truth acquisition. The method was compared to other nondestructive techniques such as low-pass filtering and normalized singular spectrum area, demonstrating an average molecular signal enhancement of 12 dB. Furthermore, when used as a binary classifier, our method achieved a detection of up to $1.81\times $ more true positives while reducing false positives by up to $1.78\times $ . These findings suggest that HOSVD could pave the way to rapid, nondestructive UMI.

Enhancing super-resolution ultrasound localisation through multi-frame deconvolution exploiting spatiotemporal consistency.