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Saleem MS, Chan TTK, Versluis M, Krug D, Lajoinie G. Additive manufacturing of 3D flow-focusing millifluidics for the production of curable microdroplets. RSC Adv 2024; 14:39276-39284. [PMID: 39670164 PMCID: PMC11635350 DOI: 10.1039/d4ra07234k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2024] [Accepted: 11/21/2024] [Indexed: 12/14/2024] Open
Abstract
Microfluidics plays a crucial role in the generation of mono-sized microdroplet emulsions. Traditional glass microfluidic chips typically lack versatility in generating curable droplets of arbitrary liquids due to the inherent hydrophilic nature of glass and to fabrication constraints. To overcome this, we designed a microdroplet generator with 3D flow-focusing capabilities that can be 3D-printed. The chip can handle oil-in-water emulsions despite its lipophilicity. Operating in the jetting regime, the chip exploits the Rayleigh-Plateau instability to enable high throughput. With its versatile design, the chip is capable of producing both single and double emulsions within the same channel. We utilize a thermoset (epoxy-melamine) based system to test its ability to handle curable chemicals and to produce in a post-processing step both solid particles and filled capsules. With a low solvent concentration in the curable material, the present system can encapsulate water-based cores of a wide range of sizes.
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Engelen Y, Krysko DV, Effimova I, Breckpot K, Versluis M, De Smedt S, Lajoinie G, Lentacker I. Optimizing high-intensity focused ultrasound-induced immunogenic cell-death using passive cavitation mapping as a monitoring tool. J Control Release 2024; 375:389-403. [PMID: 39293525 DOI: 10.1016/j.jconrel.2024.09.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 09/02/2024] [Accepted: 09/10/2024] [Indexed: 09/20/2024]
Abstract
Over the past decade, ultrasound (US) has gathered significant attention and research focus in the realm of medical treatments, particularly within the domain of anti-cancer therapies. This growing interest can be attributed to its non-invasive nature, precision in delivery, availability, and safety. While the conventional objective of US-based treatments to treat breast, prostate, and liver cancer is the ablation of target tissues, the introduction of the concept of immunogenic cell death (ICD) has made clear that inducing cell death can take different non-binary pathways through the activation of the patient's anti-tumor immunity. Here, we investigate high-intensity focused ultrasound (HIFU) to induce ICD by unraveling the underlying physical phenomena and resulting biological effects associated with HIFU therapy using an automated and fully controlled experimental setup. Our in-vitro approach enables the treatment of adherent cancer cells (B16F10 and CT26), analysis for ICD hallmarks and allows to monitor and characterize in real time the US-induced cavitation activity through passive cavitation detection (PCD). We demonstrate HIFU-induced cell death, CRT exposure, HMGB1 secretion and antigen release. This approach holds great promise in advancing our understanding of the therapeutic potential of HIFU for anti-cancer strategies.
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Nawijn CL, Segers T, Lajoinie G, Berg S, Snipstad S, Davies CDL, Versluis M. High-Speed Optical Characterization of Protein-and-Nanoparticle-Stabilized Microbubbles for Ultrasound-Triggered Drug Release. ULTRASOUND IN MEDICINE & BIOLOGY 2024; 50:1099-1107. [PMID: 38851940 DOI: 10.1016/j.ultrasmedbio.2024.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/11/2024] [Accepted: 03/21/2024] [Indexed: 06/10/2024]
Abstract
OBJECTIVE Ultrasound-triggered bubble-mediated local drug delivery has shown potential to increase therapeutic efficacy and reduce systemic side effects, by loading drugs into the microbubble shell and triggering delivery of the payload on demand using ultrasound. Understanding the behavior of the microbubbles in response to ultrasound is crucial for efficient and controlled release. METHODS In this work, the response of microbubbles with a coating consisting of poly(2-ethyl-butyl cyanoacrylate) (PEBCA) nanoparticles and denatured casein was characterized. High-speed recordings were taken of single microbubbles, in both bright field and fluorescence. RESULTS The nanoparticle-loaded microbubbles show resonance behavior, but with a large variation in response, revealing a substantial interbubble variation in mechanical shell properties. The probability of shell rupture and the probability of nanoparticle release were found to strongly depend on microbubble size, and the most effective size was inversely proportional to the driving frequency. The probabilities of both rupture and release increased with increasing driving pressure amplitude. Rupture of the microbubble shell occurred after fewer cycles of ultrasound as the driving pressure amplitude or driving frequency was increased. CONCLUSION The results highlight the importance of careful selection of the driving frequency, driving pressure amplitude and duration of ultrasound to achieve the most efficient ultrasound-triggered shell rupture and nanoparticle release of protein-and-nanoparticle-stabilized microbubbles.
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Blanken N, Heiles B, Kuliesh A, Versuis M, Jain K, Maresca D, Lajoinie G. PROTEUS: A Physically Realistic Contrast-Enhanced Ultrasound Simulator-Part I: Numerical Methods. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2024; PP:1-1. [PMID: 39008399 DOI: 10.1109/tuffc.2024.3427850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/17/2024]
Abstract
Ultrasound contrast agents have been used as vascular reporters for the past 40 years. The ability to enhance vascular features in ultrasound images with engineered lipid-shelled microbubbles has enabled break-throughs such as the detection of tissue perfusion or super-resolution imaging of the microvasculature. However, advances in the field of contrast-enhanced ultra-sound are hindered by experimental variables that are difficult to control in a laboratory setting, such as complex vascular geometries, the lack of ground truth, and tissue nonlinearities. In addition, the demand for large datasets to train deep learning-based computational ultrasound imaging methods calls for the development of a simulation tool that can reproduce the physics of ultrasound wave interactions with tissues and microbubbles. Here, we introduce a physically realistic contrast-enhanced ultrasound simulator (PROTEUS) consisting of four inter-connected modules that account for blood flow dynamics in segmented vascular geometries, intravascular microbubble trajectories, ultrasound wave propagation, and nonlinear microbubble scattering. The first part of this study describes numerical methods that enabled this development. We demonstrate that PROTEUS can generate contrast-enhanced radiofrequency data in various vascular architectures across the range of medical ultrasound frequencies. PROTEUS offers a customizable framework to explore novel ideas in the field of contrast-enhanced ultrasound imaging. It is released as an open-source tool for the scientific community.
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van de Velde L, van Helvert M, Engelhard S, Ghanbarzadeh-Dagheyan A, Mirgolbabaee H, Voorneveld J, Lajoinie G, Versluis M, Reijnen MMPJ, Groot Jebbink E. Validation of ultrasound velocimetry and computational fluid dynamics for flow assessment in femoral artery stenotic disease. J Med Imaging (Bellingham) 2024; 11:037001. [PMID: 38765874 PMCID: PMC11097197 DOI: 10.1117/1.jmi.11.3.037001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 04/05/2024] [Accepted: 04/16/2024] [Indexed: 05/22/2024] Open
Abstract
Purpose To investigate the accuracy of high-framerate echo particle image velocimetry (ePIV) and computational fluid dynamics (CFD) for determining velocity vectors in femoral bifurcation models through comparison with optical particle image velocimetry (oPIV). Approach Separate femoral bifurcation models were built for oPIV and ePIV measurements of a non-stenosed (control) and a 75%-area stenosed common femoral artery. A flow loop was used to create triphasic pulsatile flow. In-plane velocity vectors were measured with oPIV and ePIV. Flow was simulated with CFD using boundary conditions from ePIV and additional duplex-ultrasound (DUS) measurements. Mean differences and 95%-limits of agreement (1.96*SD) of the velocity magnitudes in space and time were compared, and the similarity of vector complexity (VC) and time-averaged wall shear stress (TAWSS) was assessed. Results Similar flow features were observed between modalities with velocities up to 110 and 330 cm / s in the control and the stenosed model, respectively. Relative to oPIV, ePIV and CFD-ePIV showed negligible mean differences in velocity (< 3 cm / s ), with limits of agreement of ± 25 cm / s (control) and ± 34 cm / s (stenosed). CFD-DUS overestimated velocities with limits of agreements of 13 ± 40 and 16.1 ± 55 cm / s for the control and stenosed model, respectively. VC showed good agreement, whereas TAWSS showed similar trends but with higher values for ePIV, CFD-DUS, and CFD-ePIV compared to oPIV. Conclusions EPIV and CFD-ePIV can accurately measure complex flow features in the femoral bifurcation and around a stenosis. CFD-DUS showed larger deviations in velocities making it a less robust technique for hemodynamical assessment. The applied ePIV and CFD techniques enable two- and three-dimensional assessment of local hemodynamics with high spatiotemporal resolution and thereby overcome key limitations of current clinical modalities making them an attractive and cost-effective alternative for hemodynamical assessment in clinical practice.
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Oratis AT, Dijs K, Lajoinie G, Versluis M, Snoeijer JH. A unifying Rayleigh-Plesset-type equation for bubbles in viscoelastic media. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 155:1593-1605. [PMID: 38393739 DOI: 10.1121/10.0024984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 02/05/2024] [Indexed: 02/25/2024]
Abstract
Understanding the ultrasound pressure-driven dynamics of microbubbles confined in viscoelastic materials is relevant for multiple biomedical applications, ranging from contrast-enhanced ultrasound imaging to ultrasound-assisted drug delivery. The volumetric oscillations of spherical bubbles are analyzed using the Rayleigh-Plesset equation, which describes the conservation of mass and momentum in the surrounding medium. Several studies have considered an extension of the Rayleigh-Plesset equation for bubbles embedded into viscoelastic media, but these are restricted to a particular choice of constitutive model and/or to small deformations. Here, we derive a unifying equation applicable to bubbles in viscoelastic media with arbitrary complex moduli and that can account for large bubble deformations. To derive this equation, we borrow concepts from finite-strain theory. We validate our approach by comparing the result of our model to previously published results and extend it to show how microbubbles behave in arbitrary viscoelastic materials. In particular, we use our viscoelastic Rayleigh-Plesset model to compute the bubble dynamics in benchmarked viscoelastic liquids and solids.
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van Elburg B, Deprez J, van den Broek M, De Smedt SC, Versluis M, Lajoinie G, Lentacker I, Segers T. Dependence of sonoporation efficiency on microbubble size: An in vitro monodisperse microbubble study. J Control Release 2023; 363:747-755. [PMID: 37778466 DOI: 10.1016/j.jconrel.2023.09.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/24/2023] [Accepted: 09/26/2023] [Indexed: 10/03/2023]
Abstract
Sonoporation is the process where intracellular drug delivery is facilitated by ultrasound-driven microbubble oscillations. Several mechanisms have been proposed to relate microbubble dynamics to sonoporation including shear and normal stress. The present work aims to gain insight into the role of microbubble size on sonoporation and thereby into the relevant mechanism(s) of sonoporation. To this end, we measured the sonoporation efficiency while varying microbubble size using monodisperse microbubble suspensions. Sonoporation experiments were performed in vitro on cell monolayers using a single ultrasound pulse with a fixed frequency of 1 MHz while the acoustic pressure amplitude and pulse length were varied at 250, 500, and 750 kPa, and 10, 100, and 1000 cycles, respectively. Sonoporation efficiency was quantified using flow cytometry by measuring the FITC-dextran (4 kDa and 2 MDa) fluorescence intensity in 10,000 cells per experiment to average out inherent variations in the bioresponse. Using ultra-high-speed imaging at 10 million frames per second, we demonstrate that the bubble oscillation amplitude is nearly independent of the equilibrium bubble radius at acoustic pressure amplitudes that induce sonoporation (≥ 500 kPa). However, we show that sonoporation efficiency is strongly dependent on the equilibrium bubble size and that under all explored driving conditions most efficiently induced by bubbles with a radius of 4.7 μm. Polydisperse microbubbles with a typical ultrasound contrast agent size distribution perform almost an order of magnitude lower in terms of sonoporation efficiency than the 4.7-μm bubbles. We elucidate that for our system shear stress is highly unlikely the mechanism of action. By contrast, we show that sonoporation efficiency correlates well with an estimate of the bubble-induced normal stress.
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Blanken N, Wolterink JM, Delingette H, Brune C, Versluis M, Lajoinie G. Super-Resolved Microbubble Localization in Single-Channel Ultrasound RF Signals Using Deep Learning. IEEE TRANSACTIONS ON MEDICAL IMAGING 2022; 41:2532-2542. [PMID: 35404813 DOI: 10.1109/tmi.2022.3166443] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Recently, super-resolution ultrasound imaging with ultrasound localization microscopy (ULM) has received much attention. However, ULM relies on low concentrations of microbubbles in the blood vessels, ultimately resulting in long acquisition times. Here, we present an alternative super-resolution approach, based on direct deconvolution of single-channel ultrasound radio-frequency (RF) signals with a one-dimensional dilated convolutional neural network (CNN). This work focuses on low-frequency ultrasound (1.7 MHz) for deep imaging (10 cm) of a dense cloud of monodisperse microbubbles (up to 1000 microbubbles in the measurement volume, corresponding to an average echo overlap of 94%). Data are generated with a simulator that uses a large range of acoustic pressures (5-250 kPa) and captures the full, nonlinear response of resonant, lipid-coated microbubbles. The network is trained with a novel dual-loss function, which features elements of both a classification loss and a regression loss and improves the detection-localization characteristics of the output. Whereas imposing a localization tolerance of 0 yields poor detection metrics, imposing a localization tolerance corresponding to 4% of the wavelength yields a precision and recall of both 0.90. Furthermore, the detection improves with increasing acoustic pressure and deteriorates with increasing microbubble density. The potential of the presented approach to super-resolution ultrasound imaging is demonstrated with a delay-and-sum reconstruction with deconvolved element data. The resulting image shows an order-of-magnitude gain in axial resolution compared to a delay-and-sum reconstruction with unprocessed element data.
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Engelhard S, van Helvert M, Voorneveld J, Bosch JG, Lajoinie G, Jebbink EG, Reijnen MMPJ, Versluis M. Blood Flow Quantification with High-Frame-Rate, Contrast-Enhanced Ultrasound Velocimetry in Stented Aortoiliac Arteries: In Vivo Feasibility. ULTRASOUND IN MEDICINE & BIOLOGY 2022; 48:1518-1527. [PMID: 35577661 DOI: 10.1016/j.ultrasmedbio.2022.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 03/25/2022] [Accepted: 03/28/2022] [Indexed: 06/15/2023]
Abstract
Local flow patterns influence stent patency, while blood flow quantification in stents is challenging. The aim of this study was to investigate the feasibility of 2-D blood flow quantification using high-frame-rate, contrast-enhanced ultrasound (HFR-CEUS) and particle image velocimetry (PIV), or echoPIV, in patients with aortoiliac stents. HFR-CEUS measurements were performed at 129 locations in 62 patients. Two-dimensional blood flow velocity fields were obtained using echoPIV. Visual inspection was performed by five observers to evaluate feasibility. The contrast-to-background ratio and average vector correlation were calculated and compared between stented and native vessel segments. Flow quantification with echoPIV was feasible in 128 of 129 locations (99%), with optimal quantification in 40 of 129 locations (31%). Partial quantification was achieved in 88 of 129 locations (68%), where one or multiple limiting issues occurred (not related to the stent) including loss of correlation during systole (57/129), short vessel segments (20/129), loss of contrast during diastole (20/129) and shadow regions (20/129). The contrast-to-background ratio and vector correlation were lower downstream in the imaged blood vessel, independent of the location of the stent. In conclusion, echoPIV was feasible in stents placed in the aortoiliac region, and the stents did not adversely affect flow tracking.
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Nawijn C, Segers T, Lajoinie G, Mørch Ý, Berg S, Snipstad S, de Lange Davies C, Versluis M. Multi-timescale Microscopy Methods for the Characterization of Fluorescently-labeled Microbubbles for Ultrasound-Triggered Drug Release. J Vis Exp 2021. [PMID: 34180885 DOI: 10.3791/62251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Microbubble contrast agents hold great promise for drug delivery applications with ultrasound. Encapsulating drugs in nanoparticles reduces systemic toxicity and increases circulation time of the drugs. In a novel approach to microbubble-assisted drug delivery, nanoparticles are incorporated in or on microbubble shells, enabling local and triggered release of the nanoparticle payload with ultrasound. A thorough understanding of the release mechanisms within the vast ultrasound parameter space is crucial for efficient and controlled release. This set of presented protocols is applicable to microbubbles with a shell containing a fluorescent label. Here, the focus is on microbubbles loaded with poly(2-ethyl-butyl cyanoacrylate) polymeric nanoparticles, doped with a modified Nile Red dye. The particles are fixed within a denatured casein shell. The microbubbles are produced by vigorous stirring, forming a dispersion of perfluoropropane gas in the liquid phase containing casein and nanoparticles, after which the microbubble shell self-assembles. A variety of microscopy techniques are needed to characterize the nanoparticle-stabilized microbubbles at all relevant timescales of the nanoparticle release process. Fluorescence of the nanoparticles enables confocal imaging of single microbubbles, revealing the particle distribution within the shell. In vitro ultra-high-speed imaging using bright-field microscopy at 10 million frames per second provides insight into the bubble dynamics in response to ultrasound insonation. Finally, nanoparticle release from the bubble shell is best visualized by means of fluorescence microscopy, performed at 500,000 frames per second. To characterize drug delivery in vivo, the triggered release of nanoparticles within the vasculature and their extravasation beyond the endothelial layer is studied using intravital microscopy in tumors implanted in dorsal skinfold window chambers, over a timescale of several minutes. The combination of these complementary characterization techniques provides unique insight into the behavior of microbubbles and their payload release at a range of time and length scales, both in vitro and in vivo.
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Deprez J, Lajoinie G, Engelen Y, De Smedt SC, Lentacker I. Opening doors with ultrasound and microbubbles: Beating biological barriers to promote drug delivery. Adv Drug Deliv Rev 2021; 172:9-36. [PMID: 33705877 DOI: 10.1016/j.addr.2021.02.015] [Citation(s) in RCA: 110] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/01/2021] [Accepted: 02/17/2021] [Indexed: 12/13/2022]
Abstract
Apart from its clinical use in imaging, ultrasound has been thoroughly investigated as a tool to enhance drug delivery in a wide variety of applications. Therapeutic ultrasound, as such or combined with cavitating nuclei or microbubbles, has been explored to cross or permeabilize different biological barriers. This ability to access otherwise impermeable tissues in the body makes the combination of ultrasound and therapeutics very appealing to enhance drug delivery in situ. This review gives an overview of the most important biological barriers that can be tackled using ultrasound and aims to provide insight on how ultrasound has shown to improve accessibility as well as the biggest hurdles. In addition, we discuss the clinical applicability of therapeutic ultrasound with respect to the main challenges that must be addressed to enable the further progression of therapeutic ultrasound towards an effective, safe and easy-to-use treatment tailored for drug delivery in patients.
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van Elburg B, Collado-Lara G, Bruggert GW, Segers T, Versluis M, Lajoinie G. Feedback-controlled microbubble generator producing one million monodisperse bubbles per second. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:035110. [PMID: 33820052 DOI: 10.1063/5.0032140] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Monodisperse lipid-coated microbubbles are a promising route to unlock the full potential of ultrasound contrast agents for medical diagnosis and therapy. Here, we present a stand-alone lab-on-a-chip instrument that allows microbubbles to be formed with high monodispersity at high production rates. Key to maintaining a long-term stable, controlled, and safe operation of the microfluidic device with full control over the output size distribution is an optical transmission-based measurement technique that provides real-time information on the production rate and bubble size. We feed the data into a feedback loop and demonstrate that this system can control the on-chip bubble radius (2.5 μm-20 μm) and the production rate up to 106 bubbles/s. The freshly formed phospholipid-coated bubbles stabilize after their formation to a size approximately two times smaller than their initial on-chip bubble size without loss of monodispersity. The feedback control technique allows for full control over the size distribution of the agent and can aid the development of microfluidic platforms operated by non-specialist end users.
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Lajoinie G, Segers T, Versluis M. High-Frequency Acoustic Droplet Vaporization is Initiated by Resonance. PHYSICAL REVIEW LETTERS 2021; 126:034501. [PMID: 33543968 DOI: 10.1103/physrevlett.126.034501] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/02/2020] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
Vaporization of low-boiling point droplets has numerous applications in combustion, process engineering, and in recent years, in clinical medicine. However, the physical mechanisms governing the phase conversion are only partly explained. Here, we show that an acoustic resonance can arise from the large speed of sound mismatch between a perfluorocarbon microdroplet and its surroundings. The fundamental resonance mode obeys a unique relationship kR∼0.65 between droplet size and driving frequency that leads to a threefold pressure amplification inside the droplet. Classical nucleation theory shows that this pressure amplification increases the nucleation rate by several orders of magnitude. These findings are confirmed by high-speed imaging performed at a timescale of 10 ns. The optical recordings demonstrate that droplets exposed to intense acoustic waves generated by interdigital transducers nucleate only if they match the theoretical resonance size.
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Versluis M, Stride E, Lajoinie G, Dollet B, Segers T. Ultrasound Contrast Agent Modeling: A Review. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:2117-2144. [PMID: 32546411 DOI: 10.1016/j.ultrasmedbio.2020.04.014] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 04/11/2020] [Accepted: 04/14/2020] [Indexed: 05/21/2023]
Abstract
Ultrasound is extensively used in medical imaging, being safe and inexpensive and operating in real time. Its scope of applications has been widely broadened by the use of ultrasound contrast agents (UCAs) in the form of microscopic bubbles coated by a biocompatible shell. Their increased use has motivated a large amount of research to understand and characterize their physical properties as well as their interaction with the ultrasound field and their surrounding environment. Here we review the theoretical models that have been proposed to study and predict the behavior of UCAs. We begin with a brief introduction on the development of UCAs. We then present the basics of free-gas-bubble dynamics upon which UCA modeling is based. We review extensively the linear and non-linear models for shell elasticity and viscosity and present models for non-spherical and asymmetric bubble oscillations, especially in the presence of surrounding walls or tissue. Then, higher-order effects such as microstreaming, shedding and acoustic radiation forces are considered. We conclude this review with promising directions for the modeling and development of novel agents.
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Lajoinie G, Visscher M, Blazejewski E, Veldhuis G, Versluis M. Three-phase vaporization theory for laser-activated microcapsules. PHOTOACOUSTICS 2020; 19:100185. [PMID: 32775197 PMCID: PMC7399189 DOI: 10.1016/j.pacs.2020.100185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/15/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
Precision control of vaporization, both in space and time, is critical for numerous applications, including medical imaging and therapy, catalysis and energy conversion, and it can be greatly improved through the use of micro- or nano-sized light absorbers. Ultimately, optimization of these applications also requires a fundamental understanding of the vaporization process. Upon laser irradiation, polymeric microcapsules containing a dye can vaporize, leading to the growth of a vapor bubble that emits a strong acoustic signature. Here, we compare laser-activated capsules containing either a volatile or a non-volatile oil core. We theoretically explore the vaporization of the capsules based on a three-phase thermodynamics model, that accounts for the partial vaporization of both the surrounding fluid and the oil core as well as for the interaction between heat transfer and microbubble growth. The model is compared to ultra-high-speed imaging experiments, where we record the cavitation events. Theory and experiments are in convincing agreement.
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Stride E, Segers T, Lajoinie G, Cherkaoui S, Bettinger T, Versluis M, Borden M. Microbubble Agents: New Directions. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:1326-1343. [PMID: 32169397 DOI: 10.1016/j.ultrasmedbio.2020.01.027] [Citation(s) in RCA: 107] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 01/09/2020] [Accepted: 01/26/2020] [Indexed: 05/24/2023]
Abstract
Microbubble ultrasound contrast agents have now been in use for several decades and their safety and efficacy in a wide range of diagnostic applications have been well established. Recent progress in imaging technology is facilitating exciting developments in techniques such as molecular, 3-D and super resolution imaging and new agents are now being developed to meet their specific requirements. In parallel, there have been significant advances in the therapeutic applications of microbubbles, with recent clinical trials demonstrating drug delivery across the blood-brain barrier and into solid tumours. New agents are similarly being tailored toward these applications, including nanoscale microbubble precursors offering superior circulation times and tissue penetration. The development of novel agents does, however, present several challenges, particularly regarding the regulatory framework. This article reviews the developments in agents for diagnostic, therapeutic and "theranostic" applications; novel manufacturing techniques; and the opportunities and challenges for their commercial and clinical translation.
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Gauthier A, Lajoinie G, Snoeijer JH, van der Meer D. Inverse leidenfrost drop manipulation using menisci. SOFT MATTER 2020; 16:4043-4048. [PMID: 32270805 DOI: 10.1039/c9sm02363a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Drops deposited on an evaporating liquid bath can be maintained in an inverse Leidenfrost state by the vapor emanating from the bath, making them levitate and hover without effective friction. These perfectly non-wetting droplets create a depression in the liquid interface that sustains their weight, which generates repellent forces when they approach a meniscus rising against a wall. Here, we study this reflection in detail, and show that frictionless Leidenfrost drops are a simple and efficient tool to probe the shape of an unknown interface. We then use the menisci to control the motion of the otherwise elusive drops. We create waveguides to direct and accelerate them and use parabolic walls to reflect and focus them. This could be particularly beneficial in the scale up of droplet cryopreservation processes: capillary interactions can be used to transport, gather and collect vitrified biological samples in absence of contact and contamination.
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de Matos MBC, Deckers R, van Elburg B, Lajoinie G, de Miranda BS, Versluis M, Schiffelers R, Kok RJ. Ultrasound-Sensitive Liposomes for Triggered Macromolecular Drug Delivery: Formulation and In Vitro Characterization. Front Pharmacol 2019; 10:1463. [PMID: 31866867 PMCID: PMC6906197 DOI: 10.3389/fphar.2019.01463] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 11/13/2019] [Indexed: 12/22/2022] Open
Abstract
Mistletoe lectin-1 (ML1) is a nature-derived macromolecular cytotoxin that potently induces apoptosis in target cells. Non-specific cytotoxicity to normal cells is one of the major risks in its clinical application, and we therefore propose to encapsulate ML1 in a nanocarrier that can specifically release its cargo intratumorally, thus improving the efficacy to toxicity ratio of the cytotoxin. We investigated the encapsulation of ML1 in ultrasound-sensitive liposomes (USL) and studied its release by high-intensity focused ultrasound (HAccessedIFU). USL were prepared by entrapment of perfluorocarbon nanodroplets in pegylated liposomes. The liposomes were prepared with different DPPC/cholesterol/DSPE-PEG2000 lipid molar ratios (60/20/20 for USL20; 60/30/10 for USL10; 65/30/5 for USL5) before combination with perfluorocarbon (PFC) nanoemulsions (composed of DPPC and perfluoropentane). When triggered with HIFU (peak negative pressure, 2-24 MPa; frequency, 1.3 MHz), PFC nanodroplets can undergo phase transition from liquid to gas thus rupturing the lipid bilayer of usl. Small unilamellar liposomes were obtained with appropriate polydispersity and stability. ML1 and the model protein horseradish peroxidase (HRP) were co-encapsulated with the PFC nanodroplets in USL, with 3% and 7% encapsulation efficiency for USL20 and USL10/USL5, respectively. Acoustic characterization experiments indicated that release is induced by cavitation. HIFU-triggered release of HRP from USL was investigated for optimization of liposomal composition and resulted in 80% triggered release for USL with USL10 (60/30/10) lipid composition. ML1 release from the final USL10 composition was also 80%. Given its high stability, suitable release, and ultrasound sensitivity, USL10 encapsulating ML1 was further used to study released ML1 bioactivity against murine CT26 colon carcinoma cells. Confocal live-cell imaging demonstrated its functional activity regarding the interaction with the target cells. We furthermore demonstrated the cytotoxicity of the released ML1 (I.E., After USL were treated with HIFU). The potent cytotoxicity (IC50 400 ng/ml; free ML1 IC50 345 ng/ml) was compared to non-triggered USL loaded with ML1. Our study shows that USL in combination with HIFU hold promise as trigger-sensitive nanomedicines for local delivery of macromolecular cytotoxins.
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Roovers S, Deprez J, Priwitaningrum D, Lajoinie G, Rivron N, Declercq H, De Wever O, Stride E, Le Gac S, Versluis M, Prakash J, De Smedt SC, Lentacker I. Sonoprinting liposomes on tumor spheroids by microbubbles and ultrasound. J Control Release 2019; 316:79-92. [PMID: 31676384 DOI: 10.1016/j.jconrel.2019.10.051] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/24/2019] [Accepted: 10/28/2019] [Indexed: 12/12/2022]
Abstract
Ultrasound-triggered drug-loaded microbubbles have great potential for drug delivery due to their ability to locally release drugs and simultaneously enhance their delivery into the target tissue. We have recently shown that upon applying ultrasound, nanoparticle-loaded microbubbles can deposit nanoparticles onto cells grown in 2D monolayers, through a process that we termed "sonoprinting". However, the rigid surfaces on which cell monolayers are typically growing might be a source of acoustic reflections and aspherical microbubble oscillations, which can influence microbubble-cell interactions. In the present study, we aim to reveal whether sonoprinting can also occur in more complex and physiologically relevant tissues, by using free-floating 3D tumor spheroids as a tissue model. We show that both monospheroids (consisting of tumor cells alone) and cospheroids (consisting of tumor cells and fibroblasts, which produce an extracellular matrix) can be sonoprinted. Using doxorubicin-liposome-loaded microbubbles, we show that sonoprinting allows to deposit large amounts of doxorubicin-containing liposomes to the outer cell layers of the spheroids, followed by doxorubicin release into the deeper layers of the spheroids, resulting in a significant reduction in cell viability. Sonoprinting may become an attractive approach to deposit drug patches at the surface of tissues, thereby promoting the delivery of drugs into target tissues.
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Roovers S, Lajoinie G, De Cock I, Brans T, Dewitte H, Braeckmans K, Versluis M, De Smedt SC, Lentacker I. Sonoprinting of nanoparticle-loaded microbubbles: Unraveling the multi-timescale mechanism. Biomaterials 2019; 217:119250. [DOI: 10.1016/j.biomaterials.2019.119250] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 05/20/2019] [Accepted: 06/05/2019] [Indexed: 12/12/2022]
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Li X, Wang Y, Zaytsev ME, Lajoinie G, Le The H, Bomer JG, Eijkel JCT, Zandvliet HJW, Zhang X, Lohse D. Plasmonic Bubble Nucleation and Growth in Water: Effect of Dissolved Air. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:23586-23593. [PMID: 31583035 PMCID: PMC6768170 DOI: 10.1021/acs.jpcc.9b05374] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 08/23/2019] [Indexed: 05/05/2023]
Abstract
Under continuous laser irradiation, noble metal nanoparticles immersed in water can quickly heat up, leading to the nucleation of so-called plasmonic bubbles. In this work, we want to further understand the bubble nucleation and growth mechanism. In particular, we quantitatively study the effect of the amount of dissolved air on the bubble nucleation and growth dynamics, both for the initial giant bubble, which forms shortly after switching on the laser and is mainly composed of vapor, and for the final life phase of the bubble, during which it mainly contains air expelled from water. We found that the bubble nucleation temperature depends on the gas concentration: the higher the gas concentration, the lower the bubble nucleation temperature. Also, the long-term diffusion-dominated bubble growth is governed by the gas concentration. The radius of the bubbles grows as R(t) ∝ t 1/3 for air-equilibrated and air-oversaturated water. In contrast, in partially degassed water, the growth is much slower since, even for the highest temperature we achieve, the water remains undersaturated.
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Roovers S, Segers T, Lajoinie G, Deprez J, Versluis M, De Smedt SC, Lentacker I. The Role of Ultrasound-Driven Microbubble Dynamics in Drug Delivery: From Microbubble Fundamentals to Clinical Translation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10173-10191. [PMID: 30653325 DOI: 10.1021/acs.langmuir.8b03779] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In the last couple of decades, ultrasound-driven microbubbles have proven excellent candidates for local drug delivery applications. Besides being useful drug carriers, microbubbles have demonstrated the ability to enhance cell and tissue permeability and, as a consequence, drug uptake herein. Notwithstanding the large amount of evidence for their therapeutic efficacy, open issues remain. Because of the vast number of ultrasound- and microbubble-related parameters that can be altered and the variability in different models, the translation from basic research to (pre)clinical studies has been hindered. This review aims at connecting the knowledge gained from fundamental microbubble studies to the therapeutic efficacy seen in in vitro and in vivo studies, with an emphasis on a better understanding of the response of a microbubble upon exposure to ultrasound and its interaction with cells and tissues. More specifically, we address the acoustic settings and microbubble-related parameters (i.e., bubble size and physicochemistry of the bubble shell) that play a key role in microbubble-cell interactions and in the associated therapeutic outcome. Additionally, new techniques that may provide additional control over the treatment, such as monodisperse microbubble formulations, tunable ultrasound scanners, and cavitation detection techniques, are discussed. An in-depth understanding of the aspects presented in this work could eventually lead the way to more efficient and tailored microbubble-assisted ultrasound therapy in the future.
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Koshkina O, Lajoinie G, Bombelli FB, Swider E, Cruz LJ, White PB, Schweins R, Dolen Y, van Dinther EAW, van Riessen NK, Rogers SE, Fokkink R, Voets IK, van Eck ERH, Heerschap A, Versluis M, de Korte CL, Figdor CG, de Vries IJM, Srinivas M. Multicore Liquid Perfluorocarbon-Loaded Multimodal Nanoparticles for Stable Ultrasound and 19F MRI Applied to In Vivo Cell Tracking. ADVANCED FUNCTIONAL MATERIALS 2019; 29:1806485. [PMID: 32132881 PMCID: PMC7056356 DOI: 10.1002/adfm.201806485] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Indexed: 05/22/2023]
Abstract
Ultrasound is the most commonly used clinical imaging modality. However, in applications requiring cell-labeling, the large size and short active lifetime of ultrasound contrast agents limit their longitudinal use. Here, 100 nm radius, clinically applicable, polymeric nanoparticles containing a liquid perfluorocarbon, which enhance ultrasound contrast during repeated ultrasound imaging over the course of at least 48 h, are described. The perfluorocarbon enables monitoring the nanoparticles with quantitative 19F magnetic resonance imaging, making these particles effective multimodal imaging agents. Unlike typical core-shell perfluorocarbon-based ultrasound contrast agents, these nanoparticles have an atypical fractal internal structure. The nonvaporizing highly hydrophobic perfluorocarbon forms multiple cores within the polymeric matrix and is, surprisingly, hydrated with water, as determined from small-angle neutron scattering and nuclear magnetic resonance spectroscopy. Finally, the nanoparticles are used to image therapeutic dendritic cells with ultrasound in vivo, as well as with 19F MRI and fluorescence imaging, demonstrating their potential for long-term in vivo multimodal imaging.
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Dewitte H, Engelen Y, Lajoinie G, Gomes-da-Silva L, Versluis M, Smedt SCD, Kroemer G, Breckpot K, Lentacker I. Abstract B151: Exploring the induction of immunogenic cell death (ICD) by high-intensity focused ultrasound (HIFU). Cancer Immunol Res 2019. [DOI: 10.1158/2326-6074.cricimteatiaacr18-b151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Immunogenic cell death (ICD) is an intriguing concept within cancer immunotherapy. Indeed, by inducing a specific means of cellular demise, a protective immune response can be triggered against the dying cells. As such, the dying cancer cells are—in a way—turned into a vaccine, attracting immune cells to the site of cell death, and activating them to trigger an anticancer immune response. Since the early discovery of ICD, more mechanistic insights into the hallmarks of ICD have been unraveled and several state-of-the-art cancer therapies have been identified as bona fide ICD inducers (1, 2).One of the cancer therapies which could be a potential candidate to induce ICD is high-intensity focused ultrasound (HIFU) (3). HIFU is currently used as a way of debulking solid tumors in a non-invasive, image-controlled and precise way without the use of ionizing radiation. Depending on the ultrasound parameters, tumor tissue can be ablated either in a mechanical (tissue disruption) or thermal way (heating and coagulative necrosis). Interestingly, there are some indications that HIFU may also affect the immune system: experiments in mice and man have shown attraction/activation of immune cells to/in the tumor site (4, 5). Of note: these immunostimulating effects were reported to be more prominent for mechanical HIFU than thermal HIFU. However, neither the mechanisms behind these observations, nor the possible link to the induction of ICD have been investigated. Therefore, the key aim of work is to investigate the potential of HIFU to induce ICD. Using a custom-designed HIFU set-up, we were able to—in a precise, automated and controlled way—expose B16F0 melanoma cells to HIFU in vitro. The HIFU-exposed tumor cells were subsequently evaluated for the occurrence of apoptosis and ICD hallmarks. More specifically, we evaluated the exposure of calreticulin (CRT) on the cell membrane and release of high mobility group box 1 (HMGB-1) and adenosine triphosphate (ATP). Our data show that application of mechanical HIFU protocols (using short, repeated ultrasound bursts) induce a significant fraction of apoptotic cells (as measured by a loss of mitochondrial membrane potential) within 4h after treatment. Importantly, already within the first hour after HIFU exposure, high levels of the ICD hallmark and Toll-like receptor 4 agonist HMGB-1 were found in the supernatant of the HIFU-treated cells, compared to untreated controls. To determine the effect of HIFU on ATP release, a quinacrine assay was performed to stain intracellular ATP-containing vesicles. Using flow cytometry, we observed that HIFU triggered exocytosis of these vesicles, with 2- to 3-fold reductions in quinacrine fluorescence at 4h and 24h after HIFU exposure, respectively. In addition, at 24h after HIFU exposure, >30% of the cells exposed CRT on the outer leaflet of the cell membrane, which was a drastic increase compared to blanks (<1% CRT exposure). Taken together, these results indicate that 3 key hallmarks of ICD can be detected after treatment of B16F0 melanoma cells with an optimized mechanical HIFU protocol. Currently, vaccination experiments are ongoing to determine whether HIFU-treated cells induce protective immunity in mice. If we could identify mechanical HIFU as a true ICD inducer, this might have important repercussions to how HIFU ablative therapies are applied in the clinic: modified HIFU regimens that not only focus on full ablation, but also trigger ICD could be envisaged to simultaneously tackle primary tumors as well as distant metastasis. Moreover, this could provide a solid basis for the rational combination of HIFU with other immunotherapies to strengthen the evoked immune response. References: 1. Galluzzi L, et al. Nature Reviews Immunology 2017. 2. Kroemer G, et al. Annual Review of Immunology 2013. 3. Blana A, et al. European Urology 2008. 4. Liu F, et al. Journal of Translational Medicine 2010. 5. Lu P, et al. Surgery 2009.
Citation Format: Heleen Dewitte, Yanou Engelen, Guillaume Lajoinie, Lígia Gomes-da-Silva, Michel Versluis, Stefaan C. De Smedt, Guido Kroemer, Karine Breckpot, Ine Lentacker. Exploring the induction of immunogenic cell death (ICD) by high-intensity focused ultrasound (HIFU) [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B151.
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Visscher M, Lajoinie G, Blazejewski E, Veldhuis G, Versluis M. Laser-activated microparticles for multimodal imaging: ultrasound and photoacoustics. Phys Med Biol 2019; 64:034001. [PMID: 30523821 DOI: 10.1088/1361-6560/aaf4a2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The increasing personalization of medical treatment demands refined imaging and increased monitoring capabilities, as well as an improved efficacy through targeted drug delivery. Such a transition in health care can be facilitated by the use of multimodal contrast agents. In this paper, we present a novel type of multimodal contrast agents, that enhances contrast both in ultrasound and in photoacoustic imaging, while at the same time being capable of triggered drug delivery. Upon pulsed laser irradiation, polymeric microparticles-containing a dye and an oil core-can create a cavitation bubble that subsequently emits a strong acoustic wave. We investigated different formulations of these particles, by changing the oil content, dye concentration and probing conditions using a combination of pulsed laser excitation and an ultrasound chirp. We demonstrated that capsules with a core containing a low boiling point oil give the highest photoacoustic and acoustic response. The laser activation threshold for this system is high in the visible range, but within the near infrared medical limits. The same system also produces a stable bubble. US scattering by these stable bubbles results in medically relevant frequencies, making the particles of interest for biomedical and pre-clinical imaging. Finally, the system has potential to carry a functional drug-load, and a route to these applications is discussed.
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