Single-Particle Optical Sizing of Microbubbles

Satinover, Scott J.; Dove, Jacob D.; Borden, Mark A.

doi:10.1016/j.ultrasmedbio.2013.08.018

Cited by 28 publications

(26 citation statements)

References 29 publications

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“…19,20 Size distributions and concentrations of the probe-sonicated microbubbles were measured by electrical impedance sensing using the MultiSizer 3 (Beckman Coulter, Brea, CA), which was found to be more accurate than optical extinction. 21 For enhanced stability during condensation and re-vaporization, all experiments were done in C 4 F 10 (or C 3 F 8 ) saturated PBS solution. 20 This was accomplished by stirring and degassing PBS under house vacuum for 8 h and then repressurizing it by filling the head space with C 4 F 10 (or C 3 F 8 ) and stirring for 24 h, all at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Thermal Activation of Superheated Lipid-Coated Perfluorocarbon Drops

2015

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This study explored the thermal conditions necessary for the vaporization of superheated perfluorocarbon nanodrops. Droplets C3F8 and C4F10 coated with a homologous series of saturated diacylphosphatidylcholines were formed by condensation of 4 μm diameter microbubbles. These drops were stable at room temperature and atmospheric pressure, but they vaporized back into microbubbles at higher temperatures. The vaporization transition was measured as a function of temperature by laser light extinction. We found that C3F8 and C4F10 drops experienced 90% vaporization at 40 and 75 °C, respectively, near the theoretical superheat limits (80-90% of the critical temperature). We therefore conclude that the metastabilty of these phase-change agents arises not from the droplet Laplace pressure altering the boiling point, as previously reported, but from the metastability of the pure superheated fluid to homogeneous nucleation. The rate of C4F10 drop vaporization was quantified at temperatures ranging from 55 to 75 °C, and an apparent activation energy barrier was calculated from an Arrhenius plot. Interestingly, the activation energy increased linearly with acyl chain length from C14 to C20, indicating that lipid interchain cohesion plays an important role in suppressing the vaporization rate. The vaporized drops (microbubbles) were found to be unstable to dissolution at high temperatures, particularly for C14 and C16. However, proper choice of the fluorocarbon and lipid species provided a nanoemulsion that could undergo at least ten reversible condensation/vaporization cycles. The vaporization properties presented in this study may facilitate the engineering of tunable phase-shift particles for diagnostic imaging, targeted drug delivery, tissue ablation, and other applications.

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Section: Introductionmentioning

confidence: 99%

Thermal Activation of Superheated Lipid-Coated Perfluorocarbon Drops

2015

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“…They are widely used for dense multiphase flows in industrial processes and in microstructures as well, for example for biological cell counting and sizing [6][7][8][9][10][11]. In addition to complex and expensive equipments, the main disadvantage of these techniques is their dependence on the visibility of the measurement volume and on the focal distance.…”

Section: Introductionmentioning

confidence: 99%

In-situ particle sizing at millimeter scale from electrochemical noise: simulation and experiments

Yakdi

Huet

Ngo

2015

Electrochimica Acta

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Over the last few years, particle sizing techniques in multiphase flows based on optical technologies emerged as standard tools but the main disadvantage of these techniques is their dependence on the visibility of the measurement volume and on the focal distance. Thus, it is important to promote alternative techniques for particle sizing, and, moreover, able to work in hostile environment. This paper presents a single-particle sizing technique at a millimeter scale based on the measurement of the variation of the electrolyte resistance (ER) due to the passage of an insulating sphere between two electrodes immerged in a conductive solution. A theoretical model was proposed to determine the influence of the electrode size, the interelectrode distance, the size and the position of the sphere, on the electrolyte resistance. Experimental variations of ER due to the passage of spheres and measured by using a home-made electronic device are also presented in this paper. The excellent agreement obtained between the theoretical and experimental results allows validation of both model and experimental measurements. In addition, the technique was shown to be able to perform accurate measurements of the velocity of a ball falling in a liquid.

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“…Microbubbles with DFB gas cores and phospholipid shells formed spontaneously when agitated in a Vialmix device (Lantheus Medical Imaging, N. Billerica, MA). The concentration, and diameter of microbubbles in this emulsion was measured via (single particle) optical techniques (Accusizer 780, Particle Sizing Systems, Santa Barbara, CA, USA) (Satinover et al 2014). For targeted bubbles, a biotinylated PEG was used (DSPE-PEG2000-Biotin) (Zhao et al 2004) to replace 50% of the DSPE-PEG2000.…”

Section: Methodsmentioning

confidence: 99%

Molecular Acoustic Angiography: A New Technique for High-resolution Superharmonic Ultrasound Molecular Imaging

Shelton

Lindsey

Tsuruta

et al. 2016

Ultrasound in Medicine & Biology

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Ultrasound molecular imaging utilizes targeted microbubbles to bind to vascular targets such as integrins, selectins, and other extracellular binding domains. After binding, these microbubbles are typically imaged using low pressures and multi-pulse imaging sequences. In this article, we present an alternative approach for molecular imaging using ultrasound which relies on superharmonic signals produced by microbubble contrast agents. Bound bubbles were insonified near resonance using a low frequency (4 MHz) and superharmonic echoes were received at high frequencies (25–30 MHz). While this approach was observed to produce declining image intensity during repeated imaging in both in vitro and in vivo experiments due to bubble destruction, the feasibility of superharmonic molecular imaging was demonstrated for transmit pressures which are sufficiently high to induce shell disruption in bound microbubbles. This approach was validated using microbubbles targeted to the αvβ3 integrin in a rat fibrosarcoma model (n=5), and combined with superharmonic images of free microbubbles to produce high contrast, high resolution 3D volumes of both microvascular anatomy and molecular targeting. Image intensity over repeated scans and the effect of microbubble diameter were also assessed in vivo, indicating that larger microbubbles yield increased persistence in image intensity. Using ultrasound-based acoustic angiography images rather than conventional B-mode ultrasound to provide the underlying anatomical information facilitates anatomical localization of molecular markers. Quantitative analysis of relationships between microvasculature and targeting information indicated that most targeting occurred within 50 µm of a resolvable vessel (>100 µm diameter). The combined information provided by these scans may present new opportunities for analyzing relationships between microvascular anatomy and vascular targets, subject only to limitations of the current mechanically-scanned system and microbubble persistence to repeated imaging at moderate mechanical indices.

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Single-Particle Optical Sizing of Microbubbles

Cited by 28 publications

References 29 publications

Thermal Activation of Superheated Lipid-Coated Perfluorocarbon Drops

Thermal Activation of Superheated Lipid-Coated Perfluorocarbon Drops

In-situ particle sizing at millimeter scale from electrochemical noise: simulation and experiments

Molecular Acoustic Angiography: A New Technique for High-resolution Superharmonic Ultrasound Molecular Imaging

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