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  • Acoustical Society of America (ASA)  (5)
  • de Jong, Nico  (5)
  • van Rooij, Tom  (5)
  • Comparative Studies. Non-European Languages/Literatures  (5)
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  • Acoustical Society of America (ASA)  (5)
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  • Comparative Studies. Non-European Languages/Literatures  (5)
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  • 1
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2015
    In:  Journal of the Acoustical Society of America Vol. 137, No. 4_Supplement ( 2015-04-01), p. 2252-2253
    In: Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 137, No. 4_Supplement ( 2015-04-01), p. 2252-2253
    Abstract: One of the main challenges for ultrasound molecular imaging is acoustically distinguishing non-bound microbubbles from those that have bound to their molecular target. We previously showed that biotinylated DPPC-based microbubbles (16 C-atoms) had a larger binding area and a more domed shape when bound to a streptavidin-coated surface than DSPC-based microbubbles (18 C-atoms) [1]. In the present in vitro study, we used the Brandaris 128 ultrahigh-speed camera (~15 Mfps) to compare the acoustical responses of biotinylated DPPC and DSPC-based microbubbles in a non-bound configuration and bound to a streptavidin-coated membrane, aiming to acoustically discriminate them from each other. The microbubbles were driven at a pressure of 50 kPa and at frequencies between 1 and 4 MHz. The main difference between bound and non-bound microbubbles was the lower radial excursion at the fundamental frequency for bound microbubbles. Resonance frequencies and subharmonic responses were the same for bound and non-bound microbubbles. Finally, at the second harmonic frequency, we found higher relative radial excursions for bound DSPC-based microbubbles than for non-bound DSPC microbubbles, whilst there was no difference for DPPC-based microbubbles. This might provide opportunities to acoustically discriminate bound from non-bound DSPC microbubbles. [1] Kooiman et al., Eur. J. Lipid Sci. Technol. (2014).
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2015
    detail.hit.zdb_id: 1461063-2
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  • 2
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2015
    In:  The Journal of the Acoustical Society of America Vol. 137, No. 4 ( 2015-04-01), p. 1693-1703
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 137, No. 4 ( 2015-04-01), p. 1693-1703
    Abstract: An optical characterization method is presented based on the use of the impulse response to characterize the damping imparted by the shell of an air-filled ultrasound contrast agent (UCA). The interfacial shell viscosity was estimated based on the unforced decaying response of individual echogenic liposomes (ELIP) exposed to a broadband acoustic impulse excitation. Radius versus time response was measured optically based on recordings acquired using an ultra-high-speed camera. The method provided an efficient approach that enabled statistical measurements on 106 individual ELIP. A decrease in shell viscosity, from 2.1 × 10−8 to 2.5 × 10−9 kg/s, was observed with increasing dilatation rate, from 0.5 × 106 to 1 × 107 s−1. This nonlinear behavior has been reported in other studies of lipid-shelled UCAs and is consistent with rheological shear-thinning. The measured shell viscosity for the ELIP formulation used in this study [κs = (2.1 ± 1.0) × 10−8 kg/s] was in quantitative agreement with previously reported values on a population of ELIP and is consistent with other lipid-shelled UCAs. The acoustic response of ELIP therefore is similar to other lipid-shelled UCAs despite loading with air instead of perfluorocarbon gas. The methods described here can provide an accurate estimate of the shell viscosity and damping for individual UCA microbubbles.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2015
    detail.hit.zdb_id: 1461063-2
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  • 3
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2014
    In:  The Journal of the Acoustical Society of America Vol. 135, No. 4_Supplement ( 2014-04-01), p. 2370-2370
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 135, No. 4_Supplement ( 2014-04-01), p. 2370-2370
    Abstract: Microbubbles (MBs) can be coated with different lipids, but exact influences on acoustical responses remain unclear. The distribution of lipids in the coating of homemade MBs is heterogeneous for DSPC and homogeneous for DPPC-based MBs, as observed with 4Pi confocal microscopy. In this study, we investigated whether DSPC and DPPC MBs show a different vibrational response to ultrasound. MBs composed of main lipid DSPC or DPPC (2 C-atoms less) with a C4F10 gas core, were made by sonication. Microbubble spectroscopy was performed by exciting single MBs with 10-cycle sine wave bursts having a frequency from 1 to 4 MHz and a peak negative pressure of 10, 20, and 50 kPa. The vibrational response to ultrasound was recorded with the Brandaris 128 high-speed camera at 15 Mfps. Larger acoustically induced deflation was observed for DPPC MBs. For a given resting diameter, the resonance frequency was higher for DSPC, resulting in higher shell elasticity of 0.26 N/m as compared to 0.06 N/m for DPPC MBs. Shell viscosity was similar (~10-8 kg/s) for both MB types. Non-linear behavior was characterized by the response at the subharmonic and second harmonic frequencies. More DPPC (71%) than DSPC MBs (27%) showed subharmonic response, while the behavior at the second harmonic frequency was comparable. The different acoustic responses of DSPC and DPPC MBs are likely due to the choice of the main lipid and the corresponding spatial distribution in the MB coating.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2014
    detail.hit.zdb_id: 1461063-2
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  • 4
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2017
    In:  The Journal of the Acoustical Society of America Vol. 141, No. 5_Supplement ( 2017-05-01), p. 4012-4012
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 141, No. 5_Supplement ( 2017-05-01), p. 4012-4012
    Abstract: Ultrasound insonification of gas filled microbubbles can be used to locally enhance vascular drug delivery [1]. Understanding of the underlying mechanisms requires an in vitro endothelial cell model that includes 3D cell culture and flow. We propose to use the elaborate microchannel system in the OrganoPlate™ [2] . Since it has never been used with ultrasound before, we assessed the feasibility of acoustic transmission. The oscillation of microbubbles in the OrganoPlate™ was recorded during ultrasound insonification (50 kPa, 1-4 MHz, 8 cycles) using the Brandaris 128 ultra-high-speed camera at 17 Mfps. We compared these oscillations to measurements performed in an acoustically transparent OptiCell [3]. From 1 to 1.6 MHz, larger oscillation amplitudes were observed in the OrganoPlate™, resulting from pressure amplification in the microchannels. Finite element modeling of wave propagation using PZFlex supported our findings. Successful sonoporation of 3D cultured endothelial cells was achieved in preliminary experiments using CD31 targeted microbubbles. The obtained microbubble oscillations and successful sonoporation demonstrate the potential of the OrganoPlate™ for an ideal in vitro model to investigate ultrasound-mediated drug delivery. [1] Kooiman, et al., Adv. Drug Deliv. Rev., 2014. [2] Trietsch, et al., Lab Chip, 2013. [3] van Rooij, et al., Ultrasound Med. Biol., 2015.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2017
    detail.hit.zdb_id: 1461063-2
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  • 5
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2014
    In:  The Journal of the Acoustical Society of America Vol. 135, No. 4_Supplement ( 2014-04-01), p. 2310-2310
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 135, No. 4_Supplement ( 2014-04-01), p. 2310-2310
    Abstract: Echogenic liposomes (ELIP) are under development as theragnostic ultrasound contrast agents for the diagnosis and treatment of cardiovascular disease. ELIP formulations have a phospholipid bilayer shell and are echogenic due to the presence of air; however, the exact location of the entrapped air has not been fully ascertained. Air pockets could either be stabilized by lipid monolayers within the liposome, or by the lipid bilayer shell. Our goal is to develop a more complete understanding of the encapsulation and shell properties of ELIP. This study demonstrates a method to estimate the damping coefficient using experimentally measured radius-time curves of the impulse response of individual ELIP using optical methods. The non-dimensional damping coefficient and the natural frequency of oscillation were estimated based on 140 individual impulse responses as measured with the Brandaris 128 fast-framing camera (15 Mfps) at 37°C. The damping coefficient was in agreement with the damping coefficient as measured previously using a broadband acoustic technique [Raymond et al., Ultrasound Med Biol. 40(2), 410–421 (2014)]. However, the natural frequency of oscillation was lower than previously reported.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2014
    detail.hit.zdb_id: 1461063-2
    Library Location Call Number Volume/Issue/Year Availability
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