Annals of Biomedical Engineering

, Volume 46, Issue 2, pp 222–232 | Cite as

In Vitro Sonothrombolysis Enhancement by Transiently Stable Microbubbles Produced by a Flow-Focusing Microfluidic Device

  • Adam J. Dixon
  • John Marschner Robert Rickel
  • Brian D. Shin
  • Alexander L. Klibanov
  • John A. HossackEmail author


Therapeutic approaches that enhance thrombolysis by combining recombinant tissue plasminogen activator (rtPA), ultrasound, and/or microbubbles (MBs) are known as sonothrombolysis techniques. To date, sonothrombolysis approaches have primarily utilized commercially available MB formulations (or derivatives thereof) with diameters in the range 1–4 µm and circulation lifetimes between 5 and 15 min. The present study evaluated the in vitro sonothrombolysis efficacy of large diameter MBs (d MB ≥ 10 µm) with much shorter lifetimes that were produced on demand and in close proximity to the blood clot using a flow-focusing microfluidic device. MBs with a N2 gas core and a non-crosslinked bovine serum albumin shell were produced with diameters between 10 and 20 µm at rates between 50 and 950 × 103 per second. Use of these large MBs resulted in approximately 4.0–8.8 fold increases in thrombolysis rates compared to a clinical rtPA dose and approximately 2.1–4.2 fold increases in thrombolysis rates compared to sonothrombolysis techniques using conventional MBs. The results of this study indicate that the large diameter microbubbles with transient stability are capable of significantly enhanced in vitro sonothrombolysis rates when delivered directly to the clot immediately following production by a flow focusing microfluidic device placed essentially in situ adjacent to the clot.


Thromboembolism Sonothrombolysis Microfluidics Microbubbles Ultrasound 



Partial support for this research is provided by the National Institutes of Health under Grant NIH S10 RR025594 to JAH and by NSF GRFP and Virginia Space Grant Consortium pre-doctoral fellowships to AJD. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH, NSF, or VGSC.

Supplementary material

10439_2017_1965_MOESM1_ESM.gif (3 mb)
Supplementary Video 1: Video (30 FPS) of 25 s of a sonothrombolysis experiment (Group F). The effect of radiation force on the stream of MBs is evident as the stream is pushed onto the surface of the clot when the ultrasound is on, and is separated from the clot when the ultrasound is off. The experiments were performed with 2 s of ultrasound application followed by 2 s of no ultrasound, repeated for the 30 min duration of the experiment. Supplementary material 1 (GIF 3066 kb)

Supplementary Video 2: Compilation of still images taken at 1 min intervals during a 30 min sonothrombolysis experiment (Group F). For reference, the ID of the tube is 3.05 mm. Supplementary material 2 (WMV 3174 kb)


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Copyright information

© Biomedical Engineering Society 2017

Authors and Affiliations

  • Adam J. Dixon
    • 1
  • John Marschner Robert Rickel
    • 1
  • Brian D. Shin
    • 1
  • Alexander L. Klibanov
    • 1
    • 2
  • John A. Hossack
    • 1
    Email author
  1. 1.Department of Biomedical EngineeringUniversity of VirginiaCharlottesvilleUSA
  2. 2.School of Medicine – Cardiovascular DivisionUniversity of VirginiaCharlottesvilleUSA

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