Stable Encapsulation of Air in Mesoporous Silica Nanoparticles: Fluorocarbon-Free Nanoscale Ultrasound Contrast Agents

Adem Yildirim, Rajarshi Chattaraj, Nicholas T. Blum, Galen M. Goldscheitter, Andrew P. Goodwin

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


While gas-filled micrometer-sized ultrasound contrast agents vastly improve signal-to-noise ratios, microbubbles have short circulation lifetimes and poor extravasation from the blood. Previously reported fluorocarbon-based nanoscale contrast agents are more stable but their contrast is generally lower owing to their size and dispersity. The contrast agents reported here are composed of silica nanoparticles of ≈100 nm diameter that are filled with ≈3 nm columnar mesopores. Functionalization of the silica surface with octyl groups and resuspension with Pluronic F127 create particles with pores that remain filled with air but are stable in buffer and serum. Administration of high intensity focused ultrasound (HIFU) allows sensitive imaging of the silica nanoparticles down to 1010 particles mL−1 , with continuous imaging for at least 20 min. Control experiments with different silica particles supported the hypothesis that entrapped air could be pulled into bubble nuclei, which can then in turn act as acoustic scatterers. This process results in very little hemolysis in whole blood, indicating potential for nontoxic blood pool imaging. Finally, the particles are lyophilized and reconstituted or stored in PBS (phosphate-buffered saline, at least for four months) with no loss in contrast, indicating stability to storage and reformulation.

Original languageEnglish (US)
Pages (from-to)1290-1298
Number of pages9
JournalAdvanced Healthcare Materials
Issue number11
StatePublished - Jun 8 2016
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biomaterials
  • Biomedical Engineering
  • Pharmaceutical Science


  • aur encapsulation
  • biomedical applications
  • imaging
  • mesoporous silica
  • surface science
  • ultrasound contrast agents


Dive into the research topics of 'Stable Encapsulation of Air in Mesoporous Silica Nanoparticles: Fluorocarbon-Free Nanoscale Ultrasound Contrast Agents'. Together they form a unique fingerprint.

Cite this