Stable Encapsulation of Air in Mesoporous Silica Nanoparticles: Fluorocarbon‐Free Nanoscale Ultrasound Contrast Agents
Year: 2016
Type: article
Abstract: 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 10(10) 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.
Source: Advanced Healthcare Materials
Institutions: University of Colorado Boulder, University of Colorado System
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Awards: G1656111833, G2141611582, G2300162859
OpenAlex ID: W2298250374