Theranostics 2019; 9(9):2572-2594. doi:10.7150/thno.32424

Research Paper

Colloids, nanoparticles, and materials for imaging, delivery, ablation, and theranostics by focused ultrasound (FUS)

Adem Yildirim1,2,✉, Nicholas T. Blum1, Andrew P. Goodwin1,✉

1. Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303 USA
2. Present address: CEDAR, Knight Cancer Institute, Oregon Health and Science University, Portland, OR, 97239 USA

Abstract

This review focuses on different materials and contrast agents that sensitize imaging and therapy with Focused Ultrasound (FUS). At high intensities, FUS is capable of selectively ablating tissue with focus on the millimeter scale, presenting an alternative to surgical intervention or management of malignant growth. At low intensities, FUS can be also used for other medical applications such as local delivery of drugs and blood brain barrier opening (BBBO). Contrast agents offer an opportunity to increase selective acoustic absorption or facilitate destructive cavitation processes by converting incident acoustic energy into thermal and mechanical energy. First, we review the history of FUS and its effects on living tissue. Next, we present different colloidal or nanoparticulate approaches to sensitizing FUS, for example using microbubbles, phase-shift emulsions, hollow-shelled nanoparticles, or hydrophobic silica surfaces. Exploring the science behind these interactions, we also discuss ways to make stimulus-responsive, or “turn-on” contrast agents for improved selectivity. Finally, we discuss acoustically-active hydrogels and membranes. This review will be of interest to those working in materials who wish to explore new applications in acoustics and those in acoustics who are seeking new agents to improve the efficacy of their approaches.

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How to cite this article:
Yildirim A, Blum NT, Goodwin AP. Colloids, nanoparticles, and materials for imaging, delivery, ablation, and theranostics by focused ultrasound (FUS). Theranostics 2019; 9(9):2572-2594. doi:10.7150/thno.32424. Available from http://www.thno.org/v09p2572.htm