Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Radiol. Dec 28, 2013; 5(12): 468-471
Published online Dec 28, 2013. doi: 10.4329/wjr.v5.i12.468
Nano/microparticles and ultrasound contrast agents
Shu-Guang Zheng, Hui-Xiong Xu, Hang-Rong Chen
Shu-Guang Zheng, Hui-Xiong Xu, Department of Medical Ultrasound, Shanghai Tenth People’s Hospital, Tenth People’s Hospital of Tongji University, Shanghai 200072, China
Hang-Rong Chen, State Key Laboratory of High Performance Ceramic and Superfine Microstructures, Shanghai Institute of Ceramic Chinese Academy of Science, Shanghai 200050, China
Author contributions: Zheng SG, Xu HX and Chen HR conducted the literature research; Zheng SG wrote the paper; Xu HX edited and revised the paper.
Supported by National Natural Science Foundation of China, No. 81371570; Key Project from Shanghai Health Bureau, No. 20114003; Shanghai Talent Development Project from Shanghai Human Resource and Social Security Bureau, No. 2012045
Correspondence to: Hui-Xiong Xu, MD, PhD, Department of Medical Ultrasound, Shanghai Tenth People’s Hospital, Tenth People’s Hospital of Tongji University, No. 301 Yanchangzhong Road, Shanghai 200072, China.
Telephone: +86-21-66301031 Fax: +86-21-66301031
Received: July 17, 2013
Revised: October 31, 2013
Accepted: November 15, 2013
Published online: December 28, 2013

Microbubbles have been used for many years now in clinical practice as contrast agents in ultrasound imaging. Recently, their therapeutic applications have also attracted more attention. However, the short circulation time (minutes) and relatively large size (two to ten micrometers) of currently used commercial microbubbles do not allow effective extravasation into tumor tissue, preventing efficient tumor targeting. Fortunately, more multifunctional and theranostic nanoparticles with some special advantages over the traditional microbubbles have been widely investigated and explored for biomedical applications. The way to synthesize an ideal ultrasound contrast agent based on nanoparticles in order to achieve an expected effect on contrast imaging is a key technique. Currently a number of nanomaterials, including liposomes, polymers, micelles, dendrimers, emulsions, quantum dots, solid nanoparticles etc., have already been applied to pre or clinical trials. Multifunctional and theranostic nanoparticles with some special advantages, such as the tumor-targeted (passive or active), multi-mode contrast agents (magnetic resonance imaging, ultrasonography or fluorescence), carrier or enhancer of drug delivery, and combined chemo or thermal therapy etc., are rapidly gaining popularity and have shown a promising application in the field of cancer treatment. In this mini review, the trends and the advances of multifunctional and theranostic nanoparticles are briefly discussed.

Keywords: Ultrasound contrast agent, Microbubble, Nanoparticle, Imaging, Nanomaterial

Core tip: The theranostic nanoparticles are defined as nanoparticles with double functions (for both therapeutic and diagnostic purposes) and are commonly applied to simultaneous drug delivery and molecular imaging.