title: Superhydrophobic silica nanoparticles as ultrasound contrast agents.
abstract: Microbubbles have been widely studied as ultrasound contrast agents for diagnosis and as drug/gene carriers for therapy. However, their size and stability (lifetime of 5-12min) limited their applications. The development of stable nanoscale ultrasound contrast agents would therefore benefit both. Generating bubbles persistently in situ would be one of the promising solutions to the problem of short lifetime. We hypothesized that bubbles could be generated in situ by providing stable air nuclei since it has been found that the interfacial nanobubbles on a hydrophobic surface have a much longer lifetime (orders of days). Mesoporous silica nanoparticles (MSNs) with large surface areas and different levels of hydrophobicity were prepared to test our hypothesis. It is clear that the superhydrophobic and porous nanoparticles exhibited a significant and strong contrast intensity compared with other nanoparticles. The bubbles generated from superhydrophobic nanoparticles sustained for at least 30min at a MI of 1.0, while lipid microbubble lasted for about 5min at the same settings. In summary MSNs have been transformed into reliable bubble precursors by making simple superhydrophobic modification, and made into a promising contrast agent with the potentials to serve as theranostic agents that are sensitive to ultrasound stimulation.
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Qiaofeng
authors.initials: Q
authors.lastname: Jin
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Chih-Yu
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Shih-Tsung
authors.initials: ST
authors.lastname: Kang
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: Yuan-Chih
authors.initials: YC
authors.lastname: Chang
authors.affiliation: Paul C. Lauterbur Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen China.
authors.forename: Hairong
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan. Electronic address: cmyang@mx.nthu.edu.tw.
authors.forename: Chia-Min
authors.initials: CM
authors.lastname: Yang
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan. Electronic address: ckyeh@mx.nthu.edu.tw.
authors.forename: Chih-Kuang
authors.initials: CK
authors.lastname: Yeh
keywords: Interfacial nanobubbles; Mesoporous silica nanoparticles; Superhydrophobic; Ultrasound contrast agents