Characterising the chemical and physical properties of phase-change nanodroplets

Zhang, W. et al. (2023) Characterising the chemical and physical properties of phase-change nanodroplets. Ultrasonics Sonochemistry, 97, 106445. (doi: 10.1016/j.ultsonch.2023.106445) (PMID:37257208)

Abstract

Phase-change nanodroplets have attracted increasing interest in recent years as ultrasound theranostic nanoparticles. They are smaller compared to microbubbles and they may distribute better in tissues (e.g. in tumours). They are composed of a stabilising shell and a perfluorocarbon core. Nanodroplets can vaporise into echogenic microbubbles forming cavitation nuclei when exposed to ultrasound. Their perfluorocarbon core phase-change is responsible for the acoustic droplet vaporisation. However, methods to quantify the perfluorocarbon core in nanodroplets are lacking. This is an important feature that can help explain nanodroplet phase change characteristics. In this study, we fabricated nanodroplets using lipids shell and perfluorocarbons. To assess the amount of perfluorocarbon in the core we used two methods, 19F-NMR and FTIR. To assess the cavitation after vaporisation we used an ultrasound transducer (1.1MHz) and a high-speed camera. The 19F-NMR based method showed that the fluorine signal correlated accurately with the perfluorocarbon concentration. Using this correlation, we were able to quantify the perfluorocarbon core of nanodroplets. This method was used to assess the content of the perfluorocarbon of the nanodroplets in solutions over time. It was found that perfluoropentane nanodroplets lost their content faster and at higher ratio compared to perfluorohexane nanodroplets. The high-speed camera showed that these nanodroplets have similar cavitation with commercial microbubbles. Nanodroplet characterisation should include perfluorocarbon concentration assessment as critical information for their development.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Metzger, Hilde and Prentice, Dr Paul
• Authors: Zhang, W., Metzger, H., Vlatakis, S., Claxton, A., Carbajal, M. A., Fung, L. F., Mason, J., Chan, K.L. A., Prentice, P., Fleck, R. A., Pouliopoulos, A. N., and Thanou, M.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Ultrasonics Sonochemistry
• Publisher: Elsevier
• ISSN: 1350-4177
• ISSN (Online): 1873-2828
• Published Online: 18 May 2023
• Copyright Holders: Copyright © 2023 The Authors
• First Published: First published in Ultrasonics Sonochemistry 97: 106445
• Publisher Policy: Reproduced under a Creative Commons License