Studying the photothermal activation of polydopamine-shelled, phase-change emulsion droplets into microbubbles using small- and ultra-small-angle neutron scattering

Mark Louis P Vidallon; Joshua P King; Luke W Giles; Simon A Crawford; Chris Baldwin; Dino Premilovac; Boon Mian Teo; Alexis I Bishop; Liliana de Campo; Rico F Tabor

doi:10.1016/j.jcis.2024.01.004

Studying the photothermal activation of polydopamine-shelled, phase-change emulsion droplets into microbubbles using small- and ultra-small-angle neutron scattering

J Colloid Interface Sci. 2024 Apr:659:1029-1041. doi: 10.1016/j.jcis.2024.01.004. Epub 2024 Jan 6.

Authors

Affiliations

¹ School of Chemistry, Monash University, Clayton, VIC 3800, Australia; Molecular Imaging and Theranostics Laboratory, Baker Heart and Diabetes Institute, 75 Commercial Road, Melbourne, VIC 3004, Australia; Baker Department of Cardiometabolic Health, University of Melbourne, Parkville, VIC 3010, Australia; Baker Department of Cardiovascular Research, Translation and Implementation, La Trobe Institute for Molecular Science University of Melbourne, Parkville VIC 3010, Australia. Electronic address: [email protected].
² School of Chemistry, Monash University, Clayton, VIC 3800, Australia.
³ Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, VIC 3800, Australia.
⁴ Australian Nuclear Science and Technology Organization (ANSTO), New Illawarra Rd, Lucas Heights, NSW 2234, Australia.
⁵ Tasmanian School of Medicine, University of Tasmania, 17 Liverpool Street, Hobart, TAS, 7000, Australia.
⁶ School of Physics and Astronomy, Monash University, Clayton, VIC, 3800, Australia.
⁷ Australian Nuclear Science and Technology Organization (ANSTO), New Illawarra Rd, Lucas Heights, NSW 2234, Australia. Electronic address: [email protected].
⁸ School of Chemistry, Monash University, Clayton, VIC 3800, Australia. Electronic address: [email protected].

PMID: 38241974
DOI: 10.1016/j.jcis.2024.01.004

Abstract

Polydopamine-shelled perfluorocarbon (PDA/PFC) emulsion droplets are promising candidates for medical imaging and drug delivery applications. This study investigates their phase transition into microbubbles under near-infrared (NIR) illumination in situ using small- and ultra-small-angle neutron scattering (SANS and USANS) and contrast variation techniques. Supported by optical microscopy, thermogravimetric analysis, and ultrasound imaging, SANS and USANS results reveal rapid phase transition rates upon NIR illumination, dependent on PFC content and droplet size distribution. Specifically, perfluoropentane droplets rapidly transform into bubbles upon NIR irradiation, whereas perfluorohexane droplets exhibit greater resistance to phase change (bulk boiling points = 30 °C and 60 °C, respectively). Furthermore, smaller emulsion droplets with unimodal distribution resist NIR-triggered phase changes better than their bimodal counterparts. This observation is attributable to the lower boiling points of large emulsion droplets (lower Laplace pressure than smaller droplets) and the faster photothermal heating rates due to their thicker polydopamine shells. The insights gained from these techniques are crucial for designing phase-change emulsions activated by NIR for photothermal therapies and controlled drug delivery.

Keywords: Bubbles; Near-infrared; Neutron scattering; Phase-change emulsion; Polydopamine.