title: Effects of gold nanoparticles on the stability of microbubbles.
abstract: Surfactant-coated microbubbles are utilized in a wide variety of applications, from wastewater purification to contrast agents in medical ultrasound imaging. In many of these applications, the stability of the microbubbles is crucial to their effectiveness. Controlling this, however, represents a considerable challenge. In this study, the potential for stabilizing microbubbles using solid nanoparticles adsorbed onto their surfaces was explored. A new theoretical model has been developed to describe the influence of interfacially adsorbed solid particles upon the dissolution of a gas bubble in a liquid. The aim of this work was to test experimentally the prediction of the model that the presence of the nanoparticles would inhibit gas diffusion and coalescence/disproportionation, thus increasing the life span of the bubbles. Near-monodisperse microbubbles (~100 μm diameter) were prepared using a microfluidic device and coated with a surfactant, with and without the addition of a suspension of spherical gold nanoparticles (~15 nm diameter). The experimental results confirmed the theoretical predictions that as the surface concentration of gold nanoparticles increased the bubbles underwent negligible changes in their size and size distribution over a period of 30 days at the ambient temperature and pressure. Under the same conditions, bubbles coated with the same surfactant but no nanoparticles survived only a matter of hours.
authors.affiliation: Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Headington, UK.
authors.forename: Graciela
authors.initials: G
authors.lastname: Mohamedi
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Azmin
authors.forename: Isabel
authors.initials: I
authors.lastname: Pastoriza-Santos
authors.forename: Victoria
authors.initials: V
authors.lastname: Huang
authors.forename: Jorge
authors.initials: J
authors.lastname: Pérez-Juste
authors.forename: Luis M
authors.initials: LM
authors.lastname: Liz-Marzán
authors.forename: Mohan
authors.initials: M
authors.lastname: Edirisinghe
authors.forename: Eleanor
authors.initials: E
authors.lastname: Stride
mesh_terms: D000327:Adsorption; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D045423:Microbubbles; D010316:Particle Size; D011312:Pressure; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry; D013696:Temperature
chemical_list: D013501:Surface-Active Agents; D006046:Gold