Bubble Science, Engineering & Technology 

About: Bubble Science, Engineering & Technology is an academic journal. The journal publishes majorly in the area(s): Microbubbles & Bubble. Over the lifetime, 34 publications have been published receiving 892 citations.

Microbubble Compositions, Properties and Biomedical Applications

Abstract: Over the last decade, there has been significant progress towards the development of microbubbles as theranostics for a wide variety of biomedical applications. The unique ability of microbubbles to respond to ultrasound makes them useful agents for contrast ultrasound imaging, molecular imaging, and targeted drug and gene delivery. The general composition of a microbubble is a gas core stabilized by a shell comprised of proteins, lipids or polymers. Each type of microbubble has its own unique advantages and can be tailored for specialized functions. In this review, different microbubbles compositions and physiochemical properties are discussed in the context of current progress towards developing novel constructs for biomedical applications, with specific emphasis on molecular imaging and targeted drug/gene delivery.

Microbubble Generation in Phase-Shift Nanoemulsions used as Anticancer Drug Carriers.

Abstract: The paper describes droplet-to-bubble transition in block copolymer stabilized perfluoropentane nanoemulsions. Three physical factors that trigger droplet-to-bubble transition in liquid emulsions and gels were evaluated, namely heat, ultrasound, and injections through fine-gauge needles. Among those listed, ultrasound irradiation was found the most efficient factor. Possible mechanisms of bubble generation and growth discussed in the paper include liquid-to-gas transition inside the individual bubble; bubble coalescence; and diffusion of dissolved air and/or perfluoropentane from small bubbles into larger bubbles (i.e., Oswald ripening). The last two factors result in irreversibility of the droplet-to-bubble transition. In gel matrices, ultrasound-induced droplet-to-bubble transition was substantially inhibited but was catalyzed by large (hundred micron) pre-existing bubbles irradiated by low frequency (hundred kilohertz) ultrasound. The dependence of the droplet-to-bubble transition on initial bubble size is theoretically treated and the role of increase of surface area in promoting bubble coalescence is discussed. Therapeutic implications of observed effects are discussed.

Sonoporation at a low mechanical index

Abstract: The purpose of this study was to investigate the physical mechanisms of sonoporation, in order to understand and improve ultrasound-assisted drug and gene delivery. Sonoporation is the transient permeabilisation and resealing of a cell membrane with the help of ultrasound and/or an ultrasound contrast agent, allowing for the trans-membrane delivery and cellular uptake of macromolecules between 10 kDa and 3 MDa. The authors studied the behaviour of ultrasound contrast agent microbubbles near cancer cells at low acoustic amplitudes. After administering an ultrasound contrast agent, HeLa cells were subjected to 6·6 MHz ultrasound with a mechanical index of 0·2 and observed with a high-speed camera. Microbubbles were seen to enter cells and rapidly dissolve. The quick dissolution after entering suggests that the microbubbles lose (part of) their shell while entering. The authors have demonstrated that lipid-shelled microbubbles can be forced to enter cells at a low mechanical index. Hence, if a therap...

Acoustic responses of monodisperse lipid-encapsulated microbubble contrast agents produced by flow focusing.

Abstract: Lipid-encapsulated microbubbles are used as contrast agents in ultrasound imaging. Currently available commercially made contrast agents have a polydisperse size distribution. It has been hypothesised that improved imaging sensitivity could be achieved with a uniform microbubble radius. We have recently developed microfluidics technology to produce contrast agents with a nearly monodisperse distribution. In this manuscript, we analyze echo responses from individual microbubbles from monodisperse populations in order to establish the relationship between scattered echo, microbubble radius, and excitation frequency. Simulations of bubble response from a modified Rayleigh-Plesset type model corroborate experimental data. Results indicate that microbubble echo response can be greatly increased by optimal combinations of microbubble radius and acoustic excitation frequency. These results may have a significant impact in the formulation of contrast agents to improve ultrasonic sensitivity.

Frequencies of acoustically interacting bubbles

Abstract: Work on the frequencies of mutual acoustic oscillation of finite numbers of bubbles is reviewed. In many applications in medicine, industry and nature, multiple bubbles create multiple modes of oscillation. We focus only on the linear modes established transiently on acoustic excitation. The self-consistent coupled-oscillator theory is adopted. Progressively larger numbers of bubbles are described, examining both the natural frequency, and the damping of the system. Even a single bubble has interesting behaviour when close to a wall: the wall creates a mirror image coupled to the real bubble. As more bubbles are introduced, the number of modes of mutual oscillation increases, permitting increasingly more complex behaviour. A large number of bubbles in a chain gives rise to a preferred direction for the propagation of sound, owing to the re-distribution of energy to bubbles along the chain. Finally, some applications of these phenomena are discussed.