Surfactant-stabilized contrast agent on the nanoscale for diagnostic ultrasound imaging

Microbubble size isolation by differential centrifugation

“…A significant portion of the freshly generated suspension contained submicrometer microbubbles, as previously reported [31]. Submicrometer microbubbles also have been observed by static light scattering [25] and freeze-fracture transmission electron microscopy [32]. For larger microbubbles, the number-weighted distribution tailed off near 6-8 μm diameter (Fig.…”

“…Wheatley et al reported the isolation of submicrometer bubbles using differential centrifugation [25]. Isolation was accomplished by flotation at normal gravity, or centrifugation at a relative centrifugal force (RCF) of 16 or 45 for pre-determined time intervals.…”

“…The lipid shell is highly viscous [28] and relatively impermeable to gases [29]. We therefore sought to further develop the differential centrifugation method of Wheatley et al [25], but as a rapid and facile means to isolate subpopulations of lipid-coated microbubbles. Below, we report on the experimental characterization of the initial polydisperse suspension, the development of a method to isolate size fractions of interest for biomedical applications, and characterization of the long-term stability of the isolated fractions.…”

A comparative study of microbubble generation by mechanical agitation and sonication

“…In this study, special attention has been paid to measure bubble sizes in the same conditions (e.g., sampling at the same position and timing, and recording as soon as possible). Although several instrumental methods are available for particle size analysis, some of them are unsuitable for measuring highly mobile species such as bubbles (Wheatley, Forsberg, Dube, Patel, & Oeffinger, 2006); another problem is that they could not meet the requirement of measuring the bubble size within a short time. Since a combined use of imaging analysis and instrumental analysis may provide more accurate information about the size and stability of microbubbles, the development of new techniques for measuring microbubbles is urgently required.…”

Soybean-based Surfactants and Their Applications

“…The former are referred to as bubbles while the latter are referred to as foams [Xu et al, 2008b]. Numerous studies have been performed on the use of microubbles as ultrasound contrast agents [Wheatley et al, 2006] and as delivery systems for drugs and genes [Tsutsui et al, 2004]. The application of microbubbles has been extended to aquaculture, hydroponic cultivation, water purification, and sewage treatment [Onari, 2005;Takahashi, 2005].…”