Tezel A, Sens A, Mitragotri SInvestigations of the role of cavitation in low-frequency sonophoresis using acoustic spectroscopy. J Pharm Sci 91:444-453

Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
Journal of Pharmaceutical Sciences (Impact Factor: 2.59). 02/2002; 91(2):444-53. DOI: 10.1002/jps.10024
Source: PubMed


Application of low-frequency ultrasound significantly enhances skin permeability. The enhancement of skin permeability is mediated by cavitation, oscillation, and collapse of gaseous cavities. In this article, we report detailed investigations of the occurrence of cavitation during low-frequency sonophoresis. Cavitation was monitored by recording pressure amplitudes of subharmonic emission and broadband noise at four different ultrasound frequencies in the range of 20-100 kHz and at various intensities in the range of 0-2.6 W/cm(2). Enhancement of skin conductivity, in the presence of sodium lauryl sulfate (SLS), was also measured under the same ultrasound conditions. Enhancement of skin conductivity correlated well with the amplitude of broadband noise, which suggests the role of transient cavitation in low-frequency sonophoresis. No correlation was found between the subharmonic pressure amplitude and conductivity enhancement.

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Available from: Samir Mitragotri, Apr 26, 2015
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    • "The explanation for increased transdermal permeability due to low-frequency ultrasound is linked to the thermal effects and is mainly attributed to the cavitation generated by the high vibrational frequency. Because of this cavitation, there is a micromassage effect that increases membrane permeability and protein synthesis (Tezel et al., 2002; Maruani et al., 2010). "
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    ABSTRACT: Abstract The aim of this study was to evaluate the effects of therapeutic pulsed ultrasound with gold nanoparticles on oxidative stress parameters after traumatic muscle injury in Wistar rats. The animals were randomly divided into nine groups (n = 6 each): sham (uninjured muscle); muscle injury without treatment; muscle injury and treatment with dimethyl sulfoxide (15 mg/kg); muscle injury and treatment with gold nanoparticles (27 µg); muscle injury and treatment with dimethyl sulfoxide + gold nanoparticles (Plus); muscle injury and therapeutic pulsed ultrasound; muscle injury and therapeutic pulsed ultrasound + dimethyl sulfoxide; muscle injury and therapeutic pulsed ultrasound + gold nanoparticles; and muscle injury and therapeutic pulsed ultrasound + Plus. Gastrocnemius injury was induced by a single-impact blunt trauma. Therapeutic pulsed ultrasound (6-min application, frequency 1.0 MHz, intensity 0.8 W/cm(2)) was used 2, 12, 24, and 48 h after trauma. Mitochondrial superoxide generation, lipid peroxidation, and protein carbonylation, and the activities of superoxide dismutase, glutathione peroxidase, and catalase were evaluated. The increase in the superoxide production and TBARS and carbonyl levels observed in the control group after muscle damage were reduced in animals exposed to therapeutic pulsed ultrasound plus nanoparticles. Similarly, antioxidants enzymes showed a decreased activity with the same treatment. Our work suggest that therapeutic pulsed ultrasound + dimethyl sulfoxide + gold nanoparticles has beneficial effects on the muscle healing process by inducing a decrease in oxidative stress parameters and most likely decreasing the deleterious effects of the inflammatory response.
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    • "At lower pressures, these cavities either reabsorb into the medium or remain relatively stable and oscillate with the sonic waveforms; this is referred to as stable cavitation. However, during transient cavitation such as occurs with higher intensity ultrasounds or lower frequencies, the cavities rapidly increase in size until at which point pressure becomes too great in the surrounding medium and the bubble collapses [17] "
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    ABSTRACT: Science has shown that risk of cavitation and hyperthermia following prenatal ultrasound exposure is relatively negligible provided intensity, frequency, duration of exposure, and total numbers of exposures are safely limited. However, noncavitational mechanisms have been poorly studied and occur within what are currently considered “safe” levels of exposure. To date, the teratogenic capacity of noncavitational effectors are largely unknown, although studies have shown that different forms of ultrasound-induced hydraulic forces and pressures can alter membrane fluidity, proliferation, and expression of inflammatory and repair markers. Loose regulations, poor end user training, and unreliable ultrasound equipment may also increase the likelihood of cavitation and hyperthermia during prenatal exposure with prolonged durations and increased intensities. The literature suggests a need for tighter regulations on the use of ultrasound and further studies into its teratogenicity.
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    • "TPU by transmitting as an acoustic pressure wave and indirectly applying mechanical stress to the tissues has been reported to promote protein synthesis, calcium uptake, and DNA synthesis in different cells [32-34]. Furthermore, ultrasound may enhance penetration of anti-inflammatory agents applied onto the skin in a technique called phonophoresis due to the cavitation phenomenon, the generation of gas bubbles, which oscillate and may implode at the skin surface, thus producing disorganization and/or an aqueous pathway through the stratum corneum [35-37]. Taking advantage of these properties, we introduced gold nanoparticles in the conductor gel of the pulsed ultrasound, as Figures 1, 2, and 3 show, antioxidant effects were observed. "
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