Page 206 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

8.4 Ultrasonic-activated drug delivery 205

are investigated by this method [71]. The frequency, intensity, and pressure are set to
2
about 1 MHz, 0.3 W/cm , and 1.2 MPa. Only pulsed waves are used.
8.4.3.6 Chemotherapy-loaded liposomes attached to microbubbles and
ultrasound (US + Chemo loaded micelles attached to microbubbles)
Another method is attaching the drug-loaded liposomes to a microbubble with low-
intensity ultrasound. Diagnostic ultrasound is used to confirm the presence of the
loaded microbubbles within the tumor vasculature and accurately restricting the
delivery of the chemotherapeutic agent to the neoplastic cells by microbubbles.
The breast cancer tumors in mice, glioblastoma cells and melanoma cells are studied
by this method [71]. The frequency, intensity, and pressure are set to about 1–3 MHz,
2
2 W/cm , and 0.2–0.6 MPa. Only pulsed waves are used.
8.4.3.7 Chemotherapy in presence of ultrasound and magnetic
nanoparticles loaded onto microbubbles and (US + Chemo
loaded + magnetic nanoparticle loaded microbubbles)
Owen et al. and Zhao et al. developed the multimodality imaging, that is, magnetic
resonance (MR) imaging in addition to ultrasound imaging; by encapsulation of
iron oxide nanoparticles into the microbubble [82, 83]. Niu et al. developed such
a multifunctional theranostic agent in which pelvic limb lymph node metastases in
2
rabbits were imaged by both MR and ultrasound (0.3 MHz and 2 W/cm with pulsed
waves [84].
Summary of different approaches for US mediated chemotherapy are shown in
Fig. 8.7.

8.4.4 Ultrasound-mediated gene transfection
Ultrasound-mediated gene transfection (sonotransfection) has been developed as a
new method for gene therapy, especially for cancer gene therapy. Despite the sev-
eral advantages of sonotransfection, a low transfection rate is one of the major dis-
advantages of this method. To improve the transfection rate and the efficiency of
sonotransfection, using ultrasound and microbubbles to release or deliver the genes
directly into target cells and facilitate gene delivery to neoplastic cells is considered

FIGURE 8.7 Summary of different approaches for US mediated chemotherapy.