Cavitation-induced release of liposomal chemotherapy in orthotopic murine pancreatic cancer models: A feasibility study.

Unlabelled: Targeted and triggered release of liposomal drug using ultrasound (US) induced cavitation represents a promising treatment modality to increase the therapeutic-toxicity ratio of encapsulated chemotherapy.

Objectives: To study the feasibility and efficacy of a combination of focused US and liposomal doxorubicin (US-L-DOX) release in orthotopic murine models of pancreatic cancer.

Material And Methods: A confocal US setup was developed to generate US inertial cavitation delivery in a controlled and reproducible manner and designed for two distinct murine orthotopic pancreatic cancer models.

Therapeutic efficacy of the combination of doxorubicin-loaded liposomes with inertial cavitation generated by confocal ultrasound in AT2 Dunning rat tumour model.

The combination of liposomal doxorubicin (DXR) and confocal ultrasound (US) was investigated for the enhancement of drug delivery in a rat tumour model. The liposomes, based on the unsaturated phospholipid dierucoylphosphocholine, were designed to be stable during blood circulation in order to maximize accumulation in tumour tissue and to release drug content upon US stimulation. A confocal US setup was developed for delivering inertial cavitation to tumours in a well-controlled and reproducible manner.

In vivo monitoring of liposomal release in tumours following ultrasound stimulation.

Dioeleoylphosphatidylethanolamine (DOPE)-based liposomes were recently reported as a new class of liposomes for ultrasound (US)-mediated drug delivery. The liposomes showed both high stability and in vitro US-mediated drug release (sonosensitivity). In the current study, in vivo proof-of-principle of US triggered release in tumoured mice was demonstrated using optical imaging.

Reflection and transmission at normal incidence onto air-saturated porous materials and direct measurements based on parametric demodulated ultrasonic waves.

The present work is related to the characterization of air-saturated porous media by using parametric demodulated ultrasonic waves. One uses two different powerful ultrasonic emitters working either at 47 kHz or at 162 kHz which are electronically amplitude modulated over the 200 Hz-4 kHz or 2 kHz-40 kHz bandwidths respectively. The demodulation process takes place in air, due to its nonlinearity enabling to generate audio range acoustical waves or alternatively low frequency ultrasonic waves which can be used to characterize porous materials in the reflection configuration at normal incidence.

Ultrasonic cavitation in thin liquid layers.

The generation of ultrasonic cavitation in a thin liquid layer trapped between a large radiating surface and a hard reflector and bounded laterally by a gas-liquid interface is investigated. The theoretical analysis predicts that a large amplification of the acoustical pressure is obtained with this configuration. Experiments are conducted by driving the layer with horn-type transducers having a large emitting surface.

Experimental and theoretical investigation of the mean acoustic pressure in the cavitation field.

The cavitation field radiated by a 20 kHz sonotrode-type transducer is experimentally and theoretically analyzed. Special interest is paid to the origin of the strong fluid streaming appearing in low frequency sonoreactors. A new experimental procedure is proposed to evaluate the mean acoustic pressure inside the fluid.

Cone-like bubble formation in ultrasonic cavitation field.

A new phenomenon in ultrasonic cavitation field is reported. Cavitation bubbles are observed to self-arrange in a cone-like macrostructure in the vicinity of transducer radiating surface. The cone-like macrostructure is stable while its branch-like pattern microstructure changes rapidly.

Self-induced hysteresis for nonlinear acoustic waves in cracked material.

A new phenomenon of self-induced hysteresis has been observed in the interaction of bulk acoustic waves with a cracked solid. It consists in a hysteretic behavior of material nonlinearity as a function of the incident pump wave amplitude. Hysteresis manifests itself in the self-action of the monochromatic pump wave and in the excitation of its superharmonics and of its subharmonics.