Ultrasound-responsive systems

Keywords Cavitation Mechanical effects Mechanotransduction Self-assembly Streaming Ultrasound-responsive systems... 

Besides the heavily studied pH-, temperature-, redox-, and light-responsive nanoassemblies, some other stimulus-responsive nanoassemblies such as magnetic field and ultrasound-responsive systems have also been explored and are reviewed." In addition, many multiresponsive nanoassemblies have been explored to achieve multiple functionalities. For example, many nanoassemblies dually responsive to both pH and temperature have been synthesized using copolymers containing pH- and temperature-responsive components. 

Enhanced (up to 20 times baseline) polymer erosion and drug release were observed when bioerodible samples were exposed to ultrasound. The system s response to the ultrasonic triggering was also rapid (within 2 min) and reversible. This was determined by an on-line UV spectrophotometric response in a closed-loop detection system where the concentration of the releasing agent was continuously monitored (42). 

Ultrasound is an important local stimulus for triggering drug release at the target tissue. Ultrasound-responsive drug delivery systems have become an important research focus in targeted therapy. 

Uesugi, Y., Kawata, H., Jo, J., Salto, Y, Thbata, Y. (2010). An ultrasound-responsive nano delivery system of tissue-type plasminogen activator for thrombol5fric therapy,/ Control. Release, 147,269-277. 

Ultra-sound emissions typically occur when male rodents are exposed to female odours or altricial neonates to maternal sources (Whitney, 1974 Conely and Bell, 1978). Without the VNO, sexually inexperienced male mice do not utter emissions at ultra-high frequencies (UHF), whereas those with prior experience vocalise after VN-x, as discussed above (Chap. 5). Female mouse urine contains a unique UHF-eliciting component which is non-volatile but ephemeral (Sipos et al., 1995). The signal is degraded by oxidation and disappears within 15 to 18 hours of deposition. Direct contact with freshly voided urine must occur before males will vocalise (sexually experienced or inexperienced). At least one of the olfactory systems is needed for UHF to be elicited by fresh urine complete deafferentation abolishes the response (Sipos et al., 1993). Exposure to females permits UHF to be elicited by other than chemical cues (Labov and Wysocki, 1989). Nocturnal or cryptic species conceivably use ultrasound to advertise male presence whether this is to deter other males or assist with female location is unclear. 

Industry uses special devices similar to ultrasonic baths and probes but appropriately scaled up in size and ultrasound irradiation power. The UIP16000 model from Hielscher Ultrasound Technology is by far the most powerful ultrasonic processor available worldwide the apparatus is capable of delivering a continuous power of 16000 W at efficiency above 80%. Such powerful systems have been developed in response to the demand for the ultrasonic treatment of liquids on a large scale in fact, the ultrasound power required usually increases in proportion to the amount of liquid to be treated within a certain time. 

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