Smart polymeric carriers for drug delivery nanocarriers responsive to other stimuli

6 Smart polymeric carriers for drug delivery nanocarriers responsive to other stimuli 

Other than the nanocarriers responsive to the most common stimuli described above, there are various reports in the hterature on DDS that release their payload in response to other triggers, such as exogenous light, ultrasound and magnetic field, as well as endogenous glucose and ions.lhese are described briefly in the following subsections. 

Ultrasound is another non-invasive trigger that enables drug release from nanocarriers. Even though it is very promising, this application has not been extensively exploited to date. Exposure of a part of the body to ultrasound results in hyperthermia (which might also be useful for the release from the thermally responsive carriers described above) and high- and low-pressure 

In addition, there are reports suggesting that, through the application of ultrasound, the degradation times of biodegradable polymers can be increased (Kost et al., 1988). As an example, pluronic block copolymer micelles have been tested in combination with ultrasound, and an increased drug release rate was observed (Munshi et al., 1997). Interestingly, ultrasound has also been shown to increase cellular uptake and nucleus internalization of DOX-loaded pluronic micelles (Marin et al., 2001). 

In other recent work, Du et al. (2011) prepared DOX-loaded PLGA-mPEG nanobubbles, which demonstrated drug release only upon application of ultrasound. In addition, when administered in vivo 85% more tumour inhibitory effect was observed in the group treated with the nanoparticles combined with ultrasound, as compared to the nanoparticles without ultrasound (Du et al., 2011). 

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