Stimulus-Responsive Nanoparticles for Drug Delivery

The effectiveness of nanoparticles in drug delivery can be augmented using strategies that make these systems responsive to disease-specific (endogenous) or externally applied (exogenous) stimuli. Responsiveness to these stimuli can be bestowed with the inclusion of relevant stimulus-sensitive components and/or chemical bonds in the nanoparticulate structure. Stimulus-responsive nanocarriers can allow spatial and/or temporal control in the release and/or activation of their payload. Spatiotemporally controlled drug release and/or activation can improve the targeting capability of the nanoparticles and can optimize the disease-specific activity of their drug payloads, while reducing off-target effects. Nanocarriers have been specially constructed to respond to disease-specific stimuli, such as overexpressed enzymes, pH differentials, high glucose concentration, reactive oxygen species, a reducing environment, and/or hypoxia, as well as to externally applied stimuli that are based on different forms of energy, including thermal or acoustic energy, and electromagnetic radiation. Nanocarriers that respond to more than one stimulus, i.e. multi-stimuli-responsive systems, have also been designed for multimodal drug delivery.