Exogeneous-triggered Delivery in Localized Controlled Drug Delivery Systems (LCDDSs)

Stimuli-sensitive materials and micro/nanostructures can be manipulated to release their therapeutic drugs in the target site. The release is based on a particular extracellular/cellular stimuli, triggered via physical, biochemical, and chemical changes. The trigger may change the carrier structure/chemistry to release the therapeutic drug at a specific site. When a therapeutic drug is encapsulated with a stimuli-triggered material/polymer, the release may start with changes in structures like charge switching, surface layers de-shedding and degradation of materials. Furthermore, the disruption of the bonds may result in the release of therapeutic agents that are covalently immobilized in the functional groups of materials. Exogenous stimuli are the activation of reactions/phenomena from outside the body, such as ultrasound, temperature and light. Herein, we will describe thermosensitive, light sensitive, and ultrasound-sensitive controlled drug release of LCDDS, as the mentioned exogenous stimuli have been extensively used in LCDD applications.