Abstract
Drug delivery systems (DDSs) face several challenges including site-specific delivery, stability, and the programmed release of drugs. Engineered nanoparticle (NP) surfaces with responsive moieties can enhance the efficacy of DDSs for in vitro and in vivo systems. This triggering process can be achieved through both endogenous (biologically controlled release) and exogenous (external stimuli controlled release) activation. In this review, we will highlight recent examples of the use of triggered release strategies of engineered nanomaterials for in vitro and in vivo applications.