Stimulus-responsive nanocarriers for targeted drug delivery

Abstract

Cancer is a multifactorial disease that involves unique tumor microenvironment (TEM) and abnormal organs with complex structures. Conventional anticancer drugs require high doses and systemic administration, and nonspecific tissue distribution causing serious side effects. Nanomaterials have far-reaching influences in cancer treatment, theranostics and imaging. Specifically, anticancer drug-loading into nanocarriers can avoid unnecessary systemic toxicity and achieve sustained drug release in response to all kinds of exogenous or endogenous stimuli. Nanocarriers can be stimulated by external (light irradiation and magnetic fields) or internal (pH, glutathione, enzymes and oxidative stress) elements, which have attracted growing attention in the field of drug delivery systems. On the basis of this powerful concept, environment-responsive nanocarriers have been designed to ensure delivery of the anticancer drug to the targeting lesion sites and effective release, which can overcome the biological barriers that limit conventional treatments and reduce the administered drug dose. Herein, this review will discuss the fundamentals of environment-responsive nanocarriers to enhance the permeability and retention (EPR) effect, and improve cancer therapy outcomes.