External stimuli-responsive drug delivery systems

Over the last decade, numerous nanomaterial platforms have been established as carrier systems to deliver diverse payloads such as drugs, nucleic acids, peptides, and proteins. Nanoparticles, as drug carriers, possess several advantages, namely high drug loading capacity, target specific delivery, reduced drug toxicity, and controlled drug release. Although active and passive targeting has addressed several important issues, additional modifications to the nanocarrier for attaining spatiotemporal drug release are essential. Spurred by recent advances in material sciences and drug delivery, the fabrication of stimuli-responsive drug delivery systems has gained enormous attention. Controlled by endogenous changes occurring in a diseased condition or by external devices, stimuli-responsive nanocarriers provide enhanced spatiotemporal control, rapid therapeutic effect, and lesser adverse effects at the target site. Recently, external stimuli-responsive drug delivery systems (ultrasound, magnetic, electric, light, and stretch) have gained significant attention as they can be applied remotely allowing spatiotemporal control. This chapter provides insights into recent progress in the field of external stimuli-responsive nanocarriers with a detailed focus on their design, therapeutic benefits, and drug release performance.