Recent advances in light-responsive on-demand drug-delivery systems.

The convergence of wearable sensors and personalized medicine enhance the ability to sense and control the drug composition and dosage, as well as location and timing of administration. To date, numerous stimuli-triggered smart drug-delivery systems have been developed to detect changes in light, pH, temperature, biomolecules, electric field, magnetic field, ultrasound and mechanical forces. This review examines the major advances within the last 5 years for the three most common light-responsive drug delivery-on-demand strategies: photochemical, photoisomerization and photothermal. Examples are highlighted to illustrate progress of each strategy in drug delivery applications, and key limitations are identified to motivate future research to advance this important field.