Photoswitchable Molecules in Long-Wavelength Light-Responsive Drug Delivery: From Molecular Design to Applications

Stimuli-responsive nanocarriers can release their bioactive cargo "on demand", potentially improving the selectivity, specificity, and efficacy of therapeutic drugs. Light of wavelengths between 650-1100 nm is a unique stimulus with many advantages. It is noninvasive and "bio-friendly" and can be manipulated with precision and ease. Many light-responsive nanocarriers reported in the literature employ photochromic molecules that undergo reversible isomerization upon irradiation, thereby functioning as gates or switches for the release of encapsulated bioactive compounds. This review surveys the design, synthesis, function, and application of one photon visible and near-infrared light-triggered photoswitchable compounds in the development of long-wavelength light-responsive nanocarriers.