Photo-triggered capsules based on lanthanide-doped upconverting nanoparticles for medical applications

[Display omitted] •Photo-triggered capsules application in anticancer treatments.•Lanthanide‐doped crystals are used as upconverting nanoparticles.•Upconverting UV-sensitive capsules to visible light-triggered for medical application. The conversion of low-energy light into high-energy light, also known as upconversion, can be exploited in medicine (i.e. phototherapy, bioimaging), pharmacology (i.e. development of new drugs), consumer goods (i.e. development of new materials for cosmetic active compounds delivery). In this frame, lanthanides-based nanoparticles are fascinating examples of how upconverting nanoparticles can be employed to improve release in photo-responsive capsules. One of the main problems related to the use of such platforms is that the photo-triggered release is based on a limited range of available photochromic moieties, mostly responsive to UV or visible light irradiation. The short penetration length associated to these wavelengths make these systems hardly applicable in internal medical applications. NIR light, capable to penetrate biological tissues, is converted by lanthanide-based nanoparticles that can convert it to UV–vis, photo-triggering the moieties incorporated in the capsule shells and introducing the release of encapsulated materials. In this work a wide variety of photo-triggered capsules enhanced by the lanthanide-doped upconverting nanoparticles are reviewed. Finally, the aim of this review is to open an international discussion on this hot topic and to delight this platform technology as a novel powerful medical treatment.