title: Upconversion nanoparticles as versatile light nanotransducers for photoactivation applications.
abstract: Remote activation of photoactivable therapeutic compounds by light provides a high spatial and temporal control for activating the therapeutic agent. However, photoactivable compounds are mostly responsive towards ultraviolet (UV) or visible light radiation that has poor tissue penetration depth besides being unsafe to the body in the case of UV light. Nanoparticles with energy upconversion hold potential in overcoming this limit by using safe and deeply penetrating near-infrared (NIR) light. These upconversion nanoparticles (UCNs) act as versatile nanotransducers as they convert NIR light to light of shorter wavelengths that can be tuned to the NIR, visible or UV colors to suit different activation wavelengths. Their highly unusual optical properties to fluoresce with near-zero photobleaching, photoblinking and background autofluorescence are unique and an added benefit when used simultaneously as optional imaging agents. This article reviews recent advancements in the use of UCNs for photoactivation of therapeutic agents. Specifically, we discuss the use of these UCNs for activation of light-sensitive/photocaged molecules or photosensitizers for photocontrolled-delivery and photodynamic therapy.
authors: Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Block EA #03-12, 9 Engineering Drive 1, 117576, Singapore. biezy@nus.edu.sg.
authors: Niagara Muhammad
authors: NM
authors: Idris
authors: Muthu Kumara Gnanasammandhan
authors: MK
authors: Jayakumar
authors: Akshaya
authors: A
authors: Bansal
authors: Yong
authors: Y
authors: Zhang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D007259:Infrared Rays; D028581:Lanthanoid Series Elements / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000627:therapeutic use / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D028581:Lanthanoid Series Elements; D017319:Photosensitizing Agents; D017382:Reactive Oxygen Species; D012822:Silicon Dioxide