Decoupled theranostics with rare earth doped nanoparticles

Abstract

The concept of theranostics seeks to integrate therapeutic and diagnostic functionalities in a single drug-probe system, which holds promise for more precise, timely, and effective detection and recognition of different maladies, with the possibility of their concomitant eradication. A plethora of various theranostic agents have been proposed, among which are the multi-functional rare earth doped nanoparticles (RENPs). Typically, RENPs which provide diagnostics and therapy simultaneously are researched; yet, on-demand control of therapy and diagnostics constitutes a move towards safer and more precise nanomedicines. We are exploring the possibility to optically decouple the diagnostic and therapeutic features by using excitation wavelength dependent photoluminescence of core/shell RENPs.1 These RENPs are excited with two distinct wavelengths in the near-infrared (NIR), one of which triggers downshifting (DS) emission in the NIR, while the other one prompts the process of upconversion (UC) and subsequent light emission in the ultraviolet and visible spectral ranges. Thus, DS emission is attained without any UC signal, and can be safely used for target visualization and diagnostics. Meanwhile, UC emission is harnessed for initiation of secondary photochemical processes, providing on-demand therapeutic effect. We believe, that this paradigm shift will bring RENPs closer to routine biomedical research and also to clinic, as true multi-functionality can be attained.