Covering the optical spectrum through collective rare-earth doping of NaGdF4 nanoparticles: 806 and 980 nm excitation routesElectronic supplementary information (ESI) available: Detailed description of the nanoparticle synthesis, transfer to water, complex formation with chlorin e6, structural and optical characterization; XRD and size distribution data; FTIR analysis of oleate-capped RENPs, PEG-DOPE modified aqRENPs and PEG-DOPE alone; water heating under 806 and 980 nm laser irradiation. See D

Today, at the frontier of biomedical research, the need has been clearly established for integrating disease detection and therapeutic function in one single theranostic system. Light-emitting nanoparticles are being intensively investigated to fulfil this demand, by continuously developing nanoparticle systems simultaneously emitting in both the UV/visible (light-triggered release and activation of drugs) and the near-infrared (imaging and tracking) spectral regions. In this work, rare-earth (RE) doped nanoparticles (RENPs) were synthesized via a thermal decomposition process and spectroscopically investigated as potential candidates as all-in-one optical imaging, diagnostic and therapeutic agents. These core/shell/shell nanoparticles (NaGdF 4 :Er 3+ ,Ho 3+ ,Yb 3+ /NaGdF 4 :Nd 3+ ,Yb 3+ /NaGdF 4 ) are optically excited by heating-free 806 nm light that, aside from minimizing the local thermal load, also allows to obtain a deeper sub-tissue penetration with respect to the still widely used 980 nm light. Moreover, these water-dispersed nanoplatforms offer interesting assets as triggers/probes for biomedical applications, by virtue of a plethora of emission bands (spanning the 380-1600 nm range). Our results pave the way to use these RENPs for UV/visible-triggered photodynamic therapy/drug release, while simultaneously tracking the nanoparticle biodistribution and monitoring their therapeutic action through the near-infrared signal that overlaps with biological transparency windows. Sensitization of numerous emission bands (from ultraviolet to near-infrared) in rare-earth doped multilayered nanoparticles: 806 versus 980 nm excitation.