Persistent phosphorescence nanoparticles emitting in the red and near-infrared spectral regions are strongly demanded as contrast nanoprobes for autofluorescence free bioimaging and biosensing. In this work, we have developed Sr4Al14O25:Eu2+, Cr3+, Nd3+ nanopowders that produce persistent red phosphorescence peaking at 694 nm generated by Cr3+ ions. This emission displays temperature sensitivity in the physiological temperature range (20–60 °C), which makes these nanoparticles potentially useful as fluorescence (contactless) nanothermometers operating without requiring optical excitation. Nd3+ ions, which act as shallow electron traps for the red Cr3+ persistent emission, also display infrared emission bands, extending the fluorescence imaging capability to the second biological window. This unique combination of properties makes these nanoparticles multifunctional luminescent probes with great potential applications in nanomedicine.
Persistent luminescence nanothermometers
Emma Martín Rodríguez, Gabriel López-Peña, Eduardo Montes, Ginés Lifante, José García Solé, Daniel Jaque, Luis Armando Diaz-Torres, Pedro Salas; Persistent luminescence nanothermometers. Appl. Phys. Lett. 21 August 2017; 111 (8): 081901. https://doi.org/10.1063/1.4990873
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