1.319 μm excited thulium doped nanoparticles for subtissue thermal sensing with deep penetration and high contrast imaging

• Published in: Sensors and actuators. B, Chemical Vol. 238; pp. 525 - 531
• Main Authors: Pereira, A.F., Silva, J.F., Gouveia-Neto, A.S., Jacinto, C.
• Format: Journal Article
• Language: English
• Published: 01-01-2017
• Subjects: Emission; Excitation; Fluorescence; Imaging; Nanoparticles; Nanostructure; Penetration; Upconversion
• ISSN: 0925-4005
• DOI: 10.1016/j.snb.2016.07.053

We report on the potential application of NIR-NIR two-photon excited fluorescence of Tm3+ doped sodium niobate (NaNbO3_Tm) nanoparticles with both emission (800nm) and excitation (1.319 mu m) operating respectively within first and second biological windows for high resolution and deeper penetration bio-images. Ex vivo tissue depth using 1.319 mu m was achieved as high as twice in comparison with the already conventional 800nm excitation. The spectral profile of Tm3+ upconversion luminescence was analyzed in detail in the biophysical temperature range. A twofold enhancement of the solely detected 800nm upconversion emission was obtained in the 22-90 degree C temperature interval. The population redistribution of the thermally coupled sub-levels was demonstrated useful for ratiometric nanothermometry. The outstanding penetration depth together with the fluorescence thermal sensitivity make the NaNbO3_Tm nanocrystal an excellent candidate as multifuncitional nanoprobe for high contrast and highly penetrating fluorescence imaging.