Ratiometric nanothermometer in vivo based on triplet sensitized upconversion

Abstract

Temperature is an essential factor that counts for living systems where complicated vital activities are usually temperature dependent. In vivo temperature mapping based on non-contact optical approach will be beneficial for revealing the physiological phenomena behind with minimized influence to the organism. Herein, a highly thermal-sensitive upconversion system based on triplet–triplet annihilation (TTA) mechanism is pioneered to indicate body temperature variation sensitively over the physiological temperature range. The temperature-insensitive NaYF4: Nd nanophosphors with NIR emission was incorporated into the temperature-responsive TTA-upconversion system to serve as an internal calibration unit. Consequently, a ratiometric thermometer capable of accurately monitoring the temperature changes in vivo was developed with high thermal sensitivity (~7.1% K−1) and resolution (~0.1 K).

Ratiometric upconversion nanothermometry with dual emission at the same wavelength decoded via a time-resolved technique

“…Upconversion luminescence (UCL) bioimaging can reduce auto-fluorescence from biological systems owing to its anti-Stokes process [27][28][29] . To date, several ratiometric upconversion luminescent nanothermometers, which are based on lanthanide doped upconversion nanoparticles 16,30 (UCNPs) or triplet-triplet annihilation 31 , have been applied to monitor temperature in small animals. Unfortunately, the thermal sensitive signals of these upconversion luminescent nanothermometers are still located in the visible region, which limit their detection depth due to high absorption and scattering which originate from complex tissues.…”

In vivo therapeutic response monitoring by a self-reporting upconverting covalent organic framework nanoplatform

“…To overcome these limitations, herein, we developed an upconverting COF nanoplatform for efficient NIR activated and in situ self-reporting PDT. Based on a lanthanide-doped upconversion nanoparticle (UCNP) core, [42][43][44][45][46][47][48][49][50][51][52][53] we realized the controlled synthesis of nanoscale COFs with various shell thicknesses via core-mediated imine polymerization on the UCNPs, which were termed UCCOFs (Scheme 1a). Aer tailoring the COF shell thickness, the photodynamic efficacy of the UCCOFs was greatly improved, becoming 12.5 times that of irregular COFs.…”

A stimuli responsive triplet–triplet annihilation upconversion system and its application as a ratiometric sensor for Fe3+ions

“…26 Great efforts have been made on developing TTA-UC system as a ratiometric platform for sensing oxygen 27 and temperature. 28 However, to the best of our knowledge so far, there is still no report on a ratiometric sensor based on TTA-UC for metal-ion detection. This new strategy elaborately utilizes the double-dye nature of the TTA-UC system and does not need to add an external reference, because the UC and PL signals can be internal reference for each other.…”