Multimode temperature self-monitoring in photothermal nanoplatform based on Na3InF6: Nd3+, Yb3+, Ho3+ phosphor

An accurate deep-tissue thermometer with excellent photothermal conversion efficiency is desired for effective photo-thermal therapy (PTT), which will minimize collateral damages to normal cells from overheating or ineffective treatment from insufficient heat. Herein, a nano-thermometer with Nd3+/Yb3+/Ho3+ tri-doped Na3InF6 was designed by hydrothermal method to real-time monitor tissue temperature, and its luminescent performance and temperature sensing behavior based on the luminescence intensity ratio (LIR) technology in the visible and near infrared regions were analyzed under 808 nm excitation. The advantage of temperature probes located in the near infrared (NIR) biological window region was demonstrated by the penetration depth in simulating biological tissue agar. Furthermore, the feasibility of the sample as a self-monitoring photothermal platform was verified by in vitro bactericidal experiments, which expressed excellent photothermal conversion performance and sterilizing rates reached 59.8 % (E. coli) and 53.6 % (S. aureus), respectively. Results demonstrated that the present single-phased Na3InF6:Nd3+/Yb3+/Ho3+ nanophosphor could serve as a bifunctional photothermal agent with internal tissue temperature measurement and photothermal conversion.