Fabrication, photothermal conversion and temperature sensing of novel nanoplatform-hybrid nanocomposite of NaYF4:Er3+,Yb3+@NaYF4 and Au nanorods for photothermal therapy

Novel nanoplatform with excellent photothermal conversion and temperature feedback are preferable in clinical photothermal therapy (PTT). In this work, a hybrid of NaYF 4 :Er 3+ ,Yb 3+ @NaYF 4 upconversion nanoparticles (UCNPs) conjugated with gold nanorods (GNRs) was fabricated in order to achieve effective photothermal conversion and excellent temperature detection. In this nanoplatform, the GNRs as photo-activated nano-heaters could effectively convert the 808 nm photoenergy into heat, meanwhile UCNPs as 980 nm triggered temperature probe could read the temperature in an exact microdomain where the nanocomposite was located at. The effects of excitation source, GNRs concentration and power density on photothermal conversion were investigated. In addition, the difference between eigen temperature of nanoparticles and solution temperature, and the potential for temperature feedback were analyzed under double lasers excitation. Moreover, the photothermal conversion efficiency was experimentally confirmed from thermodynamic analysis. It was found that the nanocomposite can be an excellent nanoplatform for potential application in advanced PTT.