Fig. 3
Optical and temperature sensing properties of TR-UCNS. a Upconversion luminescence spectra of YSUCNP, YSUCNP-PdPc, and YSUCNP-PdPc@DPPC-DOX (TR-UCNS) in the aqueous solution with the same concentration of Er3+ (2.5 × 10−5 mol l−1). The excitation wavelength of upconversion luminescence is 980 nm. b Absorption spectrum of TR-UCNS. c A plot of ln (I525/I545) versus 1/T to calibrate the thermometric scale for TR-UCNS. I525 and I545 indicate the intensities of UCL emission of the 2H11/2→4I15/2 and 4S3/2→4I15/2 transitions, respectively. d Elevation of apparent temperature (A.T.) and eigen temperature (E.T.) of TR-UCNS (0.5 mg ml−1) in aqueous dispersion under irradiation with a 730 nm laser at various power densities. Average value of A.T. and E.T. under different time points were given based on three times measurements. Error bars were defined as s.d. (n = 3)
