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Smart theranostic nanoprobes with the integration of multiple therapeutic modalities are preferred for precise diagnosis and efficient therapy of tumors. However, it remains a big challenge to arrange the imaging and two or more kinds of therapeutic agents without weakening the intended performances. In addition, most existing fluorescence (FL) imaging agents suffer from low spatiotemporal resolution due to the short emission wavelength (<900 nm). Here, novel three-in-one Ag 2 S quantum dot (QD)-based smart theranostic nanoprobes were proposed for in situ ratiometric NIR-II FL imaging-guided ion/gas combination therapy of tumors. Under the acidic tumor microenvironment, three-in-one Ag 2 S QDs underwent destructive degradation, generating toxic Ag + and H 2 S. Meanwhile, their FL emission at 1270 nm was weakened. Upon introduction of a downconversion nanoparticle (DCNP) as the delivery carrier and NIR-II FL reference signal unit, the formed Ag 2 S QD-based theranostic nanoprobes could achieve precise diagnosis of tumors through ratiometric NIR-II FL signals. Also, the generated Ag + and H 2 S enabled specific ion/gas combination therapy toward tumors. By combining the imaging and therapeutic functions, three-in-one Ag 2 S QDs may open a simple yet reliable avenue to design theranostic nanoprobes.

Down/upconversion Ca 14 Al 10 Zn 6 O 35 inorganic phosphors codoped with Ti 4+ /Eu 3+ or Yb 3+ /Er 3+ were prepared. The crystal structure and downconversion luminescence properties of Ca 14 Al 10 Zn 6 O 35 :Ti 4+ , Eu 3+ phosphors were studied in detail. Ti 4+ and Eu 3+ occupied Al 3+ and Ca 2+ sites in the host lattice, respectively. Under the excitation of 273 nm, the emission peak in the 300-570 nm band originated from the 2 T 2 → O 2- transition of Ti 4+ . The f-f transition of Eu 3+ ions generated multiple peaks in the 570-800 nm range. The emission intensity of Ti 4+ and Eu 3+ ions can be used as a fluorescence intensity ratio (FIR) signal. Based on the FIR technology, the maximum relative sensitivity ( S r ) and the minimum temperature uncertainty (δ T ) reached 1.41% K -1 and 0.07 K, respectively. Meanwhile, the temperature-sensing behaviors were explored by the temperature-dependent upconversion spectra of Er 3+ - and Yb 3+ -codoped Ca 14 Al 10 Zn 6 O 35 phosphors. Based on the fluorescence intensity ratio of thermal coupling levels (Er 3+ : 2 H 11/2 / 4 S 3/2 ), the maximum S r and minimum δ T of upconversion phosphors reached 1.28% K -1 and 0.08 K in the temperature range of 293-473 K, respectively. Ca 14 Al 10 Zn 6 O 35 :Ti 4+ /Eu 3+ (Yb 3+ /Er 3+ ) phosphors realize temperature sensors with higher relative sensitivity, and it is a good candidate material for optical temperature measurement.