Synchronous enhancement of upconversion and NIR-IIb photoluminescence of rare-earth nanoprobes for theranostics

Abstract

This study develops a multifunctional molecular optical nanoprobe (SiO2@Gd2O3: Yb3+/Er3+/Li+@Ce6/MC540) with a unique core-satellite form. The rare-earth doped nanodots with good crystallinity are uniformly embedded on the surface of a hydrophilic silica core, and the nanoprobe can emit near-infrared-IIb (NIR-IIb) luminescence for imaging as well as visible light that perfectly matches the absorption bands of two included photosensitizers under 980 nm irradiation. The optimal NIR-IIb emission and upconversion efficiency are attainable via regulating the doping ratios of Yb3+, Er3+ and Li+ ions. The relevant energy transfer mechanism was addressed theoretically that underpins rare-earth photoluminescence where energy back-transfer and cross relaxation processes play pivotal roles. The nanoprobe can achieve an excellent dual-drive photodynamic treatment performance, verified by singlet oxygen detections and live-dead cells imaging assays, with a synergistic effect. And a brightest NIR-IIb imaging was attained in tumoral site of mouse. The nanoprobe has a high potential to serve as a new type of optical theranostic agent for tumor.

Nanomaterials for light-mediated therapeutics in deep tissue

“…Metal ion doping, such as Li + , Ca 2+ , Fe 3+ , Zn 2+ , Mn 2+ and Na + , into the lattice could improve upconverting and downconverting luminescence through different mechanisms. 103,[128][129][130][131][132][133][134] On the other hand, PLNP intensity and afterglow time are enhanced by creating defects in the crystal lattice. 135 Substituting NaYF 4 :Yb 3+ /Tm 3+ with Ca 2+ caused a 121-fold improvement in upconversion luminescence intensity.…”