Upconversion nanotubes with tunable fluorescence properties based on Gd₂O₂S:Ln³⁺ (Ln³⁺ = Yb³⁺, Er³⁺) and derivatives...

In this study, Gd₂O₂S:Ln³⁺ (Ln³⁺ = Yb³⁺, Er³⁺) upconversion nanotubes (UCNTs) were synthesised by using Gd(OH)₃:Ln³⁺ (Ln³⁺ = Yb³⁺, Er³⁺) nanotubes as the template. The luminescent and biological properties of Gd₂O₂S:Ln³⁺ (Ln³⁺ = Yb³⁺, Er³⁺) UCNTs, along with photodynamic therapy (PDT) applications of the Gd₂O₂S:8%Yb³⁺,2%Er³⁺ UCNT-Ce6 (chlorin e6) nanocomposites, were systematically studied. The resultant UCNTs showed excellent biocompatibility with human retinal pigment cells (ARPE-19) even after a prolonged incubation time of 72 h, and could be used as luminescent probes. Microscopic imaging revealed that the UCNTs existed mainly in cytoplasm. PDT studies on the Gd₂O₂S:8%Yb³⁺,2%Er³⁺ UCNT-Ce6 nanocomposites indicate that the growth of the tumour (cell) could be inhibited dramatically when it was injected (incubated) with Gd₂O₂S:8%Yb³⁺,2%Er³⁺ UCNT-Ce6 nanocomposites under the irradiation of 980 nm laser.