Small size optical-magnetic bifunctional upconversion nanoparticles (UCNPs) that can be effectively triggered by 808 nm exhibit distinct advantages of improved tissue penetrating depth, minimized overheating effect, possible for multimodal imaging and high clearance rate, which therefore are considered as desirable candidates for bioapplications. In this research, the 808 nm triggered sub-20 nm β-NaYF 4 :Yb 3+ /Er 3+ @NaGdF 4 :Yb 3+ /Nd 3+ @NaGdF 4 active-core@active-shell@inert-shell structured UCNPs with optical and magnetic bifunctional properties were developed by seed-mediated growth method with NaOA as sodium source instead of the generally used NaOH. Through optimizing Nd 3+ doping concentration and outermost NaGdF 4 inert-shell thickness, the optical-magnetic bifunctional core-shell-shell structured UCNPs exhibited strong UC emission intensity and improved magnetic property . Furthermore, the core-shell-shell NPs were validated to be no cytotoxicity by cell viability assessment. Therefore, this research may open a general avenue for the synthesis of small size multifunctional UCNPs for practical bioapplications without overheating.
To further enhance the photocatalytic performance of BiOCl, a facile hydrothermal reduction reaction was used to synthesize the reduced graphene oxide- (rGO-) modified ternary compound photocatalyst β-NaYF 4 :Yb 3+ , Er 3+ @BiOCl-rGO (NYF–Bi-rGO). rGO prepared using a hydrothermal method showed good conductivity . Furthermore, the specific surface area of NYF-Bi-rGO was 20-fold larger than that of NYF, which is a quality that could prove highly advantageous for use in pollutant adsorption. In addition, the ternary photocatalytic system produced by rGO increased the absorption intensity of NYF-Bi in the visible light region, and caused a red-shift of the entire absorption cross-section. In particular, analysis of carrier migration showed the introduction of rGO promoted the separation of the photoelectron-hole pairs of BiOCl, inhibited its recombination and improved the photocatalytic efficiency of the ternary photocatalyst NYF-Bi-rGO.
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