A novel K_0.3Bi_0.7F_2.4 upconversion (UC) matrix has been prepared successfully by a solvothermal method. K_0.3Bi_0.7F_2.4:Yb³⁺/Ln³⁺ (Ln = Er, Ho, Tm) upconversion nanoparticles (UCNPs) show a corresponding excellent upconversion luminescence (UCL) under 980 nm laser irradiation. Especially, the strong near-infrared (NIR) UCL of K_0.3Bi_0.7F_2.4:20% Yb³⁺/0.5% Tm³⁺ (abbreviated as BYT) UCNPs is suitable for deep tissue optical imaging. Moreover, the high X-ray absorption coefficient of Bi makes the as-prepared UCNPs favorable for computed tomography (CT) imaging. The citrate-coated BYT UCNPs show good biocompatibility through the MTT assay towards HeLa cells and low hemolytic properties by hemolysis assay, which could be applied for in vivo optical and CT imaging. After intravenous injection of citrate-coated BYT UCNPs for one month, blood biochemistry and histology analysis of mice suggest the UCNPs have a negligible toxicity in vivo, implying citrate-coated BYT could be employed as a safe bioprobe for NIR optical and CT dual-modal imaging.

中文翻译：

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基于新型镧系元素掺杂的K _0.3 Bi _0.7 F _2.4上转换纳米粒子的近红外光学和X射线计算机断层摄影双模成像探头†

通过溶剂热法成功制备了新型的K _0.3 Bi _0.7 F _2.4上转换（UC）基质。K _0.3 Bi _0.7 F _2.4：Yb ³⁺ / Ln ³⁺（Ln = Er，Ho，Tm）上转换纳米粒子（UCNPs）在980 nm激光辐照下显示出相应的优异的上转换发光（UCL）。特别是K _0.3 Bi _0.7 F _2.4的强近红外（UC ）UCL ：20％Yb ³⁺ /0.5% Tm ³⁺UCNP（简称BYT）适用于深层组织光学成像。此外，Bi的高X射线吸收系数使所制备的UCNP有利于计算机断层扫描（CT）成像。柠檬酸盐包被的BYT UCNPs通过MTT分析对HeLa细胞显示出良好的生物相容性，并且通过溶血分析显示出低溶血特性，可用于体内光学和CT成像。静脉注射柠檬酸盐包覆的BYT UCNPs达一个月后，小鼠的血液生化和组织学分析表明，该UCNPs在体内的毒性可忽略不计，这暗示柠檬酸盐包覆的BYT可作为近红外光学和CT双模态的安全生物探针成像。