Lanthanide ion (Ln³⁺)-doped nanoscale hydroxyapatites (nHAp) with tunable luminescence have attracted increasing attention due to their potential applications as useful biomedical tools (e.g., imaging and clinical therapy). In this study, we reported that doping Terbium (III) ions (Tb³⁺) in self-activated luminescent nHAp via a facile hydrothermal reaction, using trisodium citrate (Cit³⁻), generates unique emission-tunable probes known as Cit/Tb-nHAp. The morphology, crystal phase, and luminescence properties of these Cit/Tb-nHAp probes are studied in detail. Moreover, the results demonstrate that the luminescence of self-activated nHAp originates from the carbon dots trapped within the nHAp crystals, in which partial energy transfer occurs from carbon dots (CDs) to Tb³⁺. The color tunability is successfully achieved by regulating the addition of Cit³⁻. Biocompatibility study indicates that when co-cultured with C6 glioma cells in vitro for 3 days, ≤800 ppm Cit/Tb-nHAp is not cytotoxic for C6 glioma cells. We also present in vitro data showing efficient cytoplasmic localization of transferrin conjugated Cit/Tb-nHAp into C6 glioma cells by fluorescence cell imaging. We have successfully engineered Cit/Tb-nHAp, a promising biocompatible agent for future in vitro and in vivo fluorescence bioimaging.

具有可调谐发光的掺杂镧系元素离子（Ln ³⁺）的纳米级羟基磷灰石（nHAp）由于其作为有用的生物医学工具（例如成像和临床治疗）的潜在应用而受到越来越多的关注。在这项研究中，我们报道了使用柠檬酸三钠（Cit ^3−）通过水热反应在自活化发光nHAp中掺杂（（III）离子（Tb ³⁺）），生成称为Cit / Tb-nHAp的独特的发射可调探针。详细研究了这些Cit / Tb-nHAp探针的形态，晶相和发光特性。此外，结果表明，自活化nHAp的发光源自捕获在nHAp晶体中的碳点，其中部分能量从碳点（CDs）转移到Tb ³⁺。通过调节Cit ^3-的添加可以成功实现颜色可调性。生物相容性研究表明，当与C6胶质瘤细胞体外共培养3天时，≤800ppm Cit / Tb-nHAp对C6胶质瘤细胞没有细胞毒性。我们还介绍了体外数据显示通过荧光细胞成像将转铁蛋白缀合的Cit / Tb-nHAp高效定位到C6胶质瘤细胞中。我们已经成功设计了Cit / Tb-nHAp，这是一种有前途的生物相容性试剂，可用于未来的体外和体内荧光生物成像。