A dual-mode assay is described for immunological determination of the anemia biomarker ferritin. It is based on the use of a gold@carbon dot (Au@CD) nanoconjugate as a colorimetric and fluorescent probe. Au@CD is hydrophilic, easily surface modified and stable in aqueous solution. The Au@CD have a red color with blue-green fluorescence and were modified with antibody against ferritin. This allows bi-modal detection of ferritin. Assays can be performed in phosphate buffer and were also analyzed in (Bovine Serum Albumin) BSA and (Fetal Bovine Serum) FBS. Detection is based on antigen-antibody interaction underlying the classical sandwich model. Response to ferritin can be detected by spectrophotometry (at 570 nm) or fluorescence (at excitation/emission maxima of 354/454 nm). Under optimal conditions, the assay has a linear response in the 1 to 120 ngmL−1 ferritin concentration range and detection limits of 20 ng (colorimetrically) and 64 ng (fluorometrically). Graphical abstract Schematic representation of the function of the designed nanoprobe. The Au@CD nanoconjugates are functionalized with ferritin antibody in the initial step which specifically interacts with ferritin molecules leading to aggregation and subsequent changes in the optical and fluorescence signals. Schematic representation of the function of the designed nanoprobe. The Au@CD nanoconjugates are functionalized with ferritin antibody in the initial step which specifically interacts with ferritin molecules leading to aggregation and subsequent changes in the optical and fluorescence signals.

中文翻译：

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使用抗体修饰的金@碳点纳米缀合物双探针（比色法和荧光法）检测铁蛋白

描述了一种双模式测定法，用于免疫学测定贫血生物标志物铁蛋白。它基于使用金@碳点 (Au@CD) 纳米共轭物作为比色和荧光探针。Au@CD 具有亲水性，易于表面改性，在水溶液中稳定。Au@CD 呈红色并带有蓝绿色荧光，并用抗铁蛋白的抗体进行了修饰。这允许双模式检测铁蛋白。检测可以在磷酸盐缓冲液中进行，也可以在（牛血清白蛋白）BSA 和（胎牛血清）FBS 中进行分析。检测基于经典夹心模型的抗原-抗体相互作用。可以通过分光光度法（570 nm）或荧光法（激发/发射最大值为 354/454 nm）检测对铁蛋白的响应。在最佳条件下，该测定在 1 至 120 ngmL-1 铁蛋白浓度范围内具有线性响应，检测限为 20 ng（比色法）和 64 ng（荧光法）。图形摘要 设计的纳米探针功能的示意图。Au@CD 纳米缀合物在初始步骤中被铁蛋白抗体功能化，铁蛋白抗体与铁蛋白分子特异性相互作用，导致聚集和随后的光学和荧光信号的变化。设计的纳米探针功能的示意图。Au@CD 纳米缀合物在初始步骤中被铁蛋白抗体功能化，铁蛋白抗体与铁蛋白分子特异性相互作用，导致聚集和随后的光学和荧光信号的变化。