A nanosensor is designed using a double antibody sandwich method based on fluorescence resonance energy transfer (FRET) between NaYF₄ (Yb, Er) upconversion nanoparticles (UCNPs) and CdTe quantum dots (QDs) for the determination of procalcitonin (PCT). The UCNPs (donor) and CdTe QDs (acceptor) were modified separately with two PCT monoclonal antibodies, and they were bound together through a specific immune reaction via the addition of PCT antigen. The fluorescence intensity of UCNPs was quenched because of the resonant energy transferred between upconversion nanoparticles and quantum dots. Under the optimal conditions, the fluorescence quenching efficiency showed a linear response to the PCT concentration with values ranging from 0.1 to 10 ng mL⁻¹ and a detection limit of 0.25 ng mL⁻¹. This method can be easily extended to the double antibody sandwich assay with potential applications in in vitro diagnostics (IVD).

中文翻译：

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基于上转换纳米粒子与量子点之间荧光共振能量转移的双抗体夹心法检测降钙素（PCT）†

使用基于NaYF ₄（Yb，Er）上转换纳米粒子（UCNPs）和CdTe量子点（QDs）之间的荧光共振能量转移（FRET）的双抗体夹心法设计纳米传感器，用于测定降钙素（PCT）。UCNP（供体）和CdTe QD（受体）分别用两种PCT单克隆抗体修饰，它们通过添加PCT抗原通过特异性免疫反应结合在一起。由于上转换纳米粒子和量子点之间转移了共振能量，UCNPs的荧光强度被猝灭了。在最佳条件下，荧光猝灭效率显示出对PCT浓度的线性响应，范围为0.1至10 ng mL ^-1检测限为0.25 ng mL ^-1。该方法可以很容易地扩展到双抗体夹心测定法，在体外诊断（IVD）中具有潜在的应用。