Lanthanide doped fluorescent nanoparticles have gained considerable attention in biomedical applications. However, the low uptake efficiency of nanoparticles by cells has limited their applications. In this work, we demonstrate how the uptake efficiency is affected by the size of nanoparticles under flow conditions. Using the same size NaYF₄:20% Yb³⁺,2% Er³⁺,2% Ce³⁺ (the contents of rare earths elements are in molar fraction) nanoparticles as core, NaYF₄:20% Yb³⁺,2% Er³⁺,2% Ce³⁺@NaYF₄ core–shell structured nanorods (NRs) with different sizes of 60–224 nm were synthesized by thermal decomposition and hot injection method. Under excitation at 980 nm, a strong upconversion green emission (541 nm, ²H_11/2 → ⁴I_15/2 of Er³⁺) is observed for all samples. The emission intensity for each size nanorod was calibrated and is found to depend on the width of NRs. Under flow conditions, the nanorods with 96 nm show a maximum uptake efficiency by endothelial cells. This work demonstrates the importance of optimizing the size for improving the uptake efficiency of lanthanide-doped nanoparticles.

镧系元素掺杂的荧光纳米粒子在生物医学应用中获得了相当大的关注。然而，细胞对纳米颗粒的低吸收效率限制了它们的应用。在这项工作中，我们展示了在流动条件下吸收效率如何受纳米颗粒大小的影响。以相同尺寸的NaYF ₄ :20% Yb ³⁺ ,2% Er ³⁺ ,2% Ce ³⁺（稀土元素含量以摩尔分数计）纳米粒子为核，NaYF ₄ :20% Yb ³⁺ ,2 % Er ³⁺ ,2% Ce ³⁺ @NaYF ₄通过热分解和热注入法合成了不同尺寸为60-224 nm的核壳结构纳米棒（NRs）。在 980 nm 激发下，所有样品均观察到强上转换绿光发射（541 nm， ² H _11/2  →  ⁴ I _15/2的 Er ^{3+ ）。}校准了每种尺寸纳米棒的发射强度，发现其取决于 NR 的宽度。在流动条件下，96 nm 的纳米棒显示出内皮细胞的最大摄取效率。这项工作证明了优化尺寸对于提高镧系元素掺杂纳米粒子的吸收效率的重要性。