Institute for Biomedical Materials and Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, New South Wales 2007, Australia.
College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, People's Republic of China.
Anal Chem. 2020 Aug 18;92(16):10913-10919. doi: 10.1021/acs.analchem.0c02143. Epub 2020 Aug 10.
One of the major challenges in using upconversion nanoparticles (UCNPs) is to improve their brightness. This is particularly true for studies, as the low power excitation is required to prevent the potential photo toxicity to live cells and tissues. Here, we report that the typical NaYF:Yb,Er nanoparticles can be highly doped, and the formula of NaYF:Yb,Er can gain orders of magnitude more brightness, which is applicable to a range of mild 980 nm excitation power densities, from 0.005 W/cm to 0.5 W/cm. Our results reveal that the concentration of Yb sensitizer ions plays an essential role, while increasing the doping concentration of Er activator ions to 6 mol % only has incremental effect. We further demonstrated a type of bright UCNPs 12 nm in total diameter for tumor imaging at a power density as low as 0.0027 W/cm, bringing down the excitation power requirement by 42 times. This work redefines the doping concentrations to fight for the issue of concentration quenching, so that ultrasmall and bright nanoparticles can be used to further improve the performance of upconversion nanotechnology in photodynamic therapy, light-triggered drug release, optogenetics, and night vision enhancement.
上转换纳米粒子（UCNPs）的主要挑战之一是提高其亮度。对于研究来说，这尤其如此，因为需要低功率激发以防止潜在的光毒性对活细胞和组织的影响。在这里，我们报告说，典型的 NaYF:Yb，Er 纳米粒子可以高度掺杂，并且 NaYF:Yb，Er 的公式可以获得亮度的数量级增加，适用于一系列温和的 980nm 激发功率密度，从 0.005 W/cm 到 0.5 W/cm。我们的结果表明，Yb 敏化剂离子的浓度起着至关重要的作用，而将 Er 激活剂离子的掺杂浓度增加到 6mol%仅具有增量效果。我们进一步展示了一种总直径为 12nm 的明亮 UCNPs，用于肿瘤成像，功率密度低至 0.0027W/cm，将激发功率要求降低了 42 倍。这项工作重新定义了掺杂浓度，以解决浓度猝灭问题，从而可以使用超小且明亮的纳米粒子来进一步提高上转换纳米技术在光动力疗法、光触发药物释放、光遗传学和夜视增强方面的性能。
