Federal Institute for Materials Research and Testing, Division Biophotonics, Richard-Willstätter-Str. 11, 12489 Berlin, Germany.
Methods Appl Fluoresc. 2019 Jan 23;7(1):014003. doi: 10.1088/2050-6120/aafe1f.
Photon upconversion nanomaterials have a wide range of applications, including biosensing and deep-tissue imaging. Their typically very weak and narrow absorption bands together with their size dependent luminescence efficiency can limit their application potential. This has been addressed by increasingly sophisticated core-shell particle architectures including the sensitization with organic dyes that strongly absorb in the near infrared (NIR). In this work, we present a simple water-dispersible micellar system that features energy transfer from the novel NIR excitable dye, 1859 SL with a high molar absorption coefficient and a moderate fluorescence quantum yield to oleate-capped NaYF:20%Yb(III), 2%Er(III) upconversion nanoparticles (UCNP) upon 808 nm excitation. The micelles were formed using the surfactants Pluronic F-127 and Tween 80 to produce a hydrophilic dye-UCNP system. Successful energy transfer from the dye to the UCNP could be confirmed by emission measurements that revealed the occurrence of upconversion emission upon excitation at 808 nm and an enhancement of the green Er(III) emission compared to direct Er(III) excitation at 808 nm.
上转换纳米材料在生物传感和深层组织成像等领域有广泛的应用。然而，它们通常非常微弱且吸收带宽较窄，同时其发光效率也依赖于粒径，这限制了其应用潜力。通过日益复杂的核壳粒子结构，包括用在近红外（NIR）区域强烈吸收的有机染料敏化，可以解决这些问题。在这项工作中，我们提出了一种简单的水分散胶束体系，该体系可以将新型 NIR 可激发染料 1859 SL 的能量有效地转移到油酸封端的 NaYF:20%Yb(III), 2%Er(III) 上转换纳米粒子（UCNP）上，1859 SL 具有高摩尔吸收系数和中等荧光量子产率，在 808nm 激发下可发生上转换发光。胶束是通过使用表面活性剂 Pluronic F-127 和 Tween 80 来形成的，从而产生了亲水性染料-UCNP 体系。通过发射测量可以证实染料到 UCNP 的能量转移，当用 808nm 激发时，可以观察到上转换发射，与直接用 808nm 激发 Er(III)相比，绿色的 Er(III)发射得到了增强。
