Antoniadou Myrto, Pilch-Wrobel Aleksandra, Riziotis Christos, Bednarkiewicz Artur, Tanasă Eugenia, Krasia-Christoforou Theodora
University of Cyprus, Department of Mechanical and Manufacturing Engineering, Nicosia 1678, Cyprus.
Methods Appl Fluoresc. 2019 May 23;7(3):034002. doi: 10.1088/2050-6120/ab1dbd.
Functional upconverting nanoparticles (UCNPs) can offer new possibilities in fluorescent applications as they exhibit desired characteristic properties like large shift between the fluorescent emission signal and the infrared excitation wavelength, multi- and narrow-band absorption and emission in visible and near infrared - Vis/NIR, together with excellent photostability and low toxicity as opposed to semiconducting quantum dots. The upconversion luminescence emission or quenching characteristics of UCNPs can be altered upon exposure to physical or chemical environmental factors providing thus a functionality that can be utilized for sensing or imaging. Furthermore their functionalization with suitable indicator dyes or recognition elements can extend the range of luminescence response and ratiometric sensing to specific analytes. Synergistically, electrospun nano- and microfibers offering large surface area can enhance the functionality of UCNPs by retaining the fluorescence efficiency and improving the overall responsivity due to dramatically increased surface. For the optimization of this hybrid material system the controllable incorporation of UCNPs is required especially at increased concentration conditions needed for high brightness. Herein, we report the fabrication, morphological and optical characterization of electrospun polymer-based nanocomposite fibers, consisting of poly(methyl methacrylate) (PMMA) and upconverting lanthanide doped nanoparticles of the type NaYF : 20% Yb/2% Er @ NaYF. Morphological studies regarding the uniformity and aggregation effects of the UCNP inclusion within the fibers have been implemented followed by upconversion emission characterization by pulsed near-infrared excitation. The study and optimization of such nanocomposite fibrous systems could provide useful insights for the development of efficient upconverting electrospun fiber mats for a number of imaging and sensing applications.
功能性上转换纳米粒子（UCNPs）在荧光应用中提供了新的可能性，因为它们具有所需的特性，如荧光发射信号与红外激发波长之间的大位移、可见光和近红外（Vis/NIR）波段的多波段和窄波段吸收与发射，以及与半导体量子点相比优异的光稳定性和低毒性。UCNPs的上转换发光发射或猝灭特性在暴露于物理或化学环境因素时会发生改变，从而提供可用于传感或成像的功能。此外，用合适的指示染料或识别元件对其进行功能化，可以将发光响应和比率传感的范围扩展到特定分析物。协同地，具有大表面积的电纺纳米纤维和微纤维可以通过保持荧光效率和由于显著增加的表面积而提高整体响应性来增强UCNPs的功能。为了优化这种混合材料系统，需要可控地掺入UCNPs，特别是在高亮度所需的增加浓度条件下。在此，我们报道了由聚甲基丙烯酸甲酯（PMMA）和NaYF:20%Yb/2%Er@NaYF型上转换镧系掺杂纳米粒子组成的电纺聚合物基纳米复合纤维的制备、形态和光学表征。对纤维中UCNP夹杂物的均匀性和聚集效应进行了形态学研究，随后通过脉冲近红外激发进行了上转换发射表征。对这种纳米复合纤维系统的研究和优化可以为开发用于多种成像和传感应用的高效上转换电纺纤维垫提供有用的见解。
