BAM Federal Institute of Materials Research and Testing, Biophotonics Division, Richard-Willstätter-Str. 11 , D-12489 Berlin , Germany.
Department of Chemistry , Humboldt-Universität zu Berlin , Brook-Taylor-Str. 2 , D-12489 Berlin , Germany.
Langmuir. 2019 Apr 16;35(15):5093-5113. doi: 10.1021/acs.langmuir.9b00238. Epub 2019 Mar 27.
An emerging class of inorganic optical reporters are near-infrared (NIR) excitable lanthanide-based upconversion nanoparticles (UCNPs) with multicolor emission and long luminescence lifetimes in the range of several hundred microseconds. For the design of chemical sensors and optical probes that reveal analyte-specific changes in their spectroscopic properties, these nanomaterials must be combined with sensitive indicator dyes that change their absorption and/or fluorescence properties selectively upon interaction with their target analyte, utilizing either resonance energy transfer (RET) processes or reabsorption-related inner filter effects. The rational development of UCNP-based nanoprobes for chemical sensing and imaging in a biological environment requires reliable methods for the surface functionalization of UCNPs, the analysis and quantification of surface groups, a high colloidal stability of UCNPs in aqueous media as well as the chemically stable attachment of the indicator molecules, and suitable instrumentation for the spectroscopic characterization of the energy-transfer systems and the derived nanosensors. These topics are highlighted in the following feature article, and examples of functionalized core-shell nanoprobes for the sensing of different biologically relevant analytes in aqueous environments will be presented. Special emphasis is placed on the intracellular sensing of pH.
一类新兴的无机光学报告物是近红外（NIR）可激发的基于镧系元素的上转换纳米粒子（UCNPs），它们具有多色发射和数百微秒范围内的长荧光寿命。对于设计化学传感器和光学探针，以揭示其光谱性质中特定分析物的变化，这些纳米材料必须与敏感的指示剂染料结合使用，这些染料在与目标分析物相互作用时选择性地改变其吸收和/或荧光性质，利用共振能量转移（RET）过程或再吸收相关的内滤效应。为了在生物环境中进行化学传感和成像，合理开发基于 UCNP 的纳米探针需要可靠的 UCNP 表面功能化方法、表面基团的分析和定量、UCNPs 在水介质中的高胶体稳定性以及指示剂分子的化学稳定附着，以及用于能量转移系统和衍生纳米传感器的光谱特性分析的合适仪器。以下专题文章重点介绍了这些主题，并展示了用于在水相环境中检测不同生物相关分析物的功能化核壳纳米探针的示例。特别强调了细胞内 pH 的感应。
