TY  - JOUR
A1  - Schäferling, Michael
A1  - Andresen, Elina
A1  - Resch-Genger, Ute
T1  - Surface Modifications for Photon-Upconversion-Based EnergyTransfer Nanoprobes
JF  - Langmuir
N2  - 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.
KW  - photon upconversion
Y1  - 2019
U6  - http://dx.doi.org/10.1021/acs.langmuir.9b00238
VL  - 35 / 2019
IS  - 15
SP  - 5093
EP  - 5113
ER  -