ABSTRACT
Chemical imaging is a powerful technique and provides spatial and temporal chemical information of a sample. Examples include direct methods such as Raman spectroscopy-based imaging or mass spectrometry imaging. In contrast, many imaging methods used in the life sciences such as fluorescence microscopy rely on labeling structures with artificial fluorophores. The resulting image provides information about the spatial and temporal distribution of the labeled structure. This approach has been extremely successful to elucidate the structure of (biological) samples such as the architecture of cells. However, the label itself does not necessarily provide information about the chemical environment around it. Alternatively, fluorescent probes/sensors are ideal candidates for chemical imaging. They are designed in such a way that they change their fluorescence properties in the presence of a specific molecule. Therefore, they report the local concentration of this molecule up to single-binding events. Fluorescent nanomaterials have many beneficial properties and are versatile building blocks for (nano)sensors. In general, the collective image of multiple fluorescent nanosensors represent a chemical image, which holds great potential for different analytical applications. In this chapter, we provide a comprehensive overview on chemical imaging with fluorescent nanosensors. We start with a general overview on the methods capable of chemical imaging. Then we introduce a theoretical framework to understand and interpret chemical images from nanosensors. This aspect is especially relevant if the sample changes over time, for example, in the case of concentration changes in biological systems. Finally, we discuss different examples that showcase the advantages of chemical imaging with nanosensors.
