“…The most commonly used indicator forms are tablets, thin films, and reagents deposited on cellulose carriers, such as paper test strips [ 12 , 13 , 14 ]. The interaction of the analyte with the reagent manifests itself in a change in color due to the formation of a colored compound [ 15 , 16 , 17 ] or bleaching of the dye [ 18 , 19 , 20 ], and also leads to a change in the spectral properties of nanoparticles [ 21 , 22 , 23 , 24 ]. In other words, solid-phase analytical reagents represent a specific class of chemosensors.…”