“…TOPO, originally employed in dissociation-enhanced lanthanide fluorescence immunoassays [DELFIA ® ( PerkinElmer, 2023 )], still seems to be the ancillary ligand of choice for the incorporation into beads as well ( Ando and Kawaguchi, 2005 ; Aikawa et al, 2016 ), the majority of beads being based on polystyrene, although pure PMMA is also of interest ( Moudam et al, 2009 ; Li et al, 2013 ; Cardoso Dos Santos et al, 2019 ). Last but not least, to act as biolabels, the surface of the beads has to exhibit functional groups that can readily be conjugated to the analyte under question; numerous protocols for the conjugation have been reported, protruding carboxylates and amines being the most prominent functional groups ( Petri et al, 2004 ; Hermanson and Hermanson, 2013 ; Sapsford et al, 2013 ; Sasaki et al, 2022 ): Depending on the specific method of preparation of the beads—especially the choice of the catalyst in the radical microemulsion polymerization—the beads “naturally” assume a high surface charge already (>+30 mV for 2,2′-Azobis(2-amidinopropane) dihydrochloride, AAPH, and of ca., −40 mV for Potassium peroxodisulfate, KPS). This surfcace charge is responsible for the good dispersion stability of the beads in water.…”