On the influence of different surfaces in nano- and submicrometer particle based fluorescence immunoassays

Recently, numerous attempts have been made to improve the performance of fluorescence immunoassays. One way pursued is the substitution of labeling molecules by micro- or nanocrystalline dyes. The surfaces of these particulate structures are typically engineered by a layerwise assembly of oppositely charged polyelectrolytes, the outer layer being constituted of biorecognition molecules, for example, immunoglobulins. In this study, we show that amphiphilic polymers such as alkylated poly(ethylene imine)s and 1,2-distearoyl-sn-glycero-3-phosphatoethanolamine-N-[amino(poly(ethylene glycol))] can fully substitute the more intricate layer-by-layer technique and evaluate the influence of surface charge and particle size on the overall performance of these assays.