Figure 4: Schematic picture of fluorescence biosensing. Various types of fluorescence biosensors are depicted as described in the picture. (A) Simple fluorophore-labeled aptasensors; (B) fluorophore/quenchere-based aptasensors; (C) gold nanoparticle/fluorophore-labeled aptasensors; (D) quantum dot aptasensors; and (E) magnetic nanoparticle/fluorophore-labeled aptasensors.