Biosensors for detection of bacteria using fluorescence

Bacteria detection plays an essential role in a variety of applications, from food contamination to public health. Moreover, fast and specific detection is extremely important. However, conventional methods (such as culture collection) tend to require several days. This lead to the development of alternative detection techniques such as optical biosensors. In this study, the metal enhanced fluorescence effect, due to the interaction of a metallic nanostructured surface with a proximal fluorophore leading to an increase in the intensity and stability of the optical signal, was exploited for the detection of bacteria such as E. coli. Starting from substrates formed by the metallic layer (either Au or Ag) and by a spacer layer (aSiC:H), the biosensor was fabricated by grafting glycans on the surface via click chemistry. Subsequently, two strains of E. coli were detected, using a sandwich strategy composed by the grafted glycans, the immobilized bacteria and fluorescent glycans deposited afterward.