Layer-By-Layer Nano-Assembly Of Charged Polyelectrolytes for Label-Free Optical Biosensing With Nanostructured Materials: The Case of Nanostructured Porous Silicon Interferometers

摘要

The nano-assembly of charged polyelectrolytes via layer-by-layer (LbL) technology on porous silicon (PSi)interferometers is here demonstrated as an effective biofunctionalization approach for high-sensitivity/selectivity labelfreeoptical biosensing, using streptavidin/biotin affinity detection as case study. Nanostructured PSi interferometers arebiofunctionalized with a nano-assembly of a positively-charged polyelectrolyte, namely, PAH (poly(allylaminehydrochloride)), and a negatively-charged biotinylated polyelectrolyte, namely, b-PMAA (poly(methacrylic acid))), viaLbL technology. The nano-assembly is stable under operating conditions and enables the selective and sensitive detectionof streptavidin with a sub-picomolar detection limit (namely, DL=0.6 pM), which is 105-fold lower than that achieved withPSi interferometers biofunctionalized using standard silane chemistry. Remarkably, the analytical performance achievedfor LbL-biofunctionalized PSi interferometers is comparable to those of state-of-the-art label-free photonic and plasmonicplatforms.