The Electrochemical Society, find out more Layer-By-Layer Nanoassembly Of Polyelectrolites Engineered With Bioreceptors For High-Sensitivity Optical Label-Free Biosensing With Nanostructured Porous Silicon

Here we report the layer-by-layer (LbL) nanoassembly of charged polyelectrolytes engineered with bioreceptors as an effective and robust alternative to covalent biofunctionalization (e.g., organosilanization and hydrosilylation) for affinity biosensing with porous silicon (PSi) interferometers [1]. As a proof of concept demonstration, a bi-layer of positively-charged poly(allylamine hydrochloride) (PAH) and negatively-charged biotinylated poly(methacrylic acid) (b-PMAA) is assembled onto the surface of oxidized PSi interferometers for the affinity detection of streptavidin in buffer and raw saliva. The LbL nanoassembly allows a homogenous coating of the inner PSi surface, ensuring a robust anchoring of the bioreceptors and, in turn, high sensitive and selective detection of streptavidin, also in raw saliva, down to a theoretical detection limit of 600 fM. This pushes PSi based biosensors at detection limit comparable to that of state-of-the-art nanostructured photonic and plasmonic platforms for biosensing. Further, the development and employment of polymers engineered with several bioreceptors or with stronger dissociation properties (e.g. PSS) could broaden the applications LbL nano-assembly in biosensing and in biomedical applications.