Polyelectrolyte multilayers stabilized plasmonic nanosensors

Surface plasmon nanosensors based on noble metal nanoparticles can detect trace amounts of chemicals and biomolecules at low concentrations without labeling. Shifts in the resonance peaks are very sensitive to changes in local dielectric constants due to the large surface areas of nanoparticles. But, the structural changes of nanoparticles after preparation can also shift the resonance peaks, which bring the stability issue of such sensors and need an additional annealing process. To eliminate the annealing process of plasmonic nanosensors, polyelectrolyte multilayers are layerby- layer deposited on an ordered array of silver nanoparticles generated by nanosphere lithography. The polymer multilayers stabilize the plasmonic resonance peaks of nanoparticles in air and liquid, and the resonance peaks shift towards long wavelength upon further attachments of polyelectrolyte films, exposures to chemicals and biomolecules. The optic transparency, easy deposition and quantitative response character of polyelectrolyte multilayer enhance the applicability of nanoparticle array based nanosensors in chemical and biological sensing.