Nanosphere lithography coupled with reactive ion etching has been used to synthesize hexagonal ordered arrays of Au–Ag bimetallic semi-nanoshells to be used as plasmonic biosensors. The degree of lateral interaction between adjacent semi-nanoshells can be controlled by tailoring the reactive ion etching time in order to boost the global plasmonic properties through the formation of near-field hot-spots, which in turn can improve the sensitivity of the biosensors. To test the efficiency of the proposedsystem as a biosensor, we used an established protocol for the detection of biomolecules (local sensi-tivity), based on the receptor–ligand approach and using the biotin–streptavidin model system. We also tested the sensitivity to a homogeneous change in the refractive index of the buffer over the sensor (bulk sensitivity). Comparing the obtained results to those of an array of nanoprisms, chosen as a benchmark, significantly higher performances both in local and bulk sensitivities have been found, in agreement with electrodynamics simulations based on finite-element methods.

Gold-silver alloy semi-nanoshell arrays for label-free plasmonic biosensors

Russo, Valentina;Michieli, Niccolo;Cesca, Tiziana;Scian, Carlo;Silvestri, Davide;Morpurgo, Margherita;Mattei, Giovanni
2017

Abstract

Nanosphere lithography coupled with reactive ion etching has been used to synthesize hexagonal ordered arrays of Au–Ag bimetallic semi-nanoshells to be used as plasmonic biosensors. The degree of lateral interaction between adjacent semi-nanoshells can be controlled by tailoring the reactive ion etching time in order to boost the global plasmonic properties through the formation of near-field hot-spots, which in turn can improve the sensitivity of the biosensors. To test the efficiency of the proposedsystem as a biosensor, we used an established protocol for the detection of biomolecules (local sensi-tivity), based on the receptor–ligand approach and using the biotin–streptavidin model system. We also tested the sensitivity to a homogeneous change in the refractive index of the buffer over the sensor (bulk sensitivity). Comparing the obtained results to those of an array of nanoprisms, chosen as a benchmark, significantly higher performances both in local and bulk sensitivities have been found, in agreement with electrodynamics simulations based on finite-element methods.
2017
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3243365
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