Rational Design of Plasmonic Nanostructures for Biomolecular Detection: Interplay Between Theory and Experiments

CORONADO E A

ACS NANO

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 6 p. 3441 - 3441

1936-0851

n this work, we report a simple strategy to obtain ultrasensitive SERS nanostructures by self-assembly and bioconjugation of Au nanospheres (NSs). Homodimer aggregates with an interparticle gap of around 8 nm are generated in aqueous dispersions by the highly specific molecular recognition of biotinylated Au NSs to streptavidin (STV), while random Au NS aggregates with a gap of 5 nm are formed in the absence of STV due to hydrogen bonding among biotinylated NSs. Both types of aggregates depict SERS analytical enhancement factors (AEF) of around 107 and the capability to detect biotin concentrations lower than 1 × 10?12 M. Quite interesting, the AEF for an external analyte, Rhodamine 6G (RH6G), using the dimer aggregates is 1 order of magnitude greater (105) than using random aggregates (around 104). The dependence on the wavelength and the differences of the AEF for Au random aggregates and dimers are rationalized with rigorous electrodynamic simulations. The dimers obtained afford a