Improved Selectivity and Stability of LSPR sensing with Surfactant-coated Au Nanoparticles

DALFOVO, MARIA C.; SALVAREZZA, ROBERTO C.; IBANEZ, F. J.

ANALYTICAL CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 8 p. 4389 - 4397

0003-2700

Here we report the use of tetraoctylammonium bromide (TOABr)-coated Au nanoparticles (NPs) for the optical sensing of volatile organic compounds (VOCs). We find that the film responded selectively to the presence of polar and non-polar vapors by changes in the maximum wavelength (λmax) towards higher and lower wavelengths, respectively as determined by UV-visible spectroscopy.  We also observed that the organic coating reorganizes when vapors partition into the film indicated by FT-IR and the film contracts in the presence of water indicated by SEM.  In the present sensor, the metallic Au core serves as the plasmonic signal while the organic coating acts as the receptor material providing vapor selectivity and sensor stability. Correlating changes in (λmax) with changes in the refractive index (RI) and nanoparticle-to-nanoparticle separation in the film is important for both fundamentally and for improving selectivity in localized surface plasmon resonance (LSPR) sensors.