Stabilization of Gold Nanoparticle Films on Glass by Thermal Embedding

Abstract

The poor adhesion of gold nanoparticles (NPs) to glass has been a known obstacle to studies and applications of NP-based systems, such as glass/Au-NP optical devices. Here we present a simple scheme for obtaining stable localized surface plasmon resonance (LSPR) transducers based on Au NP films immobilized on silanized glass and annealed. The procedure includes high-temperature annealing of the Au NP film, leading to partial embedding in the glass substrate and stabilization of the morphology and optical properties. The method is demonstrated using citrate-stabilized Au NPs, 20 and 63 nm mean diameter, immobilized electrostatically on glass microscope cover slides precoated with an aminosilane monolayer. Partial thermal embedding of the Au NPs in the glass occurs at temperatures in the vicinity of the glass transition temperature of the substrate. Upon annealing in air the Au NPs gradually settle into the glass and become encircled by a glass rim. In situ transmission UV-vis spectroscopy carried out during the annealing in a specially designed optical oven shows three regions: The most pronounced change of the surface plasmon (SP) band shape occurs in the first ca. 15 min of annealing; this is followed by a blue-shift of the SP band maximum (up to ca. 5 h), after which a steady red-shift of the SP band is observed (up to ca. 70 h, when the experiment was terminated). The development of the SP extinction spectrum was correlated to changes in the system structure, including thermal modification of the NP film morphology and embedding in the glass. The partially embedded Au NP films pass successfully the adhesive-tape test, while their morphology and optical response are stable toward immersion in solvents, drying, and thiol self-assembly. The enhanced adhesion is attributed to the metal NP embedding and rim formation. The stabilized NP films display a refractive index sensitivity (RIS) of 34-48 nm/RIU and 0.1-0.4 abs.u./RIU in SP band shift and extinction change, respectively. The RIS can be improved significantly by electroless deposition of Au on the embedded NPs, while the system stability is maintained. The method presented provides a simple route to obtaining stable Au NP film transducers.

Effects of nanosecond-pulsed laser irradiation on nanostructure formation on the surface of thin Au films on SiO2 glass substrates

“…The Au nanoparticles embedment in the glass substrate by high-temperature annealing has been reported and its mechanism has been studied in detail by Tanya Karakouz et al [35]. The mechanism of Au nanoparticle heat transfer to the glass substrate by nanosecond-pulsed laser irradiation has been also studied in detail by S.…”

Enhancing plasmonic biosensors with nanotechnology

“…Another problem is that the resulting particles usually bind poorly to the substrate (e.g. gold to glass), so the subsequent fixation or transfer of the nanoparticles to another substrate have to be solved prior any application containing fluidic systems, which could remove the nanoparticles [20].…”

Decolorization of methylene blue in aqueous suspensions of gold nanoparticles using parallel nanosecond pulsed laser

“…GNPs were prepared according to the methods reported by Mayer [16] and Karakouz et al [17] The concentration of the prepared GNPs was 58 mg/L. The preparation and characterization of the GNP suspension may be summarized as follows: All glasswares were cleaned by ultrasonication using distilled water and then dried.…”