Gold Nanoparticle Chemiresistor Sensors in Aqueous Solution: Comparison of Hydrophobic and Hydrophilic Nanoparticle Films

Abstract

Chemiresistor sensors based on thin films of gold nanoparticles capped with hydrophobic hexanethiol or hydrophilic 6-hydroxyhexanethiol self-assembled monolayers are shown to respond to organic analytes in aqueous solution. Although considerable swelling of the 6-hydroxyhexanethiol-capped nanoparticle film by water occurred, the 6-hydroxyhexanethiol-capped nanoparticle film still responded toward the presence of organic analytes in aqueous solution. The response toward nonpolar analytes (toluene, hexane, dichloromethane) was reduced for the 6-hydroxyhexanethiol-capped chemiresistor compared to the hexanethiol-capped chemiresistor. However, for polar analytes such as ethanol the response sensitivity was reversed. A simple theoretical model describing the chemiresistor response in water is presented and was used to determine the partition coefficients between the nanoparticle film and water for ethanol and toluene.

Detection of bacterial metabolites for the discrimination of bacteria utilizing gold nanoparticle chemiresistor sensors

“…2 and 3). It has previously been shown that the resistance of Au NP films increase proportionally to the concentration of analytes that partition into the nanoparticle film [29]. Based on this, the data suggests that as E. coli grow, the sensors detect an initial decrease in analyte(s) concentration followed by an increase.…”

Influence of Gold Nanoparticle Film Porosity on the Chemiresistive Sensing Performance

“…The chemiresistors function by a change in electrical resistance of the gold nanoparticle films by the partitioning of analytes into the organic caps surrounding the nanoparticles [12,13]. However, it has also been shown that the response towards analytes can depend on the nanostructure of the functionalised nanoparticle film and the method of film formation [14][15][16][17][18][19][20][21][22].…”

“…From the perspective of chemical sensing, we are interested in determining the porosity of gold nanoparticle films that are used as chemiresistive materials in liquids [11,13,[30][31][32][33][34][35][36]. The assembly of multilayered gold nanoparticles produces a disordered porous film [37].…”

Responsive polymer/gold nanoparticle composite thin films fabricated by solvent-induced self-assembly and spin-coating

“…The distinct features of nanostructured 2D Au arrays can be summarized by outlining recent achievements. First, Au thin films fabricated by alkylthiol-functionalized Au NPs were found to have vapor sensitive conductivities [7,8], they were hence widely investigated as electrical chemiresistors for sensing different vapor analytes [9][10][11] and even organic molecules in aqueous solutions [12,13]. Second, Au thin films were demonstrated to have special localized surface plasmon resonances (LSPR) [14][15][16], so that highly ordered 2D Au superlattices showed strong collective LSPR bands due to the near-field coupling of adjacent nanoparticles [17] and were employed to detect biomolecular binding [18].…”