Mesoporous thin film structures as metal nanoparticle reactors for electronic circuits: effects of matrix crystallinity and nanoparticle functionalization

D. C. DELGADO GONZÁLEZ; CATALANO, PAOLO N.; BELLINO, MARTÍN G.

Workshop; 1st Argentine-German Workshop on Nanotechnology and Nanobiosensors; 2017

There is an increasing interest in versatile nanoelectronic structures based on highly stable, accessible, spatially located and hierarchically organized arrays of metal nanoparticles [1]?[3]. However, to maximize the potential of metal nanoparticles in electronic applications, closely packed nanoparticle assembly, spatial location and hierarchical organization control are needed. Mesoporous oxide thin films (MOTF) have the inherent capabilities of highly controlled nanoreactors and thus are attractive matrices for constructing and organizing metal nanostructures [4]. In this study, by using different thermal treatments, the influences of mesoporous titania thin film crystallinity and pore features over electrical conductivity of embedded silver nanoparticles were analyzed. A barrier of mesoporous silica on titania film was used to impart localized currents along the embedded metal nanoparticles. Although matrices treated at lower temperatures have shown less pore connectivity, less extensive anatase fraction and lower silver content, they revealed higher electrical conductivity than matrices treated at higher temperatures. This was interpreted as better connectivity among particles from plasmon behavior. The stability of this system was significantly enhanced through upon chemisorption of 1-octanethiol self-assembled monolayers over silver nanoparticles. The maximum plasmon absorbance remained practically unaltered after storage for at least 15 days and the current remained stable up to 20 voltage cycles. Moreover, we identified that this meso/Ag nanoparticle circuitry can be bio-functionalized with thiolate ligands incorporating DNA by monitoring hybridization-based fluorescence changes using specific target sequences. This demonstrates that a stable and accessible conductive nanocomposite circuit consisting of thiol ligands-functionalized metal nanoparticles embedded in a mesoporous oxide thin film matrix can be produced. An especially appealing area of application of this nanoparticle array is in cheap/disposable sensors including biosensors able to detect specific target sequences owing to hybridization-based changes in the conductivity of the silver nanoparticle circuit.