ESR10: Fabrication of 2D colloidal crystals over large areas for biosensing / Thesis

Universitat Autonoma de Madrid, Spain

Paola Pellacani
PhD Thesis

Abstract
Surface plasmon resonance (SPR) devices are widely applied as biosensing platfoms to perform a potentially sensitive, rapid, real-time, label free and/or multiplexed detection. As a drawback, this technology is often challenged by high instrumentation costs, poor interfacing capabilities with other analytical techniques and a lack of sensitivity when applied to direct detection of highly diluted targets or analytes of small molecular weight. In order to overcome these challenges, an extensive research has addressed the development of advanced SPR platforms
based on innovative nanomaterials and fabrication methods, enabling a low cost and massive production of large area nanostructured surfaces, as well as affordable miniaturized detection devices.

In this thesis we report the optimization of a protocol for the production of large area plasmonic surfaces. The proposed nanofabrication technique combines colloidal lithography and plasma processes. In particular, we deeply studied the Langmuir-Blodgett formation of colloidal monolayers, acting as efficient etching masks when transferred on solid substrates. The sequential etching process, gold deposition and particle lift-off allowed obtaining a surface made of 2D plasmonic crystals. By adjusting the process parameters it is possible to nanostructure different materials, leading to a fine tuning of the final structure aspect ratio and, consequently,
of the spectral position of the optical response according to a proper acquisition setup. The versatility of this fabrication method shows great potential for easy and massive parallel fabrication of gold cavity arrays with a tailorable shape, diameter and periodicity. These surfaces have been proved to work as sensitive platforms in SPR and SERS experiments for a fast, realtime and multiplexing detection of proteomic (long pentraxin PTX3) and genomic (Wilms tumor gene) biomarkers.