Fabrication of nanopattern platforms for guest molecule immobilization and their applications as optical/electrical sensing devices

Abstract

The development of methods for patterning and immobilizing active moieties with micrometer and nanometer scale has proven integral to a range of applications such as molecular electronic and optical devices. A remaining challenge in these applications is the development of patterns that combine nanoscale feature sizes with surface chemistries that facilitate selective immobilization of guest molecules. In addition, it is required to enable large-scale parallel fabrication of larger surface areas and control over the (bio)chemical composition of the surface, together with control over topographical features. In this thesis, single-walled carbon nanotubes (SWNTs) and chitosan polymers were employed to fabricate highly periodic nanopatterns with reactive surface, which can serve as platforms to detect guest species immobilized. For electrical detection of DNA hybridization, SWNT networks patterns were modified by chemical surface treatment and integrated with metal electrodes by using conventional photolithographic techniques. We examined various approaches to immobilize DNA on the SWNT patterns including covalent bonding and noncovalent bonding methods using pyrene molecules for the efficient detection of DNA hybridization. In addition, the effect of network density on the biological sensing performance of SWNTs was investigated, which shows the existence of optimal network densities showing good selectivity in detecting complementary DNA hybridization. This strategy to control network density and binding method will provide opportunities to realize practical label-free biosensor utilizing the commercial available SWNT networks. To fabricate the efficient platform for sensor applications, highly periodic chitosan patterns over large area were developed by using soft lithographic techniques. To verify the capabilities of chitosan to immobilize guest molecules, DNA, SWNTs and graphene derivatives were immobilized on chitosan nanopatterns. The results of SEM obs...