Site-Specific Biofunctionalization of Nano-Objects for the Development of Fluorescent and Label-Free Biosensors

PhD defence by Yi-Chi Liu.

Abstract

Semiconductor nanowire field-effect transistors (NW-FETs) have been shown to be one of the attractive candidates for the development of label-free biosensors for the detection of biomolecular interactions. The sensitivity of such sensors is based on the highly sensitive properties of 1- dimentional NWs combined with the highly specific interactions intrinsic to the biological recognition elements. In this thesis we investigate the potential of site-specific and oriented protein immobilization on the NW-based bioFET for biosensing. The surface chemistry schemes were first developed to facilitate a couple of selected site-specific protein immobilization strategies. It was carried out using selected micro/nano objects, i.e., particles. Then we developed label-free and ultrasensitive biosensors using NW-bioFET. Two semiconducting materials are exploited: Silicon (Si) and Indium Arsenide (InAs). Surface functionalization of these two types of NWs was carried out as intended to facilitate a universal attachment of bio-recognition motifs with retained function. In particular, we used InAs NW-bioFET to demonstrate the potential influence of chemical functionalization on the device performance. A fluorescence technique was utilized as a complementary tool for the characterization of the interface. Moreover, we showed sensing ability of the surface-modified InAs NW-bioFET by exploiting chemical ions and a couple of model proteins.

Supervisor
Karen L. Martinez, martinez@nano.ku.dk 

Evaluation comittee
Professor Jan Halborg Jensen, Department of Chemistry, University of Copenhagen
Professor Jean-Luc Popot, Laboratorire de Physico-Chimie des Proteines Membranaires, CNRS, Université Paris Diderot
Professor Anja Boisen, DTU Nanotech, The Technical University of Copenhagen