Developing Novel Biointerfaces and Biomaterials with Surface Plasmon Resonance and SPR Imaging
Much research has focused on the development of analytical methods to monitor a multitude of biological interactions including protein-carbohydrate, protein-lipid, and protein-DNA among others. Surface plasmon resonance (SPR) remains one of the most exciting techniques that allows for real-time data collection and label free detection amenable to many biological systems. This thesis focuses on the development of novel sensing interfaces/materials for biomolecular interaction analysis (BIA) with SPR and SPR imaging (SPRi).
The first half of this work focuses on the development of unique surface chemistry designs to examine biological interactions. Firstly, in an effort to augment understanding of lectin (protein)-carbohydrate interactions, SPR spectroscopy is used to display differential binding of lectins to various synthetic carbohydrates. This biointerface was later adapted to a high-density array format for SPR imaging detection. Secondly, to expand the use of SPR to large bioparticle detection another interface based on the generation of a mass-enhancing product at the sensing interface for highly sensitive and fast detection of E. coli is presented. Results indicate a multi-fold signal enhancement of E. coli cells in buffer and on spinach leaves.
The second part of this thesis focuses on the development of new substrates for both SPR and SPR imaging experiments. Firstly, the fabrication of ultra-thin (ca. 5-8 nm) glass layers on top of a gold surface for SPR biosensing applications is demonstrated. This nanoglassy layer is created by employing a high-pressure, low-volume paint gun technique, resulting in ultra-thin and fracture-free substrates for biosensing applications including monitoring membrane protein interactions in real-time. Finally, the facile fabrication of gold-coated etched glass substrates for SPR imaging that reduces background resonance 5-fold in situ compared to the standard gold island array platform is presented. The etching of the glass substrate induces a variation in the resonance condition and thus in the resonance angle between the etched wells and the surrounding area, leading to the isolation of the array spot resonance with a significant reduction of the background resonance. Additionally, these chips enhance the SPR evanescent field intensity 3-fold compared to standard planar gold chips and significantly enhance SPR imaging surface sensitivity.