Innovative bioassay concepts for Alzheimer's disease diagnostics

In recent years, the biosensors field has experienced a remarkable growth and underwent a number of major transitions. One particularly interesting transition is the shift from ensemble measurements to so-called single-entity approaches. These systems, enabling detection of low femtomolar (fM) to even attomolar (aM) concentrations of target molecules, have been shown to be highly valuable in a wide variety of applications, including food quality control and early disease diagnosis. However, moving these techniques forward from the fundamental research stage to their actual application in the field remains challenging. For microwell-based digital bioassays in particular, two factors that are considered pivotal in overcoming this hurdle are the fabrication of microwells, and the approach for signal generation and amplification. First, the fabrication of the gold standard Teflon-based hydrophilic-in-hydrophobic (HIH) microwells is a complex, costly and labor-intensive procedure with limited upscaling potential. Second, the currently applied systems for signal generation and amplification rely solely on protein-based enzymes, which to date still suffer from drawbacks related to their protein nature, including limited stability and flexibility.

In this context, the aim of this dissertation is to study novel concepts for digital bioassays, particularly focusing on (1) simplified and scalable concepts for the fabrication of microwells, and (2) robust and flexible concepts for signal generation and amplification.