Periodic Reporting for period 1 - GlucOrigami (Modular DNA Origami Platform for the Design of Tunable Glucose Biosensor)
Reporting period: 2020-09-01 to 2022-08-31
From health monitoring to the detection of diseases, biosensors play a crucial role in our everyday lives. Unfortunately, in many cases, the practical use of biosensors requires costly instruments, time-consuming multi-step procedures and highly trained personnel to implement. Recent years, however, have witnessed tremendous efforts in the development of cheap and miniaturized optical sensing devices that can even be integrated with ubiquitous smartphone sensors and software. These point-of-care sensing approaches could not only facilitate the goal of ‘personalized medicine’ but also bring the diagnostic technology to resource-poor regions of the world where many infectious diseases are so prevalent. This technological boost creates an ever-growing need for new and improved optical biosensors capable of continuous monitoring of analytes in a single-step process with low-cost sensor devices. The development of such biosensors, nonetheless, faces several common challenges. A typical biosensor comprises a molecular recognition unit (e.g. protein or nucleic acid) and a detection unit designed to report this binding event in the form of an optical signal (e.g. as color or fluorescence change). One of the challenges here is to detect rather “inert” analytes that are not able to generate a strong optical signal upon binding to a molecular recognition site. Another challenge is posed by the strength of this molecular recognition interaction, which dictates the useful dynamic range of the biosensor. The ability to extend, narrow and tune this useful dynamic range, could greatly benefit applications where target concentrations span several orders of magnitude (e.g. monitoring progression of viral infections) or where a sharp dose response is essential to achieve high precision (e.g. monitoring of highly toxic substances). The aim of this project was to globally address these challenges by decoupling the molecular recognition and signal transduction units of the biosensor with the help of self-assembled and programmable DNA origami nanostructures. A more specific objective was to demonstrate this fundamental approach by designing a sensitive and tunable biosensor for glucose, whose sensing is of utmost importance for the disease monitoring of diabetic patients. Different biomimicry approaches were proposed to be tested that could lead to strategies to tune the useful dynamic range of the proposed biosensor platform with the aim to achieve sensitivity at a physiologically relevant glucose concentration.
During this project a modular sensing platform was designed and assembled using DNA origami which allowed to decouple the signal transduction and recognition units of a biosensor. This strategy allows for the easy fine-tuning of the different sensor properties while offering signal contrast highly superior to most other fluorescence based sensors. The first potential application was identified in the detection and quantification of glucose in blood. For this, different concepts for the combination of the DNA origami technology with the world of proteins were explored. Along the way, a model system was established using DNA-DNA interactions as a proxy for reversible ligand binding and light was shed on the many interesting fundamental questions concerning ligand binding kinetics and cooperative systems. Different strategies for the independent tuning of a sensors dissociation constant and the sharpness of the dose-response curve were outlined and demonstrated. While the proposed scheme for the detection of glucose could not be realized due to unforeseen challenges in assembling the final glucose sensors, the work carried out in this project has led to a modular and tunable sensing platform with high optical signal contrast that could be easily adapted to a wide range of biomolecular targets.
It is envisioned that the scientific milestones reached in this project will eventually lead to new biosensors and diagnostic technologies supporting the Horizon 2020 Societal Challenges on Health Demographic Change and Wellbeing. The research work developed in this project represents an important contribution and paradigm shift to the field of biosensing as it provides a new approach to completely decouple signal transduction and recognition units of the biosensor. This could potentially enable future development of tunable and modular sensors as well as provide novel strategies to develop sensors for analytes that are not able to generate a strong optical signal upon binding to a molecular recognition unit. The impact of the findings is rooted in the knowledge gain that can serve as basis for development of future clinical sensors and diagnostic assays.