Biological Sensing and DNA Templated Electronics Using Conjugated Polymers

Conjugated polymers have been found useful in a wide range of applications such as solar cells, sensor elements and printed electronics, due to their optical and electronic properties. Functionalization with charged side chains has enabled water solubility, resulting in an enhanced interaction with biomolecules. This thesis focus on the emerging research fields, where these conjugated polyelectrolytes (CPEs) are combined with biomolecules for biological sensing and DNA nanowire assembling. CPEs have shown large potential in biomolecular detection where the optical read out is due to the geometrical alternation in the backbone and aggregation state. This thesis focused on transferring the biomolecular detection to a surface of CPEs. The characterization of the CPE layer show that a hydrogel can be formed, and how the layer can undergo geometrical changes upon external stimulus such as pH change. A selective sensor surface can be created by imprinting ssDNA or an antibody in the CPE layer. The discrimination for complementary DNA hybridization and specific antibody interaction can be monitored by surface plasmon resonance or quartz crystal microbalance. We have also taken the step out from the controlled test tube experiments to the complex environment of the cell showing the potential for staining of compartments and structures in live and fixed cell. Depending on the conditions and CPE used, cell nuclei, acidic vesicles…

Contents

1 General Introduction
2 Conjugated Polymers
2.1 Orbital Structure
2.2 Photophysical Properties
2.3 Conjugated Polyelectrolytes
3 Conjugated Polyelectrolytes as Biological Reporters
3.1 Solution Detection of Biomolecules Using CPEs
3.2 Surface Detection of Biomolecules
3.2.1 Surface Plasmon Resonance (SPR)
3.2.2 Quartz Crystal Microbalance with Dissipation (QCM-D)
3.2.3 POWT Layer Properties
3.2.4 POWT Layer Dynamics in DNA Detection
3.2.5 POWT Layer Dynamics in Antibody/Antigen Interaction
3.3 Cell Staining
3.3.1 Structure of the Cell
3.3.2 CPE in Fixed Cells
3.3.3 CPE in Live Cells
4 Biotemplated Electronics
4.1 DNA Stretching
4.2 DNA Positioning
4.2.1 Soft Lithography
4.2.2 Surface Patterning to Direct DNA
4.2.3 DNA Printing
4.3 DNA Wire Functionalization
4.3.1 CPE Functionalization of DNA Wires
4.3.2 Single Molecular Spectroscopy (SMS) Evaluation
5 Future Outlook
5.1 Detecting Biological Targets
5.2 Biotemplated Electronics
6 References

Author: Bjork, Per

Source: Linkoping University

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