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© 2017 In this paper for the first time we successfully detect bacterial flagellar filaments from Proteus mirabilis using molecularly imprinted artificial receptors. These receptors acted as a sensing layer of the biosensors, assembled by imprinting flagellar proteins onto a polymeric backbone of electropolymerized phenol. In short, flagellar filaments were absorbed onto a carbon support, phenol was electropolymerized around it through the carbon conductive matrix to create the protein molecular molds, and finally the flagellar proteins were removed by enzymatic and electrochemical action. Each removed flagellar protein gave rise to an imprinted site with eventual rebinding ability. Electrical impedance spectroscopy (EIS) and square wave voltammetry (SWV) were employed to measure the interaction of flagellar filaments with the sensing layer assembled on commercial screen-printed electrodes, providing low detection limits, high precision and selectivity toward the targeted protein. The detection limit was 0.7 ng/mL by EIS and 0.9 ng/mL by SWV. The artificial receptors were further assembled on home-made paper-printed electrodes, with the three-electrode system printed on a paper substrate, offering the possibility of detecting flagellar filaments at as low as 0.6 ng/mL with a disposable and cost-effective portable device. To the best of our knowledge this is the first sensing device where molecularly imprinted artificial receptors are tailored on home-made electrode based on paper substrates with three electrodes assembled together, which is a suitable approach for the fabrication of easy and cost-effective tailored electrodes.

The objective of this thesis was to explore novel approaches for studying molecular recognition at biological and biomimetic surfaces using the quartz crystal microbalance (QCM) biosensor technique. The first two papers focused on the synthesis and study of biotin selective polymer films prepared using the molecularly imprinted polymer (MIP) technique. Control over polymer structure is of importance for sensor reproducibility and sensitivity, and was addressed in Paper I where a simple strategy for fabricating uniform thin biotin imprinted polymer films was employed. In Paper II the binding of biotin moieties to thin (3-5 nm) biomimetic polymer films was examined and consequences for sensor performance discussed. The potential for using QCM as a tool for assessing the binding of small peptides derived from phage display screening was presented Paper III. Here, screening of a phage peptide library against immobilized adenine resulted in candidate peptides that were studied using this technique. In Paper IV a whole cell-based biosensor was developed for studying interactions with cell membrane-incorporated targets. Epithelial cancer cells, SKOV3, were attached to QCM sensor chips and the binding of the monoclonal antibody HerceptinTM was studied. This approach demonstrates the potential of using QCM to study binding to membrane-incorporated targets, an alternative to assays based upon immobilized receptor structures lacking their natural context.

Methods were developed for the synthesis of three different types of macrocyclic carbohydrate/amino acid hybrid molecules. In the synthesis of the first type of macrocycles, a glucosamine derivative was oxidized at C6 and the obtained sugar amino acid was coupled to tripeptides. The resulting hybrids were transformed into dimers and cyclized in a macrolactamization step to obtain C2-symmetric macrocycles. In the second type of macrocycles, the same sugar amino acid was used together with tyrosine to prepare a C3-symmetric macrocycle with alternating sugar amino acid and tyrosine residues. In the synthesis of the third type of macrocycles, Cu(I)-catalysed 1,3-dipolar cycloaddition of azides and acetylenes was employed to form C2-symmetric carbohydrate/amino acid hybrid molecules containing two 1,2,3-triazole units. The macrocycles that were water-soluble were screened for affinity towards biomolecules. Weak, but significant, affinity was found for dAMP, dGMP, serotonin and caffeine for some of the macrocycles (Ka approx. 10 M-1) which indicates that molecules of this type have potential as artificial receptors. Possibilities to extend the developed methods to prepare further types of macrocycles are discussed.

Partial contents: Chiral Dihydropyridones as Synthetic Intermediates; Stereocontrol using Dithiane Oxide Building Blocks; Rearrangements of Isoxazoles; Reissert Compound Studies with Pyridine; Friedel's Folly Revisited - A Great New Approach to Pyridines, Quinolines, etc; New Stereoselective Methods for O-Heterocyclic Synthesis; The Versatility of Microbial Oxidation of Aromatic Compounds in the Synthesis of Heterocyclic Natural Products; Sequential Transformations in Organic Synthesis: A Synthetic Strategy with a Future; The Design and Synthesis of Selective Protein Kinase C Inhibitors; and Isocondensed Heteroaromatic Pyrroles: Syntheses, and Applications in the Syntheses of Natural Products and Conducting Polymers.