Surface interactions following assembly

For the majority of fibril systems, simple deposition results in layers of fibrils that are largely unordered. The thickness of the fibril layer can also vary. This section explores a variety of methods that can be used to induce fibrillar alignment on a surface or create surface patterns. It also details methods that can be used to induce covalent and noncovalent attachment of fibrils to the surface. 

In a second study, Mesquida again exploited electrostatic interactions between fibrils and surfaces to create surface patterns. This second study employed AFM charge writing to position fibrils in lines several microns 

Magnetism is yet another successful method for the alignment of individual peptide fibers. Magnetite (Fe304) particles approximately lOnm in size were noncovalently attached to diphenylanalanine nanotubes during fiber 

The studies outlined in this section show a number of different techniques that can be used to align fibrils and other peptide nanofibers in order to create micron-sized patterns from these self-assembling materials. This section also explored some of the covalent and noncovalent strategies for attaching fibrils to surfaces, and how these methods may be exploited to create three-dimensional patterns of fibrils that have an exciting range of potential applications. 

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Metal NPs were also used as labels to follow aptamer-substrate interactions. The supramolecular self-organization of the aptamer-substrate complexes on surfaces was implemented to develop different configurations of electrical aptasensors.88 The anticocaine aptamer was separated into two fragments (37 and 38) (Fig. 12.24a). The nucleic acid (37) was assembled on a Au electrode, whereas the nucleic acid (38) was... 

More clearly than in many other protein folds, the function of coiled coils follows from their main structural properties. Coiled coils are usually long, rigid oligomers of helices with regular packing interactions and extended exposed surfaces. This enables them to assemble into large,... 

The experimental response may deviate from that expected under ideal conditions for the following reasons. First, there may be interactions between the adsorbed molecules that cause the surface activity to differ from the surface concentration [13,14]. Alternatively, double-layer effects, ion-pairing, acid-base dissociation, and dispersion of the formal potentials can cause similar deviations. A non-zero peak splitting may indicate intermolecular interactions between the redox centers or that switching the redox composition triggers a structural change within the supramolecular assembly, e.g. adsorbate reorientation or the formation of... 

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