Peptides surface preparation

Fig. 26. The preparation of well-defined peptidic surfaces [65,66]. A Using a thiol spacer, homopolypeptides (poly-A in this case) that adopt an a-helical conformation are synthesized on a gold surface. B Using an aminopeptidase, the longer peptidic chains are hydrolyzed to yield a more homogeneous surface. (Reproduced with the permission of Ref. 65,66)...

The pin consists of a radiation-grafted polypropylene crown fitted to an inert polypropylene stem . Graft polymers used with the Multipin system include polystyrene, a methacrylamide copolymer (38), and poly(hydroxyethyl methacrylate) (34) (HEMA). We have found that the HEMA surface is best suited to peptide synthesis. Historically, peptides were prepared in a non-cleavable format on the crown surface for epitope mapping applications (39). Over the past decade, however, most peptides prepared by the Multipin method have been synthesized on cleavable linkers. The linkers used for peptide synthesis are outlined below. 

When preparing responsive peptide surfaces, a number of points need to be considered to ensure functionality and compatibility with the response mechanism and the application. These considerations are laid out first before introducing the various fabrication strategies that have been used to prepare responsive peptide surfaces. 

Preparation strategies for peptide surfaces have to meet several general criteria. First, the immobilisation of the peptide-based material to the surface has to be stable under the conditions used for the intended application. Second, the responsive material has to retain its function when immobilised, and the immobilisation procedure must be nondestructive to the peptides. It should be noted that the responsiveness of the peptide material may also be directly related to the surface attachment, for example, if the response is provided by a change in orientation of the peptide in relation to the substrate surface (Yeung et al 2010), or by electrically interfacing with the surface (Yasutomi, Morita, Imanishi, Kimura, 2004). In these instances, the peptide surface constitutes a whole new functional material that would not exist if the peptide were merely used in solution. Finally, it is desirable and sometimes necessary to control the orientation and surface density of the immobilised peptide to obtain functional and reproducible responsive materials (Yeung et al., 2010). 

Figure 3.1 Strategies for the preparation of responsive peptide surfaces—gold-based self-assembled monolayers (SAMs), (a) Direct attachment and (b) pre-functionalisation.

Figure 3.2 Strategies for the preparation of responsive peptide surfaces—silanisation. (a) Activation, (b) functionalisation, and (c) direct build-up.

Figure 3.3 Strategies for the preparation of responsive peptide surfaces—adsorption.

The different stages of the preparation of peptide surfaces can be confirmed with surface-sensitive physical and chemical analysis techniqnes. For gold-based SAMs, Mrksich and co-workers have introduced a matrix-assisted laser desorption ionisation time-of-ftight (MALDI-TOF) mass spectrometry-based analysis procedure with which they are able to identify the presence of various surface functional groups via their mass (Yeo Mrksich, 2006 Yeo et al., 2003). Although this method is applicable to SAMs, it is not strictly a surface sensitive technique, as the desorption process in MALDI is not confined to the uppermost layer of a material. 

Synthetic laminin-1 A10 and B160 peptide sequences were coupled to poly (L-lysine) coated glass or fibrin gels. In order to investigate a broad range of peptide surface concentrations in a single test specimen, a gradient in the peptide concentration on the polymer surfaces was prepared in one direction. The... 

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