Adhesives, biomimetic potentials

Potential applications of peptide-polymer conjugates include drug delivery materials, optoelectronics, biosensors, tissue scaffolds, tissue replacement materials, hydrogels, adhesives, biomimetic polymers, lithographic masks, and templates for metallic or silica nanostructures. 

Figure 8.3 Time dependence of electrochemical potential in the system. T = 20 °C, 0.03 wt.% H202 (1 biomimetic electrode 2 aluminum electrode 3 aluminum electrode with applied adhesive).

Biomimetic sensors, prepared by catalase adsorption on diasorb and agarose (treated with trypsine) and adhered to an aluminum electrode surface by Pattex adhesive, displayed an abrupt decrease of the electrode potential. Sensors prepared by catalase adsorption on A1203 (without trypsine treatment) and adhesion to the aluminum electrode with Pattex adhesive displayed a high oscillation of the electrode potential, which induces extreme instability of the operation. Hence, it should be noted that sensor operation was always better in the case of enzyme treatment with trypsine. 

A potentially important development for the future of biomimetic research was published recently. Using a procedure developed by Whitesides, nucleophiles micropattemed on a gold surface were used as initiators to prepare poly(Y-benzyl-L-glutamate). Thus, an array of poly(amino acid) layers covalently attached to the surface was obtained. These would potentially act as mediators of biomimetic reactions. German workers have described the production of protein-DNA double and triple layers adsorbed on smfaces. Adhesion between layers was provided by biotin-streptavadin interactions and binding was detected by a quartz crystal microbalance. These studies may have some relevance to the understanding of protein DNA interactions at interfaces in biological systems. 

Techniques to produce multiscale biomaterial scaffolds with designer geometries are the need of the hour to provide improved biomimetic properties for functional tissue replacements. While micrometer fibers generate an open pore stnicture, nanofibers support cell adhesion and facilitate cell-cell interactions. This was further proven by cell penetration studies, which showed superior ingrowth of cells into hierarchical structures. Mixed bimodal scaffolds of two different polymers are another promising approach, because they exhibit hierarchical pore/ surface systems and combine the beneficial properties of both polymers at two different scales. Vaiious 3D micro- and nanoscale multiscale scaffolds have been fabricated through various techniques and were found to have the potential to essentially recreate natural bone, cardiac, neural, and vascular tissues. 

Chen T, Janjua R, McDermott MK, Bernstein SL, Steidl SM, Payne GF (2006) Gelatin-based biomimetic tissue adhesive. Potential for retinal reattachment. J Biomed Mater Res B Appl Biomater 77 416-422... 

One potential application of mTG-catalyzed crosslinking is as a biomimetic soft tissue adhesive analogous to fibrin sealants. Current fibrin sealants employ protein components derived from blood and utilize the transglutaminase activity of factor Xllla to catalyze protein (i.e. fibrin) crosslinking. It may be possible to develop an alternative soft tissue adhesive based on gelatin and mTG that avoids the need for blood proteins. 

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