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Title: AFM Imaging of RGD Presenting Synthetic Extracellular Matrix using Gold Nanoparticles

item Cooke, Peter
item Fishman, Marshall

Submitted to: Macromolecular Bioscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2008
Publication Date: 6/11/2008
Citation: Hsiong, S.X., Cooke, P.H., Kong, H., Fishman, M., Ericson, M., Mooney, D.J.2008. Afm imaging of rgd presenting synthetic extracellular matrix using gold nanoparticles. Macromolecular Bioscience 8:469-477.

Interpretive Summary: The need to increase utilization of low valued carbohydrate polymer co-products derived from the processing of agricultural commodities has prompted us to investigate microscopic imaging methods for analyzing the chemical structure of carbohydrate polymers which are commonly used for the regeneration of important tissues like cartilage and bone. We collaborated with a group of tissue engineering scientists at Harvard University to investigate the use of a chemically-modified carbohydrate polymer, alginate, as part of a model system for promoting bone cell maturation. We found that a small adhesion protein, an important bone cell inducing factor, could be located on the alginate polymer, identifying an important component inducing bone cell maturation. This method opens the way to test for the substitution of alginate with pectin modified with the adhesion protein, because pectin is a carbohydrate polysaccharide found in orange peels and sugar beet pulp that is similar in structure to alginate. This research should be of help to fruit growers and processors by increasing the demand and value of their by-products without increasing the cost of the basic commodity to the consumer.

Technical Abstract: Cell-interactive polymers have been widely used as synthetic extracellular matrices (sECM) to regulate cell function and promote tissue regeneration. Although it is known that adhesion ligand density and distribution influence the proliferation and differentiation of various cell types, currently available techniques do not directly characterize sECM adhesion site presentation at the nanoscale. In this paper, we describe an Atomic Force Microscopy (AFM) method to image RGD peptides covalently conjugated to alginate hydrogels. High resolution images of RGD adhesion ligand distribution were obtained by labeling biotinylated RGD peptides with streptavidin-labeled gold nanoparticles. Our results demonstrate that high resolution imaging techniques can be powerful tools for identifying and understanding important physical properties of biomaterial characteristics and RGD ligand distribution, and this method may broadly provide a useful tool for sECM characterization and design for tissue regeneration strategies.