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Open Access Research article

Development of a strategy to functionalize a dextrin-based hydrogel for animal cell cultures using a starch-binding module fused to RGD sequence

Susana M Moreira, Fábia K Andrade, Lucíla Domingues and Miguel Gama*

Author Affiliations

IBB, Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057, Braga, Portugal

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BMC Biotechnology 2008, 8:78  doi:10.1186/1472-6750-8-78

Published: 14 October 2008



Several approaches can be used to functionalize biomaterials, such as hydrogels, for biomedical applications. One of the molecules often used to improve cells adhesion is the peptide Arg-Gly-Asp (RGD). The RGD sequence, present in several proteins from the extra-cellular matrix (ECM), is a ligand for integrin-mediated cell adhesion; this sequence was recognized as a major functional group responsible for cellular adhesion. In this work a bi-functional recombinant protein, containing a starch binding module (SBM) and RGD sequence was used to functionalize a dextrin-based hydrogel. The SBM, which belongs to an α-amylase from Bacillus sp. TS-23, has starch (and dextrin, depolymerized starch) affinity, acting as a binding molecule to adsorb the RGD sequence to the hydrogel surface.


The recombinant proteins SBM and RGD-SBM were cloned, expressed, purified and tested in in vitro assays. The evaluation of cell attachment, spreading and proliferation on the dextrin-based hydrogel surface activated with recombinant proteins were performed using mouse embryo fibroblasts 3T3. A polystyrene cell culture plate was used as control. The results showed that the RGD-SBM recombinant protein improved, by more than 30%, the adhesion of fibroblasts to dextrin-based hydrogel. In fact, cell spreading on the hydrogel surface was observed only in the presence of the RGD-SBM.


The fusion protein RGD-SBM provides an efficient way to functionalize the dextrin-based hydrogel. Many proteins in nature that hold a RGD sequence are not cell adhesive, probably due to the conformation/accessibility of the peptide. We therefore emphasise the successful expression of a bi-functional protein with potential for different applications.