Fusion of polymeric material-binding peptide to cell-adhesion artificial proteins enhances their biological function

Orientation-controlled protein immobilization on a solid substrate surface is important for the development of biomedical materials such as scaffolds used in tissue engineering. In this study, the authors demonstrated that the introduction of material-binding peptides (MBPs) in Arg-Gly-Asp (RGD)-fused artificial proteins called blocking peptide fragment (BPF), which are fragments (residues 419-607) of the molecular chaperone DnaK, enhances the oriented adsorption of proteins on the polymer surface and improves their cell adhesion capability. The authors used isotactic poly(methyl methacrylate) (it-PMMA) binding peptides (c02 peptide; ELWRPTR) as a model system. A quartz crystal microbalance study showed that the fusion of c02 peptide with BPF-RGD proteins slightly enhanced adsorption on it-PMMA surfaces. On the other hand, atomic force microscopic images of it-PMMA surfaces adsorbed with c02-BPF-RGD proteins showed a dotlike pattern, with the sizes of the dots comparable to those of BPF protein dimers, indicating that the immobilization of c02-BPF-RGD partially occurred in an oriented manner via specific interaction between the c02 peptide and it-PMMA. This is in sharp contrast to the random adsorption of BPF-RGD and BPF. These results were supported by results of the enzyme-linked immunosorbent assay using an antihistidine tag antibody. In addition, c02-BPF-RGD adsorbed on it-PMMA showed better cell attachment and spreading ability than BPF-RGD and BPF. This methodology can be applied to other MBP systems and cell-binding motifs. Thus, BPF-based artificial cell adhesion proteins fused with MBPs might be useful as surface modifiers of polymer materials for improving their cell adhesion ability.