Biomimetic Peptide-Enriched Electrospun Polymers: A Photoelectron and Infrared Spectroscopy Study G. Iucci, 1 F. Ghezzo, 2 R. Danesin, 2 M. Modesti, 2 M. Dettin 2 1 Department of Physics, INSTM and CISDiC, University ‘‘Roma Tre,’’ Via della Vasca Navale, 84 00146 Rome, Italy 2 Department of Chemical Process Engineering, University of Padova, Via Marzolo, 9-35131 Padova, Italy Received 28 April 2011; accepted 28 April 2011 DOI 10.1002/app.34768 Published online 10 August 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Biomimetic polymer nanofibers of poly(e- caprolactone) and poly(L-lactide–caprolactone) copolymer were prepared by electrospinning. Modifications of the polymer nanofibers aimed at improving their biomimetic properties were performed by two different routes: (1) immobilization of an adhesion peptide, which mimicked the adhesion sequence of the extracellular matrix protein fibronectin, on the polymer surface and (2) incorporation of self-complementary oligopeptides, which showed alter- nated hydrophilic and hydrophobic side chain groups and was capable of generating extended ordered structures by self-assembling, into the polymer nanofibers. The struc- ture of the polymer/peptide nanofibers was investigated by X-ray photoelectron and Fourier transform infrared spectroscopies. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3574–3582, 2011 Key words: polyesters; peptides; X-ray INTRODUCTION Biomaterial scaffolds have attracted increasing inter- est for the preparation of biomedical devices for tis- sue engineering; to promote cell colonization and, therefore, cell growth, scaffolds must mimic the extracellular matrix (ECM) in the best possible way. Electrospinning is one of the most promising techni- ques for the preparation of biomaterial scaffolds and for skin and cartilage reconstruction, artificial nerves, and especially, blood vessels. 1–3 In the electrospinning technique, polymeric nano- fibers are obtained by the ejection of a polymeric solu- tion from a syringe through a needle to a collector sur- face; a high voltage is applied between the needle and the collector. Compared to other extrusion techniques, electrospinning has the advantage of producing fibers having a very small caliber, in the 5–500-lm range. During the past few years, electrospun nanofibers of biocompatible polymers, such as poly(e-caprolac- tone) (PCL) and copolymers, have been studied as promising candidates for small-caliber blood vessels. The biomimetic properties of the polymer nanofibers can be improved by surface modifications 2 or by protein incorporation in the polymer blend. 4 ECM proteins play a major role in the adhesion of several cell types to the material surface; cell adhe- sion can be promoted by the immobilization of oli- gopeptides, which mimics the adhesion sequence of ECM proteins. Fibronectin is one of the main ECM proteins responsible for cell adhesion, which takes place via interaction between the RGD binding sequence of fibronectin and cell membrane integrin receptors. Immobilization of an entire protein on a surface can result in protein denaturation and a loss in the bioactivity, a drawback that can be prevented by the anchoring of short biomimetic peptides; this reproduces the protein receptor binding site, such as the (GRGDSP) 4 K peptide mimicking the RGD bend- ing site of fibronectin. 5,6 Self-assembling (SA) peptides are another class of materials studied for scaffold preparation; self-com- plementary amphiphilic oligopeptides, which show alternating positively and negatively charged side chains separated by hydrophobic side chains, can generate extended ordered structures by SA from aqueous solutions. 7,8 The most widely studied SA peptide is EAK, the so-called molecular lego, a 16- unit oligopeptide consisting of a periodic sequence of the amino acids L-alanine, L-glutamic acid, and L- lysine. 9,10 Interaction between peptide molecules in b-sheet conformation takes place via hydrogen bonds between the peptide groups of the backbone within the sheets and by hydrophobic or ionic inter- action of the side chains between the different sheets. The structure of SA EAK in the plane per- pendicular to the b sheets is shown in Figure 1. We extended our investigation to related SA pep- tides, having amino acidic residues with different side chain structures; the amino acid sequence of the inves- tigated peptides is shown in Table I. In the newly Correspondence to: G. Iucci (iucci@uniroma3.it). Contract grant sponsor: Ministero dell’Istruzione, dell’Universtita ` e della Ricerca (MIUR). Journal of Applied Polymer Science, Vol. 122, 3574–3582 (2011) V C 2011 Wiley Periodicals, Inc.