Materials Science and Engineering B 178 (2013) 1303–1310 Contents lists available at ScienceDirect Materials Science and Engineering B jou rn al hom ep age: www.elsevier.com/locate/mseb Collagen immobilization on polyethylene terephthalate surface after helium plasma treatment Magdalena Aflori a,∗ , Mioara Drobota a , Dan Gh. Dimitriu b , Iuliana Stoica a , Bogdana Simionescu a,c , Valeria Harabagiu a a Department of Polymers Physics and Polymeric Materials, “Petru Poni” Institute of Macromolecular Chemistry, 41A Gr. Ghica Voda Alley, 700487 Iasi, Romania b Faculty of Physics, “Alexandru Ioan Cuza” University, 20A Bulevardul Carol I, 700505 Iasi, Romania c “Costin D. Nenitescu” Centre of Organic Chemistry, 202B Splaiul Independentei, 71141 Bucharest, Romania a r t i c l e i n f o Article history: Received 31 October 2012 Received in revised form 21 March 2013 Accepted 4 April 2013 Available online 18 April 2013 Keywords: DC helium plasma treatments Polyethyleneterephthalate Collagen adsorbtion a b s t r a c t An attractive alternative to add new functionalities such as biocompatibility due to the micro- and nano- scaled modification of polymer surfaces is offered by plasma processing. Many vital processes of tissue repair and growth following injuries depend on the rate of adsorption and self-assembling of the collagen molecules at the interfaces. Consequently, besides the amount of protein, it is necessary to investigate the form in which the collagen molecules are organizing on the polymer surface. In this study, direct current (DC) helium plasma treatment was used in order to obtain poly(ethylene terephthalate) (PET) films with different amounts of collagen and different shapes of aggregates formed from the collagen molecules. The immobilization of collagen on PET surface was confirmed by XPS measurements, an increase of the nitrogen content by increasing the plasma exposure time being recorded. The SEM and AFM measure- ments revealed the presence of grains and dendrites of collagen formed on the polymer surface. At 15 min plasma treatment time, the polymer surface after collagen immobilization has a homogenous topography. Usually, one can find fibrils, coil or dendrimers of collagen formed in buffer solutions and immobilized on different polymer surfaces. On the other hand, in this particular configuration, the combination of DC plasma and helium gas as a PET functionalization tool is an original one. As the collagen is not covalently immobilized on the surfaces, it may interact with the cell culture medium proteins, part of the collagen might being replaced by other serum proteins. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Polymeric materials provide support surfaces for the immobi- lization of biologically active molecules and living cells, having many applications in the field of tissue engineering, such as tis- sue replacement, tissue reinforcement and organ transplant [1–3]. Polyethylene terephthalate (PET) is a polymer with excellent bulk properties, such as high strength-to-weight ratio, good resistance to corrosion and it is relatively inexpensive to produce. However, PET proved to be, in some situations, an unsuitable material to use due to its low surface energy, leading to poor wettability and poor adhesion [4,5]. It is well known that plasma technologies involved in many industrial applications from aerospace to life sciences, have been successfully applied to enhance or replace wet finishing processes in several domains such as biomedical and mechanical applications, optic, paper, textile and automobile industries, and ∗ Corresponding author. Tel.: +40 740091315. E-mail address: maflori@icmpp.ro (M. Aflori). food packaging [2]. These extended applications are due to the fact that the surface modification may be accomplished through surface activation, ablation, etching, cross-linking, functionalization, film deposition or by combining few of these effects [5–7]. Moreover, these technologies represent a low cost alternative to create a large variety of chemically active species in order to attach specific func- tional groups on the polymer surfaces and offer efficient routes for the modification of natural or synthetic polymeric materials and for non-destructive operations, as well, the result being a nanometer- sized surface layer that does not change the bulk properties of the substrate [8–10]. The proteins immobilization on different surfaces represents an important topic in the fields of biomedi- cal engineering, biosensors, biofouling of processing equipment, immobilized-enzyme bioreactors, immunological test systems and many others [11], the protein adsorption occurring when the mate- rial is being placed in contact with a biological fluid [12–14]. The field of tissue engineering, focusing on repairing damaged tissues or organs requires significant improvements and novel inventions for effective human application, an important task being the control of cell–material interactions which relies on a better understanding of 0921-5107/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.mseb.2013.04.002