Nanostructured Thin Coatings from Chitosan and an Elastin-Like Recombinamer with Acute Stimuli-Responsive Behavior Rui R. Costa 1,2,a , Artur J. Ribeiro 3,4,b , José C. Rodríguez-Cabello 3,4,c and João F. Mano 1,2,d 1 3B’s Research Group – Biomaterials, Biodegradables and Biomimetics, University of Minho, AvePark, Zona Industrial da Gandra, S. Cláudio do Barco, 4806-909 Caldas das Taipas – Guimarães, Portugal. 2 ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal. 3 G. I. R. Bioforge, University of Valladolid, Edificio I+D, Paseo de Belén, 1, 47011, Valladolid, Spain. 4 Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Valladolid, Spain. a rui.costa@dep.uminho.pt, b arturjamr@gmail.com, c cabello@bioforge.uva.es, d jmano@dep.uminho.pt Keywords: Surface engineering; Layer-by-layer; Biomaterials; Recombinant polymers. Abstract. In the present work, chitosan (CHI) and elastin-like recombinamers (ELRs) were used to conceive nanostructured thin films driven by sequential electrostatic layer-by-layer (LbL), a simple and versatile technique that discards the use of harmful reagents. Two similar ELRs were engineered to contain negatively charged aminoacids and organized and a single monoblock or a triblock. The buildup of the films was monitored in real time using a quartz-crystal microbalance with dissipation monitoring (QCM-D). Wettability transitions were observed from a moderate hydrophobic surface to an extremely wettable upon increasing the temperature to 50 ºC, accompanied by topography changes at the nanoscale as assessed by atomic force microscopy (AFM). Furthermore, the dependence on time for the surface molecular rearrangement was studied for the films with each ELR. The potential of this technology may stimulate the development of devices and biomaterials for biomedical applications in the near future, such as surfaces with tunable and patterned cell adhesion, while the use of ELRs will allow developing polypeptides with biological significance. Introduction The modification of surfaces has been a key aspect in biology and biotechnology, including cell expansion, development of biomaterials and preparation of substrates for regenerative medicine [1- 3]. The surface is the first contact with the organism and dictates the subsequent biological events, namely the cellular events and biointegration. This is an approach with potential impact not only on the properties of current healthcare systems but also in more cutting-edge ones in tissue engineering. Although several techniques may be used to modify a surface, the last decade has emphasized non-harmful and versatile techniques to modify polymeric substrates: the sequential adsorption of proteins and polysaccharides is one of the most promising today. This approach is known as layer- by-layer and is driven by a multitude of intermolecular interactions – such as electrostatic contacts, hydrophobic interactions, and hydrogen bonding – that may occur between two distinct materials [4- 6]. Much work has been done in multilayered systems using poly(styrene sulfonate)/poly(allylamine hydrochloride) and CHI/hyaluronan [7]. However, the knowledge obtained from such systems is not always easily extrapolated to other materials and that limits the use of potentially more relevant combinations for LbL in biomedical applications. In this work, we aimed to apply the concept of Materials Science Forum Vols. 730-732 (2013) pp 32-37 Online available since 2012/Nov/12 at www.scientific.net © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/MSF.730-732.32 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 157.88.202.80-13/11/12,14:18:30)