Collagen Functionalized with Unsaturated Cyclic Anhydrides— Interactions in Solution and Solid State S. Potorac, 1,2,3,4 M. Popa, 1 L. Picton, 2,3,4 V. Dulong, 2,3,4 L. Verestiuc, 5 D. Le Cerf 2,3,4 1 Department of Natural and Synthetic Polymers, “Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Str. D. Mangeron 73, 700050 Iasi, Romania 2 Normandie Universit  e, France 3 Universit  e deRouen, Laboratoire Polyme`res Biopolyme`res Surfaces, F-76821 Mont Saint Aignan, France 4 CNRS UMR 6270 & FR3038, F-76821 Mont Saint Aignan, France 5 Department of Bimedical Sciences, “Grigore T. Popa” University of Medicine and Pharmacy, Faculty of Medical Bioengineering, 16 Universitatii Street, 700115, Iasi, Romania Received 22 April 2013; revised 28 May 2013; accepted 31 May 2013 Published online 19 June 2013 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/bip.22319 ABSTRACT: Maleic anhydride (CMA) and itaconic anhydride modified collagen (CITA) were prepared as precursors for production of interpenetrated polymer networks (IPN). Calculated values for Huggins coefficient in aqueous diluted and semi-diluted solutions of modified collagen indicated a slightly tendency of aggregation for itaconic anhydride-modified collagen. In semi-diluted solution collagen (Coll) and CMA present slightly differences in the thixotropic behavior, while CITA has a pronounced thixotropic behavior. Flow and oscillatory measurements revealed an elastic behavior of the collagen solutions, pure and modified with MA or ITA, as the storage modulus (G 0 ) has always a superior value compared with the loss modulus (G 00 ). The denaturation temperature (T d ) of unmodified collagen increased from 34 o C to 40 o C for CMA and to 39 o C for CITA respectively, by formation of covalent bonds that stabilize the triple helix. V C 2013 Wiley Periodicals, Inc. Biopolymers 101: 228–236, 2014. Keywords: collagen; temperature; rheology This article was originally published online as an accepted pre- print. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com INTRODUCTION C ollagen is the most abundant protein in connective tissues of mammals and its metabolism is directly associated with the physiological process of tissue regeneration. 1 Because of its biological properties and easy availability, collagen is widely used as bio- material. 2 Thus collagen has been used in tissue engineering and drug delivery and some intrinsic relationships have been found between collagen and many diseases such as rheuma- toid arthritis and systemic sclerosis. 3 Collagen is practically insoluble in pure water, but the solubility can be increased by adding of electrolytes and adjustment of the solution pH. 4 Collagen processing involves injectable aqueous solutions for tissue augmentation 5 or matrices for drug delivery 6,7 and tissue regeneration. 8 The development of collagen matrices is an area of research with relevant applications in medical devices industry, one of the most important applications Correspondence to: Didier Le Cerf; e-mail: didier.lecerf@univ-rouen.fr Contract grant sponsor: BRAIN “Doctoral scholarships as an investment in intelligence” project, financed by the European Social Fund and Romanian Government V C 2013 Wiley Periodicals, Inc. 228 Biopolymers Volume 101 / Number 3