SHORT COMMUNICATION Preparation and characterization of collagen/chitosan poly (ethylene glycol)/nanohydroxyapatite composite scaffolds Justyna Kozlowska | Natalia Stachowiak | Alina Sionkowska Faculty of Chemistry, Nicolaus Copernicus University in Torun, Torun, Poland Correspondence J. Kozlowska, Faculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, 87‐100 Torun, Poland. Email: justynak@chem.umk.pl Funding information Narodowe Centrum Nauki, Grant/Award Number: UMO‐2013/11/B/ST8/04444; National Science Centre (NCN, Poland), Grant/Award Number: UMO‐2013/11/B/ ST8/04444 Porous three‐dimensional collagen/chitosan scaffolds combined with poly (ethylene glycol) (PEG) and hydroxyapatite were obtained through a freeze‐drying method. Physical cross‐linking was examined by dehydrothermal treatment. The prepared materials were characterized by different analyses, eg, scanning electron microscopy (SEM), measurements of porosity and swelling, mechanical properties, and resistance to enzymatic degradation. The porosity of scaffolds and their swelling ratio decreased with the addition of hydroxyapatite. Moreover, after exposure to collagenase, the collagen/chitosan matrices containing PEG showed much faster degradation rate than matrices with the addition of hydroxyapatite. The results indicated that the addition of hydroxyapatite led to improvement of stiffness. The highest degree of porosity and swelling were demonstrated by collagen/chitosan/PEG matrices without hydroxyapatite. KEYWORDS chitosan, collagen, composite materials, hydroxyapatite, poly (ethylene glycol) 1 | INTRODUCTION Porous three‐dimensional (3D) scaffolds are used extensively in biomedical field in attempts to regenerate different tissues and organs in the body. 1,2 The ideal 3D scaffold is composed of a biocompatible, biodegradable material with improved mechanical properties to guide new tissue in‐growth and regeneration. 3-5 Moreover, among their important features are also the absence of the host's immune response and bioactivity, ie, ability to interact with the surrounding living tissues or organs. 6,7 In recent years, collagen has been one of the most common naturally derived biomaterials used for fabrication of scaffolds because of its unique properties, including nontoxicity and osteoconductivity. 8-11 However, a pure collagen scaffold has insuffi- cient stiffness and thermal stability. In addition, collagen exhibits insuf- ficient bioactivity to stimulate bone formation ability. 12-14 What is more, collagen is enzymatically biodegradable and has a tendency to degrade rapidly in vivo. 15 For this reason, the development of compos- ite scaffolds comprising a mixture of several components is the major strategy to improve physicochemical properties of collagen‐based scaf- folds. 2 A typical approach is preparation of scaffolds consisting of colla- gen and chitosan. For example, a cell culture using collagen/chitosan matrices enhanced more fibroblast proliferation, compared with those of pure collagen materials. 1 The addition of chitosan to collagen matrices increases their biostability and resistance to degradation. 16 Hydroxyapatite (HAp) has been combined with collagen‐based scaffolds. 4,5,17-20 HAp [Ca 10 (PO 4 ) 6 (OH) 2 ], the main inorganic component of natural bone, possesses significant biocompatibility. It is considered to play an important role in various bone‐related applica- tions, especially in the form of nanocrystals. 19-21 The addition of HAp improves the mechanical stability of collagen scaffolds in both dry and wet conditions and accelerates osteogenesis. 21-24 Furthermore, the surface area of collagen scaffolds can be increased by combining with HAp, which leads to incremental cellular adhesion. 4,12 The objective of this investigation was to determine the physicochemical properties of 3D materials derived from collagen and chitosan with the addition of a small amount of poly (ethylene glycol) (PEG) and HAp. These matrices were obtained by freeze‐ drying and dehydrothermal cross‐linking techniques. The prepared materials were analyzed using the following measurements: water uptake ability, enzymatic degradation, porosity, and mechanical properties. The morphology of porous samples was also studied. 3D composite materials can be potentially used as soft scaffolds for bone tissue engineering. Received: 11 July 2018 Revised: 31 October 2018 Accepted: 2 November 2018 DOI: 10.1002/pat.4506 Polym Adv Technol. 2018;1–5. © 2018 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/pat 1