Morphology controllable nanostructured chitosan matrix and its cytocompatibility Lifeng Qi, 1 Susmita Pal, 2 Prasanta Dutta, 2 Mohindar Seehra, 2 Ming Pei 1 1 Department of Orthopaedics, Tissue Engineering Laboratory, West Virginia University, Morgantown, WV 26506 2 Department of Physics, West Virginia University, Morgantown, WV 26506 Received 7 May 2007; revised 12 July 2007; accepted 6 September 2007 Published online 18 December 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jbm.a.31753 Abstract: It is becoming clear that surface nanotopogra- phy of underlying substrates can influence cell behavior such as adhesion, proliferation, and orientation of mam- malian cells. Nanofabrication methods such as electron beam lithography are, however, expensive and time con- suming. In this study, a simple and cost-effective ap- proach, heterogeneous seeded growth, was developed to create nanostructured chitosan matrix (CSM) from amor- phous chitosan nanoparticles (CNPs). The physiochemical properties of CSM were characterized followed by an evaluation of CSM cytocompatibility. Shape-controllable morphology of CSM from nanoparticles to three-dimen- sional urchin-like architectures was achieved by using varying amounts of seeds. CSM was found to be cytocom- patible with human foreskin fibroblasts suggesting that the nanofibrous surface morphology and crystalline struc- ture of CSM could favor cell spread and growth. Ó 2007 Wiley Periodicals, Inc. J Biomed Mater Res 87A: 236–244, 2008 Key words: chitosan matrix; nanoparticles; nanofiber; biocompatibility; small intestine submucosa INTRODUCTION The extracellular matrix, in which cells live in vivo, has considerable topographic detail down to the nanometer scale. 1 These surface features are impor- tant in the biological activity of cells. Nanotechnol- ogy allows for the construction of devices that inter- act at the subcellular level. Controlling the nano- topography of biomaterials will allow researchers to systematically study the effects of nanotopography on live culture. 2 The next generation of scaffolds for tissue and cell engineering will not just have to be mechanically suitable, but also will have to elicit specific cell responses to control the formation of tissue in con- tact with the implant. 3 Defined nanotopography formed on the implant material provides promise for guided cell and tissue growth. There have been many studies on fabrication of nanotopography to study the effects on cell behavior. 4 However, the combined surface with nanotopography and crystal- line structure was seldom reported until now. Chitosan (CS), one kind of polysaccharide, is a potential renewable source of nanosized reinforce- ments with a natural semicrystalline state. 5 Recently, considerable attention has been given to CS-based materials and their applications in the field of ortho- paedic tissue engineering. 6 Interesting characteristics that render CS suitable for this purpose are a mini- mal foreign body reaction, an intrinsic antibacterial nature, and the ability to be molded into various geometries and forms such as porous structures that are suitable for cell growth and osteoconduction. 6 Different hybrid porous CS scaffolds have been pre- pared for tissue engineering applications. 7 In this study, morphology controllable nanostructured chi- tosan matrix (CSM) with a crystalline structure was prepared to investigate the effects on cell growth. Small intestine submucosa (SIS) is an acellular, biodegradable and naturally occurring biomaterial derived from the small intestine of pigs. SIS has been used in various tissue engineering applications due to its diverse favorable properties such as natu- ral matrix and heterogeneity of the structural fea- tures. 8 Because collagen is its major component 9 and there is good compatibility between CS and colla- gen, 10 SIS was chosen to trigger the nucleation and growth of CSM. Here we present a novel way to prepare CSM from amorphous chitosan nanopar- ticles (CNPs) seeded with SIS particles. The mor- phology of CSM can be controlled by use of varying amounts of SIS seeds. Correspondence to: M. Pei; e-mail: mpei@hsc.wvu.edu Ó 2007 Wiley Periodicals, Inc.