Coating of Polyelectrolyte Multilayer Thin Films on Nanofibrous Scaffolds to Improve Cell Adhesion Stephan T. Dubas, 1 Paveenuch Kittitheeranun, 2 Ratthapol Rangkupan, 1 Neeracha Sanchavanakit, 3 Pranut Potiyaraj 2,4 1 Metallurgy and Materials Science Research Institute, Chulalongkorn University, Bangkok, Thailand 10330 2 Center of Excellence in Textiles, Department of Materials Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand 10330 3 Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand 10330 4 National Center of Excellence for Petroleum, Petrochemicals, and Advanced Materials, Chulalongkorn University, Bangkok, Thailand 10330 Received 24 February 2009; accepted 28 April 2009 DOI 10.1002/app.30690 Published online 23 June 2009 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: The adhesion of L929 cells to poly(e-capro- lactone) (PCL) nanofibers was successfully improved via coating with polyelectrolyte multilayer thin films (PEMs), which enhanced the potential of this material as a scaffold in tissue engineering applications. With the electrostatic self-as- sembly technique, poly(diallyldimethylammonium chloride) (PDADMAC) and poly(sodium 4-styrene sulfonate) (PSS) were formed as four-bilayer PEMs on electrospun PCL nano- fiber mats. Because PDADMAC and PSS are strong polyelec- trolytes, they provided stable films with good adhesion on the fibers within a wide pH range suitable for the subse- quent processes and conditions. PDADMAC and gelatin were also constructed as four-bilayer PEMs on top of the PDADMAC- and PSS-coated nanofibers with the expectation that the gelatin would improve the cell adhesion. L929 cells from mouse fibroblasts were then seeded on both uncoated and coated scaffolds to study the cytocompatibility and in vitro cell behavior. It was revealed by the 3-(4,5-dimethylth- iazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay that both the uncoated and coated nanofiber mats were non- toxic as the cell viability was comparable to that of those cul- tured in the serum-free medium that was used as a control. The MTT assay also demonstrated that cells proliferated more efficiently on the coated nanofibers than those on the uncoated ones during the 48-h culture period. As observed by scanning electron microscopy, the cells spread well on the coated nanofibers, especially when gelatin was incorpo- rated. The surface modification of PCL nanofiber mats described in this research is therefore an effective technique for improving cell adhesion. V V C 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 1574–1579, 2009 Key words: biocompatibility; fibers; polyelectrolytes; self- assembly; thin films INTRODUCTION Tissue engineering, an emerging field in the area of human heath care, has attracted growing interest in the last few decades. One of the challenges in the development of tissue engineering applications is the need to preserve a cell’s ability to grow on syn- thetic scaffolds and maintain tissue-specific function; both depend critically on factors such as cell/scaf- fold and cell/cell interactions. 1 The key factors involved during the in vivo growth of tissue forma- tion and maturation are the viability, proliferation, and spreading of cells. To improve each of these pa- rameters, increasing efforts have been made to de- velop new coatings to improve the biocompatibility of a given surface. 2 Surface modification using poly- electrolyte multilayer thin films (PEMs) to develop biocompatible materials has attracted attention lately because of several advantages. 3 This technique is very simple because it relies only on a dipping pro- cess, and it can be applied to surfaces with a very complex morphology and variable chemistry. The assembly occurs most of the time in aqueous media and does not require the use of organic solvents, which can be a problem in further cytocompatibility studies. Finally, biopolymers, oligomers, and other proteins, which are key components of biocompati- ble surfaces, can be readily used because of their electrostatic nature. The stability of the coating is im- portant especially when one tries to achieve surface modification before cell adhesion. A loss of electro- static interaction due to the neutralization of polye- lectrolytes in PEMs can lead to decomposition or excessive swelling of the coating, as previously Journal of Applied Polymer Science, Vol. 114, 1574–1579 (2009) V V C 2009 Wiley Periodicals, Inc. Correspondence to: P. Potiyaraj (pranut.p@chula.ac.th). Contract grant sponsor: Graduate School of Chulalongkorn University [through the 90th Anniversary of Chulalongkorn University Fund (Ratchadphiseksomphot Endowment Fund)].