Coating of Titanium Plate by Photocurable Azidophenyl Chitosan Derivative for Application to Implants Si Yoong Seo, 1 Shin Hye Park, 1 Hyung Jae Lee, 1 Yun Heo, 1 Ha Na Na, 1 Kwang Il Kim, 1 Jae Hong Han, 1 Yoshihiro Ito, 2 Tae Il Son 1 1 Department of Biotechnology and Bio-Environmental Technology (BET) Research Institute, Chung-Ang University, Anseong, Gyeonggi-do 456-756, Korea 2 Nano Medical Engineering Laboratory, Riken Advanced Science Institute, 2-1 Hirosawa, Wako-Shi, Saitama 351-0198, Japan Correspondence to: T. I. Son (E-mail: tisohn@cau.ac.kr) ABSTRACT: Titanium (Ti) is widely used as an implant material. There are various kinds of Ti surface modification methods to facili- tate effective osseointegration. In this study, UV-curable azido-LMC (azidophenyl low molecular weight chitosan) was used to modify the Ti surface. Here we suggest a novel Ti coating material that confers complex, diverse improvements to the Ti surface through a simple process. First, a cytotoxicity test of azido-LMC against osteoblast MG-63 was performed. The curing ratio dependent on UV irradiation time and concentration was determined by a comparison of weight. A 5% azido-LMC solution, which showed a wide cur- ing ratio range, was used to investigate the surface properties. The contact angle value was measured to compare hydrophilicity, and osteoblast MG-63 cells were cultured on the coating surface. The Bradford assay was used to assess the protein immobilization capability. Hydroxyapatite, which has a beneficial influence on osseointegration, was included on the coating surface and observed by scanning electron microscopy. Surface roughness was measured by atomic force microscopy. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 4322–4326, 2013 KEYWORDS: biomaterials; coatings; bioengineering Received 1 August 2012; accepted 18 August 2012; published online 23 October 2012 DOI: 10.1002/app.38478 INTRODUCTION Titanium (Ti) has been used as an implant material in dental and orthopedic applications. 1 Many studies have shown that modified Ti implant surfaces have advantages in osseointegration compared to the typical Ti implant surface. Therefore, much effort has gone into the modification of Ti implant surfaces. According to these studies, the advantages are (i) hydrophilic implant surfaces allow for greater interaction with biological fluids, cells, and bone tissues leading to greater bone-to-implant contact versus hydrophobic implant surfaces. 2,3 (ii) Rough implant surfaces improve the early fixation and long-term me- chanical stability of implants compared to smooth implant surfa- ces. 4,5 (iii) Since hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 , HA] has a similar chemical composition to the mineral aspect of bone, coat- ing implant surfaces with HA allows for direct bonding between the implant and bone leading to better osseointegration and improved biocompatibility. 6–9 (iv) Implants coated with bone- stimulating agents such as growth factors, extracellular matrix (ECM), or antiresorptive drugs facilitate better osseointegra- tion. 10–13 Since modified Ti implant surfaces have the advantages mentioned above, many surface modification methods have been reported and are used in the implant industry such as plasma- spraying, grit-blasting, acid-etching, electrophoretic deposition, sputter deposition, and sol–gel. 14–16 However, the issue of taking advantage of combinations through a single process still remains. In this study, we attempted to coat Ti implant surfaces with photocurable natural polymers, especially chitosan derivatives. Photocurable natural polymers have received a considerable amount of attention in the field of tissue engineering, biomate- rial coating, and drug delivery mainly due to their mild cross- linking ability compared to other methods. 17,18 Photocurable natural polymers can be used as matrices to immobilize various bioactive compounds such as HA, growth factors, drugs, pro- teins, and DNA. 19–21 Chitosan was used as a base polymer in this study. A deacetylated form of chitin, chitosan is a natural polymer composed of 2- amino-2-deoxy-D-glucose and 2-acetamido-2-deoxy-D-glucose units. 22 Many studies have revealed its unique biological properties that include wound healing, stimulating effects on the secretion of fibroblast growth factor, in addition to antibacterial, hemostatic, fungistatic, antitumor, and anticholesteremic V C 2012 Wiley Periodicals, Inc. 4322 J. APPL. POLYM. SCI. 2013, DOI: 10.1002/APP.38478 WILEYONLINELIBRARY.COM/APP