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Journal of Wuhan University of Technology-Mater. Sci. Ed. Oct.2010 DOI 10.1007/s11595-010-0094-z


Inhibition of Bacterial Adherence on the Surface of Biliary Stent Materials Modified With Chitosan
LIU Hengquan1, HUANG Nan1*, LENG Yongxiang1, YU Hailiang2, LE Le3, LI Kezhou4
(1. Key Laboratory of Advanced Technology of Materials, Chinese Education Ministry, School of Material Science &Engineering, Southwest Jiaotong University, Chengdu 61003, China; 2. The People's Hospital of Jinniu District of Chengdu, Chengdu 610036, China;3. Department of Clinical Medcine, Luzhou Medical College, Luzhou 646000, China;4. The General Hospital of Chengdu Military Subarea, Chengdu 610083, China)

Abstract: Bacterial infection plays an important role in the initiation of biliary sludgeformation. Bacterial adherence and biofilm formation on the surface of a material have been considered as one of the main factors of stent re-occlusion in clinic. This work reported preventing bacterial adherence and bacterial biofilm formation on the surface of biliary stent material using chitosan film. The chitosan film was deposited on 316 L stainless steel (SS) plate by electrophoresis method andwas characterized by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The ability of inhibiting bacterial adherence was investigated by incubating in human fresh bile adding E. coli and Enterobacter at 37±1 ℃. Scanning electron microscopy (SEM) and fluorescence staining were used for observing bacterial colonization and biofilm formation.The results show that chitosan film was uniformly deposited on material surface, and the composition of the film did not change through cross-linking, but the crystallinity of chitosan film become well. Comparing to un-modified sample, the E. coli and Enterococcus adhesion amount and colonization on the surface of modified sample were significantly decreased by fluorescence staining and SEM. Itis suggested that chitosan could be applied to biliary stent in clinical because of its antimicrobial activities. Key words: biliary stent material; chitosan; inhibition; bacterial biofilm

1 Introduction
Biliary stent placement is a common procedure in palliating malignant or benign obstruction of bile tracts[1], but stent re-occlusion remains a major problem that also limits the long termapplication of stent placement in the management of benign biliary diseases[2]. In vitro studies have found that bacteria attach to stent and deposit a mucopolysaccharide or glycocalyx that binds the bacteria and traps crystals in bile, forming a biofilm[3]. Bacterial biofilm plays an important role in sludge formation within the biliary system and contributes to stent blockage and ductal sludgeformation[4]. So, it is believed that
©Wuhan University of Technology and Springer-Verlag Berlin Heidelberg 2010 (Received: May 21, 2009; Accepted: June 19, 2010) LIU Hengquan(刘刘刘): Ph, D; *Corresponding author: HUANG Nan(黄黄):Prof.;Ph D; E-mail: Supported by Key Basic Research Project of China (No. 2005CB623904), National Natural Science Foundation ofChina (No.RGC30831160509) and Program for New Century Excellent Talents in University (No.06-0800)

the deposition of biliary sludge due to the biochemical activities of bacterial enzymes on the surface of the materials is one of the main mechanisms of stent occlusion[5]. Prevention of bacterial infection and biofilm formation may be benefit to prolong stent patency[6]. In vitro and in vivostudies suggest that ciprofloxacin may potentially have an effect in prolonging stent patency[7]. But a number of clinical trials of antibiotic prophylaxis with quinolones have produced conflicting results[8]. Because a mixed infection present in the biliary sludge, infection or colonization of the stent by bacteria resistant or less sensitive to the antibiotic given may account for the failure of...
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