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The immobilization of cell-adhesive proteins onto titanium implant improves biological responses at the implant-tissue interface. The aim of this study is to investigate how the reaction temperature during tresylation and pretreatment of titanium surface with H20,-.1 solution influences the reactivity of titanium basic terminal OH group towards 2,2,2-trifluoroethanesuifonyl chloride (tresyl chloride) and ftbronectin. Three different titanium surfaces were prepared, i.e., mirror polished, and pretreated either with 0.1 M H10;/phosphate-buffcred saline (PBS) solution (H1O;/PBS) or with 0.1 M H10;/0.1 M NaOH aqueous solution (H10;/NaOH) after mirror polishing. The basic terminal OH groups of titanium were allowed to react with tresyl chloride at 37°C or 70°C for 2 days. The tresylated titanium disk was then immersed into a fibronectinfPBS solution. The reactivity of titanium basic terminal OH group towards tresyl chloride and fibronectin was evaluated by the measurement of X-ray photoelectron spectroscopy (XPS). The reaction of titanium basic terminal OH group towards tresyl chloride at 37°C proceeded more effectively than that at 70°C. The basic OH group on H10;/PBS-pretreated titanium showed the highest reactivity towards tresyl chloride by evaluating the Fis intensities in XPS measurement. Fibronectin could easily attach the tresylated titanium, and the attached fibroncctin remained after 60 min ultrasonic cleaning regardless the different surfaces.Therefore, we concluded that after pretreatment with 0.1 M H10;/PBS, reaction of titanium with tresyl chloride should be performed at 37°C in order to get easy attachment of fibronectin on titanium motes a desirable integration with body tissue. It is predicted that the pre-coating of titanium implant by cell-adhesive proteins enhances the cell activity or initial cell attachment around the implant material.Many researches have attempted immobilization of cell-adhesive proteins onto titanium by a covalent bond, for example, grafting of synthetic RGD peptide on polypyrrole-coated titanium, binding of collagen on gold-deposited titanium, covalently immobilization of ftbronectin onto titanium using silane coupling agents, and immobilization of collagen onto the titanium via the hot-melted poly

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The aim of this study is to evaluate the influence of fibronectin immobilization on poly-L-lactic acid (PLA) films on the initial attachment of human gingival fibroblasts. Carboxylic acid groups are chemically introduced on the PLA films' surface by surface hydrolysis with 0.5 M NaOH. The contact angle of PLA surface with respect to double-distilled water decreases significantly after NaOH hydrolysis. X-ray photoelectron spectroscopy (XPS) also reveals significantly higher intensities of C C¼O /C C-O after NaOH hydrolysis. Fibronectin is immobilized onto the hydrolyzed PLA surface through a condensation reaction between the carboxylic acid groups on the hydrolyzed PLA surface and the amino groups of fibronectin using water-soluble carbodiimide. XPS analysis shows that the fibronectin-immobilized PLA surface is enriched with nitrogen atoms. The immobilization of fibronectin significantly enhances the number of initially attached human gingival fibroblasts on the PLA surface. No obvious *Author to whom correspondence should be addressed. E-mail: m-nagai@mascat.nihon-u.ac.jp KEY WORDS: polylactic acid, fibronectin, fibroblast, initial cell attachment. JOURNAL OF BIOMATERIALS APPLICATIONS

Degradation of a new type of poly(L-lactic acid)/poly(ethylene; hexamethylene/ sebacate) block polyester and its composite containing 10 and 30 wt% tricalcium phosphate (TCP) were studied in vitro. Film specimens of thickness 100 and 250 microm for each of the three materials were immersed in phosphate buffered saline (pH 7.4) at 37 degrees C for up to 24 weeks. At appropriate intervals, water absorption, dry and wet tensile strength, molecular weight, and thermal properties of the specimens were measured by weighing, tensile strength testing, size exclusion chromatography, and differential scanning calorimetry, respectively. The decrease in tensile strength was greater in the unblended and thicker polymer film than in the other five films. The retention of tensile strength after 24 weeks increased with increasing TCP content. This trend was also noticed in the retention of molecular weight. The tensile strength of the materials having molecular weights below 5 x 10(4)-6 x 10(4) Mw or 2 x 10(4)-3 x 10(4) Mn dropped substantially and the materials became fragile. Blending of TCP to the PLLA block polyester retarded degradation, suggesting that TCP neutralized the carboxyl end groups formed by hydrolysis of ester bonds.