A coating of porous calcium phosphate compound was produced over phsophorylated chitosan films by a Ca(OH)_2 soaking and SBF(simulated body fluid solution) immersion method. Chitosan films having 0.1 to 0.2 mm thickness were prepared from chitosan powder and phosphorylated using H_3PO_4 and urea. The P content of the film was approx 0.2 wtpercent. These films were then soaked in saturated lime solution for 8 days before immersing in 1.5 x SBF solution for several days so that a calcium phosphate phase started depositing all over the film surface. Initially a mono layer of 200 nm size particles were deposited within 3-6 days and over that layer secondary nucleation had occurred leading to the formation of a continuous thick and porous coating as immersion time increases. The Ca(OH)_2 treatment facilitates the formation of a calcium phosphate precursor over the phosphorylated film, which in turn encourages the growth of a calcium deficient apatite coating over the surface upon immersion in SBF solution.
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