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Commercially pure titanium plates/coupons and pure titanium powders were soaked for 24 h in 5 M NaOH and 5 M KOH solutions, under identical conditions, over the temperature range of 37° to 90°C. Wettability of the surfaces of alkali-treated cpTi coupons were studied by using contact angle goniometry. cpTi coupons soaked in 5 M NaOH or 5 M KOH solutions were found to have hydrophilic surfaces. Hydrous alkali titanate nanofibers and nanotubes were identified with SEM/EDXS and grazing incidence XRD. Surface areas of Ti powders increased >50–220 times, depending on the treatment, when soaked in the above solutions. A solution was developed to coat amorphous calcium phosphate, instead of hydroxyapatite, on Ti coupon surfaces. In vitro cell culture tests were performed with osteoblast-like cells on the alkali-treated samples.

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Conventional flat plate-shaped brushite, dicalcium phosphate dihydrate, CaHPO 4 ·2H 2 O), produced by reacting Ca-chloride and alkali phosphate salt solutions, were found to undergo a maturation process (changing their Ca/P molar ratio from 0.8 to the theoretical value of 1) similar to those seen in biological apatites. Water lily (WL)-shaped brushite crystals were produced in nonstirred aqueous solutions at room temperature in 24 h, by using precipitated calcite and NH 4 H 2 PO 4 as the starting chemicals. The hydrothermal transformation of WLtype brushite into octacalcium phosphate (OCP) or Ca-deficient hydroxyapatite (CDHA) was tested at 37°C by using four different biomineralization solutions, including Tris-buffered SBF (synthetic body fluid) and sodium lactate-buffered SBF solutions. All four solutions used in this study consumed the starting brushite in 1 week and caused transformation into a biphasic mixture of nanocrystalline OCP and CDHA of high surface area. WL-type brushite crystals when synthesized in the presence of small amounts of Zn 2+ ions resulted in the formation of, for the first time, spherical micro-granules of brushite.

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