Effect of Adsorption of Dodecyl Phosphate on the Crystal Growth and Surface Modification of Hydroxyapatite in an Aqueous Phase

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Water-insoluble dodecylphosphate (DP) was solubilized by a micelle of a nonionic surfactant such as Triton X-100(TX) and Triton N (TN) , f orming a mixed micelle. The mixed micelle was adsorbed by HAP after isomorphous substitution of phosphate group of DP for orthophosphate ion on HAP and electrostatic attractive force between a negative charge of DP and Ca2+ on HAP. As a result, nonadsorbable nonionic surfactant was adsorbed indirectly to HAP together with DP forming hemi-and/or admicelle. In an aqueous solution of CaCl2 , the solution of nonionic surfactant-DP became turbid. DP was selectively captured by Ca2+ , resulting in formation of the Ca-DP precipitate, which was separated from the mixed micelle. However, nonionic surfactant remained in an aqueous phase. Thus, the mixed micelle showed different behavior on the surface of HAP and in an aqueous phase .

Section: Figurementioning

confidence: 91%

“…Column [1] is water alone , [2] TX or TN, [3]-[8] for an aqueous solution of TX-DP or TN-DP . A concentration of added CaCl2/mM= 0(column [3]), 2(column [4]) , 4(column [5]), 6(column [6]), 8(column [7]), and 10(column [8]). The concentrations of both Triton and DP in the columns [3]-[8] were kept constant at 10mM.…”

Section: Figurementioning

confidence: 99%

Binding Mechanism of Triton X-100 and Triton N to the Surface of Hydroxyapatite in an Aqueous Phase

Oda

Shimabayashi

2005

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Preparation and Adsorption Properties of Hydroxyapatite Surface-Modified by Cetylphosphate

Warabino

Ueno

Hino

et al. 2006

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Hydroxyapatite (HAP) was prepared from CaCl 2 , Na 2 HPO 4 and NaOH in an aqueous phase mixed with a chloroform solution of cetylphosphate (CP). The CP was incorporated mainly on the surface of HAP but not to its bulk phase, resulting in formation of a hydrophobic surface. This surface-modified HAP has various characteristic properties different from those of the intact HAP. Some of the examples are as follows; an increase in a contact angle of water droplet, a decrease in a mean diameter of the HAP particle, and increases in the amounts of adsorption of various organic compounds. The aim of this study was of characterization of the surface-modified HAP through determining the adsorption amounts of various organic compounds on the surface. As for the adsorption of a surfactant to the modified HAP, it was concluded that hydrophobic interaction between alkyl chains of a surfactant and those of CP implanted on the surface became more important than hydrophilic interaction between polar/ionic groups of a surfactant and ions exposed on the intact area of the HAP. In the adsorption of bovine serum albumin (BSA), it was denatured by the CP implanted on the surface of the modified HAP (i.e., surface denaturation). Adsorption properties of the surface-modified HAP were quite different from those of the intact HAP.

Adsorption Characteristics of Non-Adsorbable Nonionic Surfactant, Tx-100, on the Surface of Hydroxyapatite in the Presence of an Anionic Surfactant

Shimabayashi

Hino

Hoshino

et al. 2001

Although polyethyleneglycol mono-p-isooctylphenyl ether (TX-100) was not adsorbed on the surface of hydroxyapatite(HAP) in an aqueous phase, it was adsorbed in the presence of sodium dodecylsulfate(SDS) or arginine dodecylphosphate(DP). This fact was explained in terms of modification of the surface of HAP by the adsorption of SDS or DP and complex formation on the surface through hydrophobic interaction between hydrophobic tails of TX-100 and SDS or DP. The effects of the mixing ratio between them and of a concentration of added NaCl were discussed.