ZETA POTENTIAL OF HYDROXYAPATITE PARTICLES IN THE PRESENCE OF POLYETHYLENE GLYCOL MONO-<I>p</I>-ISOOCTYLPHENYL ETHER AND SODIUM DODECYLSULFATE IN AN AQUEOUS PHASE

Abstract

Zeta potential of hydroxyapatite (HAP, Ca10(PO4)6(OH)2) particle in an aqueous phase was measured in the presence of various concentrations of NaCl, sodium dodecylsulfate (SDS), and polyethylene glycol mono-p-isooctyl-phenyl ether (TX-100). It was found that the intact particle was negatively charged. Zeta potential of the particle became more negative with a concentration of SDS because of its adsorption. The potential decreased furthermore with a concentration of TX-100 at a given concentration of SDS when NaCl was not added to the system. On the other hand, the potential became less negative with a concentration of TX-100 at a constant concentration of SDS when 500 mmol/L NaCl was added. The mechanisms to explain these facts and the effect of NaCl in particular were discussed, taking into consideration the mixed micelle formation, hydration, adsorption of SDS and TX-100, and shifting of the slipping plane into an aqueous phase.

Preparation and Characterization of Hydroxyapatite Particles Having Hydrophobic Surface

“…The alkyl chains protruding from the surface could easily f orm the intermolecular complex with Triton-X 100 by virtue of hydrophobic interacti on, resulting in formation of an admicelle and/or a hemimicelle on the surface . 3,4) We also expect that other hydrophobic compounds might be adsorbed to the HAP treated with AP in a similar manner as that mentioned above . Measurements of the adsorption amounts of hydrophilic/hydrophobic compounds are important for understanding physicochemical properties of modified surface of the HAP.…”

Preparation and Adsorption Properties of Hydroxyapatite Surface-Modified by Cetylphosphate

“…The alkyl chains of CP might not distribute uniformly on the surface of the modified HAP, but they might form patches/islands of the CP just like a surface micelle by virtue of hydrophobic interaction among them. [7][8][9] Polar groups of BSA, therefore, could interact with the ionic groups exposed on the surface of HAP.…”

“…The surface of HAP also shows affinity for phosphorylated organic compounds. [5][6][7][8] Alkylphosphates (AP), which are esters of alkyl alcohols and phosphoric acid, could be easily adsorbed on the surface of HAP. The adsorption mechanism was of an ion exchange or of an isomorphorus substitution of a surface phosphate ion for a phosphate group of AP.…”

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

“…Open and closed columns show the data for TX and TN , respectively. 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 surface tension of an aqueous solu`tion of nonionic surfactant-DP-CaCl2 was measured, of which results are shown in FIGURE 4. We could expect that if the precipitate contains both the nonionic surfactant and DP, the surface tension should increase with the amount of the precipitate and be located between nonionic surfactant (column [2]) and water(column [1]). If the DP selectively precipitates as a salt of Ca-DP, the surface tension should be between that of nonionic surfactant-DP(column [3]) and nonionic surfactant(column [2]).…”