Modification of Hydroxyapatite with Ion-Selective Complexants: 1-Hydroxyethane-1,1-diphosphonic Acid

Abstract

Hydroxyapatite (HAP) was modified with 1-hydroxyethane-1,1-diphosphonic acid (HEDP), and its effect on divalent metal ion binding was determined. HAP was synthesized from calcium hydroxide and phosphoric acid. After calcination, it was modified with HEDP, and the influence of time and temperature on the modification was investigated. HEDP incorporation increased as its initial solution concentration increased from 0.01 to 0.50 M. Unmodified and modified HAP were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and specific surface area analysis. Ca/P ratios, acid capacities, and phosphorus elemental analyses gave the effect of modification on composition and surface characteristics. A high reaction temperature produced new phosphonate bands at 993, 1082, and 1144 cm–1 that indicated the presence of HEDP. HAP modification at a high temperature–long reaction time had the highest HEDP loading and gave the sharpest XRD peaks. The emergence of new HAP–HEDP strands was observed in SEM images for treated samples while EDS showed high phosphorus contents in these strands. Modified HAP had a high acid capacity from the additional P–OH groups in HEDP. The P(O)OH groups maintain their ability to bind metal ions within the HAP matrix: contacting the modified HAP with 10–4 N nitrate solutions of five transition metal ions gives an affinity sequence of Pb(II) > Cd(II) > Zn(II) > Ni(II) > Cu(II). This result is comparable to that of commercially available di(2-ethylhexyl)phosphoric acid, a common solvent extractant, and the trend is consistent with the Misono softness parameter of metal ion polarizabilities.

Sulfonated nanohydroxyapatite functionalized with 2-aminoethyl dihydrogen phosphate (HAP@AEPH2-SO3H) as a new recyclable and eco-friendly catalyst for rapid one-pot synthesis of 4,4′-(aryl methylene)bis(3-methyl-1H-pyrazol-5-ol)s

“…then sulfonated with chlorosulfonic acid (HAP@AEPH 2 -SO 3 H) (Scheme 1). In addition to the principal absorption bands of nanoHAP, appearance of two absorption bands at 2917 and 2851 cm -1 due to asymmetric and symmetric vibrational frequencies of -CH 2 , confirmed the successful attachment of AEPH 2 on the surface of the nanoHAP(Figure 1 a) 52. As can be seen, the stretching and bending vibration of OH − ion in hydroxyapatite were detected around 3572 and 630 cm −1 respectively.…”

Direct Synthesis of Nitriles from Aldehydes and Hydroxylamine Hydrochloride Catalyzed by a HAP@AEPH2-SO3H Nanocatalyst

“…1a). [31] In the FT-IR spectrum of HAP@AEPH 2 -SO 3 H (Fig. 1b), the intensity of the absorption band at 3450-3050 cm À1 was increased because of the presence of more OH groups which appeared after sulfonation.…”

Resorbable Mg2+-Containing Phosphates for Bone Tissue Repair

“…Thus, Mg225 and Mg225d seem to be prospective bone substitutes for a variety of loads that should be investigated further. The efficiency of crystallization inhibitors and modifying additives depends on the reaction conditions [130,131]. There is also another field of interest that represents the production and study of ceramic materials from calcium and magnesium orthophosphates [132,133].…”