Introduction
Hydroxyapatite, also known as basic calcium phosphate, is the natural mineralization of calcium apatite (Ca5(PO4)3(OH)). But it is often written as Ca10(PO4)6(OH)2 to highlight that it is made up of two parts - Hydroxyl and Apatite. OH-hydroxyl can be replaced by fluoride, chloride and carbonate ions to form fluoro- or chloro-apatite.
Flow rate and scale of crystalline hydroxyapatite in industrial production are limited due to the stiffness of crystal structure,. In the 1980s, scientists created stronger porous hydroxyapatite materials by burning them at high temperatures. Since then hydroxyapatite materials can withstand higher flow rates and pressures in large-scale industrial production, greatly improving production efficiency. This type of high-temperature-processed hydroxyapatite material is commonly known as ceramic hydroxyapatite. Now ceramic hydroxyapatite has been widely used in the purification and preparation of biological macromolecules, the adsorption and removal of heavy metal ions and bone repair materials.
Mechanism
Hydroxyapatite consists of two binding sites: Ca2+ and PO43-. These binding sites are regularly distributed throughout the crystal structure. PO43- ions are bonded with positively charged proteins through cation exchange. Ca2+ ions are metal chelated to the free carboxyl clusters of negatively charged proteins.
Cation exchange: Positively charged protein amino groups can interact ionically with PO43- and repel Ca2+. Ion exchange interactions are affected by the concentration of neutral salts (such as NaCl) in the eluting buffer or by the concentration of phosphate in the equilibrium solution. Interactions will weaken with the increase of pH. Therefore, increasing the concentration of salt and phosphate or increasing pH will weaken the interaction between the target protein and PO43-.
Calcium-metal chelation: Ca2+ can metal-chelate with carboxyl clusters or phosphoryl groups on the surface of proteins or other molecules (such as nucleic acids) while simultaneously repelling PO43-. The binding force is 15-60 times that of normal ion exchange. Therefore, this binding mode is less affected by ions and is not sensitive to NaCl. This binding force increases the metal chelating ability of calcium affinity with the increase of ionic strength, because ionic strength shields the mutual repulsion between functional groups on molecular surface and PO43-. The metal affinity interactions can be eluted by sodium phosphate.
Regeneration
Washing the CV with 500 mM neutral phosphate or potassium phosphate solution or 400 mM trisodium phosphate (pH 11-12) for 3-5 CV. The column can also be washed with neutral 1-2 M KCl, NaCl, 6M urea or 8M guanidine HCl containing 5 mM phosphate.
Storage
Unused BG-CHT should be stored at room temperature, sealed tight. Once wetted, store in 0.1 M NaOH at room temperature. If using less than 100 mM NaOH, add 10 mM phosphate. Used CHT, after regeneration and sterilization, should be stored in 1 M or less NaOH in shades at room temperature.
Sanitization
The column can be sanitized in up to 2M NaOH, and also could be stored in 0.1-1M NaOH.
Quality Assurance
Items | Specifications | Standard |
Appearence | White free flow powder | Visual |
Lysozyme binding assay | ≥ 12.5 mg/g power | Enterprise standard |
Protein sample separation | Passes test | |
Particle size (mean) | 30 - 50 μm | |
Tapped density | 0.6 - 0.7 g/mL | |
FTIR | Passes test | |
Endotoxin | ≤ 0.01 EU/kU |
Appearence:White free flow powder |
Lysozyme binding assay ≥ 12.5mg/g |
Protein sample separation:Passes |
Particle sizes (mean):30-50 μM |
Endotoxin:≤ 0.01 EU/kU |
Tapped density:0.6 - 0.7 g/mL |
FTIR: Passes |
According to enterprise standard test
储存分类代码 | WGK | 闪电(F) |
10-Combustible liquids | WGK 1 | Not Applicable |
闪电(C) | 个人防护装备 | |
Not Applicable | Eye shields, gloves |
COMPOSITION HYDROXYAPATITE | |
PARTICLE SIZE(MEAN) 20/40/80 μM;MEAN:43 μM | |
CAT.No GC01.01/GC01.02 | APPEARENCE WHITE FREE FLOWING POWDER |
ENDOTOXINES < 0.01 EU/mg | FUNCTIONAL GROUPS Ca+,PO-,OH |
pH STABILITY 6.5 - 14 | BASE STABILITY > 1 YEAR IN 1 N NaOH |
TAPPED DENSITY 0.63 g/mL | LYSOZYME BINDING ASSAY 14 mg/g |
DYNAMIC BINDING CAPACITY TYPE I:25 - 60 mg POLYCLONAL IgG/mL CHT;TYPE II:15 - 25 mg POLYCLONAL IgG/mL CHT | |
REGENERATION 0.4 M SODIUM PHOSPHATE,pH 7-7.5;1 M TRISODIUM PHOSPHATE,pH 11-12 | |
AUTOCLAVABILITY(BULK) 121°C,20 MIN IN PHOSPHATE BUFFER,pH 7 | |
TYPICAL LINEAR FLOW RATE 500-1000 CM/HR |
Specs
FAQs
Ca+,PO-,OH-