Hydroxyapatite is a biological material composed of calcium and phosphate. It exhibits excellent biocompatibility and biological activity. Notably, chromatography resins made from hydroxyapatite demonstrate high separation efficiency, selectivity, reproducibility, and stability. As a result, hydroxyapatite has gained widespread recognition in the field of biomolecule separation and purification.

Principles of Separation and Purification

Hydroxyapatite chromatography resin operates on a unique principle of separation and purification that combines both cation exchange and metal chelation. The phosphate ions within its crystal structure can bind to positively charged proteins, demonstrating cation exchange properties, which can be eluted by varying the NaCl concentration. Meanwhile, calcium ions interact with free carboxyl groups on proteins through metal chelation, and these can be eluted by adjusting the phosphate concentration. Consequently, the chromatography resin can be eluted using a single gradient of sodium phosphate or through a dual gradient elution model. In the latter approach, elution begins with a NaCl gradient, followed by equilibration with a low-concentration sodium phosphate buffer, and concludes with elution using a sodium phosphate concentration gradient. This method enhances the efficiency of impurity removal.

Hydroxyapatite Chromatography Resin Properties

Hydroxyapatite is classified into two types based on distinct ceramicization processes: Type I and Type II.

? Type I has a small pore size, which allows for greater retention of proteins and a higher dynamic binding capacity for acidic proteins. It primarily purifies most proteins effectively.

? Type II features a large pore size that allows for greater retention of macromolecules, such as antibodies and nucleic acids. Additionally, it possesses a higher dynamic capacity, making it more suitable for the purification of antibodies and nucleic acids.

Advantages of Hydroxyapatite Chromatography Resin:

? High dynamic capacity, high flow rate, and high productivity;

? Enhanced chemical stability and mechanical strength provide a longer lifespan;

? The rigid structure ensures stability at a pH greater than 6.5 and can be cleaned with sodium hydroxide (NaOH);

? Good batch-to-batch reproducibility and ease of scalability.

You can freely choose between cationic and metal chelation methods to separate and purify proteins or other molecules.

Applications of Hydroxyapatite Chromatography Resin

Monoclonal Antibody Purification

Hydroxyapatite chromatography resin is utilized for the purification of monoclonal antibodies. This process involves capturing the target antibody through a phosphate gradient and eluting it using a non-phosphate system, such as a sodium chloride gradient. This method effectively removes antibody aggregates, leached Protein A ligands, endotoxins, and other impurities, thereby ensuring the purity and yield of the final product.

Nucleic Acid Purification

Hydroxyapatite chromatography resin can interact with the phosphate group on nucleic acids through the C site and can be directly used to purify mRNA. Unlike traditional anion exchange chromatography resins, the retention time of mRNA on hydroxyapatite chromatography resin increases with the number of mRNA bases, providing better resolution for nucleic acids of varying lengths.

Polysaccharide Vaccine Purification

The impurities in the production of polysaccharide vaccines primarily consist of host cell proteins (HCP), host cell DNA, pigments, and other polysaccharide substances. Hydroxyapatite chromatography resin can specifically absorb HCP and DNA, thereby enhancing the purity and effectiveness of polysaccharide vaccines.

Now, Bogen, a Duoning Company, has launched our new generation of hydroxyapatite chromatography resin, including both Type I and Type II, to better support your chromatography process efforts.