Fabrication of Magnetic Hydroxyapatite Microcapsule for Protein Collection

Abstract

When pH or temperature of simulated body fluid (SBF) is raised, fine particles of calcium phosphate are precipitated. We found that this fine particle actively induces hydroxyapatite from body fluid or SBF and named the particle Apatite Nucleus (AN). In this study, we attached AN on the surface of γ-Fe2O3 nanoparticles and soaked them in SBF. By this treatment, hydroxyapatite was induced from AN and covered the whole surface of the γ-Fe2O3 nanoparticles, then hydroxyapatite microcapsule encapsulated γ-Fe2O3 was fabricated. We dispersed the microcapsules in urease solution, and collected the microcapsules by neodymium magnet. It was indicated that the urease was adsorbed to the hydroxyapatite microcapsules and collected by the magnetism of γ-Fe2O3 successfully.

Biomimetic Method for Production of Magnetic Hydroxyapatite Microcapsules for Enzyme Immobilization

“…1 shows the SEM image of the hydroxyapatite microcapsules fabricated by using ANs and SBF. It can be seen that the whole surface of the microcapsule was coated by needle-like crystallites and the diameter of the microcapsule was 1-2 μm similar to our previous studies [14,15].…”

“…In our previous studies, we fabricated some kinds of hydroxyapatite microcapsules covering core particles through hydroxyapatite formation induced by AN. The core particles we used were Ag microspheres [11], silicagel microspheres [12], magnetite microspheres [13] and maghemite (γ-Fe 2 O 3 ) nanoparticles [14]. γ-Fe 2 O 3 has ferrimagnetism and is chemically stable.…”

Immobilization and collection of enzymes by hydroxyapatite/maghemite composite particles with magnetism

“…Urease [molecular weight (MW) = 480 kDa, isoelectric point (pI) = 5.1] is one of the metalloenzymes which possesses Ni at its active centers and promotes urea decomposition by hydrolysis. In the previous study, we investigated the amount of collected urease 19) and the presence or absence of urea decomposition ability 20) using a constant amount of urease. However, it is essential to investigate the effect of the amount of HA/Fe 2 O 3 particles on that of collected urease and the effect of the amount of immobilized urease on the speed of urea decomposition.…”

Biomimetic Porous Bone-Like Apatite Coatings on Metals, Organic Polymers and Microparticles

“…Porous bone-like apatite formed in SBF has flake-like crystalline structure and porous body [46,47]. Focusing on these features of porous bone-like apatite, the author has intended to fabricate porous bone-like apatite microcapsules encapsulating various kinds of substances such as PLLA [48], silver [48], silica gel [48,49], magnetite [50], maghemite [51,52], agarose gel [53,54] and corn oil [55]. Among them, the author introduces the details of encapsulation of corn oil in the porous bone-like apatite microcapsules as representative cases in this chapter.…”

“…As described in Section 4.1, this fabrication method for porous bone-like apatite microcapsules was applicable to other kinds of core materials such as encapsulating various kinds of substance such as PLLA [48], silver [48], silica gel [48,49], magnetite [50], maghemite [51,52] and agarose gel [53,54] by optimizing the fabrication condition. In the case of silver, sustained release of silver was attained by existence of porous coatings of bone-like apatite.…”