Preparation of injectable hydroxyapatite/collagen paste using sodium alginate and influence of additives

Abstract

Preparation of injectable hydroxyapatite/collagen bone-like nanocomposite (HAp/Col) paste utilizing sodium alginate (Na-Alg) and influence of additives on the paste properties were investigated. The HAp/Col at the HAp and collagen mass ratio of 80:20 synthesized by a simultaneous titration method was pelletized to 100212¯m. The HAp/Col powder and that treated with 100 mM CaCl 2 (Ca-HAp/Col) were used as starting powders. A paste was prepared by mixing of the starting powder and Na-Alg solution at one of several powder/liquid ratios. The paste was directly injected into 100 mM CaCl 2 solution to confirm setting capability, and examined a viscosity, hardening behavior, compressive strength and decay property. In addition, the paste supplemented with an organic acid or a calcium compound as an additive was also prepared to examine influences of the additive on paste properties. The organic acid was chosen from citric, succinic, malic, lactic and glycolic acids, and the calcium compound was chosen from Ca(OH) 2 , Ca(CO) 3 , CaSO 4 ·0.5H 2 O and calcium citrate. The prepared paste was set by direct injection to 100 mM CaCl 2 solution. The suitable mixing conditions of the paste were a P/L ratio of 0.6 at the 90:10 mass ratio of Ca-HAp/Col and solution of low viscous Na-Alg. All additives increased the paste viscosity; however, the mechanisms were different between organic acids and calcium compounds. Organic acids rapidly decreased pH to form Alg gel by deposition of Alg. Contrarily, calcium compounds supplied Ca 2+ ions to form egg-box structure for gelation of Alg, and the reaction depended on solubility of compound. Additives also increased decaying time but could not realize anti-decay in the present conditions. The results suggested that the HAp/Col injectable paste can be utilized in rapid prototyping materials and might be good candidate for injectable artificial bone with further improvement in anti-decay property.

Hydroxyapatite/Collagen Bone-Like Nanocomposite

“…In addition to the results mentioned above, HAp/Col is also expected to be used as a gene transfer bioresorbable substrate based on calcium phosphate-plasmid DNA composite coating method 20,21) and as an injectable material including raw material for rapid prototyping using sodium alginate as lubricant and gelation reagents. 22) Considering its useful properties as a bone substitute, HAp/Col material used for applications discussed in this paper promises far better outcomes for patients than currently used materials.…”

Fabrication of Gentamicin-Loaded Hydroxyapatite/Collagen Bone-Like Nanocomposite for Anti-Infection Bone Void Fillers

“…The obtained HAp/Col was compacted to a disk at 32 mm in diameter and 2 mm in thickness by a uniaxial pressing at 20 MPa for 18 h to squeeze water out of the obtained HAp/Col [17]. The HAp/Col disk was frozen and freeze-dried at −20 • C, crushed by hand, and sorted into 100-212 µm by sieving.…”

Preparation of anti-decay self-setting pastes of hydroxyapatite/collagen utilizing (3-glycidoxypropyl)trimethoxysilane

“…(1) HAp/Col powders are easily dispersed from the paste mixtures in aqueous solutions, even in highly viscous solutions such as alginate solution [16]. (2) A preliminary anti-washout test for HAp/Col-GTMS pastes prepared with HAp/Col powder, in which collagen molecules were dehydrothermally crosslinked at amino and carboxyl groups, demonstrated rapid decay of the pastes with no retention of any GPTMS gels during the test period.…”

“…Hence, HAp/Col is a promising candidate for use as a bioresorbale bone substitute for other materials besides porous materials. We recently reported on HAp/Col pastes using sodium alginate as a hardening agent [16][17][18] and concluded that supplementation of large amounts of calcium salts other than HAp was necessary to obtain sufficient anti-washout properties. Even though the chemicals calcium citrate and calcium carbonate show no harm to tissues, huge amounts of them might decrease and/or inhibit the biological advantages of HAp/Col.…”