Hydroxyapatite Scaffolds Produced by Hydrothermal Deposition of Monetite on Polyurethane Sponges Substrates

Abstract

Hydroxyapatite scaffolds have been being produced by a wide range of processes. The optimun material to be used as bone graft has to be partially resorbable, with resorption rates similar to new bone formation ones. The samples must have porosity compatible with tissue ingrowth. Hydroxyapatite and tricalcium phosphate ceramics are good choices for designing such materials. In the present study, polymeric sponges were coated with hydroxyapatite and sintered. The method consists of coating polyurethane sponges substrates in an aqueous solution rich in phosphate (PO4)3-and calcium (Ca)2+ions. The solution is composed by 0.5M Ca(OH)2, 0.3M H3PO4and 1M CH3CHCO2HOH (lactic acid) at pH of 3.7. The sponges were immersed in a beaker with the solution and heated up to 80°C to precipitate monetite on the sponge. Continuous and adherent coatings were formed on the surface of sponges interconections. These coatings were characterised by X-ray diffractometry and the only identified phase was monetite. The substrates were converted to hydroxyapatite in an alkali solution.The total conversion from monetite to hydroxyapatite was confirmed by XRD analyses. The struts were heat treated in order to eliminate the organic sponge and sinter the scaffolds. After sintering, hydroxyapatite and tricalcium phosphate were identified on the struts. Optical microscopy revealed the morphology of the struts, while scanning electron microscopy (SEM) showed the precipitates morphology. The method showed to be efficient in the production of porous scaffolds.

Calcium orthophosphate deposits: Preparation, properties and biomedical applications

“…ACCEPTED MANUSCRIPT 39 Hydrothermal process was used to deposit CaPO 4 on both metallic [408,409,[487][488][489][490][491][492][493][494][495][496][497][498] and polymeric [499,500] substrates. Ones this technique was called as "a chemical bath method" [501].…”

Calcium Orthophosphate-Based Bioceramics

“…Since calcium orthophosphates are either thermally unstable (MCPM, MCPA, DCPA, DCPD, OCP, ACP, CDHA) or have a melting point at temperatures exceeding ~1400 °C with a partial decomposition (α-TCP, β-TCP, HA, FA, TTCP), only the first and the second consolidation approaches are used to prepare bulk bioceramics and scaffolds. The methods include uniaxial compaction [198,199,200], isostatic pressing (cold or hot) [108,201,202,203,204,205,206,207], granulation [208,209,210,211,212,213], loose packing [214], slip casting [93,215,216,217,218,219,220], gel casting [188,189,221,222,223,224,225], pressure mold forming [226], injection molding [227,228,229], polymer replication [230,231,232,233,234,235,236,237], extrusion [238,239,240,241,242], slurry dipping and spraying [243]. In addition, to form ceramic sheets from slurries, tape casting [105,223,244,245,246], doctor blade [247] and colander me...…”

Surface modification using the biomimetic method in alumina‐zirconia porous ceramics obtained by the replica method

“…The significant interest in calcium phosphate phases is due to their similarity between the X‐ray diffraction patterns of the inorganic bone phase and the phase of a carbonated HA, found in bones …”

“…1,2,17 The significant interest in calcium phosphate phases is due to their similarity between the X-ray diffraction patterns of the inorganic bone phase and the phase of a carbonated HA, found in bones. 18 Synthetic HA has great potential in bone implants due to its properties, such as biocompatibility, bioactivity and osseointegration. 19 This integration (unification) of the bone tissue with the implanted material is favored by the exchange of ions of the physiological, thereby inducing bone growth.…”