title: Highly biocompatible, nanocrystalline hydroxyapatite synthesized in a solvothermal process driven by high energy density microwave radiation.
abstract: A microwave, solvothermal synthesis of highly biocompatible hydroxyapatite (HAp) nanopowder was developed. The process was conducted in a microwave radiation field having a high energy density of 5 W/mL and over a time less than 2 minutes. The sample measurements included: powder X-ray diffraction, density, specific surface area, and chemical composition. The morphology and structure were investigated by scanning electron microscopy as well as transmission electron microscopy (TEM). The thermal behavior analysis was conducted using a simultaneous thermal analysis technique coupled with quadruple mass spectrometry. Additionally, Fourier transform infrared spectroscopy tests of heated samples were performed. A degradation test and a biocompatibility study in vitro using human osteoblast cells were also conducted. The developed method enables the synthesis of pure, fully crystalline hexagonal HAp nanopowder with a specific surface area close to 240 m(2)/g and a Ca/P molar ratio equal to 1.57. TEM measurements showed that this method results in particles with an average grain size below 6 nm. A 28-day degradation test conducted according to the ISO standard indicated a 22% loss of initial weight and a calcium ion concentration at 200 μmol/dm(3) in the tris(hydroxymethyl)aminomethane hydrochloride test solution. The cytocompatibility of the obtained material was confirmed in a culture of human bone derived cells, both in an indirect test using the material extract, and in direct contact. A quantitative analysis was based on the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide. Viability assay as well as on DNA content measurements in the PicoGreen test. Indirect observations were performed at one point in time according to the ISO standard for in vitro cytotoxicity (ie, after 24 hours of cell exposure to the extracts). The direct contact tests were completed at three time points: after 24 hours, on day 7, and on day 14 of a culture in an osteogenic medium. All of the tests revealed good tolerance of cells toward the material; this was also shown by means of live/dead fluorescent staining. Both quantitative results and morphological observations revealed much better cell tolerance toward the obtained HAp compared to commercially available HAp NanoXIM, which was used as a reference material.
authors: Polish Academy of Science, Institute of High Pressure Physics, Warsaw, Poland. smolendarek@gmail.com
authors: Dariusz
authors: D
authors: Smolen
authors: Tadeusz
authors: T
authors: Chudoba
authors: Iwona
authors: I
authors: Malka
authors: Aleksandra
authors: A
authors: Kedzierska
authors: Witold
authors: W
authors: Lojkowski
authors: Wojciech
authors: W
authors: Swieszkowski
authors: Krzysztof Jan
authors: KJ
authors: Kurzydlowski
authors: Małgorzata
authors: M
authors: Kolodziejczyk-Mierzynska
authors: Małgorzata
authors: M
authors: Lewandowska-Szumiel
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D017886:Durapatite / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D008422:Materials Testing; D008872:Microwaves; D053758:Nanoparticles / Q000737:chemistry*; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects; D013552:Swine; D013818:Thermogravimetry
chemical_list: D018786:Bone Substitutes; D017886:Durapatite
keywords: HAp; bone regeneration; bone substitute; microwave