A comparative study on cytotoxicity and genotoxicity of the hydroxyapatite-bioactive glass and fluorapatite-bioactive glass nanocomposite foams as tissue scaffold for bone repair.

Considering to the possibility of cellular and genetic damage by the implant materials in the patient and the clinician, the safety of the biomaterials should be evaluated. The purpose of this study was to compare the cytotoxicity and genotoxicity induced by two nanocomposites, hydroxyapatite/bioactive glass (HA/BG) and fluorapatite/bioactive glass (FA/BG) in vitro. Biomaterial extracts (BMEX, 100%) were prepared by incubating 100 mg/mL of each biomaterial powder in complete culture medium (RPMI1640 + 10% FBS) for 72 h. Saos-II cells were exposed to different concentrations of BMEXs for different periods of time and evaluated at the end of each period. According to 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay results, both BMEXs at low concentrations (<25%) has no inhibitory effects on the cells growth. After 24 h of exposure, only HA/BG BMEX at 100% concentration showed significant cytotoxic effect. After 48 and 72 h, both HA/BG and FA/BG BMEXs showed similar cytotoxic effect at concentration higher than 75 and 50%, respectively. The results of the comet assay showed that the tail elongation, and proportionally DNA damage, increased in a dose/time dependently fashion with BMEXs exposure. Based on low and similar cytotoxicity and genotoxicity profiles on the Saos-II cell line, it could be concluded that FA/BG, like HA/BG, could be a good candidate for further in vivo biocompatibility studies to be used in bone tissue repair. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2605-2612, 2018.

The hematological and biochemical changes in rats exposed to britholite mineral.

The present study was to investigate the alteration of biochemical and hematological parameters on the rats exposed to natural radiation caused by britholite mineral (REE, Ca, Na)5 [(Si,P)O4]3(OH,F) within 15 days. Britholite was collected from Kuluncak mining area, Malatya, bearing radioactive 232Th isotope (average 2.68% ThO2), which is rare earth elements found high amounts. Britholite is toxic for the living animal and human and emits the radiation to natural surroundings about 0.8R/h due to its radioactive 232Th properties. In this study, animals were divided to two groups, one groups exposed to 232Th, the other group was served as control group. All animals were fed with same food and water during the experimental study (15 days). After 15 days, the hematologic and biochemical parameters (Na, K, Ca, P, Cl, Mg, glucose, cholesterol, HDL, LDL, albumin, Uric acid, AST, ALT, total protein, Fe, urea and creatine level and hormonal parameters (TSH, T3 and T4)) were analyzed The levels of serum triglyceride in the ionizing radiation group generated by 232Th isotope (p < 0.05) statistically significantly increased compared with control group value. Lymphocytes, TSH, T3 and T4 decreased in the ionizing radiation group generated by 232Th isotope while neutrophils increased in the ionizing radiation group generated by 232Th isotope. The rats exposed to ionizing radiation generated by 232Th isotope caused significant changes in the hematological and biochemical parameters and the most significantly alteration was observed in the thyroid hormonal levels, which might be due to high radiation doses within short time. These results should be kept in mind to maintain healthy life in people who lives in britholite mineral vicinity.

Lead bioaccumulation in Opuntia ficus-indica following foliar or root exposure to lead-bearing apatite.

The contamination of edible leafy vegetables by atmospheric heavy metal-bearing particles is a major issue in environmental toxicology. In this study, the uptake of lead by cladodes of Opuntia ficus-indica (Ofi), traditionally used in Mexican cuisine and in livestock fodder, is investigated after a 4-months exposure of either cladodes or roots to synthetic Pb-fluorapatite particles. Atomic Absorption Spectroscopy (AAS) for the quantitative analysis of Pb levels, Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectroscopy (SEM-EDX) for the examination of the cladode surface and fate of particles, and Micro-X-ray fluorescence (µXRF) measurements for elemental mapping of Pb in cladodes, were used. The results evidence that foliar contamination may be a major pathway for the transfer of Pb within Ofi cladodes. The stomata, areoles, and cuticle of cladode surface, play an obvious role in the retention and the incorporation of lead-bearing apatite, thus revealing the hazard of eating contaminated cladodes. The possibility of using series of successive cladodes for biomonitoring the atmospheric pollution in arid and semi-arid regions is also rapidly discussed.

Ecotoxicological response of marine organisms to inorganic and organic sediment amendments in laboratory exposures.

Experimental materials currently being investigated for use as amendments for the in situ remediation of contaminated sediments were assessed for their potential impacts on marine benthos. Laboratory toxicity tests involving lethal and sublethal endpoints were conducted on sediments amended with apatite, organoclay, chitin, or acetate, with the polychaete Neanthes arenaceodentata, the amphipod Eohaustorius estuarius, and the larval sheepshead minnow Cyprinodon variegatus. Amendments were mixed loosely into uncontaminated or metal-contaminated sediments, and also added inside experimental geotextile mats, at sediment dry weight (dw) concentrations ranging from 0.5% to 10%. The geotextile mats, containing apatite (5 or 10% dw), and/or organoclay (5%) did not result in adverse effects on any of the test organisms. Chitin and acetate, however, repetitively resulted in adverse effects on survival and/or adverse or positive effects on organism growth at concentrations of ≤ 2.5% dw. The adverse effects were attributed to water quality degradation in the exposure vessels (notably ammonia and dissolved oxygen concentration, for chitin and acetate, respectively) as a result of the microbial breakdown of the amendments. For N. arenaceodentata, growth was enhanced in the presence of chitin at concentrations as low as 0.5% sediment dw, which stimulated bacterial growth that may have provided an additional food source for the polychaete. Sediment chitin concentrations of 0.5% resulted in a statistically significant reduction in N. arenaceodentata body burdens of 61%, 29%, and 54%, relative to unamended contaminated sediment, for Cu, Zn, and Cd, respectively. The studies suggest a lack of inherent toxicity of these materials on the experimental organisms, as the adverse or positive responses observed are likely related to artifacts associated with laboratory exposure. Assessments in field settings are needed to verify this conclusion.

Synthesis of fluorapatite-hydroxyapatite nanoparticles and toxicity investigations.

In this study, calcium phosphate nanoparticles with two phases, fluorapatite (FA; Ca(10)(PO(4))(6)F(2)) and hydroxyapatite (HA; Ca(10)(PO(4))(6)(OH)(2)), were prepared using the solgel method. Ethyl phosphate, hydrated calcium nitrate, and ammonium fluoride were used, respectively, as P, Ca, and F precursors with a Ca:P ratio of 1:72. Powders obtained from the sol-gel process were studied after they were dried at 80°C and heat treated at 550°C. The degree of crystallinity, particle and crystallite size, powder morphology, chemical structure, and phase analysis were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zetasizer experiments. The results of XRD analysis and FTIR showed the presence of hydroxyapatite and fluorapatite phases. The sizes of the crystallites estimated from XRD patterns using the Scherrer equation and the crystallinity of the hydroxyapatite phase were about 20 nm and 70%, respectively. Transmission electron microscope and SEM images and Zetasizer experiments showed an average size of 100 nm. The in vitro behavior of powder was investigated with mouse fibroblast cells. The results of these experiments indicated that the powders were biocompatible and would not cause toxic reactions. These compounds could be applied for hard-tissue engineering.

In vitro effects of fluor-hydroxyapatite, fluorapatite and hydroxyapatite on colony formation, DNA damage and mutagenicity.

The number of biomaterials used in biomedical applications has rapidly increased in the past two decades. Fluorapatite (FA) is one of the inorganic constituents of bone or teeth used for hard-tissue repairs and replacements. Fluor-hydroxyapatite (FHA) is a new synthetically prepared composite that in its structure contains the same molecular concentration of OH(-) groups and F(-) ions. The aim of this experimental investigation was to evaluate cytotoxic, genotoxic and mutagenic effects of FHA and FA eluates on Chinese hamster V79 cells and to compare them with the effects of hydroxyapatite (HA) eluate. Cytotoxicity of the biomaterials tested was evaluated by use of the cell colony-formation assay and by direct counting of the cells in each colony. Genotoxicity was assessed by single-cell gel electrophoresis (comet assay) and mutagenicity was evaluated by the Hprt gene-mutation assay and in bacterial mutagenicity tests using Salmonella typhimurium TA100. The results show that the highest test concentrations of the biomaterials (100% and 75% eluates) induced very weak inhibition of colony growth (about 10%). On the other hand, the reduction of cell number per colony induced by these concentrations was in the range from 43% to 31%. The comet assay showed that biomaterials induced DNA breaks, which increased with increasing test concentrations in the order HA

Preparation of germanium apatite and its cytotoxicity.

Germanium apatite was synthesized via the solid-state reaction between GeO(2) and (NH(4))(3)PO(4). The synthesized materials were characterized using XRD, and thermal analysis was carried out using TG-DTA. Ge(2)P(2)O(7) was preferentially produced at temperatures between 300-900 degrees C, and at temperatures above 1000 degrees C, germanium apatite (Ge(5)O(PO(4))(6), GeAp) was synthesized. In solubility tests, 0.36% and 0.65% of Ge ions were liberated from GeAp powder in distilled water at 37 and 80 degrees C after four weeks, respectively. A GeAp aqueous solution maintained at 37 degrees C was strongly acidic with a pH=1.67 after four weeks. The growth rate of human adult gingival fibroblast cells in a medium that included GeAp, HA, and GeO(2) was investigated. The growth rate of the cells in a 0.1 mg/ml GeAp medium was almost the same as that in the control. The cell growth was restricted in a 1.0 mg/ml GeAp medium, whereas the cell growth in a pH-adjusted 1.0 mg/ml GeAp medium at pH=7.60 was higher than that in non-adjusted medium at pH = 7.06.

Effect of niobium content on the microstructure and thermal properties of fluorapatite glass-ceramics.

Niobium oxide has been shown to improve biocompatibility and promote bioactivity. The purpose of this study was to evaluate the effect of niobium oxide additions on the microstructure and thermal properties of fluorapatite glass-ceramics for biomedical applications. Four glass-ceramic compositions with increasing amounts of niobium oxide from 0 to 5 wt % were prepared. The glass compositions were melted at 1,525 degrees C for 3 h, quenched, ground, melted again at 1,525 degrees C for 3 h and furnace cooled. The coefficient of thermal expansion was measured by dilatometry. The crystallization behavior was evaluated by differential thermal analysis. The nature of the crystalline phases was investigated by X-ray diffraction. The microstructure was studied by SEM. In addition, the cytotoxicity of the ceramics was evaluated according to the ASTM standard F895--84. The results from X-ray diffraction analyses showed that fluorapatite was the major crystalline phase in all glass-ceramics. Differential thermal analyses revealed that fluorapatite crystallization occurred between 800 and 934 degrees C depending on the composition. The coefficient of thermal expansion varied from 7.6 to 9.4 x 10(-6)/ degrees C. The microstructure after heat treatment at 975 degrees C for 30 min consisted of submicroscopic fluorapatite crystals (200--300 nm) for all niobium-containing glass-ceramics, whereas the niobium-free glass-ceramic contained needle-shaped fluorapatite crystals, 2 microm in length. None of the glass-ceramics tested exhibited any cytotoxic activity as tested by ASTM standard F895--84.

Osteogenic cell cytotoxicity and biomechanical strength of the new ceramic Diopside.

Diopside was prepared by sintering a powder compact composed of CaMgSi2O6 at 1573K for 2 h. In order to clarify the biocompatibility of Diopside, the cytotoxicity of Diopside against the osteogenic cell line MC3T3-E1 and the bone-Diopside interface strength were examined. On both the 14th and 21st days of incubation of MC3T3-E1 cells with Diopside, ALP activities were not significantly lower than those of the CTRL. TEM photographs of MC3T3-E1 on Diopside after 14 days of incubation showed active secretion of crystals from osteoblast-like cells. Scanning electron microscopic analysis showed that the cells on Diopside formed multiple cell layers similar to those on the CTRL both 14 and 21 days after incubation. These results showed that Diopside had no cytotoxic effect on MC3T3-E1. The pulling test showed that failure loads of Diopside were significantly lower than those of AWGC. Histologically, there was no fibrous tissue or foreign body reaction at the bone interface. SEM-EPMA showed that Diopside had attached to the bone via a calcium-phosphorus layer. SEM back-scattered electron imaging showed that the Diopside plate had degraded to a porous state 12 weeks after implantation. These findings indicate that Diopside is a biodegradable ceramic.

Protection of crystal-induced polymorphonuclear leukocyte membranolysis by phosphocitrate.

The protection afforded by phosphocitrate, a phosphorylated polycarboxylic acid, against crystal-induced membrane damage to polymorphonuclear leukocytes was studied in vitro. Membranolysis was assessed by nitro blue tetrazolium salt reduction, lactate dehydrogenase release, and scanning electron microscopy. Phosphocitrate protected strongly against hydroxyapatite crystal-induced damage, an action attributable to crystal surface binding of phosphocitrate rather than to the membrane. The ability of phosphocitrate to prevent hydroxyapatite crystallization, together with its membrane protective effect against preformed crystals, would suggest that the compound might have a useful future role against crystal-induced arthropathies.