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The structural and luminescent properties of Ca2Y8(SiO4)6O2 (CYS) silicate based oxyapatite doped with Eu3+ ions have been reported in this paper. The sample was synthesized using reflux method assisted by urea subsequent degradation. Very specific, shеlland rope-like morphologies were observed by SEM. The powder X-ray diffraction study revealed that the Eu3+: CYS system crystallized in a hexagonal lattice structure (space group P63/m) characteristic of oxyapatite. In the host oxyapatite structure, а partial replacement of Ca2+ аnd Y3+ ions by luminescent active Eu3+ ions have been done, and its photoluminescent spectra were analyzed. The performed analysis indicate the presence of Eu3+ ions in both, nine-fold coordinated 4f, and seven-fold coordinated 6h sites, showing a slight shift towards the blue area in comparison to a typical spectra of other yttrium-silicate phases as hosts. [Projekat Ministarstva nauke Republike Srbije, br. 142066]

Release kinetics of tigecycline, a potential antibiotic in treatment of osteomyelitis, from calcium hydroxyapatite (CHA), as one of the most important ceramic materials in bone tissue engineering, was investigated in this study. Tigecycline, in solid state, was mixed with CHA powder and the obtained mixture was compressed into tablets using two different pressures. These tablets were immersed in a phosphate-buffered saline solution and tigecycline release was measured by a UV-VIS spectrophotometer. The total release time was 5 or 28 days, depending on the pressure applied during compression. It was shown that there is a close relationship between pore sizes and drug release rate. The drug release kinetics was interpreted on the base of pore sizes and pore size distribution. [Projekat Ministarstva nauke Republike Srbije, br. 172026]

The magnetic properties of mesoscopic materials are modified by size and surface effects. We present a sol-gel method used to tailor these effects, and illustrate it on Co1+yAl2-yO4 spinel. Nanocomposites made of spinel oxide Co1+yAl2-yO4 particles dispersed in an amorphous SiO2 matrix were synthesized. Samples with various mass fractions -x of Co1+yAl2-yO4 in composite, ranging from predominantly SiO2 (x = 10 wt%) to predominantly spinel (x = 95 wt%), and with various Co concentrations in spinel y were studied. The spinel grain sizes were below 100 nm with a large size distribution, for samples with predominant spinel phase. Those samples showed Curie-Weiss paramagnetic behavior with antiferromagnetically interacting Co ions (θ ≈ -100 K). The grain sizes of spinel stays confined in 100 nm range even in the spinel samples diluted with as low as 5 wt% concentration of amorphous SiO2. For the samples with predominant SiO2 the crystalline nanoparticles are well separated and of size of around 100 nm, but with presence of much smaller spinel nanoparticles of about 10 nm. The magnetic properties of the samples with predominant silica phase showed complex behavior, spin-glass magnetic freezing at the lowest temperatures and lower absolute value of θ and consequently lower exchange constant. [Projekat Ministarstva nauke Republike Srbije, br. 172026]

The synthesis of active silicate phases by combined sol gel and high-temperature selfpropagating wave method, is described in this paper. They show a significant decrease of setting time and good mechanical properties, which are very important for its potential application in endodontic practice. Particularly, process of hydration of calcium silicate phases is carefully analyzed, from the aspect of phase changes during their soaking in water for 1, 3, 7 and 28 days. XRD and FTIR methods were used for phase analysis of all samples, while morphological characteristics and chemical composition of the given phases were investigated by SEM and EDS. [Projekat Ministarstva nauke Republike Srbije, br. 172026]

The SiO2 thin films (STFs) were deposited on the surfaces of stainless steel tapes and their activity was particularly investigated from the aspect of the number density of hydroxyl groups on their surfaces. The calculation procedure of density of active OH groups includes determination of average length of silica chains that constitute silica sol particles with almost uniform size, on the base of thermogravimetric analysis. The size of SiO2 particles is analyzed by transmission electron microscopy and dynamic light scattering method. Fibroblast (L929) cell densities on the surfaces of these films were investigated using phase contrast microcopy. It was shown that there is a relationship between OH group densities and density of attached cells. Besides, the cytotoxicity effect was studied and compared for various thermally treated STFs. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1707-1714, 2014. [ABSTRACT FROM AUTHOR]

The structural and luminescent properties of Ca2Y8(SiO4)6O2 (CYS) silicate based oxyapatite doped with Eu3+ ions have been reported in this paper. The sample was synthesized using reflux method assisted by urea subsequent degradation. Very specific, shell-and rope-like morphologies were observed by SEM. The powder X-ray diffraction study revealed that the Eu3+: CYS system crystallized in a hexagonal lattice structure (space group P63/m) characteristic of oxyapatite. In the host oxyapatite structure, a partial replacement of Ca2+ and Y3+ ions by luminescent active Eu3+ ions have been done, and its photoluminescent spectra were analyzed. The performed analysis indicate the presence of Eu3+ ions in both, nine-fold coordinated 4f, and seven-fold coordinated 6h sites, showing a slight shift towards the blue area in comparison to a typical spectra of other yttrium-silicate phases as hosts. [ABSTRACT FROM AUTHOR]

Abstract: Mesoporous silica materials have already proved to be non-toxic and biocompatible, and also to have large pore volume and very high specific surface area suitable for loading of small molecules. Having this in mind and the fact that silicon dioxide (SiO2) powders can be so designed to obtain particle structures organized at multi levels, SiO2 was chosen as a potential carrier for metronidazole, an antibiotic drug. SiO2 powder was synthesized in two stages: first silica sol was prepared by hydrothermal synthesis and second the sol was converted into powder by dry spraying with simultaneous incorporation of the antibiotic into its structure. Scanning and transmission electron microscopy study revealed very complex structure and sub-structure of SiO2 particles. Cell viability tests were used for estimation of cytotoxicity of so synthesized SiO2. The drug release data showed that the system can provide drug release for a long time. Also, the device behavior is fully predictable, according to our theoretical model of multilevel structure design, and gives many opportunities for model investigations of drug release and its kinetics. The pore sizes and their distribution were observed as a limiting factor of drug release kinetics. Therefore, as the pore sizes are given as a set of discrete values, the kinetics of drug release might also be given as a set of corresponding discrete values. [Copyright &y& Elsevier]

The magnetic properties of mesoscopic materials are modified by size and surface effects. We present a sol-gel method used to tailor these effects, and illustrate it on Co1+yAl2-yO4 spinel. Nanocomposites made of spinel oxide Co1+yAl2-yO4 particles dispersed in an amorphous SiO2 matrix were synthesized. Samples with various mass fractions -x of Co1+yAl2-yO4 in composite, ranging from predominantly SiO2 (x = 10 wt%) to predominantly spinel (x = 95 wt%), and with various Co concentrations in spinel y were studied. The spinel grain sizes were below 100 nm with a large size distribution, for samples with predominant spinel phase. Those samples showed Curie-Weiss paramagnetic behavior with antiferromagnetically interacting Co ions (θ ≈ -100 K). The grain sizes of spinel stays confined in 100 nm range even in the spinel samples diluted with as low as 5 wt% concentration of amorphous SiO2. For the samples with predominant SiO2 the crystalline nanoparticles are well separated and of size of around 100 nm, but with presence of much smaller spinel nanoparticles of about 10 nm. The magnetic properties of the samples with predominant silica phase showed complex behavior, spin-glass magnetic freezing at the lowest temperatures and lower absolute value of θ and consequently lower exchange constant. [ABSTRACT FROM AUTHOR]

Titanium is widely used as implant material since it shows very good corrosion resistance, good mechanical behaviour and biocompatibility, but it has low wear resistance and high friction coefficient which limits its more extensive application. This can be overcome by production of stable oxide coatings on the titanium surface using various methods. In this study, samples of titanium implant were treated with plasma electrolytic oxidation, subsequent ionic exchange and thermal treatment in order to obtain bioactive layer on their surface. XRD analysis was used to investigate phase composition of the obtained coatings, while their morphology was investigated by SEM. Cytotoxicity investigations by MTT, LDH and propidium iodide assays and light microscopy were done using murine fibroblasts cells L929. The obtained coatings consisted of titanium oxide, calcium and sodium titanates and hydroxyapatite. SEM revealed that the given method, besides corresponding phase composition, enabled specific nanotopology suitable for cell attachment and proliferation. Cytotoxicity investigations showed that these coatings were not cytotoxic to L929 cells. [ABSTRACT FROM AUTHOR]

The effects of a new material based on hydroxyapatite and calcium silicates, named ALBO-MPCA, were investigated on the liver, kidney and spleen. The material was administrated orally for 120 days in an in vivo model in Wistar rats, and untreated animals served as a control. Hematological and biochemical blood parameters were analyzed. Qualitative histological analysis of tissues, change in mitotic activity of cells, and histological characteristics was conducted, as well as quantitative stereological analysis of parenchymal cells, blood sinusoids, and connective tissues. Additionally, the protein expressions of Ki67 and CD68 markers were evaluated. Histological analysis revealed no pathological changes after the tested period. It showed the preservation of the architecture of blood sinusoids and epithelial cells and the presence of mitosis. Additionally, the significantly increased number of the Ki67 in the presence of ALBO-MPCA confirmed the proliferative effect of the material noticed by stereological analysis, while immunoreactive CD68 positive cells did not differ between groups. The study showed non-toxicity of the tested material based on the effects on the hematological, biochemical, and observed histological parameters; in addition, it showed evidence of its biocompatibility. These results could be the basis for further steps toward the application of tested materials in endodontics.

The titanium implant was treated with plasma electrolytic oxidation and subsequent ionic exchange and thermal treatment in order to obtain bioactive layer consisting of titanium oxide, calcium and sodium titanates and hydroxyapatite, as confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) revealed that the given method, besides corresponding phase composition, enables suitable nanotopology for cell attachment and proliferation. Cytotoxicity investigations by MTT, LDH and propidium iodide assays and light microscopy showed that these coatings were not toxic to L929 cells.

The aim of this study was to investigate the biocompatibility of nanostructured materials based on highly active calcium silicates mixed with different radiocontrast agents in comparison to MTA + using in vitro and in vivo model. Morphology of materials' samples was analyzed using SEM while the phase compositions were identified by XRD. pH values of materials' suspensions were conducted by pH-meter. The cytotoxicity of materials' solutions was tested by MTT test (100, 50, 25 and 12.5 mg/ml). LDH and 3 H-thymidine assay were utilized for biocompatibility investigations of materials' eluates (24 h, 7 day and 21 day). Eighteen Guinea pigs were used for intramuscular implantation, as teflon tubes with freshly prepared materials were placed into intramuscular pockets. All samples were composed of round and needle-like particles equally distributed with Ca/Si ratio ~2.7 at%, with the presence of hydrated calcium silicate phases. The pH values of ALBO-MPCA 1 and ALBO-MPCA 2 were high alkaline, while in case of MTA + they were lower and continuously declined (p < 0.05). Investigated materials didn't exhibit dose-dependent effect on metabolic activity of L929 cells (p > 0.05). Significant differences in the percentage of cytotoxicity between diluted and undiluted extracts between all tested materials after 24 h and 7 day were noticed (p < 0.05). Increase in L929 cells proliferation was noticed in case of undiluted eluates of ALBO-MPCA 1 and ALBO-MPCA 2 after 7 day (p < 0.05). There were no statistically significant differences in the intensity of inflammatory response between investigated materials and control group after 60 day (p > 0.05). Evaluation of biocompatibility of both ALBO-MPCA 1 and ALBO-MPCA 2 indicate their potential clinical use.

This study examined the potential of a new porous calcium hydroxyapatite scaffold covered with poly (lactide-co-glycolide) (PLGA) as a bone substitute, identifying its advantages over Geistlich Bio-Oss®, considered the gold standard, in in vivo biofunctionality investigations. Structural and morphological properties of the new scaffold were analyzed by scanning electron and atomic force microscopy. The biofunctionality assays were performed on New Zealand white rabbits using new scaffold for filling full-thickness defects of critical size. The evaluated parameters were: the presence of macrophages, giant cells, monoocytes, plasma cells, granulocytes, neoangiogenesis, fibroplasia, and the percentage of mineralization. Parallel biofunctionality assays were performed using Geistlich Bio-Oss®. The appearance of bone defects 12 weeks after the new scaffold implantation showed the presence of a small number of typical immune response cells. Furthermore, significantly reduced number of capillary buds, low intensity of fibroplasia and high degree of mineralization in a lamellar pattern indicated that the inflammation process has been almost completely overcome and that the new bone formed was in the final phase of remodeling. All biofunctionality assays proved the new scaffold's suitability as a bone substitute for applications in maxillofacial surgery. It showed numerous biological advantages over Geistlich Bio-Oss® which was reflected mainly as a lower number of giant cells surrounding implanted material and higher degree of mineralization in new formed bone.

Introduction: Biodegradable porous scaffolds are found to be very promising bone substitutes, acting as a temporary physical support to guide new tissue regeneration, until the entire scaffold is totally degraded and replaced by the new tissue., Objective: The aim of this study was to investigate cytotoxicity of a synthesized calcium hydroxyapatitebased scaffold, named ALBO-OS, with high porosity and optimal topology., Methods: The ALBO-OS scaffold was synthesized by the method of polymer foam template. The analysis of pore geometry and scaffold walls’ topography was made by scanning electron microscope (SEM). The biological investigations assumed the examinations of ALBO-OS cytotoxicity to mouse L929 fibroblasts, using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromidefor (MTT) and lactate dehydrogenase (LDH) tests and inverse phase microscopy., Results: The SEM analysis showed high porosity with fair pore distribution and interesting morphology from the biological standpoint. The biological investigations showed that the material is not cytotoxic to L929 cells. Comparison of ALBO-OS with Bio-Oss, as the global gold standard as a bone substitute, showed similar results in MTT test, while LDH test showed significantly higher rate of cell multiplication with ALBO-OS., Conclusion: The scaffold design from the aspect of pore size, distribution, and topology seems to be very convenient for cell adhesion and occupation, which makes it a promising material as a bone substitute. The results of biological assays proved that ALBO-OS is not cytotoxic for L929 fibroblasts. In comparison with Bio-Oss, similar or even better results were obtained.