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Article Corrigendum to: Developing a novel resorptive hydroxyapatite-based bone substitute for over-critical size defect reconstruction: physicochemical and biological characterization and proof of concept in segmental rabbit’s ulna reconstruction was published on June 28, 2022 in the journal Biomedical Engineering / Biomedizinische Technik

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.

Physicochemical properties of thin films on the base of titanium oxides, obtained by a cathodic arc evaporation on the surface of glass substrate are analysed in details. The analysis of these films was made by using XRD, FTIR, SEM, XPS analysis and ellipsometry. On the basis of these analyses, particularly analysis obtained by XPS, the oxidative state Ti and corresponding phases are determined through various film layers from the surface to the substrate. The depth of the various levels and their extinction coefficients and refractory indexes are estimated by ellipsometry.

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 aim of this study was to develop novel hydroxyapatite (HAP)-based bioactive bone replacement materials for segmental osteotomy reconstruction. Customized three-dimensional (3D) bone construct was manufactured from nanohydroxyapatite (nHAP) with poly(lactide-co-glycolide) (PLGA) coating using 3D models derived from the computed tomography (CT) scanning of the rabbit's ulna and gradient 3D printing of the bone substitute mimicking the anatomical shape of the natural bone defect. Engineered construct revealed adequate micro-architectural design for successful bone regeneration having a total porosity of 64% and an average pore size of 256 μm. Radiography and micro-CT analysis depicted new bone apposition through the whole length of the reconstructed ulna with a small area of non-resorbed construct in the central area of defect. Histological analysis revealed new bone formation with both endochondral and endesmal type of ossification. Immunohistochemistry analysis depicted the presence of bone formation indicators-bone morphogenetic protein (BMP), osteocalcin (OCN) and osteopontin (OPN) within newly formed bone. Manufactured personalized construct acts as a "smart" responsive biomaterial capable of modulating the functionality and potential for the personalized bone reconstruction on a clinically relevant length scale.

Thin films of titanium oxides, titanium oxynitrides and titanium nitrides were deposited on glass substrates by the methods of direct current (DC) and pulsed magnetron sputtering and cathodic arc evaporation. Phase analysis of the deposited films by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) showed the presence of phases with various Ti oxidative states, which indicated a high concentration of oxygen vacancies. The films morphology was investigated by scanning electron microscopy (SEM). Investigations of the films wettability, either with water or ethylene glycol, showed that it depends directly on the concentration of oxygen vacancies. The wettability mechanism was particularly discussed.

Aim: To examine the potential systemic toxicity of nanostructured materials based on calcium silicate and calcium aluminate, for potential application in Dentistry. Methodology: Twenty-four Albino Wistar rats aged 2 months were used as an in vivo animal model for subcutaneous implantation of the investigated materials, placed in polyethylene tubes. Thirty days after implantation, the livers of the rats were analysed and following histological and stereological parameters were evaluated for volume density of hepatocytes and blood sinusoids, number and numerical density of hepatocytes, surface of hepatocytes and their nucleuses, nucleocytoplasmic ratio and mitotic index of hepatocytes. Stereological measurements were achieved using Cavalieri's principle, with grid P2 and unbiased analysis. Additionally, immunohistochemistry studies were performed to further analyse changes in liver tissue. Several haematological and biochemical parameters of blood of experimental animals were also analysed, as well as local tissue reactions around the implants. Statistical analysis was performed using parametric (anova and t-test) and nonparametric tests (Kruskal–Wallis and Mann–Whitney U-test) depending on data distribution. Results: Implanted dental cements led to an increase in stereological and histological parameters in liver tissue compared to control rats. Although the investigated parameters mostly showed significant differences between control and experimental animals, the liver tissue of the experimental animals did not have visible signs of pathological changes. This was supported by the analysis of blood parameters which were not significantly different between control and experimental animals. Also, the subcutaneous tissues had minimal inflammatory reactions. Immunohistochemistry studies revealed that nanostructured materials induced proliferation of hepatocytes, but that the immunological response to the materials was not strong enough to induce proliferation of immunore

The synthesis of a new endodontic mixture based on calcium aluminate cement is reported. Physico-chemical and mechanical properties of the mixture were investigated before and after various hydration periods. Phase analysis of the mixture was performed using X-ray diffraction (XRD), while morphological analysis was performed by scanning electron microscopy (SEM) equipped with EDS which revealed elemental composition of the mixture sample. Investigations of mechanical properties showed that this new endodontic mixture possessed good mechanical properties (compressive strength after 28 days aging was 94 MPa) and relatively short setting time (2 h). Additionally, cytotoxicity of the mixture was investigated by MTT assay, while genotoxicity was investigated by Comet assay, using MRC-5 cell line. The obtained results make this material very promising for potential application in dental practice. © 2019 Elsevier Ltd and Techna Group S.r.l.

Background/Aim. The deposition of hydroxyapatite (HAP) on the surface of titanium (Ti) alloys enhances bioactivity and osseointegration of the alloys which are widely used as implant materials in dentistry and orthopaedic surgery. However, the stability of HAP and subsequent biocompatibility of such alloys depends on the coating technique. The aim of this work was to test the cytotoxicity of a Ti alloy (Ti6Al4V), coated with HAP by a new plasma deposition method. Methods. The Ti6Al4V samples prepared as discs, 10 mm in diameter and 2 mm in thickness, were coated with HAP (one or both sides of the alloy) by an innovative atmospheric plasma jet method. The cytotoxicity of uncoated and HAP coated Ti6Al4V samples was evaluated by examining the morphological changes and viability of L929 fibroblasts in direct contact with the test materials. Adequate negative (polystyrene) and positive (nickel) control discs of the same size were used. The indirect cytotoxicity was determined by cultivating L929 cells with conditioning medium (CM), prepared as extract of the test samples incubated in the complete Roswell Park Memorial Institute (RPMI) 1640 medium for cell cultures. The cytotoxic effect was evaluated based on the degree of metabolic activity, necrosis, apoptosis and proliferation of L929 cells, using the appropriate assays. Results. Uncoated and one side HAP coated Ti6Al4V alloys were classified as non-cytotoxic according to the current ISO 10993-5 criteria, whereas two sides HAP coated Ti6Al4V alloy samples were slightlymoderate cytotoxic. The cytotoxicity manifested as the inhibition of metabolic activity and proliferation of L929 cells as well as the induction of their apoptosis and necrosis was significantly reduced by conditioning of HAP/Ti6Al4V alloys for 24 hours. The cytotoxic effect of HAP/Ti6Al4V CM only partly decreased in the presence of nifelate, a calcium (Ca) channel blocker, suggesting that Ca ions were not the only responsible cytotoxic agent. Conclusion.

Optical properties of TixOy thin film, of thickness 125 nm, obtained by pulsed magnetron sputtering were investigated in this paper. XRD analysis revealed the presence of anatase, rutile, TiO, Ti2O3and Ti3O5phases. XPS analysis showed similar results. SEM analysis showed quite smooth surface of the film. Spectroscopic ellipsometry revealed sharp decrease of refractive index in wavelength range 300-500 nm and extremely low values of extinction coefficients which are less than 0.01 at wavelengths equal to or higher than 500 nm.

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 3H-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-MPCA1 and ALBO-MPCA2 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-MPCA1 and ALBO-MPCA2 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-MPCA1 and ALBO-MPCA2 indicate their potential clinical use. [Figure not available: see fulltext.]. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

As an alternative to MTA, a new endodontic material based on hydroxyapatite and calcium silicates (ALBO-MPSA) has been synthesized, and its biocompatibility has been studied in many in vitro and in vivo studies. The current study aims to evaluate a subchronic systemic toxicity of ALBO-MPSA on the rat animal model, as a continuation of the previous studies. Biochemical parameters of blood and histological parameters of the liver, kidneys, and spleen of the rats were analyzed after 120 days of consumption of the aqueous extract of ALBO-MPSA. The results showed no myelotoxic effect or autoimmune effect on peripheral blood cells and no pathological effect on the liver, kidney, and spleen tissues. Besides, no changes in the skin and hair of the rats, neither the change in the consumption of food and water, nor the change in their usual behavior were noticed during the experiment.

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 (R), 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, neo-angiogenesis, fibroplasia, and the percentage of mineralization. Parallel biofunctionality assays were performed using Geistlich Bio-Oss (R). 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 scaffolds suitability as a bone substitute for applications in maxillofacial surgery. It showed numerous biological advantages over Geistlich Bio-Oss (R) which was reflected mainly as a lower number of giant cells surrounding implanted material and higher degree of mineralization in new formed bone.

Structural and optical properties of nanometric titanium oxide (TixOy) films obtained by cathodic arc plasma deposition were investigated. Phase analysis by x-ray diffraction and Fourier-transform infrared spectroscopy showed the presence of anatase, rutile, Ti2O3, Ti4O7 and amorphous phases. Scanning electron microscopy images showed well-developed surface morphology with nano-patterns. Spectroscopic ellipsometry revealed film thicknesses of 53 and 50 nm, variable refractive indices dependent on the light wavelength and close to zero extinction coefficients for wavelengths higher than 500 nm. On the basis of ultraviolet-visible spectroscopy data and using the Tauc equation, band gap values for direct and indirect electron transitions were determined.

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 hydroxyapatite-based 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 wallstopography 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 (MU) 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.

A synthetic bone substitute based on calcium hydroxyapatite (CHA) and poly(lactic-co-glycolic) acid (PLGA), described in this paper, was synthesized to fulfill specific requirements like biodegradability, satisfying mechanical properties, optimal porosity and nanotopology, osteoinductive and osteoconductive properties, and so forth. Structural and morphological properties of the new scaffold were analyzed by micro computed tomography and scanning electron microscopy, while its physicochemical properties were investigated by X-ray diffraction and infrared spectroscopy. In vivo biological investigations of the synthesized scaffold were conducted over the cutaneous irritation and biofunctionality assays on rabbits and the test of acute systemic toxicity on mice. The results showed that the scaffold is not irritant and that it does not exhibit any symptoms of acute toxicity. Biofunctionality assays which include evaluation of the presence of various cells of immune response, the presence of neoangiogenesis, percentage of mineralization of newly formed bone, and fibroplasia in the tissue indicated that the new scaffold is suitable for the application in maxillofacial and dental surgery as a bone substitute. Also, it showed significant advantages over commercial product Geistlich Bio-Oss(R) from the aspect of some parameters of immunological response.

Introduction: Calcium silicate cements (CSCs) with the addition of nanohydroxyapatite and calcium carbonate play a critical role in dental applications. To further improve their properties, particularly radiopacity and biointeractivity, the fluoride-containing radiopacifier ytterbium trifluoride (YbF3) was added to their composition, and biological and mechanical characteristics were evaluated. Methods: YbF3 was added to 3 different CSCs: cement I (CSC + calcium carbonate), cement II (CSC + nanohydroxyapatite), and Portland cement. Material characterization encompassed measurements of pH, calcium, ytterbium, and fluoride ion release; radiopacity; setting time; porosity; microindentation properties; wettability; and Fourier transform infrared spectroscopic, x-ray diffraction, and scanning electron microscopic analyses. Osteoblast- and osteoclast-like cells were grown on the materials surface to evaluate their adherence. Results: The addition of calcium carbonate, nanohydroxyapatite, and 30 wt% of YbF3 improved radiopacity and the setting time of experimental cements. The pH values did not differ among the groups. The greatest ytterbium and fluoride releases occurred in the Portland cement + YbF3 group. Combined x-ray diffraction and Fourier transform infrared spectroscopic analysis showed the presence of calcium hydroxide and calcium silicate hydrates. In addition, the presence of calcium ytterbium fluoride and ytterbium oxide proved that YbF3 reacted with cement compounds. Wettability of cement I + YbF3 was superior to other formulations, but its porosity and microindentation properties were weaker than in the Portland cement + YbF3 mixture. Cement II + YbF3 presented micromechanical indentation and porosity characteristics similar to the Portland-based cement formulation. Osteoclast- and osteoblast-like cells adhered to the cements surfaces without alteration of the cell structural integrity. Conclusions: YbF3-containing CSCs with nanostructured hydroxyapatite and

Hydroxyapatite (HA) coatings were deposited on high purity titanium substrate by atmospheric plasma spraying (APS) with high electric energy input. Previously, the surface of the titanium was prepared by alkali etching with NaOH and subsequent diverse thermal treatments. The phase composition, structure and morphology of the nano-structured HA coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Auger electron spectroscopy (AES). The XRD pattern showed that the coatings deposited by APS consisted mainly of HA with crystallite sizes between 15.5 and 31 nm and small quantities of the amorphous HA phase. The SEM observation showed that the as-deposited coatings had very different morphology with typical features of micro-structural patterns, which are desirable for improving the biological performances of HA coatings. AES analysis of various spots of the titanium substrate-coating interface showed the presence of an oxide layer with implanted Ca ions owing to the high kinetic energy of the plasma jet. This layer caused a significant increase in the measured adhesive strength, showing values in the range of 51.8-62.5 MPa. The sintering mechanism was studied using several approaches that show that the dominant sintering mechanism was volume diffusion.

The aim of this study was to synthesize and characterize new superplastic endodontic mixtures (named as ALBO-MPSA) with strongly accelerated hydration rate. Two different ALBO-MPSA mixtures were prepared using combination of hydrothermal and high-temperature self-propagating method. Phase analysis of the mixtures, before and after hydration, was carried out by X-ray diffraction (XRD), while morphological analysis was performed by scanning electron microscopy (SEM). Investigations of mechanical properties showed that new superplastic, quick-bonding endodontic mixtures with good mechanical properties were obtained (compressive strength after 28days aging was from 35.7 +/- 0.5 and 37.4 +/- 0.5 MPa). The final phase compositions after hydration of the mixtures were determined on the base of XRD data, assumed mechanism of hydration and rational chemical analysis. The constitutive phases were tobermorite, portlandite, and amorphous Ca(OH)(2), ettringite and amorphous like ettringite phase, gypsum, hydroxyapatite and barite.

The influence of monomeric and micellar concentrations of the cationic monomeric, dodecyltrimethylammonium bromide (DTAB), and the corresponding dimeric, bis(N, N-dimethyl-N-dodecyl) ethylene-1,2-diammonium dibromide (12-2-12), surfactants on the formation and transformation of amorphous calcium phosphate (ACP) was investigated. The combination of microscopy (AFM and TEM) and light scattering techniques (size and zeta potential measurements) enabled, for the first time, the simultaneous monitoring of the effect that additives exert on different length scales during CaP formation in solution - from prenucleation clusters and ACP particles to the crystalline phase. Depending on their aggregation state (monomers or micelles) and the geometry of the aggregate (spherical or elongated micelles), DTAB and 12-2-12 have exhibited different effects on the rate of ACP transformation, as well as on the morphology of the amorphous and crystalline phases. It was shown that the effect of surfactants on the precipitation process observed on the microscale could be a result of different pathways on the nanoscale. The obtained results may have implications for the understanding of the general mechanism of inorganic-organic interactions underlying the biomineralization processes, as well as for materials science.

The structural and luminescent properties of Ca2Y8(SiO4)(6)O-2 (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 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.

A synthesis of a new dental material, based on nano-structured highly active calcium silicates and calcium carbonates, is described in this paper. Phase analysis of this material, before and after hydration, was performed by X-ray diffraction and showed that active silicate phases were transformed into tobermorite phase, while carbonates remained unchanged. The mechanism of hydration was fully described. The morphology of the sample was studied by SEM, and typical appearance of the present phases was particularly discussed. The mechanical properties and setting time of this material make it very promising for potential application in dental practice.

Tetracalcium phosphate (TTCP, Ca-4(PO4)(2)O) is one of the major powder components of self-setting orthopedic and dental cements. Traditionally, TTCP powders are produced by a solid-state reaction of Ca- and P-containing precursors between 1350 and 1500 degrees C. Such procedures require expensive high-temperature furnaces and subsequent grinding of sintered particles. Grinding not only leads to the contamination but also alters the structure of TTCP, thereby reducing its bioactivity. The present paper offers an innovative approach to the inverse micelle method of TTCP synthesis, with a subsequent thermal treatment to obtain purer TTCP phase. The obtained powder was a mixture of TTCP and octacalcium phosphate (OCP) phases for thermally untreated sample, while for the sample thermally treated at 800 degrees C it was a mixture of TTCP and beta-TCP phases. The TTCP phase was prevailing phase in both cases. A typical shape of TTCP nanoparticles was needle-like. Somewhere, needles are joined together forming platelet-like structures. Investigations of the obtained phases were made by XRD and TEM. The mechanism of chemical synthesis and structural arrangements of the obtained phases were particularly investigated. The specific surface area and mechanical properties (compressive and flexural strength) of cements based on needle like TTCP (n-TTCP) and irregular shape TTCP (i-TTCP), as the most frequent form of TTCP appeared in literature, were compared. It was shown, by corresponding calculations, that the specific surface area of n-TTCP (determined from TEM micrographs) was much higher than in the case of i-TTCP (determined from SEM micrographs). Beside, compressive and flexural strength of n-TTCP based cement were significantly improved, because n-TTCP whiskers considerably reinforced structure of hardened cement paste. (C) 2013 Elsevier B.V. All rights reserved.

The biomimetic deposition of hydroxyapatite (HA) on the surface of SiO2 thin film coated metal substrates was developed and investigated. The structural investigations of HA were made by XRD and FTIR-ATR, while morphological and chemical changes during HA biomimetic deposition on the surfaces of silica thin films were investigated by SEM with EDS. The HA film thicknesses were estimated from the mass changes of samples including the corresponding correction of the pore volume inside of them, which was calculated by the Lecloux and Pirard method based on the Dollimore-Heal method. (c) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Predmet ove doktorske disertacije proističe iz aktuelne problematike inženjerstva koštanog tkiva, vezane za procese osteointegracije, implantiranja, kao i rešavanja problema inflamacije na mestima ugradnje implanata.Prvi deo disertacije posvećen je problemima vezanim za biokompatibilnost i osteointegraciju materijala koji se koriste kao implanti u inženjerstvu koštanog tkiva. S tim u vezi, ispitivano je formiranje bioaktivnih prevlaka kalcijum hidroksiapatita (HAP) na površini dve vrste potencijalnih implanata: metalnih i keramičkih, biomimičnom metodom. Ova metoda je pogodna jer omogućava dobijanje HAP-a sličnih strukturnih i morfoloških karakteristika kao prirodna kost. Zasnovana je na korišćenju rastvora sličnog jonskog sastava kao krvna plazma (poznatih kao simulirajući telesni fluidi-STF) pa su i uslovi nukleacije HAP-a slični uslovima nukleacije u biološkim sistemima. Površina metala (nerđajući čelik) prethodno je aktivirana nabacivanjem tankog sloja silicijum dioksida, sa ugrađenim OH grupama koje služe kao aktivni centri heterogene nukleacije apatita. Keramički supstrat- porozni HAP tretiran je u biomimičnom medijumu u cilju unapređenja nanotopologije unutratrašnjih zidova poroznog nosača koja je optimalna za rast i aktivaciju ćelija koštanog tkiva. Tri različita polimera (PLGA, celuloza i alginat) korišćena su za funkcionalizaciju zidova poroznog nosača radi njegovog dodatnog nanodizajniranja i povećanja njegove aktivnosti na površini. STF, kao i STF kombinovan sa serumom iz fetusa govečeta i Iglovim medijumom korišćeni su kao bioaktivni tečni medijumi u kojima se odvija biomimična nukleacija apatita.Analizom faza formiranih u biomimičnom medijumu, metodom difrakcije X-zraka, potvrđeno je da je HAP formiran na površini svih uzoraka. Infracrvenom spektroskopijom je utvrđeno da se radi o HAP-u blago promenjene stehiometrije. Mikroskopija atomskih sila ukazala je na mehanizam nukleacije, dok je skenirajuća elektronska mikroskopija ukazala na morfologiju nuklei, The subject of this PhD thesis is derived from current problems of bone tissue engineering, related to processes of osteointegration, implantation and resolution of the problems arising from the implantation site inflammation.The first part of the thesis examines problems of biocompatibility and osteointegration of materials used as implants in bone tissue engineering. Thus, the formation of bioactive coatings of calcium hydroxyapatite (CHA) on two potential types of implants, metal and ceramic, using biomimetic method, was investigated. This method is appropriate because it enables formation of CHA with similar structural and morphological properties of a natural bone. It is based on the use of the solution of similar ionic composition as human plasma (they are known as simulated body fluids- SBF) and the conditions of CHA nucleation are similar to the conditions found in biological systems. The metal surface (stainless steel) was previously activated by spraying with the thin silica film, with OH groups that act as active centers of heterogeneous nucleation of apatite. Ceramic substrate- porous CHA scaffold was treated in biomimetic medium in order to improve nanotopology of scaffold inner walls, optimal for growth and activation of bone tissue cells. Three different polymers (PLGA, cellulose and alginate) were used for the functionalization of the scaffold walls in order to achieve its additional nanodesigning and increase of its surface activity. SBF, as well as the SBF combined with fetal calf serum and Eagle’s minimal essential medium, were used as bioactive liquid medium, where biomimetic nucleation of apatite occurs.The analysis of the phases formed in the biomimetic medium, using X ray diffraction method, confirmed that CHA was formed on the surface of all samples. Infrared spectroscopy showed that this is CHA of slightly shifted stoichiometry. Atomic force microscopy pointed the mechanism of nucleation, while scanning electron microscopy showed the morphol

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.

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 (theta approximate to -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 theta and consequently lower exchange constant.

Low-temperature synthesis of fluorapatite/fluorohydroxyapatite with precursor mixture previously mechanochemically treated is described in this article. Ethylene vinylacetate/versatate copolymer as a surface active substance was mechanically treated to obtain a core-shell system with strongly controlled grain size. Despite usual behavior of mechanically activated systems, only an amorphous phase formed from precursor ions present in the mixture composed of -Ca2P2O7, CaCO3, CaF2, and unreacted Ca(OH)(2) was obtained during milling for 5min to 8h. The mixture contained depots of labile F- ions conserved in micelles cages, which are useful for teeth protection from carries. For transformation of these amorphous phases into fluorapatite, an additional low thermal treatment was necessary. The mechanism of the precursor mixture transformation into fluorapatite during milling and thermal treatment was investigated using FTIR spectroscopy and X-ray diffraction. The morphology and size distribution of the obtained powders was studied using SEM and TEM.

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. (c) 2012 Elsevier B.V. All rights reserved.

The synthesis of active silicate phases by combined sol gel and high-temperature self-propagating 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.

In this article, the synthesis and structural design of spherical, nonagglomerated particles of copper powder, synthesized by ultrasonic atomization of copper sulfate solutions in hydrogen atmosphere at 1173 K (900 A degrees C), was investigated. Well-controlled particle sizes of Cu powders were obtained from precursor solutions of various concentrations. The mean particle diameters and the ranges of particle size distribution were investigated by scanning electron microscopy (SEM). The diameter values of Cu particles obtained experimentally and estimated theoretically, using the most frequently applied atomization models, were compared. Special attention was paid to our break up capillary waves model, described elsewhere and significantly advanced by JokanoviA double daggers theoretical approach, which was applied for the first time to a copper metal system as described in this article. The best agreement between the calculated and the experimentally obtained values was found using this model.

Calcium hydroxyapatite (CHA), as one of the most important ceramic materials in bone tissue engineering, was used as a delivery system for tigecycline, a potential antibiotic in treatment of osteomyelitis. Tigecycline, in a solid state, was mixed with CHA powder and the obtained mixture was compressed into tablets. The release of tigecycline from these tablets in a pH 7.4 phosphate-buffered saline solution was measured by a UV-vis spectrophotometer at 37 degrees C. The total dose of tigecycline was released for 5 to 30 days, depending on the applied pressure and drug concentration. A new drug release mechanism that determines the relationship between pore sizes and drug release rate is proposed. It explains and quantifies the drug release kinetics based on pore sizes and pore size distribution. (c) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

The role of the process of designing a scaffold in bone tissue engineering is to provide optimal conditions for new bone tissue growth. The primary concern of such engineering is to create an adequate nanotopology of the scaffold inner walls, which can initiate the growth and activity of bone cells. Here, we present a completely new scaffold designing process based on a biomimetic approach in order to improve the nanostructure of pore walls of previously-made calcium hydroxyapatite (CHA) porous scaffolds. CHA porous scaffolds were covered with different polymer thin films (alginate, cellulose and PLGA) and exposed to simulated body fluid (SBF) for 42 days. SBF induced in situ formation of bone-like apatite phases on the surface of CHA/polymer composites. Fourier Transformed Infrared (FTIR) spectroscopy showed that the biomimetically-assembled phase is CHA of slightly shifted stoichiometry. X-ray diffraction confirmed that CHA is self-assembled on the surface of all investigated thin films. The calculation of crystallite sizes showed small differences in the degree of crystallinity between different samples. Scanning electron microscopy revealed a dominant blow-ball morphology of CHA particles (size 1 - 5 mu m) with nano-sized branches on their surfaces.

Calcium hydroxyapatite (CHA) formation was produced by biomimetic deposition on the surfaces of silica layers of the steel bands, using slightly modified simulated body fluid (SBF). The used SBF had a pH value of 7.4 and a similar ionic composition like human plasma. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) method was used to analyse obtained phases on the surfaces of silica films after various times of sample soaking in SBF. Atomic force microscopy (AFM) investigations pointed out the mechanism of CHA nucleation. Mass changes investigations of the CHA thin films showed that the depth of CHA films was dependent on the aging time of silica substrate in SBF.

The synthesis of calcium hydroxyapatite in a slightly modified SBF fluid by self-assembly on the surfaces of SiO(2) thin films was investigated in this study. The mechanism of their nucleation on the surface of silica thin films of various depths was particullarly investigated by using AFM. The analysis of the obtained phases after different times of sample ageing in modified SBF was determined using the FTIR-ATR method. The thicknesses of the film were investigated over the mass changes of the samples. The corresponding corrections related to the total pore volume inside of them were included in the final results of their thicknesses.

The ultrasonic spray pyrolysis technique has been, during last three decades, one of the major techniques of synthesis a wide variety of materials. One of the most important among the ionic conductors is lithium phosphorous doped tungsten bronze. The main goal of this investigation is producing full or hallows spheres of these bronzes of very narrow distribution. The mean size and size distribution specter of all materials were determined by the SEM analysis. The results were compared with the values obtained from the theoretical model. The assembled results indicate the possibility of a rigorous particle structure designing of all obtained powders.

In this study, the synthesis of thin films of Mg phosphorus doped tungsten bronzes (MgPTB; MgHPW(12)O(40).29H(2)O) by the self-assembly of nano-structured particles of MgPTB obtained using the ultrasonic spray pyrolysis method was investigated. As the precursor, MgPTB, prepared by the ionic exchange method, was used. Nano-structured particles of MgPTB were obtained using the ultrasonic spray pyrolysis method. The nano-structure of the particles used as the building blocks in the MgPTB thin film were investigated experimentally and theoretically, applying the model given in this article. The obtained data for the mean particle size and their size distribution show a high degree of agreement. These previously tailored particles used for the preparation of thin films during the next synthesis step, by their self-assembly over slow deposition on a silica glass substrate, show how it is possible to create thin MgPTB films under advance projected conditions of the applied physical fields with a fully determined nanostructure of their building block particles, with a relatively small roughness and unique physical properties.