Vukoman Jokanović

Magnetic and structural studies of CoFe 2 O 4 nanoparticles suspended in an organic liquid

We present a study of magnetic and structural properties of CoFe2O4 nanoparticles suspended in an organic liquid. Transmission electron microscopy shows that the nanoparticles have a narrow size distribution of average particle size 5.9 ± 1.0 nm. X-ray diffraction shows that the particles are of cubic spinel crystal structure. Dynamic light scattering measurements reveal the existence of an organic shell around the CoFe2O4 nanoparticles with an average hydrodynamic diameter of 14.4 nm. Coercive magnetic field at T = 5K is found to be 11.8 kOe. Disappearance of the coercive field and remanent magnetization at about 170K suggests that the CoFe2O4 nanoparticles are superparamagnetic at higher temperatures which is confirmed by the room temperature Mossbauer spectrum analysis. Saturation magnetization of the nanoparticles of 80.8 emu/g(CoFe2O4) at 5K reaches the value detected in the bulk material and remains very high also at room temperature. The cobalt ferrite nanoparticle system synthesized in this work exhibits magnetic properties which are very suitable for various biomedical applications.

Relationship between activity of silica thin films and density of cells occupation

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.

In Vivo Investigation of ALBO-OS Scaffold Based on Hydroxyapatite and PLGA

A synthetic bone substitute based on calcium hydroxyapatite CHA and polylactic-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® from the aspect of some parameters of immunological response.

Subchronic Systemic Toxicity of New Endodontic Material Based on Calcium Hydroxyapatite and Calcium Silicates

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.

Nanomaterials as scaffolds in bone tissue engineering in dental medicine

Abstract Traditional strategies for skeletal regeneration in the orofacial region involve the use of autogenous and allogenic bone grafts that may not always be available or safe. One alternative is to develop materials for use as scaffolds for tissue engineering. These calcium-phosphate-based materials are porous, have a large surface area to volume ratio, and can be used to deliver drugs or cells. This enables the development of scaffolds for applications in tissue engineering and bone regeneration. Nanostructured materials promote greater amounts of specific protein interactions and more efficiently stimulate new bone formation. When features of scaffolds are nanoscaled, a variety of interactions can be stimulated at the cellular level. The main requirements for bone tissue engineering scaffolds are discussed, as well as the main types and design strategies. The mechanism by which nanomaterials promote bone formation is explained and the current research status of main types of nanostructured scaffolds is reviewed.

Nanosynthesized calcium-silicate-based biomaterials in endodontic treatment of young permanent teeth

Calcium-silicate-based materials are used in many endodontic and oral-surgical procedures. The advantages of calcium-silicate-based materials are good apical sealing, setting in the presence of moisture, and acquiring high pH after mixing. However, these materials also have some disadvantages: low flowability, dry consistency, and long setting time. By applying nanotechnology during synthesis, very active calcium silicate, such as nanostructured mineral polyoxide carbonate aggregate, may be used to overcome the above-mentioned disadvantages and further enhance physical properties of the reaction mixture consisting of calcite and monoclinic bismuth oxide. Application of the sol–gel method for calcite production and combination of such a method with high-temperature, self-propagating synthesis of calcium silicates makes the strategy completely innovative. Materials based on nanostructured calcium silicates may represent effective therapeutic agents for root canal obturation, especially in the case of immature roots. The application of calcium-silicate-based materials may significantly decrease the duration of therapy, reduce the risk of tooth fractures, and overcome incomplete calcification problem.