Žarko Mitić

Synthesis, physicochemical and spectroscopic characterization of copper(II)-polysaccharide pullulan complexes by UV–vis, ATR-FTIR, and EPR

Bioactive copper(II) complexes with polysaccharides, like pullulan and dextran, are important in both veterinary and human medicine for the treatment of hypochromic microcitary anemia and hypocupremia. In aqueous alkaline solutions, Cu(II) ion forms complexes with the exopolysaccharide pullulan and its reduced low-molecular derivative. The metal content and the solution composition depend on pH, temperature, and time of the reaction. The complexing process begins in a weak alkali solution (pH >7) and involves OH groups of pullulan monomer (glucopyranose) units. Complexes of Cu(II) ion with reduced low-molecular pullulan (RLMP, M(w) 6000 g mol(-1)) were synthesized in water solutions, at the boiling temperature and at different pH values ranging from 7.5 to 12. The Cu(II) complex formation with RLMP was analyzed by UV-vis spectrophotometry and other physicochemical methods. Spectroscopic characterizations (ATR-FTIR, FT-IRIS, and EPR) and spectra-structure correlation of Cu(II)-RLMP complexes were also carried out.

Deconvoluted Fourier-transform LNT-IR study of coordination copper(II) compounds with dextran derivatives

Deconvoluted Fourier-transform IR spectra, recorded at room and liquid nitrogen temperature, of polysaccharide dextran and its coordination compounds with the copper(II) ion were analyzed in order to find the most specific spectral peculiarities. This allows one to obtain information about the structure and conformation of these polymer compounds. Different influences on the system of intra-and intermolecular interactions were exhibited by analogs recrystallized from D2O. The changes in intensity and width of the IR bands in the region 1450–1050 cm−1 were related to changes in conformation and short-range interactions of the dextran. In the synthesized copper(II)-dextran complexes, the presence of water molecules was confirmed. The results of the FTIR spectroscopy study allowed one to suggest a predominant crystalline form of the copper(II)-dextran complexes.

Investigating an organ-targeting platform based on hydroxyapatite nanoparticles using a novel in situ method of radioactive 125Iodine labeling

In this study, we have investigated the synthesis of nanoparticles of hydroxyapatite (HAp) and hydroxyapatite coated with chitosan (HAp/Ch) and the chitosan-poly-d,l-lactide-co-glycolide polymer blend (HAp/Ch-PLGA) as an organ-targeting system. We have examined and defined the final destination, as well as the dynamics and the pathways of the synthesized particles following intravenous administration in vivo. The XRD, ZP, FT-IR and SEM analyses have confirmed that the hydroxyapatite nanoparticles with d50=72 nm are coated with polymers. Radioactive 125-Iodine ((125)I), a low energy gamma emitter, was used to develop a novel in situ method for the radiolabeling of particles and investigation of their biodistribution. (125)I-labeled particles exhibited high stability in saline and serum over the second day, which justified their use in the following in vivo studies. The biodistribution of (125)I-labeled particles after intravenous injection in rats differed significantly: HAp particles mostly targeted the liver, HAp/Ch the spleen and the liver, while HAp/Ch-PLGA targeted the lungs. Twenty-four hours post injection, HAp particles were excreted completely, while both (125)I-HAp/Ch and (125)I-HAp/Ch-PLGA were retained in the body for a prolonged period of time with more than 20% of radioactivity still found in different organs.

Addition of blood to a phycogenic bone substitute leads to increased in vivo vascularization

The present study aimed to analyze the effects of the addition of blood to the phycogenic bone substitute Algipore(®) on the severity of in vivo tissue reaction. Initially, Fourier-transform infrared spectroscopy (FTIR) of the bone substitute was conducted to analyze its chemical composition. The subcutaneous implantation model in Balb/c mice was then applied for up to 30 d to analyze the tissue reactions on the basis of specialized histochemical, immunohistochemical, and histomorphometrical methods. The data of the FTIR analysis showed that the phycogenic bone substitute material is mainly composed of hydroxyapatite with some carbonate content. The in vivo analyses revealed that the addition of blood to Algipore(®) had a major impact on both angiogenesis and vessel maturation. The higher vascularization seemed to be based on significantly higher numbers of multinucleated TRAP-positive cells. However, mostly macrophages and a relatively low number of multinucleated giant cells were involved in the tissue reaction to Algipore(®). The presented data show that the addition of blood to a bone substitute impacts the tissue reaction to it. In particular, the immune response and the vascularization were influenced, and these are believed to have a major impact on the regenerative potential of the process of bone tissue regeneration.

Fourier-Transform IR spectroscopic investigations of Cobalt(II)–dextran complexes by using D2O isotopic exchange

Co(II) ion complexes with reduced low-molar dextran (RLMD) derivatives Mw= 5000 − 6000 g/mol, their FTIR spectroscopic characterization, as well as the spectra-structure correlation was investigated in this work. The samples of Co(II) ion complexes with RLMD were deuterated (D2O, Merck) for 2 h, at room temperature, in vacuum. FTIR spectra as an average of 40 scans were recorded at room temperature in the range 4000 – 400 cm−1. FTIR investigation of Co(II)–RLMD complexes by D2O isotopic exchange proved to be a very sensitive method for determining OH group coordination and is related to the hydrogen bond strength. The results of our investigation point to the dextran and their complexes with Co(II) ion are crystalline hydrate molecules. The correlation of physicochemical, spectrophotometric and spectroscopic investigations of these complexes, coordination chemistry of Co(II) ion and the structure of an exopolysaccharide chain are proposed different model structures of the synthesized Co(II) complexes.

Synthesis and spectroscopic characterization of copper(H)-dextran complexes

Synthesis of stable copper(II) complexes with reduced dextran derivatives can be realized with low molar polysaccharides of an average molar mass 5000 g mol−1. A copper(II) content of 4–20% is achieved at pH 7–8 and at the boiling point. Copper(II) complex formation with dextran was analyzed by spectrophotometric VIS methods. The IR spectra of copper(II) complexes with dextran were analyzed to find the most stable conformation of the glucopyranose unit. The ESR parameters of the spectrum indicate a square-planar coordination of the Cu(II) ion with four oxygen ligand atoms in the same plane. Copper deficiency causes a number of pathological states [1]. In both human and veterinary medicine, commercial copper preparations based on dextran and its derivatives are used for such purposes [2]. According to the literature data, dextran has the ability of complex formation with various biometals (Zn, Fe, Co, Ca, and Mg) [3–6]. Iron complexes with different polysaccharides have special importance and they have been described in detail [7]. Synthetic procedures for the complex formation of Cu(II) with polysaccharides, including dextran, are described in scientific and patent literature [8]. However, literature data on the complex formation possibility of the Cu(II) ion with dextran derivatives are scarce.

Instrumental methods and techniques for structural and physicochemical characterization of biomaterials and bone tissue: A review

A review of recent advances in instrumental methods and techniques for structural and physicochemical characterization of biomaterials and bone tissue is presented in this paper. In recent years, biomaterials attracted great attention primarily because of the wide range of biomedical applications. This paper focuses on the practical aspects of instrumental methods and techniques that were most often applied (X-ray methods, vibrational spectroscopy (IR and Raman), magnetic-resonance spectroscopy (NMR and ESR), mass spectrometry (MS), atomic absorption spectrometry (AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES), thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM)) in the structural investigation and physicochemical characterization of biomaterials and bone tissue. The application of some other physicochemical methods was also discussed. Hands-on information is provided about these valuable research tools, emphasizing practical aspects such as typical measurement conditions, their limitations and advantages, interpretation of results and practical applications.

Apatite formation on nanomaterial calcium phosphate/poly-dL-lactide-co-glycolide in simulated body fluid

Simulated body fluid (SBF) is an artificial fluid which has ionic composition and ionic concentration similar to human blood plasma. Purpose This paper compares the interaction between the nanomaterial containing calcium phosphate/poly-DL-lactide-co-glycolide (N-CP/PLGA) and SBF, in order to investigate whether and to what extent inorganic ionic composition of human blood plasma leads to the aforementioned changes in the material. Methods N-CP/PLGA was incubated for 1, 2, 3, and 5 weeks in SBF. The surface of the material was analyzed on SEM-EDS and FTIR spectrometer, while SBF was subjected to pH and electrical conductivity measurement. Results Our results indicate that dissolution of the polymer component of the material N-CP/PLGA and precipitation of the material similar to hydroxyapatite on its surface are based on the morphologic changes seen in this material. Conclusions The mechanism of the apatite formation on the bioceramic surface was intensively studied and was considered crucial in designing the new biomaterials. The results obtained in this work indicate that N-CP/PLGA may be a good candidate for application to bone regeneration.

SEM-EDX Analysis of Bio-Oss® Granules After Incubation In Cell Culture Medium

The aim of this study was to analyze changes in the surface and chemical composition of Bio-Oss® granules after incubation in cell culture medium. Appropriate amount of Bio-Oss® material was incubated in Dulbecco’s Modified Eagle’s Medium (DMEM) at 37 °C for 3 days. After that, granules were dried, coated with gold and analyzed using scanning electron microscope (SEM) equipped with EDX (JEOL, JSM 5300). SEM analysis revealed that the surface of Bio-Oss® particles looks less grainy after incubation in DMEM. The impression is that an incubation in DMEM made erosion of cam bumps or that larger and wider reefs compared to the material before incubation are made by depositing of new material. Semi-quantitative analysis of calcium and phosphorous content in Bio-Oss® before and after incubation in DMEM was determined by EDX spectroscopy and results show that concentration of calcium and phosphorous ions increases after incubation in DMEM.

Spectroscopic Characterization of Cobalt (II) Complexes with Reduced Low-Molar Dextran Derivatives

Summary The formation of Co(II) ion complexes with reduced low-molar dextran (RLMD, Mw 5000 g/mol) was studied at the pH range from 7.0 to 13.5. The cobalt content in synthesized Co(II)-RLMD complexes was ~3–12% (AAS) and it generally increases with pH. Co(II)-RLMD complexes were characterized by UV-Vis spectrophotometry and FTIR spectroscopy. UV-Vis data for synthesized complexes indicate tetragonally distorted Oh coordination of Co(II) ions with O atoms from ligand. The presence of IR bands at 765 cm−1 and 910 cm−1 in Co(II)-RLMD complexes indicates the existence of α-(1→6)O-glycosidic bonds. The similarities in the γ(C–H) range of the IR spectra indicate that there is no difference in the conformation of the glucopyranose units in RLMD and Co(II)-RLMD complexes. The occurrence of water molecules in Co(II)-RLMD complexes was confirmed by FTIR spectroscopy of deuterated samples.