Marzena Kuras

A Solid-State NMR Study of Selenium Substitution into Nanocrystalline Hydroxyapatite

The substitution of selenium oxyanions in the hydroxyapatite structure was examined using multinuclear solid-state resonance spectroscopy (ssNMR). The study was supported by powder X-ray diffractometry (PXRD) and wavelength dispersion X-ray fluorescence (WD-XRF). Samples of pure hydroxyapatite (HA300) and selenate (HA300-1.2SeO4) or selenite (HA300-1.2SeO3) substituted hydroxyapatites were synthesized using the standard wet method and heated at 300 °C to remove loosely bonded water. PXRD data showed that all samples are single-phase, nanocrystalline hydroxyapatite. The incorporation of selenite and selenate ions affected the lattice constants. In selenium-containing samples the concentration of Se was very similar and amounted to 9.55% and 9.64%, for HA300-1.2SeO4 and HA300-1.2SeO3, respectively. PXRD and ssNMR data showed that the selenite doping significantly decreases the crystallite size and crystallinity degree. 31P and 1H NMR experiments demonstrated the developed surface hydrated layer in all samples, especially in HA300-1.2SeO3. 1H NMR studies showed the dehydroxylation of HA during the selenium oxyanions substitution and the existence of hydrogen bonding in structural hydroxyl group channels. 1H→77Se cross polarization NMR experiments indicated that selenites and selenates are located in the crystal lattice and on the crystal surface.

Cannabis Profiling Based on Its Elemental Composition—Is It Possible?

Abstract:  Elemental composition of 85 cannabis samples was established using GF AAS and ICP OES methods. The robustness of the method was determined by analyzing eight independently prepared replicates from a single cannabis plant. The accuracy of the method was established by analyzing four plant certified reference material samples. The ability of discriminant analysis using elemental compositions to distinguish between fiber cannabis samples collected from four different regions of Poland was evaluated. Then, a classification model was developed that correctly classified selected samples of known origin. Cannabis samples confiscated by law enforcement agencies have also been subjected to discriminant analysis. A classification model has been developed for four locations in Poland (Białystok, Kościerzyna, the environs of Skarżysko Kamienna, and Bydgoszcz), to help determine where samples of unknown origin could have been grown.

Kinetics of 1H→13C NMR cross-polarization in polymorphs and solvates of the antipsychotic drug olanzapine

The (1)H→(13)C NMR cross-polarization (CP) was studied under magic-angle spinning at 7.5 kHz in various crystal forms of the antipsychotic drug olanzapine: two polymorphs (metastable I and stable II) and eight solvates containing organic solvent and water molecules. The CP kinetics followed the non-classical I-I(*)-S model, in which CP begins in a spin cluster of proximate abundant spins I(*) and rare spins S, then is controlled by spin diffusion of the abundant spins I from bulk to the I(*) spins of the spin cluster and finally is governed by spin-lattice relaxation of the abundant spins in the rotating frame. The corresponding CP kinetics parameters were determined and analyzed. It was demonstrated that the, λ and T(df) values (the CP time constant, the cluster composition parameter and the (1)H spin-diffusion constant, respectively) were very useful to discriminate the functional groups, especially in the 3D parameter space. In order to conveniently analyze the large amount (175) of the collected CP parameters, the number of the observed variables was reduced using the principal component (PC) analysis. The 2D plot of PC2 vs. PC1 showed adequate separation of the CH(3), CH(2), CH and C cases (C stands for carbons without adjacent hydrogens). It was demonstrated that those cases were located along the PC1 axis in the order of increasing (1)H-(13)C dipolar couplings: C

Effect of carbonate substitution on physicochemical and biological properties of silver containing hydroxyapatites

Ag+-substituted hydroxyapatites (Ag-HAs) and Ag+/CO32--co-substituted hydroxyapatites (Ag-CHAs) with two different concentrations of silver ions were synthesized by the standard precipitation method. For comparison, pure hydroxyapatite (HA) and carbonated hydroxyapatite (CHA) were synthesized using the same method. The obtained powders were examined by various physicochemical methods, such PXRD, TEM, FTIR and ssNMR. Elemental analysis was provided by WD-XRF and ICP-MS methods. The strains of Staphylococcus aureus and Escherichia coli were used to evaluate the antibacterial activity of the materials. The study demonstrates that the substituted samples are homogenous and poorly crystalline. Introducing carbonates into the crystal structure significantly affects the physicochemical properties of the silver containing hydroxyapatite, i.e., crystallinity, lattice parameters, crystal size and morphology or content of structural hydroxyl groups. Carbonate substitution leads to a significant increase in the contribution of the hydrated surface layer. Ag-CHA nanocrystals with an enhanced hydrated surface layer and higher solubility demonstrate an admirable antibacterial effect.

In Vitro Dissolution of Calcium Carbonate from the Chicken Eggshell: A Study of Calcium Bioavailability

In vitro dissolution is a major indicator of potential in vivo calcium absorption. It can be used to assess the bioavailability of Ca from different sources. The aim of this study was to analyze the in vitro dissolution of calcium carbonate from the eggshell samples collected before and after the incubation period. The samples of chicken eggshell were characterized by good dissolution, better than that of precipitated CaCO3. The dissolution of the eggshell before incubation was found to be faster than that after incubation. Good dissolution (after 30 min both types of eggshells were dissolved in over 75%) of the chicken eggshell and the presence of other valuable microelements (boron, strontium) make this biomaterial an excellent source for dietary supplements production.

The composition of bee pollen color fractions evaluated by solid-state 1H and 13C NMR: their macroelement content and antioxidant properties

Honey bee pollen is a good source of nourishing substances with a wide range of potential therapeutic properties. The aim of the present study was to evaluate the composition and antioxidant activities of bee pollens collected from commercial hives in Poland. Plant sources were buckwheat and rapeseed. The pollen loads differed in color, so samples were separated into color fractions. The highest content of minerals (K, Ca, P) was in samples from: buckwheat (S1) and rapeseed (S7). The rapeseed pollen had significantly higher amounts of polyphenols and flavonoids, and higher values of antioxidant capacities as measured by DPPH, FRAP and ORAC assays. 13C CPMAS NMR spectra revealed the presence of carbohydrates (including polymers), lipids, polyphenols and amino acids. Solid-state 1H MAS spectra showed the resonances of lipids, sugars and different amounts of water. Our results indicate that 1H and 13C MAS NMR spectroscopy can be very useful to characterize bee pollen types.

Cyto- and genotoxicity evaluation of the biomedical polyesters obtained in the presence of new zinc catalytic systems

ABSTRACT A preliminary evaluation of cyto- and genotoxicity of the biomedical polyesters obtained in the presence of new zinc catalytic systems was performed. A series of biomedical poly(ε-caprolactone)s (PCLs) and poly(rac-lactide)s (PLAs) synthesized in the presence of diethylzinc/propyl gallate or diethylzinc/gallic acid catalytic systems were tested using the luminescent bacterium Vibrio fischeri, the ciliated protozoan Spirostomum ambiguum as well as Salmonella typhimurium TA1535. The main goal of our work was to find the correlation between the zinc catalyst content in the synthesized products and cyto- or genotoxicity of the synthesized polyesters or their degradation products. To remove the metal catalyst residue, the obtained polyesters were subjected to the purification procedure. The Zn content in the synthesized polymers was determined by flame atomic absorption spectrometry. It was found that the purified PCLs and PLAs which contained the Zn below ca. 450 ppm were not cyto- or genotoxic. Importantly, the Zn content in the synthesized PCLs and PLAs after the second polymer precipitation was significantly reduced to 14 ppm. We believe that our results are satisfactory enough for the biomedical applications, i.e., for the synthesis of biomedical polyesters used as drug delivery systems. GRAPHICAL ABSTRACT