scholarly journals Hydroxyapatite-poly(d,l-lactide) Nanografts. Synthesis and Characterization as Bone Cement Additives

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 424
Author(s):  
Kristina L. Goranova ◽  
Anne Kathrine Kattenhøj Sloth Overgaard ◽  
Ivan Gitsov
Keyword(s):  
Bone Cement ◽  
Molecular Mass ◽  
Size Exclusion ◽  
Thermal Methods ◽  
Mass Distributions ◽  
Exclusion Chromatography ◽  
Ft Ir ◽  
Thermal Analysis Techniques ◽  
Hydroxyapatite Nanocrystals ◽  
Ft Ir Spectroscopy

This paper reports the creation of hydroxyapatite/polyester nanografts by “graft-from” polymerization of d,l-lactide with [Ca5(OH)(PO4)3]2 as the initiator and tin(II)-2-ethylhexanoate as the catalyst. Model polymerizations were performed with cyclooctanol as initiator to confirm the grafting on the surface of the hydroxyapatite nanocrystals. Polymers with the highest molecular mass (Mn) between 4250 Da (cyclooctanol) and 6100 Da (hydroxyapatite) were produced. In both cases the molecular mass distributions of the polymers formed were monomodal. The materials obtained were characterized by size-exclusion chromatography, NMR and FT-IR spectroscopy, and thermal methods. Their suitability as additives for commercial bone cement (Simplex P Speedset, Stryker Orthopaedics) has been confirmed by thermal analysis techniques and mechanical testing. The results obtained show that addition of the hydroxyapatite/ polyester nanografts improved both thermal and mechanical properties of the bone cement.

scholarly journals Synthesis of L-DOPA Based Melanins with Reproducible Physic-Chemical Properties

2018 ◽  
Author(s):  
Koen Vercruysse ◽  
Jayla Moore
Keyword(s):  
Ir Spectroscopy ◽  
Enzymatic Synthesis ◽  
Chemical Properties ◽  
Size Exclusion ◽  
Synthesis Methods ◽  
Ongoing Research ◽  
Vis Spectroscopy ◽  
Exclusion Chromatography ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

This report expands our ongoing research efforts into the non-enzymatic synthesis of melanins. We have explored four different methods for the synthesis of L-DOPA based melanins and evaluated the reproducibility of some of their physic-chemical properties. The melanins were synthesized through the addition of NaOH, tyrosinate or Fe<sup>2+</sup>/H<sub>2</sub>O<sub>2</sub>. Two different approaches for the reactions involving Fe<sup>2+</sup> and H<sub>2</sub>O<sub>2</sub> were tested: a) addition of H<sub>2</sub>O<sub>2</sub> spread out over multiple days or b) addition of H<sub>2</sub>O<sub>2</sub> in one fraction at the start of the reaction. The physic-chemical properties of the melanins explored involved: 1) retention on size exclusion chromatography column, 2) FT-IR spectroscopy, 3) UV-Vis spectroscopy and 4) the capacity to reduce a redox dye, dichlorophenolindophenol. Overall the results obtained indicated that 1) the various synthesis methods lead to melanins with reproducible physic-chemical properties, 2) that the melanins synthesized in the presence of Fe<sup>2+</sup>/H<sub>2</sub>O<sub>2</sub> are distinctly different from the melanins synthesized in the presence of NaOH or tyrosinate and 3) that no distinctly different melanins were generated when comparing the two different synthesis approaches involving Fe<sup>2+</sup>/H<sub>2</sub>O<sub>2</sub>. Only the melanins synthesized in the presence of Fe<sup>2+</sup>/H<sub>2</sub>O<sub>2</sub> appeared to possess the capacity to reduce dichlorophenolindophenol.

scholarly journals Interleukin-1β and -6 release from immune cells by DOPA-based melanin as free pigment or complexed to carboxymethylcellulose

2017 ◽  
Author(s):  
Koen P. Vercruysse ◽  
Tonie S. Farris ◽  
Margaret M. Whalen
Keyword(s):  
Immune Cells ◽  
Broad Class ◽  
Water Soluble ◽  
Size Exclusion ◽  
Potent Effect ◽  
Pathological Conditions ◽  
Exclusion Chromatography ◽  
Ft Ir ◽  
Soluble Polysaccharide ◽  
Ft Ir Spectroscopy

AbstractWe have observed that many polysaccharides can promote the oxidation of 3,4-dihydroxyphenylalanine (DOPA) into melanin-like pigments leading to the formation of water-soluble polysaccharide/melanin complexes. These pigments were characterized by size exclusion chromatography and FT-IR spectroscopy. The effect on the secretion of interleukin (IL)-lβ and IL-6 from immune cells by DOPA-based melanin synthesized in the presence or absence of carboxymethylcellulose (CMC) was evaluated. We observed that the melanin/CMC complex had a more potent effect on both IL secretions compared to the melanin prepared from DOPA in the absence of any polysaccharide. The study of the effect of melanins on the IL secretion by immune or other cells will help illuminate the potential contributions of this broad class of pigments to pathological conditions like Parkinson’s disease or ochronosis.

Errors in the determination of molecular mass distributions of coal derivatives by size-exclusion chromatography

1986 ◽  
Vol 58 (12) ◽  
pp. 2403-2408 ◽  
Author(s):  
Keith D. Bartle ◽  
Derek G. Mills ◽  
Michael J. Mulligan ◽  
Ifeanyi O. Amaechina ◽  
Norman. Taylor
Keyword(s):  
Molecular Mass ◽  
Size Exclusion Chromatography ◽  
Size Exclusion ◽  
Mass Distributions ◽  
Exclusion Chromatography

Effect of dextran and enzymatically decomposed dextran on the sucrose crystal shape

2019 ◽  
pp. 588-596
Author(s):  
Karin Abraham ◽  
Henriette Brykczynski ◽  
E.S.J. Rudolph-Flöter ◽  
Karl Schlumbach ◽  
A. Schäfer ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Molecular Mass Distribution ◽  
Size Exclusion ◽  
Crystal Shape ◽  
Reaction Products ◽  
Mass Distributions ◽  
Crystallization Experiments ◽  
Exclusion Chromatography ◽  
Molecular Masses ◽  
Sucrose Crystals

The effect of dextran’s molecular mass distribution on the sucrose crystal shape was key to this study. Therefore, sucrose crystals were produced by evaporating crystallization experiments using synthetic thick juices in the form of pure sugar syrups containing high (T2000) and low (T40) molecular mass dextran fractions as well as enzymatically decomposed dextran. The combined analysis of molecular mass distributions by size exclusion chromatography and sucrose crystal shapes by static image analysis were used to identify the least harmful reaction products resulting from the enzymatic decomposition of dextran. The combined evaluation of two shape parameters, circularity and width-to-length ratio, has shown that three different shape modifications can be related to the presence of dextran, namely cube-shaped crystals, elongated needle-shaped crystals and agglomerates. In the main, the data indicated that high T2000 contents and generally all T40 dextran contents led to an increased occurrence of agglomerated and occasionally elongated crystals. The latter was especially found for high T2000 dextran contents. In contrast, low T2000 dextran contents predominantly increased the amount of cube-like crystals. The enzymatic decomposition of dextran resulted in a gradual reduction of the molecular mass. It was shown that an insufficient decomposition to broadly distributed low molecular mass dextran fragments, which are realistic to assume for technical cane and beet juices, still dramatically affected the sucrose crystal shape. Once dextran was decomposed to molecules with molecular masses of less than 5 kDa, no dextran-related effects on the sucrose crystal shape were found.

The Calibration of Size Exclusion Chromatography Columns:  Molecular Mass Distributions of Heavy Hydrocarbon Liquids

2004 ◽  
Vol 18 (3) ◽  
pp. 778-788 ◽  
Author(s):  
Fatma Karaca ◽  
Carlos A. Islas ◽  
Marcos Millan ◽  
Mahtab Behrouzi ◽  
Trevor J. Morgan ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Size Exclusion Chromatography ◽  
Size Exclusion ◽  
Heavy Hydrocarbon ◽  
Mass Distributions ◽  
Exclusion Chromatography ◽  
Chromatography Columns

scholarly journals Synthesis of L-DOPA Based Melanins with Reproducible Physic-Chemical Properties

2018 ◽  
Author(s):  
Koen Vercruysse ◽  
Jayla Moore
Keyword(s):  
Ir Spectroscopy ◽  
Enzymatic Synthesis ◽  
Chemical Properties ◽  
Size Exclusion ◽  
Synthesis Methods ◽  
Ongoing Research ◽  
Vis Spectroscopy ◽  
Exclusion Chromatography ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

This report expands our ongoing research efforts into the non-enzymatic synthesis of melanins. We have explored four different methods for the synthesis of L-DOPA based melanins and evaluated the reproducibility of some of their physic-chemical properties. The melanins were synthesized through the addition of NaOH, tyrosinate or Fe<sup>2+</sup>/H<sub>2</sub>O<sub>2</sub>. Two different approaches for the reactions involving Fe<sup>2+</sup> and H<sub>2</sub>O<sub>2</sub> were tested: a) addition of H<sub>2</sub>O<sub>2</sub> spread out over multiple days or b) addition of H<sub>2</sub>O<sub>2</sub> in one fraction at the start of the reaction. The physic-chemical properties of the melanins explored involved: 1) retention on size exclusion chromatography column, 2) FT-IR spectroscopy, 3) UV-Vis spectroscopy and 4) the capacity to reduce a redox dye, dichlorophenolindophenol. Overall the results obtained indicated that 1) the various synthesis methods lead to melanins with reproducible physic-chemical properties, 2) that the melanins synthesized in the presence of Fe<sup>2+</sup>/H<sub>2</sub>O<sub>2</sub> are distinctly different from the melanins synthesized in the presence of NaOH or tyrosinate and 3) that no distinctly different melanins were generated when comparing the two different synthesis approaches involving Fe<sup>2+</sup>/H<sub>2</sub>O<sub>2</sub>. Only the melanins synthesized in the presence of Fe<sup>2+</sup>/H<sub>2</sub>O<sub>2</sub> appeared to possess the capacity to reduce dichlorophenolindophenol.

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