Constantin Tanase - Academia.edu (original) (raw)
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Papers by Constantin Tanase
Key Engineering Materials, 2013
ABSTRACT Composites based on calcium phosphates (CP) and mixtures of biopolymers (chitosan and hy... more ABSTRACT Composites based on calcium phosphates (CP) and mixtures of biopolymers (chitosan and hyaluronic acid) have been prepared by a biomimetic co-precipitation method and tested as scaffolds for bone tissue engineering. The biomimetic strategy is inspired by natural mineralization processes, where the synthesized minerals are usually combined with proteins, polysaccharides or other mineral forms to form composite, in physiological conditions of temperature and pH. Fourier transformed infrared spectroscopy, scanning electron microscopy, X-ray diffraction and XPS analyses confirmed the porous morphology of the scaffolds and formation of various forms of calcium phosphates with amorphous nature. The in vitro degradation studies showed a slow degradation process for CP-biopolyiners composites and limited swelling in simulated body fluids. The scaffolds compositions have no negative effect on osteoblasts cell, emphasizing a good biocompatibility.
Materials Science and Engineering: C, 2014
Novel composites based on PLA, chitosan and keratin was obtained via blend preparation. The goal ... more Novel composites based on PLA, chitosan and keratin was obtained via blend preparation. The goal of this contribution was to evaluate mechanical and in vitro behavior of the composites. The results point out composites with improved Young modulus and decreased tensile strength, significant increase in hardness (compared to PLA) and a good uptake of the surface properties. Biological assessments using human osteosarcoma cell line on these composites indicate a good viability/proliferation outcome. Hence preliminary results regarding mechanical behavior and in vitro osteoblast response suggest that these composites might have prospective application in medical field.
Journal of Biomedical …, 2012
A novel biomimetic technique for obtaining chitosan-calcium phosphates (Cs-CP) scaffolds are pres... more A novel biomimetic technique for obtaining chitosan-calcium phosphates (Cs-CP) scaffolds are presented: calcium phosphates are precipitated from its precursors, CaCl 2 and NaH 2 PO 4 on the Cs matrix, under physiological conditions (human body temperature and body fluid pH; 37 o C and pH ¼ 7.2, respectively). Materials composition and structure have been confirmed by various techniques: elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). FTIR and SEM data have shown the arrangement of the calcium phosphates-hydroxyapatite (CP-Hap) onto Cs matrix. In this case the polymer is acting as glue, bonding the calcium phosphates crystals. Behavior in biological simulated fluids (phosphate buffer solution-PBS and PBS-albumin) revealed an important contribution of the chelation between ÀNH þ 3 and Ca 2þ on the scaffold interaction with aqueous mediums; increased quantities of chitosan in composites permit the interaction with human albumin and improve the retention of fluid. The composites are slightly degraded by the lysozyme which facilitates an in vivo degradation control of bone substitutes. Modulus of elasticity is strongly dependent of the ratio chitosan/calcium phosphates and recommends the obtained biomimetic composites as promising materials for a prospective bone application. V C 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 700-708, 2012. How to cite this article: Tanase CE, Popa MI, Verestiuc L. 2012. Biomimetic chitosan-calcium phosphate composites with potential applications as bone substitutes: Preparation and characterization. J Biomed Mater Res Part B 2012:100B:700-708.
![Research paper thumbnail of ChemInform Abstract: Synthesis of New Oxabicyclo[3.3.0]octane Nucleoside Analogues with Pyrimidine Bases](https://attachments.academia-assets.com/46532317/thumbnails/1.jpg)
](ChemInform, 2012
Synthesis of new nucleosides with an oxabiciclo[3.3.0]octane fragment in the sugar moiety was per... more Synthesis of new nucleosides with an oxabiciclo[3.3.0]octane fragment in the sugar moiety was performed by Vorbruggen nucleoside synthesis with silylated pyrimidine bases: 5-FU, 5-ClU, 5-BrU, C and 6-aza-U. The compounds were characterized by IR, MS, 1 H-NMR and 13 C-NMR spectra and tested for their antitumor activity comparatively with U-34 and 5IU-34. Our study points out that Cl-U-34, Br-U-34 and I-U-34 might be more efficient than U-34 against the multiplication of cancer cells, like Jurkat T lymphoblasts.
Environmental Health Risk V, 2009
... US Dpt of health and human services, pp 102225, 2005 [3] Basaran, N., and Undeger, U.(2000).... more ... US Dpt of health and human services, pp 102225, 2005 [3] Basaran, N., and Undeger, U.(2000). ... Immunology, Eds Rose NR, de Macario EC, Fahey JL, Friedman H., Penn GM, American Society for Microbiology, Washington DC, pp 942 52, 1992 [43] Samet, JM, What can we ...
Experimental and Clinical Endocrinology & Diabetes, 2008
![Research paper thumbnail of New carbocyclic nucleoside analogues with a bicyclo[2.2.1]heptane fragment as sugar moiety; Synthesis, X-ray crystallography and anticancer activity](https://attachments.academia-assets.com/46532327/thumbnails/1.jpg)
](Bioorganic & Medicinal Chemistry, 2014
An amine group was synthesized starting from an optically active bicyclo[2.2.1]heptane compound, ... more An amine group was synthesized starting from an optically active bicyclo[2.2.1]heptane compound, which was then used to build the 5 atoms ring of a key 6-chloropurine intermediate. This was then reacted with ammonia and selected amines obtaining new adenine-and 6-substituted adenine conformationally constrained carbocyclic nucleoside analogues with a bicyclo[2.2.1]heptane skeleton in the sugar moiety. X-ray crystallography confirmed an exo-coupling of base to the ring and a L configuration of the nucleoside analogues. The compounds were tested for anticancer activity.
Journal of Labelled …, 2007
... Short Research Article. Synthesis of [5-3 H]uracil nucleoside analogue . Cristian Postolache... more ... Short Research Article. Synthesis of [5-3 H]uracil nucleoside analogue . Cristian Postolache 1,* ,; Constantin Tanase 2 ,; Lidia Matei 1 ,; Violeta Serban 1. Article first published online: 30 JUL 2007. DOI: 10.1002/jlcr.1305. Copyright © 2007 John Wiley & Sons, Ltd. Issue. ...
Key Engineering Materials, 2013
ABSTRACT Composites based on calcium phosphates (CP) and mixtures of biopolymers (chitosan and hy... more ABSTRACT Composites based on calcium phosphates (CP) and mixtures of biopolymers (chitosan and hyaluronic acid) have been prepared by a biomimetic co-precipitation method and tested as scaffolds for bone tissue engineering. The biomimetic strategy is inspired by natural mineralization processes, where the synthesized minerals are usually combined with proteins, polysaccharides or other mineral forms to form composite, in physiological conditions of temperature and pH. Fourier transformed infrared spectroscopy, scanning electron microscopy, X-ray diffraction and XPS analyses confirmed the porous morphology of the scaffolds and formation of various forms of calcium phosphates with amorphous nature. The in vitro degradation studies showed a slow degradation process for CP-biopolyiners composites and limited swelling in simulated body fluids. The scaffolds compositions have no negative effect on osteoblasts cell, emphasizing a good biocompatibility.
Materials Science and Engineering: C, 2014
Novel composites based on PLA, chitosan and keratin was obtained via blend preparation. The goal ... more Novel composites based on PLA, chitosan and keratin was obtained via blend preparation. The goal of this contribution was to evaluate mechanical and in vitro behavior of the composites. The results point out composites with improved Young modulus and decreased tensile strength, significant increase in hardness (compared to PLA) and a good uptake of the surface properties. Biological assessments using human osteosarcoma cell line on these composites indicate a good viability/proliferation outcome. Hence preliminary results regarding mechanical behavior and in vitro osteoblast response suggest that these composites might have prospective application in medical field.
Journal of Biomedical …, 2012
A novel biomimetic technique for obtaining chitosan-calcium phosphates (Cs-CP) scaffolds are pres... more A novel biomimetic technique for obtaining chitosan-calcium phosphates (Cs-CP) scaffolds are presented: calcium phosphates are precipitated from its precursors, CaCl 2 and NaH 2 PO 4 on the Cs matrix, under physiological conditions (human body temperature and body fluid pH; 37 o C and pH ¼ 7.2, respectively). Materials composition and structure have been confirmed by various techniques: elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). FTIR and SEM data have shown the arrangement of the calcium phosphates-hydroxyapatite (CP-Hap) onto Cs matrix. In this case the polymer is acting as glue, bonding the calcium phosphates crystals. Behavior in biological simulated fluids (phosphate buffer solution-PBS and PBS-albumin) revealed an important contribution of the chelation between ÀNH þ 3 and Ca 2þ on the scaffold interaction with aqueous mediums; increased quantities of chitosan in composites permit the interaction with human albumin and improve the retention of fluid. The composites are slightly degraded by the lysozyme which facilitates an in vivo degradation control of bone substitutes. Modulus of elasticity is strongly dependent of the ratio chitosan/calcium phosphates and recommends the obtained biomimetic composites as promising materials for a prospective bone application. V C 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 700-708, 2012. How to cite this article: Tanase CE, Popa MI, Verestiuc L. 2012. Biomimetic chitosan-calcium phosphate composites with potential applications as bone substitutes: Preparation and characterization. J Biomed Mater Res Part B 2012:100B:700-708.
ChemInform, 2012
Synthesis of new nucleosides with an oxabiciclo[3.3.0]octane fragment in the sugar moiety was per... more Synthesis of new nucleosides with an oxabiciclo[3.3.0]octane fragment in the sugar moiety was performed by Vorbruggen nucleoside synthesis with silylated pyrimidine bases: 5-FU, 5-ClU, 5-BrU, C and 6-aza-U. The compounds were characterized by IR, MS, 1 H-NMR and 13 C-NMR spectra and tested for their antitumor activity comparatively with U-34 and 5IU-34. Our study points out that Cl-U-34, Br-U-34 and I-U-34 might be more efficient than U-34 against the multiplication of cancer cells, like Jurkat T lymphoblasts.
Environmental Health Risk V, 2009
... US Dpt of health and human services, pp 102225, 2005 [3] Basaran, N., and Undeger, U.(2000).... more ... US Dpt of health and human services, pp 102225, 2005 [3] Basaran, N., and Undeger, U.(2000). ... Immunology, Eds Rose NR, de Macario EC, Fahey JL, Friedman H., Penn GM, American Society for Microbiology, Washington DC, pp 942 52, 1992 [43] Samet, JM, What can we ...
Experimental and Clinical Endocrinology & Diabetes, 2008
Bioorganic & Medicinal Chemistry, 2014
An amine group was synthesized starting from an optically active bicyclo[2.2.1]heptane compound, ... more An amine group was synthesized starting from an optically active bicyclo[2.2.1]heptane compound, which was then used to build the 5 atoms ring of a key 6-chloropurine intermediate. This was then reacted with ammonia and selected amines obtaining new adenine-and 6-substituted adenine conformationally constrained carbocyclic nucleoside analogues with a bicyclo[2.2.1]heptane skeleton in the sugar moiety. X-ray crystallography confirmed an exo-coupling of base to the ring and a L configuration of the nucleoside analogues. The compounds were tested for anticancer activity.
Journal of Labelled …, 2007
... Short Research Article. Synthesis of [5-3 H]uracil nucleoside analogue . Cristian Postolache... more ... Short Research Article. Synthesis of [5-3 H]uracil nucleoside analogue . Cristian Postolache 1,* ,; Constantin Tanase 2 ,; Lidia Matei 1 ,; Violeta Serban 1. Article first published online: 30 JUL 2007. DOI: 10.1002/jlcr.1305. Copyright © 2007 John Wiley & Sons, Ltd. Issue. ...