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Organic/Inorganic bioactive materials Part II: in vitro bioactivity of Collagen-Calcium Phosphate Silicate/Wollastonite hybrids

100%
Radev L., Hristov V., Samuneva B., Ivanova D.
Open Chemistry
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2009
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vol. 7
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issue 4
711-720
EN
In the present study, novel hybrid materials of Collagen (C) and Calcium Phosphate Silicate/Wollastonite (CPS/W) were synthesized. The CPS/W ceramic was prepared via polystep sol-gel method. The dissolution test of CPS/W ceramic was filled with TRIS-HCl buffer. FTIR depicts that hydroxyl carbonate apatite (OHCO3HA) was observed after 3 days of immersion in TRIS-HCl buffer. Biohybrids of C-CPS/W were produced from diluted hydrochloric acid collagen type I and ceramic powder with different ratios of C and CPS/W equal to 25:75 and 75:25 wt.%. The synthesized hybrids were characterized by FTIR, XRD and SEM. FTIR depicts a “red shift” if amide I could be attributed to the fact that the collagen prefers to chelate Ca2+ from partial dissolution of CPS/W ceramic. The growth of B-type carbonate containing hydroxyapatite (B-CO3HA) on the C-CPS/W hybrids soaked in 1.5SBF was observed. The negatively charged carboxylate groups from the collagen may be responsible for hydroxyapatite (HA) deposition. This fact was confirmed by the “red shift” of carboxylate groups of collagen in FTIR spectra. The formation of HA was observed by FTIR, XRD and SEM.
2
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Morphology and thermal stability of bacterial cellulose/collagen composites

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Albu M., Vuluga Z., Panaitescu D., Vuluga D., Căşărică A., Ghiurea M.
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issue 9
968-975
EN
The aim of this paper was to prepare composites of bacterial cellulose (BC) and collagen to evaluate both the effect of collagen on the morphological, mechanical and thermal properties of BC and the effect of BC on the thermal stability of collagen for designing composites with increased potential biomedical applications. Two series of composites were prepared, the first series by immersing BC pellicle in solutions of collagen obtained in three forms, collagen gel (CG), collagen solution (CS) and hydrolysed collagen (HC), followed by freeze drying; and the second series of composites by mixing BC powder in solutions of collagen (CG, CS and HC), also followed by freeze drying. The properties of obtained composites were evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), mechanical tests, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results revealed that BC acts as a thermal stabilizer for CS matrix, while with CG matrix it interacts synergistically leading to composites with improved properties. On the other hand, the BC sheet impregnated with collagen has a significantly improved thermal stability. Collagen (as HC, CS or CG) has also a positive influence on the mechanical properties of lyophilized BC sheet. A four times increase of modulus was observed in BC/HC and BC/CG composites. and an increase of 60 times for BC/CS. The spectacular increase of elastic modulus and tensile strength in the case of BC/CS composite was explained by the easier penetration of collagen solution in the BC network and impregnation of BC fibrils as revealed by SEM and AFM analyzes.
3
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Synthesis, characterization and bioevaluation of irinotecan-collagen hybrid materials for biomedical applications as drug delivery systems in tumoral treatments

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Voicu G., Geanaliu R., Ghiţulică C., Ficai A., Grumezescu A., Bleotu C.
Open Chemistry
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2013
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vol. 11
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issue 12
2134-2143
EN
The purpose of the present study is the preparation and characterization of collagen/antitumor drug hybrids as drug delivery systems. Materials used for obtaining collagen-based drug delivery systems were collagen type I (Coll) as matrix and irinotecan (I) as hydrophilic active substances. After incorporation of I into Coll in differing ratios, the obtained hybrid materials (Coll/I) could be used according to our results as potential drug delivery systems in medicine for the topical (local) treatment of cancerous tissues or bone. The released amount of I varies with amount of Coll from hybrid materials: the higher, the slower the release amount of irinotecan transferred is in the first 6 hours. The in vitro citotoxicity demonstrates an antitumoral activity of the obtained hybrid materials and their potential use for biomedical applications as drug delivery systems in tumoral treatments. [...]
4
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Organic / inorganic bioactive materials Part I: Synthesis, structure and in vitro assessment of collagen/silicocarnotite biocoatings

100%
Hristov V., Radev L., Samuneva B., Apostolov G.
Open Chemistry
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2009
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vol. 7
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issue 4
702-710
EN
The silicocarnotite, as an inorganic part of the coatings, has been synthesized using a polystep sol-gel method. The chemical composition of the prepared silicocarnotite sol is described as 58.12 CaO, 29.42 P2O5, 12.45 SiO2 (wt%), where Ca/P+Si = 1,67. The acid soluble type I collagen, as an organic part of the obtained coatings, was mixed with silicocarnotite powder in a weight ratio of 25:75 and 75:25 weight ratio without cross-linkage. The acidity of the obtained mixture was readjust with 25% NH4OH to pH = 9.0. The mixture was then dried at 37°C for 12 h. The growth of B-type carbonate containing hydroxyapatite (B-type CO3HA) in which CO3 2+→PO4 3− on the surface of collagen/silicocarnotite coatings soaked in 1.5 simulated body fluid (1.5 SBF) was observed. The nucleation of B-type CO3HA was estimated on the obtained coatings after 3 days immersion in 1.5 SBF. The negatively charged carboxylate groups from the collagen surface may be responsible for the HA deposition. This was confirmed by the “red shift” of carboxylate groups of collagen molecules in the FTIR spectra. After soaking in 1.5 SBF, the morphology of prepared coatings and HA formation was observed by SEM.
5
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New approaches in layer by layer synthesis of collagen/hydroxyapatite composite materials

88%
Ilie A., Andronescu E., Ficai D., Voicu G., Ficai M., Maganu M., Ficai A.
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EN
The aim of this work was to increase our understanding of collagen (COLL)/ hydroxyapatite (HA) composite materials; more specifically, we focused on the study of the influence of the precursorconcentrations over the final content of deposited HA. We found that the increase of the precursor concentrations led to better mineralization (on the basis of the content of deposited mineral phase). Regardless of the precursor concentrations, the content of the deposited amount was found to increase with the increase of the number of deposited layers. Quantification of the mineral phase amount was achieved by gravimetric determination. Based on the determined deposition equation the number of layers can be easily determined in order to obtain composite materials with desired content of mineral phase.
6
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The effects of parenteral glutamine on intestinal adaptation in a rat model of short bowel syndrome

88%
Ucar A., Kocdor H., Canda A., Unlu S., Cehreli R., Kocdor M.
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EN
Short bowel syndrome (SBS) is characterized by the malabsorption of nutrients and fluids that occurs after major intestinal resection, resulting from an adaptation process that begins immediately to increase the mucosal surface area and absorption. Certain nutrients and trophic factors are widely used to increase intestinal adaptation following massive intestinal resection. The efficacy and benefits of glutamine on the intestinal adaptation process is still controversial. This study was conducted to determine the effects of parenteral glutamine administration on intestinal adaptation in a rat model of SBS. Fourteen male Wistar rats were divided into two groups; all 14 underwent 75% small bowel resection. Within each group, rats were assigned to 14 days of treatment with subcutaneous glutamine (0.3 g/kg/day) or isotonic saline daily. Weight changes and histological intestinal adaptation parameters (mucosal thickness, villus height, and crypt depth) were measured. Non-mucosal intestinal changes were evaluated by intestinal fractioned collagen analysis. All rats initially lost weight and began to gain weight postoperatively; however, they did not reach their preoperative weights during the experiment and there was no significant difference between the groups. Histological adaptation parameters were significantly increased after 75% intestinal resection in both groups compared to paired native samples (P<0.01); although the percent of increase was slightly higher in Gln group, no significant difference was detected between the two groups. Fractioned-collagen amounts were found to be similar between groups. The results indicated that parenteral glutamine administration alone does not improve the intestinal adaptation process after massive intestinal resection in rats.
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