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Oddone Schiavon - One of the best experts on this subject based on the ideXlab platform.
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relevance of folic acid Polymer Ratio in targeted peg epirubicin conjugates
Journal of Controlled Release, 2010Co-Authors: Fabiana Canal, Maria J Vicent, Gianfranco Pasut, Oddone SchiavonAbstract:Abstract A series of PEG–epirubicin conjugates with different folic acid contents per Polymer chain was synthesized in order to study the influence of Polymer/targeting moiety Ratio on selective cytotoxicity, cellular uptake and intracellular localization. Analogous carboxyl-terminated conjugates without folic acid were studied as control. The heterobifunctional HO-PEG-COOH was used as Polymeric carrier, allowing the synthesis of conjugates with a good control over the chemical structure and the drug/Polymer and Polymer/targeting residue Ratios. A dendron structure was synthesized at one end of the PEG chain with the aim to increase the number of folic acid molecules. L-2-aminoadipic acid was used as branching unit. The conjugates showed high stability under several physiological conditions. Biological evaluation was carried out in A549, HeLa and KB-3-1 human cell lines, as these cells have different levels of folate receptor (FR) expression. In particular A549 cells are FR negative (FR−), HeLa cells are FR positive (FR+) and KB-3-1 cells over-express FR (FR++). It was clearly shown that the biological activity of the conjugates was influenced by the presence and the number of folic acid molecules per Polymer chain and by the level of FR expression on cell surface. Conjugates conformation in solution was also studied, as differences in size might well affect cell internalization. In the cell viability assay, conjugates without folic acid were unexpectedly more cytotoxic than the targeted conjugates, but their IC50 values were similar in the three cell lines. Differently, the anti-proliferative activity of targeted derivatives markedly increased going from FR(−) to FR(++) cells. FACS and confocal microscopy studies showed greater cellular internalization with the targeted conjugates than with their non-targeted analogues; more importantly, this relationship is clearly dependent on folic acid content in the conjugates and FR expression level in the cell line used.
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Relevance of folic acid/Polymer Ratio in targeted PEG-epirubicin conjugates.
Journal of controlled release : official journal of the Controlled Release Society, 2010Co-Authors: Fabiana Canal, Maria J Vicent, Gianfranco Pasut, Oddone SchiavonAbstract:Abstract A series of PEG–epirubicin conjugates with different folic acid contents per Polymer chain was synthesized in order to study the influence of Polymer/targeting moiety Ratio on selective cytotoxicity, cellular uptake and intracellular localization. Analogous carboxyl-terminated conjugates without folic acid were studied as control. The heterobifunctional HO-PEG-COOH was used as Polymeric carrier, allowing the synthesis of conjugates with a good control over the chemical structure and the drug/Polymer and Polymer/targeting residue Ratios. A dendron structure was synthesized at one end of the PEG chain with the aim to increase the number of folic acid molecules. L-2-aminoadipic acid was used as branching unit. The conjugates showed high stability under several physiological conditions. Biological evaluation was carried out in A549, HeLa and KB-3-1 human cell lines, as these cells have different levels of folate receptor (FR) expression. In particular A549 cells are FR negative (FR−), HeLa cells are FR positive (FR+) and KB-3-1 cells over-express FR (FR++). It was clearly shown that the biological activity of the conjugates was influenced by the presence and the number of folic acid molecules per Polymer chain and by the level of FR expression on cell surface. Conjugates conformation in solution was also studied, as differences in size might well affect cell internalization. In the cell viability assay, conjugates without folic acid were unexpectedly more cytotoxic than the targeted conjugates, but their IC50 values were similar in the three cell lines. Differently, the anti-proliferative activity of targeted derivatives markedly increased going from FR(−) to FR(++) cells. FACS and confocal microscopy studies showed greater cellular internalization with the targeted conjugates than with their non-targeted analogues; more importantly, this relationship is clearly dependent on folic acid content in the conjugates and FR expression level in the cell line used.
Seham A. Elkheshen - One of the best experts on this subject based on the ideXlab platform.
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Interaction of Verapamil Hydrochloride with Carbopol 934P and Its Effect on the Release Rate of the Drug and the Water Uptake of the Polymer Matrix
Drug development and industrial pharmacy, 2001Co-Authors: Seham A. ElkheshenAbstract:In the present study, investigation of the possibility of interaction of verapamil hydrochloride with Carbopol 934P using differential scanning calorimetric analysis and Fourier transform infrared analysis was performed. The effect of the drug-to-Polymer Ratio, the electrolyte concentRation, and the pH of the medium on the extent of interaction of the drug with the Polymer using 23 factorial design was investigated. The study also investigated the effect of this interaction on the rate of water uptake of the matrix or the rate of release of verapamil hydrochloride from the swelling Polymer matrix. Results revealed that the drug-to-Polymer Ratio had the most influential effect on both the extent of interaction between the drug and the Polymer and the rate of water uptake of the Polymer matrix. On the other hand, the pH of the medium had the most significant effect on the rate of drug release. Interaction of the tertiary amine nitrogen of the drug with the anionic carboxyl group on the Polymer, forming an i...
Nuran Işıklan - One of the best experts on this subject based on the ideXlab platform.
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Microwave-assisted synthesis of alginate-g-polyvinylpyrrolidone coPolymer and its application in controlled drug release
Polymer Bulletin, 2014Co-Authors: Mustafa Yiğitoğlu, Gülden Aydın, Nuran IşıklanAbstract:The aim of this study is to synthesize graft coPolymer (NaAlg-g-PVP) in microwave oven and prepare pH-responsive beads with high entrapment efficiency. For this purpose, PVP was grafted onto sodium alginate using microwave radiation. The coPolymer obtained was characterized using FTIR, ^1H-NMR, elemental analysis and thermogravimetric analysis. A series of NaAlg-g-PVP beads were prepared as drug delivery matrices for ibuprofen (IB) by cross-linking into beads via glutaraldehyde. The chemical stability of IB after encapsulation into beads was confirmed by FTIR, DSC, and X-RD analysis. Synthesis conditions of beads were optimized by considering entrapment efficiency, particle size, swelling capacity and their release data. Effects of such variables as graft yield and drug/Polymer Ratio were investigated at 1.2 and 7.4 pH values. Increasing the drug/Polymer Ratio and extent of cross-linking caused decrease in the IB release. On the other hand, increase in the graft yield led to increase in the IB release as well. The results also showed that NaAlg-g-PVP beads were positive pH-responsive.
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release characteristics of diclofenac sodium from poly vinyl alcohol sodium alginate and poly vinyl alcohol grafted poly acrylamide sodium alginate blend beads
European Journal of Pharmaceutics and Biopharmaceutics, 2007Co-Authors: Oya Sanli, Nuran Ay, Nuran IşıklanAbstract:In this study, acrylamide (AAm) was grafted onto poly(vinyl alcohol) (PVA) with UV radiation at ambient temperature. The graft coPolymer (PVA-g-PAAm) was characterized by using Fourier transform infrared spectroscopy (FTIR), elemental analysis and differential scanning calorimetry (DSC). Polymeric blend beads of PVA-g-PAAm and PVA with sodium alginate (NaAlg) were prepared by cross-linking with glutaraldehyde (GA) and used to deliver a model anti-inflammatory drug, diclofenac sodium (DS). PrepaRation condition of the beads was optimized by considering the percentage entrapment efficiency, particle size, swelling capacity of beads and their release data. Effects of variables such as PVA/NaAlg Ratio, acrylamide content, exposure time to GA and drug/Polymer Ratio on the release of DS were discussed at three different pH values (1.2, 6.8, 7.4). It was observed that, DS release from the beads decreased with increasing PVA/NaAlg (m/m) Ratio, drug/Polymer Ratio (d/p) and extent of cross-linking. However, DS release increased with increasing acrylamide content of the PVA-g-PAAm Polymer. The highest DS release was obtained to be 92% for 1/1 PVA-g-PAAm/NaAlg Ratio beads. It was also observed from release results that DS release from the beads through the external medium is much higher at high pH (6.8 and 7.4) than that at low pH (1.2). The drug release from the beads mostly followed Case II transport.
Francisco Céspedes - One of the best experts on this subject based on the ideXlab platform.
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Strategies for the optimization of carbon nanotube/Polymer Ratio in composite materials: Applications as voltammetric sensors
Sensors and Actuators B: Chemical, 2010Co-Authors: Rosa Olivé-monllau, Ma José Esplandiu, Jordi Bartrolí, Mireia Baeza, Francisco CéspedesAbstract:Multiwall carbon nanotubes and resin epoxy have been used to fabricate a composite electrode for electroanalytical purposes. The optimum composite proportions for high electrode sensitivity, low limit of detection and fast response were investigated. Compositions were characterized by percolation theory, electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, atomic force microscopy and chronoamperometry. We found that around the optimum composite proportion, the electrode performance is less affected by small variations in the composition of the composite. These composite electrodes provide easy surface renewal, low background current, an efficient mass transport and are suitable for chemical modification. The potentiality of this approach in terms of electroanalytical response is demonstrated by means of the amperometric detection of ascorbic acid in water solution.
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strategies for the optimization of carbon nanotube Polymer Ratio in composite materials applications as voltammetric sensors
Sensors and Actuators B-chemical, 2010Co-Authors: Rosa Olivemonllau, Ma José Esplandiu, Jordi Bartrolí, Mireia Baeza, Francisco CéspedesAbstract:Multiwall carbon nanotubes and resin epoxy have been used to fabricate a composite electrode for electroanalytical purposes. The optimum composite proportions for high electrode sensitivity, low limit of detection and fast response were investigated. Compositions were characterized by percolation theory, electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, atomic force microscopy and chronoamperometry. We found that around the optimum composite proportion, the electrode performance is less affected by small variations in the composition of the composite. These composite electrodes provide easy surface renewal, low background current, an efficient mass transport and are suitable for chemical modification. The potentiality of this approach in terms of electroanalytical response is demonstrated by means of the amperometric detection of ascorbic acid in water solution.
Fabiana Canal - One of the best experts on this subject based on the ideXlab platform.
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relevance of folic acid Polymer Ratio in targeted peg epirubicin conjugates
Journal of Controlled Release, 2010Co-Authors: Fabiana Canal, Maria J Vicent, Gianfranco Pasut, Oddone SchiavonAbstract:Abstract A series of PEG–epirubicin conjugates with different folic acid contents per Polymer chain was synthesized in order to study the influence of Polymer/targeting moiety Ratio on selective cytotoxicity, cellular uptake and intracellular localization. Analogous carboxyl-terminated conjugates without folic acid were studied as control. The heterobifunctional HO-PEG-COOH was used as Polymeric carrier, allowing the synthesis of conjugates with a good control over the chemical structure and the drug/Polymer and Polymer/targeting residue Ratios. A dendron structure was synthesized at one end of the PEG chain with the aim to increase the number of folic acid molecules. L-2-aminoadipic acid was used as branching unit. The conjugates showed high stability under several physiological conditions. Biological evaluation was carried out in A549, HeLa and KB-3-1 human cell lines, as these cells have different levels of folate receptor (FR) expression. In particular A549 cells are FR negative (FR−), HeLa cells are FR positive (FR+) and KB-3-1 cells over-express FR (FR++). It was clearly shown that the biological activity of the conjugates was influenced by the presence and the number of folic acid molecules per Polymer chain and by the level of FR expression on cell surface. Conjugates conformation in solution was also studied, as differences in size might well affect cell internalization. In the cell viability assay, conjugates without folic acid were unexpectedly more cytotoxic than the targeted conjugates, but their IC50 values were similar in the three cell lines. Differently, the anti-proliferative activity of targeted derivatives markedly increased going from FR(−) to FR(++) cells. FACS and confocal microscopy studies showed greater cellular internalization with the targeted conjugates than with their non-targeted analogues; more importantly, this relationship is clearly dependent on folic acid content in the conjugates and FR expression level in the cell line used.
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Relevance of folic acid/Polymer Ratio in targeted PEG-epirubicin conjugates.
Journal of controlled release : official journal of the Controlled Release Society, 2010Co-Authors: Fabiana Canal, Maria J Vicent, Gianfranco Pasut, Oddone SchiavonAbstract:Abstract A series of PEG–epirubicin conjugates with different folic acid contents per Polymer chain was synthesized in order to study the influence of Polymer/targeting moiety Ratio on selective cytotoxicity, cellular uptake and intracellular localization. Analogous carboxyl-terminated conjugates without folic acid were studied as control. The heterobifunctional HO-PEG-COOH was used as Polymeric carrier, allowing the synthesis of conjugates with a good control over the chemical structure and the drug/Polymer and Polymer/targeting residue Ratios. A dendron structure was synthesized at one end of the PEG chain with the aim to increase the number of folic acid molecules. L-2-aminoadipic acid was used as branching unit. The conjugates showed high stability under several physiological conditions. Biological evaluation was carried out in A549, HeLa and KB-3-1 human cell lines, as these cells have different levels of folate receptor (FR) expression. In particular A549 cells are FR negative (FR−), HeLa cells are FR positive (FR+) and KB-3-1 cells over-express FR (FR++). It was clearly shown that the biological activity of the conjugates was influenced by the presence and the number of folic acid molecules per Polymer chain and by the level of FR expression on cell surface. Conjugates conformation in solution was also studied, as differences in size might well affect cell internalization. In the cell viability assay, conjugates without folic acid were unexpectedly more cytotoxic than the targeted conjugates, but their IC50 values were similar in the three cell lines. Differently, the anti-proliferative activity of targeted derivatives markedly increased going from FR(−) to FR(++) cells. FACS and confocal microscopy studies showed greater cellular internalization with the targeted conjugates than with their non-targeted analogues; more importantly, this relationship is clearly dependent on folic acid content in the conjugates and FR expression level in the cell line used.