Liliana Verestiuc - Academia.edu (original) (raw)
Papers by Liliana Verestiuc
2013 E-Health and Bioengineering Conference (EHB), 2013
Porous scaffolds based on collagen and chitosan have been obtained from mixed bio-polymeric solut... more Porous scaffolds based on collagen and chitosan have been obtained from mixed bio-polymeric solutions and mixture freeze-drying method in the purpose of using them as materials for post-burns tissue regeneration. Soluble collagen from bovine leather was obtained by acid-base extraction (isoelectric pH = 4.82). Two types of chitosan (CS I, M(w) = 755.900, de-acetylating degree of 79.2% and CS II, M(w) = 309.900, de-acetylating degree of 79.7%), were provided by Vascon Co., Canada. Various compositions were prepared and then structurally and morphologically characterized. In vitro degradation studies were performed in buffered collagenase or chitosan solutions, respectively, and the kinetic data were analysed. Materials effect on the tissue regeneration was tested on heat-induced burns in Wistar rats by covering the damaged tissue with collagen-chitosan scaffolds for a period of 28 days. Materials were changed every 7 days. At the end of the follow-up period skin tissue samples were harvested for histological investigation. By freeze-drying of collagen-chitosan solutions porous scaffolds were obtained with a lamellar morphology and porosity closer to chitosan than to collagen. In vitro degradation tests in simulated body fluid with collagenase revealed a decrease of the degradation rate of the collagen by mixing with chitosan. By using chitosan with lower molecular weight the degradation rate of the materials was decreased too, and the influence of the proportion of chitosan in composition diminished; stronger interactions between polymers hinder the enzyme diffusion to the following amino-acids groups: glycine - leucine (Gly-Leu), glycine - isoleucine (Gly-Ile), alanine-proline-glycine/leucine (-Ala-Pro-Gly-/-Leu-). In vivo tests and histological examination revealed a differentiated repair process of the post-combustion wounds in accordance with the scaffold-type influence. Scaffolds based on collagen and chitosan are biocompatible materials with promising results for tissue regeneration of the wounds.
The paper presents synthesis, swelling properties and in vitro degradation tests of collagen-hydr... more The paper presents synthesis, swelling properties and in vitro degradation tests of collagen-hydroxyapatite composites, in the order to obtain new bone substitutes. Also, by using a 3D analysis with finite element the tension distribution at bone--synthesised substitute interface and in bone by comparing to bone substitute was determined. Collagen type I from tendon bovine source, provided from Sigma-Aldrich, has been used for materials synthesis. Composite materials have been obtained by hydroxyapatite (HA) precipitation from its precursors (aqueous solutions of CaCl2 and NaH2PO4), in the presence of NH4OH and process finalising at 37 degrees C. Three types of materials have been prepared: 75% collagen--25% HA(w/w)--Coll75-HA; 50% collagen--50% HA(w/w)--Coll50-HA; 25% collagen--75% HA(w/ w)--Coll25-HA. Swelling properties of the composite materials were evaluated gravimetrically and in vitro degradation in buffered collagenase was studied. The elasticity modulus was calculated from the dependence force versus material's strain. The 3D analysis with finite element at bone--synthesised substitute interface was performed for a right osteosynthesised fracture from femur. Materials swelling in simulated body fluids revealed higher equilibrium swelling degree for HA-collagen composites with increased content of collagen. Materials are degraded by collagenase, the degradation rate being strongly dependent by composition; a higher content of collagen makes the composites more sensitive to the specific enzyme. SEM data have shown the forming of hydroxyapatite crystals onto collagen fibers. The mechanical characterisation has shown a limited elasticity at an increased value of the applied force for Coll25-HA. Over these forces the plasticity was observed. By using the 3D analysis with finite element at bone--synthesised substitute interface a higher strength was determined in the bone by comparison to bone substitute. The superior elasticity properties of the synthesised collagen-HA by comparison to physiological biomechanical limits indicate a good behaviour as resistance bone substitute with applications in the extensive bones reconstruction (endoprosthesis revision, bone infections etc.).
Biofunctionalized magnetic composites have been obtained by immobilization of biotin via activati... more Biofunctionalized magnetic composites have been obtained by immobilization of biotin via activation with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDAC) on chitosan-magnetite based particles. FT-IR and TEM analyses confirmed that biotinylated particles have been successfully prepared. Dynamic light scattering measurements showed that bio-functionalized particles have sub-micron size. These particles exhibit a superparamagnetic behavior and good magnetic saturation, characteristics that recommend them for
Industrial & Engineering Chemistry Research
In the present work we describe a novel route for preparation of biomimetic bone scaffolds based ... more In the present work we describe a novel route for preparation of biomimetic bone scaffolds based on biopolymers as chitosan (Cs), hyaluronic acid (Hya), chondroitin sulfate (ChS) and calcium phosphate (CP). The biopolymers-CP composite scaffolds were analyzed by Fourier transformed infrared spectroscopy, scanning electron microscopy, X-ray diffraction, mechanical test, cell culture and MTS (3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium) assay. The results show the interactions among biopolymers and CP through chemical bond interactions between Ca ions and -OH groups of CP, -NH3+ groups of Cs and -OSO3- groups of ChS or -COO- groups of Hya and -NH2 or -OH groups of Cs. The different forms of CP obtained, combined with the mixture of biopolymers highlight the prospective use of these composite scaffolds in bone tissue engineering. The scaffolds compositions have no negative effect on cell, emphasizing a good biocompatibility.
Thermochimica Acta, 2015
ABSTRACT The thermal decomposition of hydrogels based on N-maleoyl chitosan and poly(acrylic acid... more ABSTRACT The thermal decomposition of hydrogels based on N-maleoyl chitosan and poly(acrylic acid-co-ethyl acrylate) (NMACs-P(AA-co-EA)) and its precursors (chitosan and N-maleoyl chitosan) was studied by thermogravimetric analysis coupled to Fourier transform infrared spectroscopy and mass spectrometry (TGA/FTIR/MS). These coupled techniques allow collecting simultaneous information about the decomposition process as well as of the composition of gas-phase evolved from samples, identifying the structures for all degradation products. The effect of ethyl acrylate ratio on thermal stability and degradation mechanism of hydrogels is also discussed. An increase of ethyl acrylate monomer ratio resulted in a slightly decreased weight loss, indicating a low thermostability for NMACs-P(AA-co-EA) hydrogels. Also, the main thermal degradation pathways followed dehydration and condensation of comonomers with anhydride formation, chitosan depolymerization, decarboxylation, fragmentation and chain scission.
Journal of Hydrogels, 2015
International Journal of Pharmaceutics, 2004
The synthesis and characterisation of semi-interpenetrating polymeric networks obtained by the ra... more The synthesis and characterisation of semi-interpenetrating polymeric networks obtained by the radical-induced polymerisation of N-isopropylacrylamide in the presence of chitosan using tetraethyleneglycoldiacrylate as the crosslinker is described. The influence of the degree of crosslinking and that of the ratio of chitosan to poly(N-isopropylacrylamide) on the "pH/temperature induced" phase transition behaviour and swelling characteristics of the hydrogel system are investigated. The ability of the same system to act as a controlled release vehicle for pilocarpine hydrochloride is evaluated.
2014 International Conference and Exposition on Electrical and Power Engineering (EPE), 2014
2009 Advanced Technologies for Enhanced Quality of Life (AT-EQUAL), 2009
buffered lysozyme solution and the degraded polysaccharide was measured; the SEM data, before and... more buffered lysozyme solution and the degraded polysaccharide was measured; the SEM data, before and after degradation, revealed that composites morphology had not appreciable changed. 'In vitro' degradation studies indicate that these composite have slighter degradation rate which is coupled to the degree of N-deacetylation, hydrophilicity and crystallinity. Swelling properties measurements in simulated body fluids have shown that the swelling ratio of composites is decreased when the content of Hap is higher. The obtained results revealed that obtained Cs-Hap composites are promising materials as bone substitute due to their adequate swelling properties and controlled degradation rate.
2013 E-Health and Bioengineering Conference (EHB), 2013
The paper presents the preparation and characteristics of novel composites based on mixtures of b... more The paper presents the preparation and characteristics of novel composites based on mixtures of biopolymers (chitosan and hyaluronic acid) and calcium phosphate, obtained through a biomimetic procedure. Scanning electron microscopy revealed the interconnected pore morphology of the materials. Low in vitro degradation rate confirm the tightly connection of the polymeric matrix with calcium phosphates, which limits the enzyme access to the degradable components. Tests on composites interaction with osteoblastic cells showed no differences of cell morphology after incubation with prepared composites. The cells adhere to the composites and the number of the adherent cells on the material surface is highly dependent on composition.
Key Engineering Materials, 2013
Composites based on calcium phosphates (CP) and mixtures of biopolymers (chitosan and hyaluronic ... more 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-biopolymers composites and limited swelling in simulated body fluids. The scaffolds compositions have no negative effect on osteoblasts cell, emphasizing a good biocompatibility.
2013 E-Health and Bioengineering Conference (EHB), 2013
ABSTRACT Functionalized superparamagnetic nanoparticles based on poly (succinimide)- b -poly(ethy... more ABSTRACT Functionalized superparamagnetic nanoparticles based on poly (succinimide)- b -poly(ethylene glycol) and magnetite have been obtained by immobilization of superoxide dismutase via activation with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDAC). Dynamic light scattering measurements showed that hydrodynamic mean diameters of the functionalized particles were about 700 nm. These particles exhibit a superparamagnetic behaviour and high magnetic saturation, good cell biocompatibility and enzymatic activity, characteristics that recommend them in application as versatile carriers for targeted antioxidant enzyme therapy.
Advanced Science, Engineering and Medicine, 2013
ABSTRACT Gelatin-hydroxyethyl cellulose nanoparticles were prepared using reverse emulsion w/o me... more ABSTRACT Gelatin-hydroxyethyl cellulose nanoparticles were prepared using reverse emulsion w/o method. Crosslinking was carried out with glutaric aldehyde within aqueous droplets containing polymers mixture, dispersed into toluene in presence of surfactants. Various formulations were prepared by varying the ratio of gelatin and hydroxyethyl cellulose, the concentration of polymers solution and the ratio of polymers mixture and glutaric aldehyde. The influence of those parameters on the composition, size, size dispersity, particle swelling and their ability for drug inclusion and release was studied. The particles size range of nanoparticles was between 200–700 nm. The ability to take-up drugs and the size are directly correlated with the degree of swelling and gelatin content within the nanoparticles. In vitro rifampicin loading/release from nanoparticles was studied. The very low toxicity, the hemocompatibility and biodegradability of these nanoparticles makes them potential drug carriers.
2013 E-Health and Bioengineering Conference (EHB), 2013
ABSTRACT Hydrogels with semi-interpenetrating (semi-IPN) structure were synthesized by radical co... more ABSTRACT Hydrogels with semi-interpenetrating (semi-IPN) structure were synthesized by radical copolymerization of maleoyl-chitosan (N-MA-Cs) and acrylic acid (AA) in the presence of ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TEMED) as initiating system. Network structure and morphology were confirmed by Fourier Transform Infrared Spectroscopy coupled with Attenuated Total Reflection technique (ATR-FTIR) and scanning electron microscopy (SEM). Water uptake in scaffolds is influenced by both composition and the porosity of the matrices. The prepared scaffolds are degradable by lysozyme and the degradation rate can be modulated by the content of acrylic acid. The materials cytocompatibility and physical-chemical characteristics indicate that these scaffolds exhibit the prerequisite behaviour for use in soft tissue engineering.
Polymer-Plastics Technology and Engineering, 2012
Chitosan-based hydrogels are widely used as ophthalmic drug delivery systems due to the polymer a... more Chitosan-based hydrogels are widely used as ophthalmic drug delivery systems due to the polymer advantageous properties. The present work was focused on synthesis and characterization of new chitosan derivatives with polymerisable functions, by reaction with maleic anhydride. The influence of nature and amount of micromolecular reagent, as well as the reaction temperature upon the functionalization degree and solubilization properties of
Materials Science and Engineering: C, 2000
New hydrogels based on maleic anhydride (MA) modified collagen were prepared with the aim of over... more New hydrogels based on maleic anhydride (MA) modified collagen were prepared with the aim of overcoming the high degradation rate displayed by collagen that is not otherwise chemically crosslinked. Semi-interpenetrated matrices were obtained by free radical polymerization of maleilated collagen (CM) and 2-hydroxyethyl methacrylate (HEMA) in the presence of ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TEMED) as initiating system. The resulting
2013 E-Health and Bioengineering Conference (EHB), 2013
Porous scaffolds based on collagen and chitosan have been obtained from mixed bio-polymeric solut... more Porous scaffolds based on collagen and chitosan have been obtained from mixed bio-polymeric solutions and mixture freeze-drying method in the purpose of using them as materials for post-burns tissue regeneration. Soluble collagen from bovine leather was obtained by acid-base extraction (isoelectric pH = 4.82). Two types of chitosan (CS I, M(w) = 755.900, de-acetylating degree of 79.2% and CS II, M(w) = 309.900, de-acetylating degree of 79.7%), were provided by Vascon Co., Canada. Various compositions were prepared and then structurally and morphologically characterized. In vitro degradation studies were performed in buffered collagenase or chitosan solutions, respectively, and the kinetic data were analysed. Materials effect on the tissue regeneration was tested on heat-induced burns in Wistar rats by covering the damaged tissue with collagen-chitosan scaffolds for a period of 28 days. Materials were changed every 7 days. At the end of the follow-up period skin tissue samples were harvested for histological investigation. By freeze-drying of collagen-chitosan solutions porous scaffolds were obtained with a lamellar morphology and porosity closer to chitosan than to collagen. In vitro degradation tests in simulated body fluid with collagenase revealed a decrease of the degradation rate of the collagen by mixing with chitosan. By using chitosan with lower molecular weight the degradation rate of the materials was decreased too, and the influence of the proportion of chitosan in composition diminished; stronger interactions between polymers hinder the enzyme diffusion to the following amino-acids groups: glycine - leucine (Gly-Leu), glycine - isoleucine (Gly-Ile), alanine-proline-glycine/leucine (-Ala-Pro-Gly-/-Leu-). In vivo tests and histological examination revealed a differentiated repair process of the post-combustion wounds in accordance with the scaffold-type influence. Scaffolds based on collagen and chitosan are biocompatible materials with promising results for tissue regeneration of the wounds.
The paper presents synthesis, swelling properties and in vitro degradation tests of collagen-hydr... more The paper presents synthesis, swelling properties and in vitro degradation tests of collagen-hydroxyapatite composites, in the order to obtain new bone substitutes. Also, by using a 3D analysis with finite element the tension distribution at bone--synthesised substitute interface and in bone by comparing to bone substitute was determined. Collagen type I from tendon bovine source, provided from Sigma-Aldrich, has been used for materials synthesis. Composite materials have been obtained by hydroxyapatite (HA) precipitation from its precursors (aqueous solutions of CaCl2 and NaH2PO4), in the presence of NH4OH and process finalising at 37 degrees C. Three types of materials have been prepared: 75% collagen--25% HA(w/w)--Coll75-HA; 50% collagen--50% HA(w/w)--Coll50-HA; 25% collagen--75% HA(w/ w)--Coll25-HA. Swelling properties of the composite materials were evaluated gravimetrically and in vitro degradation in buffered collagenase was studied. The elasticity modulus was calculated from the dependence force versus material's strain. The 3D analysis with finite element at bone--synthesised substitute interface was performed for a right osteosynthesised fracture from femur. Materials swelling in simulated body fluids revealed higher equilibrium swelling degree for HA-collagen composites with increased content of collagen. Materials are degraded by collagenase, the degradation rate being strongly dependent by composition; a higher content of collagen makes the composites more sensitive to the specific enzyme. SEM data have shown the forming of hydroxyapatite crystals onto collagen fibers. The mechanical characterisation has shown a limited elasticity at an increased value of the applied force for Coll25-HA. Over these forces the plasticity was observed. By using the 3D analysis with finite element at bone--synthesised substitute interface a higher strength was determined in the bone by comparison to bone substitute. The superior elasticity properties of the synthesised collagen-HA by comparison to physiological biomechanical limits indicate a good behaviour as resistance bone substitute with applications in the extensive bones reconstruction (endoprosthesis revision, bone infections etc.).
Biofunctionalized magnetic composites have been obtained by immobilization of biotin via activati... more Biofunctionalized magnetic composites have been obtained by immobilization of biotin via activation with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDAC) on chitosan-magnetite based particles. FT-IR and TEM analyses confirmed that biotinylated particles have been successfully prepared. Dynamic light scattering measurements showed that bio-functionalized particles have sub-micron size. These particles exhibit a superparamagnetic behavior and good magnetic saturation, characteristics that recommend them for
Industrial & Engineering Chemistry Research
In the present work we describe a novel route for preparation of biomimetic bone scaffolds based ... more In the present work we describe a novel route for preparation of biomimetic bone scaffolds based on biopolymers as chitosan (Cs), hyaluronic acid (Hya), chondroitin sulfate (ChS) and calcium phosphate (CP). The biopolymers-CP composite scaffolds were analyzed by Fourier transformed infrared spectroscopy, scanning electron microscopy, X-ray diffraction, mechanical test, cell culture and MTS (3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium) assay. The results show the interactions among biopolymers and CP through chemical bond interactions between Ca ions and -OH groups of CP, -NH3+ groups of Cs and -OSO3- groups of ChS or -COO- groups of Hya and -NH2 or -OH groups of Cs. The different forms of CP obtained, combined with the mixture of biopolymers highlight the prospective use of these composite scaffolds in bone tissue engineering. The scaffolds compositions have no negative effect on cell, emphasizing a good biocompatibility.
Thermochimica Acta, 2015
ABSTRACT The thermal decomposition of hydrogels based on N-maleoyl chitosan and poly(acrylic acid... more ABSTRACT The thermal decomposition of hydrogels based on N-maleoyl chitosan and poly(acrylic acid-co-ethyl acrylate) (NMACs-P(AA-co-EA)) and its precursors (chitosan and N-maleoyl chitosan) was studied by thermogravimetric analysis coupled to Fourier transform infrared spectroscopy and mass spectrometry (TGA/FTIR/MS). These coupled techniques allow collecting simultaneous information about the decomposition process as well as of the composition of gas-phase evolved from samples, identifying the structures for all degradation products. The effect of ethyl acrylate ratio on thermal stability and degradation mechanism of hydrogels is also discussed. An increase of ethyl acrylate monomer ratio resulted in a slightly decreased weight loss, indicating a low thermostability for NMACs-P(AA-co-EA) hydrogels. Also, the main thermal degradation pathways followed dehydration and condensation of comonomers with anhydride formation, chitosan depolymerization, decarboxylation, fragmentation and chain scission.
Journal of Hydrogels, 2015
International Journal of Pharmaceutics, 2004
The synthesis and characterisation of semi-interpenetrating polymeric networks obtained by the ra... more The synthesis and characterisation of semi-interpenetrating polymeric networks obtained by the radical-induced polymerisation of N-isopropylacrylamide in the presence of chitosan using tetraethyleneglycoldiacrylate as the crosslinker is described. The influence of the degree of crosslinking and that of the ratio of chitosan to poly(N-isopropylacrylamide) on the "pH/temperature induced" phase transition behaviour and swelling characteristics of the hydrogel system are investigated. The ability of the same system to act as a controlled release vehicle for pilocarpine hydrochloride is evaluated.
2014 International Conference and Exposition on Electrical and Power Engineering (EPE), 2014
2009 Advanced Technologies for Enhanced Quality of Life (AT-EQUAL), 2009
buffered lysozyme solution and the degraded polysaccharide was measured; the SEM data, before and... more buffered lysozyme solution and the degraded polysaccharide was measured; the SEM data, before and after degradation, revealed that composites morphology had not appreciable changed. 'In vitro' degradation studies indicate that these composite have slighter degradation rate which is coupled to the degree of N-deacetylation, hydrophilicity and crystallinity. Swelling properties measurements in simulated body fluids have shown that the swelling ratio of composites is decreased when the content of Hap is higher. The obtained results revealed that obtained Cs-Hap composites are promising materials as bone substitute due to their adequate swelling properties and controlled degradation rate.
2013 E-Health and Bioengineering Conference (EHB), 2013
The paper presents the preparation and characteristics of novel composites based on mixtures of b... more The paper presents the preparation and characteristics of novel composites based on mixtures of biopolymers (chitosan and hyaluronic acid) and calcium phosphate, obtained through a biomimetic procedure. Scanning electron microscopy revealed the interconnected pore morphology of the materials. Low in vitro degradation rate confirm the tightly connection of the polymeric matrix with calcium phosphates, which limits the enzyme access to the degradable components. Tests on composites interaction with osteoblastic cells showed no differences of cell morphology after incubation with prepared composites. The cells adhere to the composites and the number of the adherent cells on the material surface is highly dependent on composition.
Key Engineering Materials, 2013
Composites based on calcium phosphates (CP) and mixtures of biopolymers (chitosan and hyaluronic ... more 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-biopolymers composites and limited swelling in simulated body fluids. The scaffolds compositions have no negative effect on osteoblasts cell, emphasizing a good biocompatibility.
2013 E-Health and Bioengineering Conference (EHB), 2013
ABSTRACT Functionalized superparamagnetic nanoparticles based on poly (succinimide)- b -poly(ethy... more ABSTRACT Functionalized superparamagnetic nanoparticles based on poly (succinimide)- b -poly(ethylene glycol) and magnetite have been obtained by immobilization of superoxide dismutase via activation with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDAC). Dynamic light scattering measurements showed that hydrodynamic mean diameters of the functionalized particles were about 700 nm. These particles exhibit a superparamagnetic behaviour and high magnetic saturation, good cell biocompatibility and enzymatic activity, characteristics that recommend them in application as versatile carriers for targeted antioxidant enzyme therapy.
Advanced Science, Engineering and Medicine, 2013
ABSTRACT Gelatin-hydroxyethyl cellulose nanoparticles were prepared using reverse emulsion w/o me... more ABSTRACT Gelatin-hydroxyethyl cellulose nanoparticles were prepared using reverse emulsion w/o method. Crosslinking was carried out with glutaric aldehyde within aqueous droplets containing polymers mixture, dispersed into toluene in presence of surfactants. Various formulations were prepared by varying the ratio of gelatin and hydroxyethyl cellulose, the concentration of polymers solution and the ratio of polymers mixture and glutaric aldehyde. The influence of those parameters on the composition, size, size dispersity, particle swelling and their ability for drug inclusion and release was studied. The particles size range of nanoparticles was between 200–700 nm. The ability to take-up drugs and the size are directly correlated with the degree of swelling and gelatin content within the nanoparticles. In vitro rifampicin loading/release from nanoparticles was studied. The very low toxicity, the hemocompatibility and biodegradability of these nanoparticles makes them potential drug carriers.
2013 E-Health and Bioengineering Conference (EHB), 2013
ABSTRACT Hydrogels with semi-interpenetrating (semi-IPN) structure were synthesized by radical co... more ABSTRACT Hydrogels with semi-interpenetrating (semi-IPN) structure were synthesized by radical copolymerization of maleoyl-chitosan (N-MA-Cs) and acrylic acid (AA) in the presence of ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TEMED) as initiating system. Network structure and morphology were confirmed by Fourier Transform Infrared Spectroscopy coupled with Attenuated Total Reflection technique (ATR-FTIR) and scanning electron microscopy (SEM). Water uptake in scaffolds is influenced by both composition and the porosity of the matrices. The prepared scaffolds are degradable by lysozyme and the degradation rate can be modulated by the content of acrylic acid. The materials cytocompatibility and physical-chemical characteristics indicate that these scaffolds exhibit the prerequisite behaviour for use in soft tissue engineering.
Polymer-Plastics Technology and Engineering, 2012
Chitosan-based hydrogels are widely used as ophthalmic drug delivery systems due to the polymer a... more Chitosan-based hydrogels are widely used as ophthalmic drug delivery systems due to the polymer advantageous properties. The present work was focused on synthesis and characterization of new chitosan derivatives with polymerisable functions, by reaction with maleic anhydride. The influence of nature and amount of micromolecular reagent, as well as the reaction temperature upon the functionalization degree and solubilization properties of
Materials Science and Engineering: C, 2000
New hydrogels based on maleic anhydride (MA) modified collagen were prepared with the aim of over... more New hydrogels based on maleic anhydride (MA) modified collagen were prepared with the aim of overcoming the high degradation rate displayed by collagen that is not otherwise chemically crosslinked. Semi-interpenetrated matrices were obtained by free radical polymerization of maleilated collagen (CM) and 2-hydroxyethyl methacrylate (HEMA) in the presence of ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TEMED) as initiating system. The resulting