Marin Micutz - Academia.edu (original) (raw)

Papers by Marin Micutz

Research paper thumbnail of Synthesis, Physicochemical Characteristics, and Biocompatibility of Multi-Component Collagen-Based Hydrogels Developed by E-Beam Irradiation

Journal of Functional Biomaterials

Herein, three different recipes of multi-component hydrogels were synthesized by e-beam irradiati... more Herein, three different recipes of multi-component hydrogels were synthesized by e-beam irradiation. These hydrogels were obtained from aqueous polymer mixtures in which different proportions of bovine collagen gel, sodium carboxymethylcellulose (CMC), poly(vinylpyrrolidone), chitosan, and poly(ethylene oxide) were used. The cross-linking reaction was carried out exclusively by e-beam cross-linking at 25 kGy, a dose of irradiation sufficient both to complete the cross-linking reaction and effective for hydrogel sterilization. The hydrogels developed in this study were tested in terms of physical and chemical stability, mechanical, structural, morphological, and biological properties. They are transparent, maintain their structure, are non-adhesive when handling, and most importantly, especially from the application point of view, have an elastic structure. Likewise, these hydrogels possessed different swelling degrees and expressed rheological behavior characteristic of soft solids ...

Research paper thumbnail of Liquid Crystalline and Gel Properties of Luminescent Cyclometalated Palladium Complexes with Benzoylthiourea Ligands

Gels

The design and development of new luminescent metallogels formed by cyclometalated palladium(II) ... more The design and development of new luminescent metallogels formed by cyclometalated palladium(II) complexes in protic solvents were investigated by a combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM), and rheology. Cyclometalated palladium(II) complexes based on imine ligand and ancillary benzoylthiourea (BTU) ligand showed red emission in solid and gel states. The formation of a lyotropic liquid crystal phase was observed for the complex bearing shorter alkyl groups on the BTU ligand. This complex also behaved as a thermotropic liquid crystal that displays a monotropic smectic A phase (SmA). Dynamic rheology measurements (frequency sweep in the 5–90 °C range) of the 1-decanol solution of palladium(II) complexes highlighted their supramolecular self-association ability to generate 3D networks and form gels as a final result.

Research paper thumbnail of Liquid Crystalline and Gel Properties of Luminescent Cyclometalated Palladium Complexes with Benzoylthiourea Ligands

Gels

The design and development of new luminescent metallogels formed by cyclometalated palladium(II) ... more The design and development of new luminescent metallogels formed by cyclometalated palladium(II) complexes in protic solvents were investigated by a combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM), and rheology. Cyclometalated palladium(II) complexes based on imine ligand and ancillary benzoylthiourea (BTU) ligand showed red emission in solid and gel states. The formation of a lyotropic liquid crystal phase was observed for the complex bearing shorter alkyl groups on the BTU ligand. This complex also behaved as a thermotropic liquid crystal that displays a monotropic smectic A phase (SmA). Dynamic rheology measurements (frequency sweep in the 5–90 °C range) of the 1-decanol solution of palladium(II) complexes highlighted their supramolecular self-association ability to generate 3D networks and form gels as a final result.

Research paper thumbnail of Novel Gemini Surfactant for Binding Eu(III)-Polyoxometalate into Hydrogels and Polymer Latexes

Gels

The incorporation of rare-earth ions into polymer matrices can lead to useful materials in variou... more The incorporation of rare-earth ions into polymer matrices can lead to useful materials in various fields such as biomarkers, lasers, luminescent devices, optical storage materials, and so on. Methods of incorporation are either extremely simple, such as mixing the polymer and the ion of interest in adequate solvents, or more sophisticated such as synthesizing predesigned monomers that contain the rare-earth ion or binding the ion on an already formed polymer chain. Cationic gemini surfactants represent a class of surfactants that can be used to incorporate metal-oxygen cluster compounds by means of strong electrostatic interactions. In this study, first, a novel cationic gemini surfactant having double bonds on both side chains was designed and prepared. After characterization, the surfactant was used to synthesize hydrogels with different degrees of crosslinking and also as a surfmer in emulsion polymerization of methyl methacrylate. The resulted polymer matrices were able to bind...

Research paper thumbnail of Characterization and in Vitro Release of Chlorhexidine Digluconate Contained in Type I Collagen Porous Matrices

Rev. Roum. …, 2011

Porous collagen matrices containing chlorhexidine digluconate (CHXD) were obtained by freeze-dryi... more Porous collagen matrices containing chlorhexidine digluconate (CHXD) were obtained by freeze-drying of three series of 1.1% collagen hydrogels having the pHs 3.8, 7.4 or 7.4 plus 0.15% glutaric aldehyde (GA) reported to the collagen from hydrogel, each series containing 0, 0.02, 0.05 or 0.10% CHXD reported to the amount of gel. FT-IR spectra show that freeze drying, pH, CHXD or/and GA do not affect the triple helical conformation of collagen molecules forming fibrils. CHXD increases a bit the crosslinking of matrices obtained from acid hydrogels irrespective of its concentration, while of those resulted from slight basic ones is reduced to a slight extent in the absence of GA and much more in its presence, which means that the crosslinking decreases with CHXD concentration increase due to its reaction with the carboxyl groups of collagen and GA respectively. Matrices' morphology reflects the changes produced in hydrogels by CHXD and/or GA: those obtained from acid hydrogels have lamellar structure, which becomes denser with increasing of CHXD concentration, orientation disappears in the matrices obtained from slight basic hydrogels, CHXD produces the agglomeration of fibrils that increases with CHXD concentration and GA enhances it. In the matrices containing 0.1% CHXD a part of it separates due to the regression of its solubility in basic media. The amounts of CHXD released from the matrices increase with CHXD concentration irrespective of pH and GA presence. The lowest amounts are released by the matrices obtained from the hydrogels with acid medium and the highest ones from the non-crosslinked matrices obtained from hydrogels with slight basic pH containing 0.1% CHXD.

Research paper thumbnail of Evidence of Counterion Size Effect on the Stability of Columnar Phase of Ionic Liquid Crystals Based on Pyridinium Salts Derived from N-3,4,5-Tri(alkyloxy)-benzyl-4-pyridones

Crystals, May 17, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of 3D Porous Collagen Matrices—A Reservoir for In Vitro Simultaneous Release of Tannic Acid and Chlorhexidine

Pharmaceutics

The treatment of wounds occurring accidentally or as a result of chronic diseases most frequently... more The treatment of wounds occurring accidentally or as a result of chronic diseases most frequently requires the use of appropriate dressings, mainly to ensure tissue regeneration/healing, at the same time as treating or preventing potential bacterial infections or superinfections. Collagen type I-based scaffolds in tandem with adequate antimicrobials can successfully fulfill these requirements. In this work, starting from the corresponding hydrogels, we prepared a series of freeze-dried atelocollagen type I-based matrices loaded with tannic acid (TA) and chlorhexidine digluconate (CHDG) as active agents with a broad spectrum of antimicrobial activity and also as crosslinkers for the collagen network. The primary aim of this study was to design an original and reliable algorithm to in vitro monitor and kinetically analyze the simultaneous release of TA and CHDG from the porous matrices into an aqueous solution of phosphate-buffered saline (PBS, pH 7.4, 37 °C) containing micellar carri...

Research paper thumbnail of Rheological Behaviour of Some Dispersions for Long Lasting Protection of Copper-Aluminium Contacts in Power Transmission Equipment

Electric and heat conducting coatings with good heat and corrosion resistance for long lasting pr... more Electric and heat conducting coatings with good heat and corrosion resistance for long lasting protection of copper-aluminium electric joints on degradation in power transmission equipment were obtained using a low viscosity epoxy resin as heat resistant binder, non-leafing aluminium powder paste and graphite as heat and electric conducting pigments, titanium dioxide and red iron oxide as anticorrosive pigments, a solution of a low molecular weight unsaturated polycarboxylic acid polymer as wetting additive, a polysiloxane copolymer as dispersing additive and n-butyl acetate as carrier. In view of establishing of optimum amount, three amounts of rheologic modifier based on a solution of a modified urea (BYK E410) was introduced into the selected base dispersion to make it more viscous at rest and thixotropic – more fluid under shear stress. Stationary rheological measurements show that the dispersion containing 40% epoxy resin, 20% aluminium pigment and 1% rheologic modifier BYK E 4...

Research paper thumbnail of Correlations on the Structure and Properties of Collagen Hydrogels Produced by E-Beam Crosslinking

Materials

In this study, a collagen hydrogel using collagen exclusively produced in Romania, was obtained b... more In this study, a collagen hydrogel using collagen exclusively produced in Romania, was obtained by electron beam (e-beam) crosslinking. The purpose of our study is to obtain new experimental data on the crosslinking of collagen and to predict as faithfully as possible, its behavior at high irradiation doses and energies. To pursue this, the correlations between macromolecular structure and properties of collagen hydrogels were determined by rheological analysis, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC), respectively. The gel fraction, swelling degree, and network parameters of the collagen hydrogels were also investigated at different irradiation doses. Through experimental exploration, we concluded that irradiation with e-beam up to 25 kGy induces crosslinking processes in collagen structure without producing advanced degradation processes. E-beam technology is a great method to develop new mater...

Research paper thumbnail of CCDC 948668: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of E-Beam Cross-Linking of Complex Hydrogels Formulation: The Influence of Poly(Ethylene Oxide) Concentration on the Hydrogel Properties

Gels

In the present study, we report on the complex hydrogels formulations based on collagen-poly(viny... more In the present study, we report on the complex hydrogels formulations based on collagen-poly(vinyl pyrrolidone) (PVP)-poly(ethylene oxide) (PEO) cross-linked by e-beam irradiation in an aqueous polymeric solution, aiming to investigate the influence of different PEO concentrations on the hydrogel properties. The hydrogel networks’ structure and their composition were investigated using equilibrium swelling degree, complex rheological analysis, and FT-IR spectroscopy. Rheological analysis was performed to determine the elastic (G′) and viscous (G″) moduli, the average molecular weight between cross-linking points (Mc), cross-link density (Ve), and the mesh size (ξ). The effect of the PEO concentration on the properties of the hydrogel was investigated as well. Depending on the PEO concentration added in their composition, the hydrogels swelling degree depends on the absorbed dose, being lower at low PEO concentrations. All hydrogel formulations showed higher G′ values (9.8 kPa) compa...

Research paper thumbnail of CCDC 948667: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 948666: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 963300: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Wide-Range Columnar and Lamellar Photoluminescent Liquid-Crystalline Lanthanide Complexes with Mesogenic 4-Pyridone Derivatives

Chemistry - A European Journal, 2018

A series of liquid crystals with various lanthanide ions (EuIII , SmIII , and TbIII ) was designe... more A series of liquid crystals with various lanthanide ions (EuIII , SmIII , and TbIII ) was designed and prepared starting from the corresponding lanthanide nitrates and N-alkylated 4-pyridone derivatives bearing mesogenic 3,4,5-tris(alkyloxy)benzyl moieties (alkyl=hexyl, octyl, decyl, dodecyl, tetradecyl, or hexadecyl). These new lanthanidomesogens were investigated for their mesogenic properties by a combination of differential scanning calorimetry, polarizing optical microscopy, and temperature-dependent powder X-ray diffraction (XRD). Their thermal stability was assessed by thermogravimetric analysis. All of these complexes show enantiotropic liquid-crystalline behavior with lamellar (SmA) phases in the case of shorter-chain complexes (C6 and C8 ) or hexagonal columnar phases (Colh ) for complexes with longer alkyl chains (C12 , C14 , and C16 ), which were assigned on the basis of their characteristic textures and XRD studies. For complexes with an intermediate number of carbon atoms in the side chains (C10 ), both a lamellar phase at lower temperatures and a Colh phase at higher temperatures were evidenced. In the solid state, all these complexes show characteristic emissions assigned to the corresponding lanthanide ion. In addition, the luminescence decay curves showed single-exponential decays with characteristic times in the millisecond range (0.75-0.90 ms for EuIII , 0.045-0.060 ms for SmIII , and 0.75-1.05 ms for TbIII ).

Research paper thumbnail of Luminescent palladium(II) metallomesogens based on cyclometalated Schiff bases and N -benzoyl thiourea derivatives as co-ligands

Journal of Organometallic Chemistry, 2017

Luminescent cyclometalated palladium(II) complexes based on Schiff bases and N-benzoylthiourea (B... more Luminescent cyclometalated palladium(II) complexes based on Schiff bases and N-benzoylthiourea (BTU) ligands with different numbers of alkoxy groups at their periphery were designed and prepared. The BTU ligands coordinate through the O and S atoms in a deprotonated bidentate fashion as confirmed by IR and NMR spectroscopy data. Additionally, giving the asymmetrical structure of BTU ligands, the 1 H-NMR showed the presence of only one of the two possible isomers. The liquid crystalline behavior of these palladium(II) complexes was investigated by a combination of polarized optical microscopy (POM) and differential scanning calorimetry (DSC) while their thermal stability was studied by thermogravimetric analysis (TGA). The mesomorphic behavior of palladium(II) complexes depends on the number and chain length of alkoxy groups grafted on BTU derivatives (monotropic smectic A and C phases). The palladium(II) complexes are thermally stable on a broad temperature range up to about 220 C. Interestingly, when the number of alkoxy groups on the BTU ancillary ligands was increased, the corresponding palladium(II) complexes lost their mesogenicity and only melting to the isotropic state was observed. The solid-state emission spectra of palladium(II) complexes show two maxima around 580 and 650 nm, respectively, with a shoulder around 710 nm when the samples are irradiated in the 330e380 nm range.

Research paper thumbnail of Tuning the liquid crystalline properties of palladium(II) metallomesogens: A study of rod-like to disc-like transition in cyclopalladated complexes with N-benzoyl thiourea derivatives

Journal of Molecular Liquids, 2017

Tuning the liquid crystalline properties of palladium(II) metallomesogens: A study of rod-like to... more Tuning the liquid crystalline properties of palladium(II) metallomesogens: A study of rod-like to disc-like transition in cyclopalladated complexes with N-benzoyl thiourea derivatives,

Research paper thumbnail of Analysis of bimodal thermally-induced denaturation of type I collagen extracted from calfskin

RSC Adv., 2015

DSC tracks of collagen in solution revealing a bimodal behaviour during its heat-induced denatura... more DSC tracks of collagen in solution revealing a bimodal behaviour during its heat-induced denaturation.

Research paper thumbnail of Luminescent liquid crystalline materials based on palladium(ii) imine derivatives containing the 2-phenylpyridine core

Dalton Transactions, 2014

In this work we report our studies concerning the synthesis and characterisation of a series of i... more In this work we report our studies concerning the synthesis and characterisation of a series of imine derivatives that incorporate the 2-phenylpyridine (2-ppy) core. These derivatives were used in the cyclometalating reactions of platinum(II) or palladium(II) in order to prepare several complexes with liquid crystalline properties. Depending on the starting materials used as well as the solvents employed, different metal complexes were obtained, some of them showing both liquid crystalline behaviour and luminescence properties at room temperature. It was found that, even if there are two competing coordination sites, the cyclometalation process takes place always at the 2-ppy core with (for Pt) or without (for Pd) the imine bond cleavage. We successfully showed that it is possible to prepare emissive room temperature liquid crystalline materials based on double cyclopalladated heteroleptic complexes by varying the volume fraction of the long flexible alkyl tails on the ancillary benzoylthiourea (BTU) ligands.

Research paper thumbnail of Influence of hydrocarbon moieties of partially fluorinated N -benzoyl thiourea compounds on their gelation properties. A detailed rheological study of complex viscoelastic behavior of decanol/ N -benzoyl thiourea mixtures

Journal of Molecular Liquids, 2018

Influence of hydrocarbon moieties of partially fluorinated N-benzoyl thiourea compounds on their ... more Influence of hydrocarbon moieties of partially fluorinated N-benzoyl thiourea compounds on their gelation properties. A detailed rheological study of complex viscoelastic behavior of decanol/N-benzoyl thiourea mixtures. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Molliq(2017),

Research paper thumbnail of Synthesis, Physicochemical Characteristics, and Biocompatibility of Multi-Component Collagen-Based Hydrogels Developed by E-Beam Irradiation

Journal of Functional Biomaterials

Herein, three different recipes of multi-component hydrogels were synthesized by e-beam irradiati... more Herein, three different recipes of multi-component hydrogels were synthesized by e-beam irradiation. These hydrogels were obtained from aqueous polymer mixtures in which different proportions of bovine collagen gel, sodium carboxymethylcellulose (CMC), poly(vinylpyrrolidone), chitosan, and poly(ethylene oxide) were used. The cross-linking reaction was carried out exclusively by e-beam cross-linking at 25 kGy, a dose of irradiation sufficient both to complete the cross-linking reaction and effective for hydrogel sterilization. The hydrogels developed in this study were tested in terms of physical and chemical stability, mechanical, structural, morphological, and biological properties. They are transparent, maintain their structure, are non-adhesive when handling, and most importantly, especially from the application point of view, have an elastic structure. Likewise, these hydrogels possessed different swelling degrees and expressed rheological behavior characteristic of soft solids ...

Research paper thumbnail of Liquid Crystalline and Gel Properties of Luminescent Cyclometalated Palladium Complexes with Benzoylthiourea Ligands

Gels

The design and development of new luminescent metallogels formed by cyclometalated palladium(II) ... more The design and development of new luminescent metallogels formed by cyclometalated palladium(II) complexes in protic solvents were investigated by a combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM), and rheology. Cyclometalated palladium(II) complexes based on imine ligand and ancillary benzoylthiourea (BTU) ligand showed red emission in solid and gel states. The formation of a lyotropic liquid crystal phase was observed for the complex bearing shorter alkyl groups on the BTU ligand. This complex also behaved as a thermotropic liquid crystal that displays a monotropic smectic A phase (SmA). Dynamic rheology measurements (frequency sweep in the 5–90 °C range) of the 1-decanol solution of palladium(II) complexes highlighted their supramolecular self-association ability to generate 3D networks and form gels as a final result.

Research paper thumbnail of Liquid Crystalline and Gel Properties of Luminescent Cyclometalated Palladium Complexes with Benzoylthiourea Ligands

Gels

The design and development of new luminescent metallogels formed by cyclometalated palladium(II) ... more The design and development of new luminescent metallogels formed by cyclometalated palladium(II) complexes in protic solvents were investigated by a combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM), and rheology. Cyclometalated palladium(II) complexes based on imine ligand and ancillary benzoylthiourea (BTU) ligand showed red emission in solid and gel states. The formation of a lyotropic liquid crystal phase was observed for the complex bearing shorter alkyl groups on the BTU ligand. This complex also behaved as a thermotropic liquid crystal that displays a monotropic smectic A phase (SmA). Dynamic rheology measurements (frequency sweep in the 5–90 °C range) of the 1-decanol solution of palladium(II) complexes highlighted their supramolecular self-association ability to generate 3D networks and form gels as a final result.

Research paper thumbnail of Novel Gemini Surfactant for Binding Eu(III)-Polyoxometalate into Hydrogels and Polymer Latexes

Gels

The incorporation of rare-earth ions into polymer matrices can lead to useful materials in variou... more The incorporation of rare-earth ions into polymer matrices can lead to useful materials in various fields such as biomarkers, lasers, luminescent devices, optical storage materials, and so on. Methods of incorporation are either extremely simple, such as mixing the polymer and the ion of interest in adequate solvents, or more sophisticated such as synthesizing predesigned monomers that contain the rare-earth ion or binding the ion on an already formed polymer chain. Cationic gemini surfactants represent a class of surfactants that can be used to incorporate metal-oxygen cluster compounds by means of strong electrostatic interactions. In this study, first, a novel cationic gemini surfactant having double bonds on both side chains was designed and prepared. After characterization, the surfactant was used to synthesize hydrogels with different degrees of crosslinking and also as a surfmer in emulsion polymerization of methyl methacrylate. The resulted polymer matrices were able to bind...

Research paper thumbnail of Characterization and in Vitro Release of Chlorhexidine Digluconate Contained in Type I Collagen Porous Matrices

Rev. Roum. …, 2011

Porous collagen matrices containing chlorhexidine digluconate (CHXD) were obtained by freeze-dryi... more Porous collagen matrices containing chlorhexidine digluconate (CHXD) were obtained by freeze-drying of three series of 1.1% collagen hydrogels having the pHs 3.8, 7.4 or 7.4 plus 0.15% glutaric aldehyde (GA) reported to the collagen from hydrogel, each series containing 0, 0.02, 0.05 or 0.10% CHXD reported to the amount of gel. FT-IR spectra show that freeze drying, pH, CHXD or/and GA do not affect the triple helical conformation of collagen molecules forming fibrils. CHXD increases a bit the crosslinking of matrices obtained from acid hydrogels irrespective of its concentration, while of those resulted from slight basic ones is reduced to a slight extent in the absence of GA and much more in its presence, which means that the crosslinking decreases with CHXD concentration increase due to its reaction with the carboxyl groups of collagen and GA respectively. Matrices' morphology reflects the changes produced in hydrogels by CHXD and/or GA: those obtained from acid hydrogels have lamellar structure, which becomes denser with increasing of CHXD concentration, orientation disappears in the matrices obtained from slight basic hydrogels, CHXD produces the agglomeration of fibrils that increases with CHXD concentration and GA enhances it. In the matrices containing 0.1% CHXD a part of it separates due to the regression of its solubility in basic media. The amounts of CHXD released from the matrices increase with CHXD concentration irrespective of pH and GA presence. The lowest amounts are released by the matrices obtained from the hydrogels with acid medium and the highest ones from the non-crosslinked matrices obtained from hydrogels with slight basic pH containing 0.1% CHXD.

Research paper thumbnail of Evidence of Counterion Size Effect on the Stability of Columnar Phase of Ionic Liquid Crystals Based on Pyridinium Salts Derived from N-3,4,5-Tri(alkyloxy)-benzyl-4-pyridones

Crystals, May 17, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of 3D Porous Collagen Matrices—A Reservoir for In Vitro Simultaneous Release of Tannic Acid and Chlorhexidine

Pharmaceutics

The treatment of wounds occurring accidentally or as a result of chronic diseases most frequently... more The treatment of wounds occurring accidentally or as a result of chronic diseases most frequently requires the use of appropriate dressings, mainly to ensure tissue regeneration/healing, at the same time as treating or preventing potential bacterial infections or superinfections. Collagen type I-based scaffolds in tandem with adequate antimicrobials can successfully fulfill these requirements. In this work, starting from the corresponding hydrogels, we prepared a series of freeze-dried atelocollagen type I-based matrices loaded with tannic acid (TA) and chlorhexidine digluconate (CHDG) as active agents with a broad spectrum of antimicrobial activity and also as crosslinkers for the collagen network. The primary aim of this study was to design an original and reliable algorithm to in vitro monitor and kinetically analyze the simultaneous release of TA and CHDG from the porous matrices into an aqueous solution of phosphate-buffered saline (PBS, pH 7.4, 37 °C) containing micellar carri...

Research paper thumbnail of Rheological Behaviour of Some Dispersions for Long Lasting Protection of Copper-Aluminium Contacts in Power Transmission Equipment

Electric and heat conducting coatings with good heat and corrosion resistance for long lasting pr... more Electric and heat conducting coatings with good heat and corrosion resistance for long lasting protection of copper-aluminium electric joints on degradation in power transmission equipment were obtained using a low viscosity epoxy resin as heat resistant binder, non-leafing aluminium powder paste and graphite as heat and electric conducting pigments, titanium dioxide and red iron oxide as anticorrosive pigments, a solution of a low molecular weight unsaturated polycarboxylic acid polymer as wetting additive, a polysiloxane copolymer as dispersing additive and n-butyl acetate as carrier. In view of establishing of optimum amount, three amounts of rheologic modifier based on a solution of a modified urea (BYK E410) was introduced into the selected base dispersion to make it more viscous at rest and thixotropic – more fluid under shear stress. Stationary rheological measurements show that the dispersion containing 40% epoxy resin, 20% aluminium pigment and 1% rheologic modifier BYK E 4...

Research paper thumbnail of Correlations on the Structure and Properties of Collagen Hydrogels Produced by E-Beam Crosslinking

Materials

In this study, a collagen hydrogel using collagen exclusively produced in Romania, was obtained b... more In this study, a collagen hydrogel using collagen exclusively produced in Romania, was obtained by electron beam (e-beam) crosslinking. The purpose of our study is to obtain new experimental data on the crosslinking of collagen and to predict as faithfully as possible, its behavior at high irradiation doses and energies. To pursue this, the correlations between macromolecular structure and properties of collagen hydrogels were determined by rheological analysis, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC), respectively. The gel fraction, swelling degree, and network parameters of the collagen hydrogels were also investigated at different irradiation doses. Through experimental exploration, we concluded that irradiation with e-beam up to 25 kGy induces crosslinking processes in collagen structure without producing advanced degradation processes. E-beam technology is a great method to develop new mater...

Research paper thumbnail of CCDC 948668: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of E-Beam Cross-Linking of Complex Hydrogels Formulation: The Influence of Poly(Ethylene Oxide) Concentration on the Hydrogel Properties

Gels

In the present study, we report on the complex hydrogels formulations based on collagen-poly(viny... more In the present study, we report on the complex hydrogels formulations based on collagen-poly(vinyl pyrrolidone) (PVP)-poly(ethylene oxide) (PEO) cross-linked by e-beam irradiation in an aqueous polymeric solution, aiming to investigate the influence of different PEO concentrations on the hydrogel properties. The hydrogel networks’ structure and their composition were investigated using equilibrium swelling degree, complex rheological analysis, and FT-IR spectroscopy. Rheological analysis was performed to determine the elastic (G′) and viscous (G″) moduli, the average molecular weight between cross-linking points (Mc), cross-link density (Ve), and the mesh size (ξ). The effect of the PEO concentration on the properties of the hydrogel was investigated as well. Depending on the PEO concentration added in their composition, the hydrogels swelling degree depends on the absorbed dose, being lower at low PEO concentrations. All hydrogel formulations showed higher G′ values (9.8 kPa) compa...

Research paper thumbnail of CCDC 948667: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 948666: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 963300: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Wide-Range Columnar and Lamellar Photoluminescent Liquid-Crystalline Lanthanide Complexes with Mesogenic 4-Pyridone Derivatives

Chemistry - A European Journal, 2018

A series of liquid crystals with various lanthanide ions (EuIII , SmIII , and TbIII ) was designe... more A series of liquid crystals with various lanthanide ions (EuIII , SmIII , and TbIII ) was designed and prepared starting from the corresponding lanthanide nitrates and N-alkylated 4-pyridone derivatives bearing mesogenic 3,4,5-tris(alkyloxy)benzyl moieties (alkyl=hexyl, octyl, decyl, dodecyl, tetradecyl, or hexadecyl). These new lanthanidomesogens were investigated for their mesogenic properties by a combination of differential scanning calorimetry, polarizing optical microscopy, and temperature-dependent powder X-ray diffraction (XRD). Their thermal stability was assessed by thermogravimetric analysis. All of these complexes show enantiotropic liquid-crystalline behavior with lamellar (SmA) phases in the case of shorter-chain complexes (C6 and C8 ) or hexagonal columnar phases (Colh ) for complexes with longer alkyl chains (C12 , C14 , and C16 ), which were assigned on the basis of their characteristic textures and XRD studies. For complexes with an intermediate number of carbon atoms in the side chains (C10 ), both a lamellar phase at lower temperatures and a Colh phase at higher temperatures were evidenced. In the solid state, all these complexes show characteristic emissions assigned to the corresponding lanthanide ion. In addition, the luminescence decay curves showed single-exponential decays with characteristic times in the millisecond range (0.75-0.90 ms for EuIII , 0.045-0.060 ms for SmIII , and 0.75-1.05 ms for TbIII ).

Research paper thumbnail of Luminescent palladium(II) metallomesogens based on cyclometalated Schiff bases and N -benzoyl thiourea derivatives as co-ligands

Journal of Organometallic Chemistry, 2017

Luminescent cyclometalated palladium(II) complexes based on Schiff bases and N-benzoylthiourea (B... more Luminescent cyclometalated palladium(II) complexes based on Schiff bases and N-benzoylthiourea (BTU) ligands with different numbers of alkoxy groups at their periphery were designed and prepared. The BTU ligands coordinate through the O and S atoms in a deprotonated bidentate fashion as confirmed by IR and NMR spectroscopy data. Additionally, giving the asymmetrical structure of BTU ligands, the 1 H-NMR showed the presence of only one of the two possible isomers. The liquid crystalline behavior of these palladium(II) complexes was investigated by a combination of polarized optical microscopy (POM) and differential scanning calorimetry (DSC) while their thermal stability was studied by thermogravimetric analysis (TGA). The mesomorphic behavior of palladium(II) complexes depends on the number and chain length of alkoxy groups grafted on BTU derivatives (monotropic smectic A and C phases). The palladium(II) complexes are thermally stable on a broad temperature range up to about 220 C. Interestingly, when the number of alkoxy groups on the BTU ancillary ligands was increased, the corresponding palladium(II) complexes lost their mesogenicity and only melting to the isotropic state was observed. The solid-state emission spectra of palladium(II) complexes show two maxima around 580 and 650 nm, respectively, with a shoulder around 710 nm when the samples are irradiated in the 330e380 nm range.

Research paper thumbnail of Tuning the liquid crystalline properties of palladium(II) metallomesogens: A study of rod-like to disc-like transition in cyclopalladated complexes with N-benzoyl thiourea derivatives

Journal of Molecular Liquids, 2017

Tuning the liquid crystalline properties of palladium(II) metallomesogens: A study of rod-like to... more Tuning the liquid crystalline properties of palladium(II) metallomesogens: A study of rod-like to disc-like transition in cyclopalladated complexes with N-benzoyl thiourea derivatives,

Research paper thumbnail of Analysis of bimodal thermally-induced denaturation of type I collagen extracted from calfskin

RSC Adv., 2015

DSC tracks of collagen in solution revealing a bimodal behaviour during its heat-induced denatura... more DSC tracks of collagen in solution revealing a bimodal behaviour during its heat-induced denaturation.

Research paper thumbnail of Luminescent liquid crystalline materials based on palladium(ii) imine derivatives containing the 2-phenylpyridine core

Dalton Transactions, 2014

In this work we report our studies concerning the synthesis and characterisation of a series of i... more In this work we report our studies concerning the synthesis and characterisation of a series of imine derivatives that incorporate the 2-phenylpyridine (2-ppy) core. These derivatives were used in the cyclometalating reactions of platinum(II) or palladium(II) in order to prepare several complexes with liquid crystalline properties. Depending on the starting materials used as well as the solvents employed, different metal complexes were obtained, some of them showing both liquid crystalline behaviour and luminescence properties at room temperature. It was found that, even if there are two competing coordination sites, the cyclometalation process takes place always at the 2-ppy core with (for Pt) or without (for Pd) the imine bond cleavage. We successfully showed that it is possible to prepare emissive room temperature liquid crystalline materials based on double cyclopalladated heteroleptic complexes by varying the volume fraction of the long flexible alkyl tails on the ancillary benzoylthiourea (BTU) ligands.

Research paper thumbnail of Influence of hydrocarbon moieties of partially fluorinated N -benzoyl thiourea compounds on their gelation properties. A detailed rheological study of complex viscoelastic behavior of decanol/ N -benzoyl thiourea mixtures

Journal of Molecular Liquids, 2018

Influence of hydrocarbon moieties of partially fluorinated N-benzoyl thiourea compounds on their ... more Influence of hydrocarbon moieties of partially fluorinated N-benzoyl thiourea compounds on their gelation properties. A detailed rheological study of complex viscoelastic behavior of decanol/N-benzoyl thiourea mixtures. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Molliq(2017),