Daniela Apreutesei - Academia.edu (original) (raw)
Papers by Daniela Apreutesei
Pharmaceutics
In the last 20 years, the development of stimuli-responsive drug delivery systems (DDS) has recei... more In the last 20 years, the development of stimuli-responsive drug delivery systems (DDS) has received great attention. Hydrogel microparticles represent one of the candidates with the most potential. However, if the role of the cross-linking method, polymer composition, and concentration on their performance as DDS has been well-studied, still, a lot needs to be explained regarding the effect caused by the morphology. To investigate this, herein, we report the fabrication of PEGDA–ALMA-based microgels with spherical and asymmetric shapes for 5-fluorouracil (5-FU) on-demand loading and in vitro pH-triggered release. Due to anisotropic properties, the asymmetric particles showed an increased drug adsorption and higher pH responsiveness, which in turn led to a higher desorption efficacy at the target pH environment, making them an ideal candidate for oral administration of 5-FU in colorectal cancer. The cytotoxicity of empty spherical microgels was higher than the cytotoxicity of empty ...
Revue Roumaine de Chimie
This paper reports the density and viscosity of acetic acid-toluene mixtures at five temperatures... more This paper reports the density and viscosity of acetic acid-toluene mixtures at five temperatures in the range 23°C to 46°C throughout the whole concentration range. The excess molar volumes and viscosity deviations were calculated from experimental data and fitted to a Redlich-Kister polynomial function. Results were analyzed in terms of molecular interactions.
Revue Roumaine de …, 2008
The present paper studies the prediction possibilities of the liquid crystalline behavior for som... more The present paper studies the prediction possibilities of the liquid crystalline behavior for some symmetrically derivatives with two ferrocene units using the artificial intelligence methods neural networks. The liquid crystalline property is correlated with chemical structure of the ...
1 Results Liquid crystalline dendrimers and structurally related multipodes are supermolecules co... more 1 Results Liquid crystalline dendrimers and structurally related multipodes are supermolecules consisting of an amorphous hyper-branched core at the periphery of which are attached mesogenic groups capable of self-organization.Two opposite tendencies compete in these systems: the internal dendrimer tends to adopt a pseudo-spherical architecture that has a disordering influence on the packing of the mesogenic parts whose tend to self-organize into partially ordered structures.These kinds of systems show ...
Molecular Crystals and Liquid Crystals, 2008
In order to contribute to the understanding of the origin of biaxial nematic ordering in tetrapod... more In order to contribute to the understanding of the origin of biaxial nematic ordering in tetrapodes, a deuterium NMR study was performed on mixtures of monomers from organosiloxane tetrapodes with a deuterated nematic probe. Contrary to the tetrapode system previously studied, which exhibits a biaxial nematic phase, the results for monomers are compatible, within the experimental error, with uniaxial nematic
Molecular Crystals and Liquid Crystals, 2006
The synthesis and the phase behaviour of nematic dimers, built up from rod and disc shaped mesoge... more The synthesis and the phase behaviour of nematic dimers, built up from rod and disc shaped mesogens, separated by extended spacers is described. Miscibility studies with the rod as well as disc shaped mesogens were performed and OPM data of contact samples and the results of detailed DSC experiments of mixtures are presented. Full miscibility in the nematic phase was
Journal of Materials Chemistry, 2007
The investigation of this class of materials is therefore important for the fundamental understan... more The investigation of this class of materials is therefore important for the fundamental understanding of structureproperties relationships of mesomorphic systems. Investigations are, however, very often hampered by the generally high transition temperatures observed for oxadiazoles, ...
Electrochemistry Communications, 2008
The syntheses and characterization of two ferrocene oils, 4-octyloxy-2-{5-[1,1,3,3-tetramethyl-3-... more The syntheses and characterization of two ferrocene oils, 4-octyloxy-2-{5-[1,1,3,3-tetramethyl-3-(11oxo-11-ferrocenyl-undecyl)-disiloxanyl]-pentyloxy}-benzoic acid 4 0-undecyloxy-biphenyl-4-yl ester, Fc1SiM and an octakis(ferrocene) species, Fc8Si8M 0 are reported, and their biphasic aqueous voltammetry contrasted. Surprisingly, both hydrophobic species undergo single-wave electrochemical dissolution. This can be advantageous to electroanalytical applications.
Chemical Communications, 2006
Disc and rod shaped molecules which are completely miscible in the nematic phase were synthesised... more Disc and rod shaped molecules which are completely miscible in the nematic phase were synthesised and the miscibility behaviour was investigated and confirmed by POM, DSC and XRD studies.
Physical Review E, 2008
High-resolution adiabatic scanning calorimetry and differential scanning calorimetry have been em... more High-resolution adiabatic scanning calorimetry and differential scanning calorimetry have been employed to study the thermal behaviour of an organo-siloxane tetrapode reported to exhibit a biaxial nematic phase. No signature of the uniaxial to biaxial nematic phase transition could be retraced in sequential heating and cooling runs under different scanning rates, within the experimental resolution. The results obtained in this work reveal that an extremely small heat should be involved in the uniaxial to biaxial nematic phase transition. The isotropic to uniaxial nematic transition at 318 ± 0.01 K is very stable and it is weakly first order with a rather small latent heat of 0.20 ± 0.02 J/g.
Liq Cryst, 2007
The synthesis and mesogenic properties of some Schiff bases containing ferrocene, azobenzene unit... more The synthesis and mesogenic properties of some Schiff bases containing ferrocene, azobenzene units and flexible end chains with 17 or 18 carbon atoms are reported. The compounds have been characterized by H‐NMR and C‐NMR spectroscopy, DSC and optical microscopy in polarized light.
Journal of Optoelectronics and Advanced Materials, 2006
Ferrocene liquid crystals received a great attention in the last years, mainly because of its int... more Ferrocene liquid crystals received a great attention in the last years, mainly because of its interesting properties and the combination between liquid crystals properties with metals properties. Only few examples of ferrocene liquid crystals bearing either cholesteryl or azo aromatic unit could be found in the literature. The presence of each of three groups contribute by specific properties to the obtaining of materials capable of responding in electric or magnetic field or to UV light exposure. The azo aromatic units are photo-sensitive due to cis-trans photoizomerization and can be used as switchers in liquid crystals devises. On the other hand, the cholesteryl unit induces chiral mesophases with the advantage of fast response on stimuli, high birefringence and the presence of physical colors. Since mesomorphic behavior for the thermotropic liquid crystals are due to the increasing of temperature in the system, it is easy to understand the importance of thermal stability for such kind of systems. The purpose of the paper is the study the thermal stability of some ferrocene liquid crystals bearing both azo and cholesteryl and to evaluate the influence of each structural factor such as: ferrocenyl, cholesteryl, azo units and the length of the flexible chain on the thermal stability of these compounds.
Ferrocene liquid crystals received a great attention in the last years, mainly because of its int... more Ferrocene liquid crystals received a great attention in the last years, mainly because of its interesting properties and the combination between liquid crystals properties with metals properties. Only few examples of ferrocene liquid crystals bearing either cholesteryl or azo aromatic unit could be found in the literature. The presence of each of three groups contribute by specific properties to the
Physical Review E, 2008
High-resolution adiabatic scanning calorimetry and differential scanning calorimetry have been em... more High-resolution adiabatic scanning calorimetry and differential scanning calorimetry have been employed to study the thermal behavior of an organo-siloxane tetrapode reported to exhibit a biaxial nematic phase. No signature of the uniaxial to biaxial nematic phase transition could be retraced in sequential heating and cooling runs under different scanning rates, within the experimental resolution. The results obtained reveal that an extremely small heat should be involved in the uniaxial to biaxial nematic phase transition. The isotropic to uniaxial nematic transition at 318+/-0.01 K is very stable, and it is weakly first order with a rather small latent heat of 0.20+/-0.02 J/g .
Molecular Crystals and Liquid Crystals, 2008
Molecular Crystals and Liquid Crystals, 2006
The synthesis and the phase behaviour of nematic dimers, built up from rod and disc shaped mesoge... more The synthesis and the phase behaviour of nematic dimers, built up from rod and disc shaped mesogens, separated by extended spacers is described. Miscibility studies with the rod as well as disc shaped mesogens were performed and OPM data of contact samples and the results of detailed DSC experiments of mixtures are presented. Full miscibility in the nematic phase was
Liquid Crystals, 2007
The synthesis and mesogenic properties of some Schiff bases containing ferrocene, azobenzene unit... more The synthesis and mesogenic properties of some Schiff bases containing ferrocene, azobenzene units and flexible end chains with 17 or 18 carbon atoms are reported. The compounds have been characterized by H‐NMR and C‐NMR spectroscopy, DSC and optical microscopy in polarized light.
Liquid Crystals, 2007
The synthesis and characterization of new liquid crystalline compounds containing ferrocene azo o... more The synthesis and characterization of new liquid crystalline compounds containing ferrocene azo or imino aromatic and cholesteryl units is reported. The purpose of this research was to combine the properties of metals (colour, electronic density, magnetism and polarizability) with those of chiral nematics (high birefringence and presence of physical colours) and correlate relationships between chemical structures and properties in the
Journal of Thermal Analysis and Calorimetry, 2006
Liquid crystals are materials in which the meso-morphic properties appear in a certain temperatur... more Liquid crystals are materials in which the meso-morphic properties appear in a certain temperature domain, so that thermal stability plays an important role for such compounds [1]. For example, in the case of liquid crystals with the clearing point above the de-composition ...
Journal of Materials Chemistry, 2007
The investigation of this class of materials is therefore important for the fundamental understan... more The investigation of this class of materials is therefore important for the fundamental understanding of structureproperties relationships of mesomorphic systems. Investigations are, however, very often hampered by the generally high transition temperatures observed for oxadiazoles, ...
Pharmaceutics
In the last 20 years, the development of stimuli-responsive drug delivery systems (DDS) has recei... more In the last 20 years, the development of stimuli-responsive drug delivery systems (DDS) has received great attention. Hydrogel microparticles represent one of the candidates with the most potential. However, if the role of the cross-linking method, polymer composition, and concentration on their performance as DDS has been well-studied, still, a lot needs to be explained regarding the effect caused by the morphology. To investigate this, herein, we report the fabrication of PEGDA–ALMA-based microgels with spherical and asymmetric shapes for 5-fluorouracil (5-FU) on-demand loading and in vitro pH-triggered release. Due to anisotropic properties, the asymmetric particles showed an increased drug adsorption and higher pH responsiveness, which in turn led to a higher desorption efficacy at the target pH environment, making them an ideal candidate for oral administration of 5-FU in colorectal cancer. The cytotoxicity of empty spherical microgels was higher than the cytotoxicity of empty ...
Revue Roumaine de Chimie
This paper reports the density and viscosity of acetic acid-toluene mixtures at five temperatures... more This paper reports the density and viscosity of acetic acid-toluene mixtures at five temperatures in the range 23°C to 46°C throughout the whole concentration range. The excess molar volumes and viscosity deviations were calculated from experimental data and fitted to a Redlich-Kister polynomial function. Results were analyzed in terms of molecular interactions.
Revue Roumaine de …, 2008
The present paper studies the prediction possibilities of the liquid crystalline behavior for som... more The present paper studies the prediction possibilities of the liquid crystalline behavior for some symmetrically derivatives with two ferrocene units using the artificial intelligence methods neural networks. The liquid crystalline property is correlated with chemical structure of the ...
1 Results Liquid crystalline dendrimers and structurally related multipodes are supermolecules co... more 1 Results Liquid crystalline dendrimers and structurally related multipodes are supermolecules consisting of an amorphous hyper-branched core at the periphery of which are attached mesogenic groups capable of self-organization.Two opposite tendencies compete in these systems: the internal dendrimer tends to adopt a pseudo-spherical architecture that has a disordering influence on the packing of the mesogenic parts whose tend to self-organize into partially ordered structures.These kinds of systems show ...
Molecular Crystals and Liquid Crystals, 2008
In order to contribute to the understanding of the origin of biaxial nematic ordering in tetrapod... more In order to contribute to the understanding of the origin of biaxial nematic ordering in tetrapodes, a deuterium NMR study was performed on mixtures of monomers from organosiloxane tetrapodes with a deuterated nematic probe. Contrary to the tetrapode system previously studied, which exhibits a biaxial nematic phase, the results for monomers are compatible, within the experimental error, with uniaxial nematic
Molecular Crystals and Liquid Crystals, 2006
The synthesis and the phase behaviour of nematic dimers, built up from rod and disc shaped mesoge... more The synthesis and the phase behaviour of nematic dimers, built up from rod and disc shaped mesogens, separated by extended spacers is described. Miscibility studies with the rod as well as disc shaped mesogens were performed and OPM data of contact samples and the results of detailed DSC experiments of mixtures are presented. Full miscibility in the nematic phase was
Journal of Materials Chemistry, 2007
The investigation of this class of materials is therefore important for the fundamental understan... more The investigation of this class of materials is therefore important for the fundamental understanding of structureproperties relationships of mesomorphic systems. Investigations are, however, very often hampered by the generally high transition temperatures observed for oxadiazoles, ...
Electrochemistry Communications, 2008
The syntheses and characterization of two ferrocene oils, 4-octyloxy-2-{5-[1,1,3,3-tetramethyl-3-... more The syntheses and characterization of two ferrocene oils, 4-octyloxy-2-{5-[1,1,3,3-tetramethyl-3-(11oxo-11-ferrocenyl-undecyl)-disiloxanyl]-pentyloxy}-benzoic acid 4 0-undecyloxy-biphenyl-4-yl ester, Fc1SiM and an octakis(ferrocene) species, Fc8Si8M 0 are reported, and their biphasic aqueous voltammetry contrasted. Surprisingly, both hydrophobic species undergo single-wave electrochemical dissolution. This can be advantageous to electroanalytical applications.
Chemical Communications, 2006
Disc and rod shaped molecules which are completely miscible in the nematic phase were synthesised... more Disc and rod shaped molecules which are completely miscible in the nematic phase were synthesised and the miscibility behaviour was investigated and confirmed by POM, DSC and XRD studies.
Physical Review E, 2008
High-resolution adiabatic scanning calorimetry and differential scanning calorimetry have been em... more High-resolution adiabatic scanning calorimetry and differential scanning calorimetry have been employed to study the thermal behaviour of an organo-siloxane tetrapode reported to exhibit a biaxial nematic phase. No signature of the uniaxial to biaxial nematic phase transition could be retraced in sequential heating and cooling runs under different scanning rates, within the experimental resolution. The results obtained in this work reveal that an extremely small heat should be involved in the uniaxial to biaxial nematic phase transition. The isotropic to uniaxial nematic transition at 318 ± 0.01 K is very stable and it is weakly first order with a rather small latent heat of 0.20 ± 0.02 J/g.
Liq Cryst, 2007
The synthesis and mesogenic properties of some Schiff bases containing ferrocene, azobenzene unit... more The synthesis and mesogenic properties of some Schiff bases containing ferrocene, azobenzene units and flexible end chains with 17 or 18 carbon atoms are reported. The compounds have been characterized by H‐NMR and C‐NMR spectroscopy, DSC and optical microscopy in polarized light.
Journal of Optoelectronics and Advanced Materials, 2006
Ferrocene liquid crystals received a great attention in the last years, mainly because of its int... more Ferrocene liquid crystals received a great attention in the last years, mainly because of its interesting properties and the combination between liquid crystals properties with metals properties. Only few examples of ferrocene liquid crystals bearing either cholesteryl or azo aromatic unit could be found in the literature. The presence of each of three groups contribute by specific properties to the obtaining of materials capable of responding in electric or magnetic field or to UV light exposure. The azo aromatic units are photo-sensitive due to cis-trans photoizomerization and can be used as switchers in liquid crystals devises. On the other hand, the cholesteryl unit induces chiral mesophases with the advantage of fast response on stimuli, high birefringence and the presence of physical colors. Since mesomorphic behavior for the thermotropic liquid crystals are due to the increasing of temperature in the system, it is easy to understand the importance of thermal stability for such kind of systems. The purpose of the paper is the study the thermal stability of some ferrocene liquid crystals bearing both azo and cholesteryl and to evaluate the influence of each structural factor such as: ferrocenyl, cholesteryl, azo units and the length of the flexible chain on the thermal stability of these compounds.
Ferrocene liquid crystals received a great attention in the last years, mainly because of its int... more Ferrocene liquid crystals received a great attention in the last years, mainly because of its interesting properties and the combination between liquid crystals properties with metals properties. Only few examples of ferrocene liquid crystals bearing either cholesteryl or azo aromatic unit could be found in the literature. The presence of each of three groups contribute by specific properties to the
Physical Review E, 2008
High-resolution adiabatic scanning calorimetry and differential scanning calorimetry have been em... more High-resolution adiabatic scanning calorimetry and differential scanning calorimetry have been employed to study the thermal behavior of an organo-siloxane tetrapode reported to exhibit a biaxial nematic phase. No signature of the uniaxial to biaxial nematic phase transition could be retraced in sequential heating and cooling runs under different scanning rates, within the experimental resolution. The results obtained reveal that an extremely small heat should be involved in the uniaxial to biaxial nematic phase transition. The isotropic to uniaxial nematic transition at 318+/-0.01 K is very stable, and it is weakly first order with a rather small latent heat of 0.20+/-0.02 J/g .
Molecular Crystals and Liquid Crystals, 2008
Molecular Crystals and Liquid Crystals, 2006
The synthesis and the phase behaviour of nematic dimers, built up from rod and disc shaped mesoge... more The synthesis and the phase behaviour of nematic dimers, built up from rod and disc shaped mesogens, separated by extended spacers is described. Miscibility studies with the rod as well as disc shaped mesogens were performed and OPM data of contact samples and the results of detailed DSC experiments of mixtures are presented. Full miscibility in the nematic phase was
Liquid Crystals, 2007
The synthesis and mesogenic properties of some Schiff bases containing ferrocene, azobenzene unit... more The synthesis and mesogenic properties of some Schiff bases containing ferrocene, azobenzene units and flexible end chains with 17 or 18 carbon atoms are reported. The compounds have been characterized by H‐NMR and C‐NMR spectroscopy, DSC and optical microscopy in polarized light.
Liquid Crystals, 2007
The synthesis and characterization of new liquid crystalline compounds containing ferrocene azo o... more The synthesis and characterization of new liquid crystalline compounds containing ferrocene azo or imino aromatic and cholesteryl units is reported. The purpose of this research was to combine the properties of metals (colour, electronic density, magnetism and polarizability) with those of chiral nematics (high birefringence and presence of physical colours) and correlate relationships between chemical structures and properties in the
Journal of Thermal Analysis and Calorimetry, 2006
Liquid crystals are materials in which the meso-morphic properties appear in a certain temperatur... more Liquid crystals are materials in which the meso-morphic properties appear in a certain temperature domain, so that thermal stability plays an important role for such compounds [1]. For example, in the case of liquid crystals with the clearing point above the de-composition ...
Journal of Materials Chemistry, 2007
The investigation of this class of materials is therefore important for the fundamental understan... more The investigation of this class of materials is therefore important for the fundamental understanding of structureproperties relationships of mesomorphic systems. Investigations are, however, very often hampered by the generally high transition temperatures observed for oxadiazoles, ...