Dario Solinas - Academia.edu (original) (raw)
Papers by Dario Solinas
Journal of Pharmaceutical and Biomedical Analysis
Bollettino chimico farmaceutico, 1982
Future Medicinal Chemistry, 2010
This study describes the influence of microwave irradiation (MW) on the preparation and propertie... more This study describes the influence of microwave irradiation (MW) on the preparation and properties of solvent-free solid dispersions (SDs) employing vitamin E D-α-tocopheryl polyethylene glycol (TPGS) 1000 succinate, with itraconazole as a model drug. Itraconazole is characterized by low aqueous solubility and vitamin E TPGS was chosen as the surfactant carrier for the formulation of MW solid dispersions in different ratios. Their physicochemical characteristics were investigated by means of powder x-ray diffraction (PXRD), differential scanning calorimetry (DSC), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and hot-stage microscopy. Comparison with the corresponding physical mixtures and the drug alone allowed the relationship between influence of the technological process on physicochemical and morphological properties of the systems to be examined. PXRD data confirmed the absence of phase transitions in the solid state of the drug subjected to MW alone. On the other hand, an amorphous form of the drug was obtained in the solid dispersion with the highest content of carrier investigated (1:3 w/w). All the SDs showed an improvement in the solubility and dissolution profile of the drug, with the best results obtained in the case of the 1:3 w/w SD. This was related to an interaction between the drug and the carrier with a complex that formed due to favorable H bonds, as demonstrated by DRIFT analysis. It was demonstrated that the amorphization of the drug led to an increase in wettability and a significant improvement in bioavailability. Therefore, SDs obtained by MW technique using vitamin E TPGS as carrier provide a promising way to increase the dissolution rate and solubility of poorly bioavailable drugs.
ABSTRACT Biosorption of Ni (II) on industrial anaerobic sludge was investigated at 308.1 K and 7.... more ABSTRACT Biosorption of Ni (II) on industrial anaerobic sludge was investigated at 308.1 K and 7.5 pH in a batch reactor. The effective metal sorption capacity was of 10.25 mgNi/gTSS. Equilibrium data were fitted using Langmuir and Freundlinch models and the results compared by non-linear regression. A better agreement with experimental data was shown by Freundlich isotherm. Effects on methane production were also studied with the purpose of investigate if the biosorption process could occur without any variation in the ability of the anaerobic sludge to produce biogas. The results reveal that methane production rapidly drops for low metal concentration and that it can be partially recovered with further mental addition.
Chemical Engineering & Technology, 2014
Supercritical carbon dioxide (sc-CO 2 ) extraction was applied to extract lipids from spent coffe... more Supercritical carbon dioxide (sc-CO 2 ) extraction was applied to extract lipids from spent coffee grounds. The effects of different process conditions on the extraction yield and composition of the extracts were investigated by response surface methodology. A comparison of the experimental results with those obtained by conventional solvent extraction was also performed. In all these samples, the main fatty acids were rich in palmitic and linoleic acids. Moreover, a new method was developed and validated for the gas chromatographic analysis of sterols and tocopherols. The results demonstrate that sc-CO 2 extraction is principally a potential candidate method for the extraction of lipids and high value-added compounds from residues/by-products.
The Journal of Supercritical Fluids, 2012
The solubility of pharmaceutical solid compounds in supercritical carbon dioxide is of great impo... more The solubility of pharmaceutical solid compounds in supercritical carbon dioxide is of great importance in a wide range of applications that include: development of drug delivery systems, powder processing, and precipitation/crystallization processes.
The Journal of Supercritical Fluids, 2010
Supercritical carbon dioxide (SCO 2 ) was used as anti-solvent to precipitate Piroxicam, a nonste... more Supercritical carbon dioxide (SCO 2 ) was used as anti-solvent to precipitate Piroxicam, a nonsteroidal anti-inflammatory drug, from different organic solvents (acetone, ethyl acetate and dichloromethane). Physicochemical properties of the samples were analyzed before and after the treatment to highlight possible changes in the form of the crystals. The solid state analysis of both products untreated and treated with CO 2 , showed that the applied method choose a particle size reduction and transition to the pure ␣ form resulting in needle-shaped crystals, regardless of the chosen solvent. In order to identify which process was responsible for the above results, Piroxicam was further precipitated from the same three solvents by traditional evaporation method (RV-samples).
The Journal of Supercritical Fluids, 2010
Drug solubility in compressed carbon dioxide is usually low, and for this reason, CO 2 is not con... more Drug solubility in compressed carbon dioxide is usually low, and for this reason, CO 2 is not considered a suitable solvent. However, it can be used as antisolvent to crystallize a solute from a liquid solution. The choice of optimal pressure and the CO 2 /drug solution ratio is a crucial point of the process, and these values must be optimized. An estimation method based on the Peng-Robinson's equation of state is presented here with which to calculate the solubility of drugs such as Acetaminophen, Acyclovir, Atenolol, Carbamazepine, Ibuprofen, Naproxen, Nimesulide, and Sotalol hydrochloride in mixtures of CO 2 and common organic solvents at a constant temperature but a variable pressure. The model temperature was 298 K for Ibuprofen and Naproxen, 315 K for Acetaminophen and 313 K for any other systems. This method is a practical and rapid alternative to experimental determination.
Journal of Chemical & Engineering Data, 2011
ABSTRACT Infinite-dilution activity coefficients for nine classes of volatile organic compounds (... more ABSTRACT Infinite-dilution activity coefficients for nine classes of volatile organic compounds (paraffins, olefins, cycloparaffins, aromatics, ketones, nitriles, alcohols, esters, and chlorocompounds) in a series of four cyclic olefin copolymers were determined using an inverse gas chromatography technique with a packed column. Abraham’s equation of solvation was used for the evaluation of the different types of interactions between the solvents and polymers. The results are compared with the activity coefficients at infinite dilution obtained for other polymers of similar use.
Journal of Chemical & Engineering Data, 2011
ABSTRACT A supercritical antisolvent precipitation process was applied to recrystallize vitamin B... more ABSTRACT A supercritical antisolvent precipitation process was applied to recrystallize vitamin B6 from ethanol solution in CO2. By means of the Peng–Robinson equation of state (PR EoS), we performed preliminary studies to identify better operative conditions in terms of the organic solvent, pressure, temperature, and ability to carry a precipitate of the solute. This simulation was also considered to estimate the vitamin B6 particle size starting from supersaturation conditions.
European Journal of Pharmaceutics and Biopharmaceutics, 2012
The 'clas... more The 'classical' loop diuretic drug Furosemide has been used as a model compound to investigate the possibility of enhancing the dissolution rate of poorly water-soluble drugs using supercritical anti-solvent techniques (SASs). In the present study we report upon the in vitro bioavailability improvement of Furosemide through particle size reduction as well as formation of solid dispersions (SDs) using the hydrophilic polymer Crospovidone. Supercritical carbon dioxide was used as the processing medium for these experiments. In order to successfully design a CO(2) antisolvent process, preliminary studies of Furosemide microparticles generation were conducted using Peng Robinson's Equation of State. These preliminary studies indicated using acetone as a solvent with pressures of 100 and 200bar and a temperature of 313K would yield optimum results. These operative conditions were then adopted for the SDs. Micronization by means of SAS at 200bar resulted in a significant reduction of crystallites, particle size, as well as improved dissolution rate in comparison with untreated drug. Furosemide recrystallized by SAS at 100bar and using traditional solvent evaporation. Moreover, changes in polymorphic form were observed in the 200bar samples. The physicochemical characterization of Furosemide:crospovidone SDs (1:1 and 1:2 w/w, respectively) generated by SAS revealed the presence of the drug amorphously dispersed in the 1:2 w/w sample at 100bar still remaining stable after 6months. This sample exhibits the best in vitro dissolution performance in the simulated gastric fluid (pH 1.2), in comparison with the same SD obtained by traditional method. No interactions between drug and polymer were observed. These results, together with the presence of the selected carrier, confirm that the use of Supercritical fluids antisolvent technology is a valid mean to increase the dissolution rate of poorly soluble drugs. Theoretical in vivo-in vitro relation was predicted by means of a pharmacokinetics mathematical model.
Applied Physics Letters, 2003
Supercritical carbon dioxide (SCCO2) extraction of a CO 2 -soluble poly(propylene glycol) (PPG) p... more Supercritical carbon dioxide (SCCO2) extraction of a CO 2 -soluble poly(propylene glycol) (PPG) porogen from poly(methylsilsesquioxane) (PMSSQ) cured to temperatures adequate to initiate matrix condensation, but still below the decomposition temperature of the porogen is demonstrated to produce nanoporous, ultralow dielectric constant thin films. Both closed and open cell porous structures were prepared simply by varying the porogen load in the organic/inorganic hybrid films. The porogen loads investigated in the present work ranged from 25 -55 wt.%. Structural characterization of the samples conducted using transmission electron microscope (TEM), small angle X-ray scattering (SAXS) and Fourier transform infrared spectroscopy (FTIR) confirms the successful extraction of the porogen from the PMSSQ matrix at relatively low temperatures (≤200 o C). The standard thermal decomposition process is performed at much higher temperatures (typically in the range of 400 o C-450 o C). The values of dielectric constants and refractive indices measured are in good agreement with the structural properties of these samples.
Biomacromolecules, 2012
The development of biomaterials endowed with bioactive features relies on a simultaneous insight ... more The development of biomaterials endowed with bioactive features relies on a simultaneous insight into a proper terminal sterilization process. FDA recommendations on sterility of biomaterials are very strict: a sterility assurance level (SAL) of 10 −6 must be guaranteed for biomaterials to be used in human implants. In the present work, we have explored the potential of supercritical CO 2 (scCO 2 ) in the presence of H 2 O 2 as a low-temperature sterilization process for thermoset materials and their bioactive surfaces. Different conditions allowing for terminal sterilization have been screened and a treatment time−amount of H 2 O 2 relationship proposed. The selected terminal sterilization conditions did not notably modify the mechanical properties of the thermoset nor of their fiber-reinforced composites. This was confirmed by μCT analyses performed prior to and after the treatment. On the contrary, terminal sterilization in the presence of H 2 O 2 induced a slight decrease in the surface hardness. The treatment of the thermoset material with scCO 2 led to a reduction in the residual unreacted monomers content, as determined by means of high performance liquid chromatography (HPLC) analyses. Finally, it was found that a thermoset coated with a polysaccharide layer containing silver nanoparticles maintained a very high antimicrobial efficacy even after the scCO 2 -based terminal sterilization.
Journal of Pharmaceutical and Biomedical Analysis
Bollettino chimico farmaceutico, 1982
Future Medicinal Chemistry, 2010
This study describes the influence of microwave irradiation (MW) on the preparation and propertie... more This study describes the influence of microwave irradiation (MW) on the preparation and properties of solvent-free solid dispersions (SDs) employing vitamin E D-α-tocopheryl polyethylene glycol (TPGS) 1000 succinate, with itraconazole as a model drug. Itraconazole is characterized by low aqueous solubility and vitamin E TPGS was chosen as the surfactant carrier for the formulation of MW solid dispersions in different ratios. Their physicochemical characteristics were investigated by means of powder x-ray diffraction (PXRD), differential scanning calorimetry (DSC), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and hot-stage microscopy. Comparison with the corresponding physical mixtures and the drug alone allowed the relationship between influence of the technological process on physicochemical and morphological properties of the systems to be examined. PXRD data confirmed the absence of phase transitions in the solid state of the drug subjected to MW alone. On the other hand, an amorphous form of the drug was obtained in the solid dispersion with the highest content of carrier investigated (1:3 w/w). All the SDs showed an improvement in the solubility and dissolution profile of the drug, with the best results obtained in the case of the 1:3 w/w SD. This was related to an interaction between the drug and the carrier with a complex that formed due to favorable H bonds, as demonstrated by DRIFT analysis. It was demonstrated that the amorphization of the drug led to an increase in wettability and a significant improvement in bioavailability. Therefore, SDs obtained by MW technique using vitamin E TPGS as carrier provide a promising way to increase the dissolution rate and solubility of poorly bioavailable drugs.
ABSTRACT Biosorption of Ni (II) on industrial anaerobic sludge was investigated at 308.1 K and 7.... more ABSTRACT Biosorption of Ni (II) on industrial anaerobic sludge was investigated at 308.1 K and 7.5 pH in a batch reactor. The effective metal sorption capacity was of 10.25 mgNi/gTSS. Equilibrium data were fitted using Langmuir and Freundlinch models and the results compared by non-linear regression. A better agreement with experimental data was shown by Freundlich isotherm. Effects on methane production were also studied with the purpose of investigate if the biosorption process could occur without any variation in the ability of the anaerobic sludge to produce biogas. The results reveal that methane production rapidly drops for low metal concentration and that it can be partially recovered with further mental addition.
Chemical Engineering & Technology, 2014
Supercritical carbon dioxide (sc-CO 2 ) extraction was applied to extract lipids from spent coffe... more Supercritical carbon dioxide (sc-CO 2 ) extraction was applied to extract lipids from spent coffee grounds. The effects of different process conditions on the extraction yield and composition of the extracts were investigated by response surface methodology. A comparison of the experimental results with those obtained by conventional solvent extraction was also performed. In all these samples, the main fatty acids were rich in palmitic and linoleic acids. Moreover, a new method was developed and validated for the gas chromatographic analysis of sterols and tocopherols. The results demonstrate that sc-CO 2 extraction is principally a potential candidate method for the extraction of lipids and high value-added compounds from residues/by-products.
The Journal of Supercritical Fluids, 2012
The solubility of pharmaceutical solid compounds in supercritical carbon dioxide is of great impo... more The solubility of pharmaceutical solid compounds in supercritical carbon dioxide is of great importance in a wide range of applications that include: development of drug delivery systems, powder processing, and precipitation/crystallization processes.
The Journal of Supercritical Fluids, 2010
Supercritical carbon dioxide (SCO 2 ) was used as anti-solvent to precipitate Piroxicam, a nonste... more Supercritical carbon dioxide (SCO 2 ) was used as anti-solvent to precipitate Piroxicam, a nonsteroidal anti-inflammatory drug, from different organic solvents (acetone, ethyl acetate and dichloromethane). Physicochemical properties of the samples were analyzed before and after the treatment to highlight possible changes in the form of the crystals. The solid state analysis of both products untreated and treated with CO 2 , showed that the applied method choose a particle size reduction and transition to the pure ␣ form resulting in needle-shaped crystals, regardless of the chosen solvent. In order to identify which process was responsible for the above results, Piroxicam was further precipitated from the same three solvents by traditional evaporation method (RV-samples).
The Journal of Supercritical Fluids, 2010
Drug solubility in compressed carbon dioxide is usually low, and for this reason, CO 2 is not con... more Drug solubility in compressed carbon dioxide is usually low, and for this reason, CO 2 is not considered a suitable solvent. However, it can be used as antisolvent to crystallize a solute from a liquid solution. The choice of optimal pressure and the CO 2 /drug solution ratio is a crucial point of the process, and these values must be optimized. An estimation method based on the Peng-Robinson's equation of state is presented here with which to calculate the solubility of drugs such as Acetaminophen, Acyclovir, Atenolol, Carbamazepine, Ibuprofen, Naproxen, Nimesulide, and Sotalol hydrochloride in mixtures of CO 2 and common organic solvents at a constant temperature but a variable pressure. The model temperature was 298 K for Ibuprofen and Naproxen, 315 K for Acetaminophen and 313 K for any other systems. This method is a practical and rapid alternative to experimental determination.
Journal of Chemical & Engineering Data, 2011
ABSTRACT Infinite-dilution activity coefficients for nine classes of volatile organic compounds (... more ABSTRACT Infinite-dilution activity coefficients for nine classes of volatile organic compounds (paraffins, olefins, cycloparaffins, aromatics, ketones, nitriles, alcohols, esters, and chlorocompounds) in a series of four cyclic olefin copolymers were determined using an inverse gas chromatography technique with a packed column. Abraham’s equation of solvation was used for the evaluation of the different types of interactions between the solvents and polymers. The results are compared with the activity coefficients at infinite dilution obtained for other polymers of similar use.
Journal of Chemical & Engineering Data, 2011
ABSTRACT A supercritical antisolvent precipitation process was applied to recrystallize vitamin B... more ABSTRACT A supercritical antisolvent precipitation process was applied to recrystallize vitamin B6 from ethanol solution in CO2. By means of the Peng–Robinson equation of state (PR EoS), we performed preliminary studies to identify better operative conditions in terms of the organic solvent, pressure, temperature, and ability to carry a precipitate of the solute. This simulation was also considered to estimate the vitamin B6 particle size starting from supersaturation conditions.
European Journal of Pharmaceutics and Biopharmaceutics, 2012
The 'clas... more The 'classical' loop diuretic drug Furosemide has been used as a model compound to investigate the possibility of enhancing the dissolution rate of poorly water-soluble drugs using supercritical anti-solvent techniques (SASs). In the present study we report upon the in vitro bioavailability improvement of Furosemide through particle size reduction as well as formation of solid dispersions (SDs) using the hydrophilic polymer Crospovidone. Supercritical carbon dioxide was used as the processing medium for these experiments. In order to successfully design a CO(2) antisolvent process, preliminary studies of Furosemide microparticles generation were conducted using Peng Robinson's Equation of State. These preliminary studies indicated using acetone as a solvent with pressures of 100 and 200bar and a temperature of 313K would yield optimum results. These operative conditions were then adopted for the SDs. Micronization by means of SAS at 200bar resulted in a significant reduction of crystallites, particle size, as well as improved dissolution rate in comparison with untreated drug. Furosemide recrystallized by SAS at 100bar and using traditional solvent evaporation. Moreover, changes in polymorphic form were observed in the 200bar samples. The physicochemical characterization of Furosemide:crospovidone SDs (1:1 and 1:2 w/w, respectively) generated by SAS revealed the presence of the drug amorphously dispersed in the 1:2 w/w sample at 100bar still remaining stable after 6months. This sample exhibits the best in vitro dissolution performance in the simulated gastric fluid (pH 1.2), in comparison with the same SD obtained by traditional method. No interactions between drug and polymer were observed. These results, together with the presence of the selected carrier, confirm that the use of Supercritical fluids antisolvent technology is a valid mean to increase the dissolution rate of poorly soluble drugs. Theoretical in vivo-in vitro relation was predicted by means of a pharmacokinetics mathematical model.
Applied Physics Letters, 2003
Supercritical carbon dioxide (SCCO2) extraction of a CO 2 -soluble poly(propylene glycol) (PPG) p... more Supercritical carbon dioxide (SCCO2) extraction of a CO 2 -soluble poly(propylene glycol) (PPG) porogen from poly(methylsilsesquioxane) (PMSSQ) cured to temperatures adequate to initiate matrix condensation, but still below the decomposition temperature of the porogen is demonstrated to produce nanoporous, ultralow dielectric constant thin films. Both closed and open cell porous structures were prepared simply by varying the porogen load in the organic/inorganic hybrid films. The porogen loads investigated in the present work ranged from 25 -55 wt.%. Structural characterization of the samples conducted using transmission electron microscope (TEM), small angle X-ray scattering (SAXS) and Fourier transform infrared spectroscopy (FTIR) confirms the successful extraction of the porogen from the PMSSQ matrix at relatively low temperatures (≤200 o C). The standard thermal decomposition process is performed at much higher temperatures (typically in the range of 400 o C-450 o C). The values of dielectric constants and refractive indices measured are in good agreement with the structural properties of these samples.
Biomacromolecules, 2012
The development of biomaterials endowed with bioactive features relies on a simultaneous insight ... more The development of biomaterials endowed with bioactive features relies on a simultaneous insight into a proper terminal sterilization process. FDA recommendations on sterility of biomaterials are very strict: a sterility assurance level (SAL) of 10 −6 must be guaranteed for biomaterials to be used in human implants. In the present work, we have explored the potential of supercritical CO 2 (scCO 2 ) in the presence of H 2 O 2 as a low-temperature sterilization process for thermoset materials and their bioactive surfaces. Different conditions allowing for terminal sterilization have been screened and a treatment time−amount of H 2 O 2 relationship proposed. The selected terminal sterilization conditions did not notably modify the mechanical properties of the thermoset nor of their fiber-reinforced composites. This was confirmed by μCT analyses performed prior to and after the treatment. On the contrary, terminal sterilization in the presence of H 2 O 2 induced a slight decrease in the surface hardness. The treatment of the thermoset material with scCO 2 led to a reduction in the residual unreacted monomers content, as determined by means of high performance liquid chromatography (HPLC) analyses. Finally, it was found that a thermoset coated with a polysaccharide layer containing silver nanoparticles maintained a very high antimicrobial efficacy even after the scCO 2 -based terminal sterilization.