The recyclability of opaque PET, which contains TiO2 nanoparticles, has not been as well-studied ... more The recyclability of opaque PET, which contains TiO2 nanoparticles, has not been as well-studied as that of transparent PET. The objective of this work is to recycle post-consumer opaque PET through reactive extrusion with Joncryl. The effect of the reactive extrusion process on the molecular structure and on the thermal/mechanical/rheological properties of recycling post-consumer opaque PET (r-PET) has been analyzed. A 1% w/w Joncryl addition caused a moderate increase in the molecular weight. A moderate increase in chain length could not explain a decrease in the overall crystallization rate. This result is probably due to the presence of branches interrupting the crystallizable sequences in reactive extruded r-PET (REX-r-PET). A rheological investigation performed by SAOS/LAOS/elongational studies detected important structural modifications in REX-r-PET with respect to linear r-PET or a reference virgin PET. REX-r-PET is characterized by a slow relaxation process with enlarged el...
The treatment of osteochondral defects remains a challenge. Four scaffolds were produced using Fo... more The treatment of osteochondral defects remains a challenge. Four scaffolds were produced using Food and Drug Administration (FDA)-approved polymers to investigate their therapeutic potential for the regeneration of the osteochondral unit. Polycaprolactone (PCL) and poly(vinyl-pyrrolidone) (PVP) scaffolds were made by electrohydrodynamic techniques. Hydroxyapatite (HAp) and/or sodium hyaluronate (HA) can be then loaded to PCL nanofibers and/or PVP particles. The purpose of adding hydroxyapatite and sodium hyaluronate into PCL/PVP scaffolds is to increase the regenerative ability for subchondral bone and joint cartilage, respectively. Human bone marrow-derived mesenchymal stem cells (hBM-MSCs) were seeded on these biomaterials. The biocompatibility of these biomaterials in vitro and in vivo, as well as their potential to support MSC differentiation under specific chondrogenic or osteogenic conditions, were evaluated. We show here that hBM-MSCs could proliferate and differentiate both ...
The objective of the present work was to produce gastroresistant Eudragit® RS100 nanoparticles by... more The objective of the present work was to produce gastroresistant Eudragit® RS100 nanoparticles by a reproducible synthesis approach that ensured mono-disperse nanoparticles under the size of 100 nm. Batch and micromixing nanoprecipitation approaches were selected to produce the demanded nanoparticles, identifying the critical parameters affecting the synthesis process. To shed some light on the formulation of the targeted nanoparticles, the effects of particle size and homogeneity of fluid dynamics, and physicochemical parameters such as polymer concentration, type of solvent, ratio of solvent to antisolvent, and total flow rate were studied. The physicochemical characteristics of resulting nanoparticles were studied applying dynamic light scattering (DLS) particle size analysis and electron microscopy imaging. Nanoparticles produced using a micromixer demonstrated a narrower and more homogenous distribution than the ones obtained under similar conditions in conventional batch react...
For the effective management of infected chronic wounds, the incorporation of antimicrobial drugs... more For the effective management of infected chronic wounds, the incorporation of antimicrobial drugs into wound dressings can increase their local availability at the infection site. Mesoporous silicon dioxide SBA-15 is an excellent drug carrier with tunable drug release kinetics. In this work, synthesized SBA-15 loaded with the natural antimicrobial compound thymol (THY) was incorporated into polycaprolactone (PCL) electrospun nanofibers to obtain an advanced wound dressing. Rod-shaped particles with internal parallel channels oriented along the longitudinal axis (diameter: 138 ± 30 nm, length: 563 ± 100 nm) were loaded with 70.8 wt.% of THY. Fiber mats were prepared using these particles as nanofillers within polycaprolactone (PCL) electrospun fibers. The resulting mats contained 5.6 wt.% of THY and more than half of this loading was released in the first 7 h. This release would prevent an initial bacterial colonization and also inhibit or eliminate bacterial growth as in vitro shown...
Titanium dioxide (TiO2) nanoparticles have recently appeared in PET waste because of the introduc... more Titanium dioxide (TiO2) nanoparticles have recently appeared in PET waste because of the introduction of opaque PET bottles. We prepare polymer blend nanocomposites (PBNANOs) by adding hydrophilic (hphi), hydrophobic (hpho), and hydrophobically modified (hphoM) titanium dioxide (TiO2) nanoparticles to 80rPP/20rPET recycled blends. Contact angle measurements show that the degree of hydrophilicity of TiO2 decreases in the order hphi > hpho > hphoM. A reduction of rPET droplet size occurs with the addition of TiO2 nanoparticles. The hydrophilic/hydrophobic balance controls the nanoparticles location. Transmission electron microscopy (TEM_ shows that hphi TiO2 preferentially locates inside the PET droplets and hpho at both the interface and PP matrix. HphoM also locates within the PP matrix and at the interface, but large loadings (12%) can completely cover the surfaces of the droplets forming a physical barrier that avoids coalescence, leading to the formation of smaller droplets...
The development of advanced probiotic delivery systems, which preserve bacteria from degradation ... more The development of advanced probiotic delivery systems, which preserve bacteria from degradation of the gastrointestinal tract and achieve a targeted release mediated by pH-independent swelling, is of great interest to improve the efficient delivery of probiotic bacteria to the target tissue. Gram-positive and Gram-negative bacteria models (Lactobacillus acidophilus (Moro) Hansen and Mocquot (ATCC® 4356™) and Escherichia coli S17, respectively) have been successfully encapsulated for the first time in pH-independent microparticulate polymethacrylates (i.e., Eudraguard biotic) used for the targeted delivery of nutraceuticals to the colon. These bacteria have also been encapsulated within the mucoadhesive polymethacrylate Eudragit RS 100 widely used as targeted release formulation for active pharmaceutical ingredients. The enteric microparticles remained unaltered under simulated gastric conditions and released the contained viable microbial cargo under simulated intestinal conditions...
The conversion of carbon dioxide into selective hydrocarbons is vital for green energy generation... more The conversion of carbon dioxide into selective hydrocarbons is vital for green energy generation. Due to the chemical instability and lower activity, environmentally stable transition metal oxides (e.g. CuO) are unpopular for CO2 electroreduction catalysis. Here, we demonstrate substitution of Cu with isomorphic atom i.e. Ni in the CuO and utilize it for improving the hydrocarbon selectivity by 4 times as compared to pristine CuO. Hydrocarbon formation is achieved at the lowest possible applied potential (-0.2 V RHE). This gives the overpotential of about 0.37 V for methane and 0.28 V for ethylene, the lowest ever reported. Employing the ionic interaction between Ni and Cu, this catalyst suppresses the hydrogen evolution reaction (HER) to improve the hydrocarbon selectivity prominently. It is observed that current normalized by the BET surface area gives 15 to 20 times enhancement in the case of Ni substituted CuO compared to undoped CuO. The in situ experiments indicate that Ni do...
One-step synthesis of luminescent mesoporous rods with enhanced photocatalytic response as novel ... more One-step synthesis of luminescent mesoporous rods with enhanced photocatalytic response as novel metal-free peroxidase-like nanozymes.
BACKGROUND: Silver loaded hydroxyapatite nanoparticles were incorporated into poly(vinyl alcohol)... more BACKGROUND: Silver loaded hydroxyapatite nanoparticles were incorporated into poly(vinyl alcohol) (PVA) membranes obtained by supercritical CO 2 (SC-CO 2) assisted phase inversion. Ag 3 PO 4 crystals of 2.2±0.6 nm were dispersed in synthesized needle-like hydroxyapatite nanoparticles (20x65 nm) and were uniformly deposited on the internal surfaces of the PVA membranes. Operative conditions to produce membranes by SC-CO 2 , PVA concentration and the effect on membranes porosity and morphology were studied. RESULTS: Solutions at 20% w/w PVA produced membranes with cellular morphology and nanoporous walls; whereas, 30 and 50% w/w solutions produced nanostructured membranes. Silver ions were released from PVA membranes mainly by diffusion according to Peppas-Sahlin model. Membranes obtained at 20% w/w PVA showed a significant E. coli inhibition at an Ag concentration of 9 ppm, reaching the Minimal Inhibitory Concentration (MIC) and improving the bactericidal activity of the nanoparticles. CONCLUSION: A concentration of Ag 3 PO 4 crystals of about 22 ppm was calculated as capable to completely destroy these bacteria, reaching the Minimum Bactericidal Concentration (MBC).
Even though essential oils (EOs) have been used for therapeutic purposes, there is now a renewed ... more Even though essential oils (EOs) have been used for therapeutic purposes, there is now a renewed interest in the antimicrobial properties of phytochemicals and EOs in particular. Their demonstrated low levels of induction of antimicrobial resistance make them interesting for bactericidal applications, though their complex composition makes it necessary to focus on the study of their main components to identify the most effective ones. Herein, the evaluation of the antimicrobial action of different molecules present in EOs against planktonic and biofilm-forming Gram-positive () and Gram-negative () bacteria was assessed. The bactericidal mechanisms of the different molecules, as well as their cytocompatibility, were also studied. Carvacrol, cinnamaldehyde, and thymol exhibit the highest in vitro antimicrobial activities against and , with membrane disruption the bactericidal mechanism identified. The addition of those compounds (≥0.5 mg/mL) hampers biofilm formation and partially ...
International journal of biological macromolecules, Jan 23, 2018
Bovine Serum Albumin (BSA) and Horseradish Peroxidase (HRP) have been encapsulated within micropa... more Bovine Serum Albumin (BSA) and Horseradish Peroxidase (HRP) have been encapsulated within microparticulated matrices composed of Eudragit RS100 by the water-in-oil-in-water double emulsion solvent evaporation method. Good encapsulation efficiencies were achieved for BSA and HRP, 88.4 and 95.8%, respectively. The stability of the loaded proteins was confirmed by using circular dichroism and fluorescence. The gastroresistance of the protein-loaded microparticles was evaluated under simulated gastric conditions demonstrating the preservation of the structural integrity of the proteins loaded inside the particles. The enzymatic activity of HRP after being released from the enteric microparticles was evaluated by using the peroxidase substrate, revealing that the released enzyme preserved its 100% function. The high drug loadings achieved, reduced cytotoxicity and efficient gastric protection point out towards the potential use of those carriers as oral delivery vectors of therapeutic pr...
The recyclability of opaque PET, which contains TiO2 nanoparticles, has not been as well-studied ... more The recyclability of opaque PET, which contains TiO2 nanoparticles, has not been as well-studied as that of transparent PET. The objective of this work is to recycle post-consumer opaque PET through reactive extrusion with Joncryl. The effect of the reactive extrusion process on the molecular structure and on the thermal/mechanical/rheological properties of recycling post-consumer opaque PET (r-PET) has been analyzed. A 1% w/w Joncryl addition caused a moderate increase in the molecular weight. A moderate increase in chain length could not explain a decrease in the overall crystallization rate. This result is probably due to the presence of branches interrupting the crystallizable sequences in reactive extruded r-PET (REX-r-PET). A rheological investigation performed by SAOS/LAOS/elongational studies detected important structural modifications in REX-r-PET with respect to linear r-PET or a reference virgin PET. REX-r-PET is characterized by a slow relaxation process with enlarged el...
The treatment of osteochondral defects remains a challenge. Four scaffolds were produced using Fo... more The treatment of osteochondral defects remains a challenge. Four scaffolds were produced using Food and Drug Administration (FDA)-approved polymers to investigate their therapeutic potential for the regeneration of the osteochondral unit. Polycaprolactone (PCL) and poly(vinyl-pyrrolidone) (PVP) scaffolds were made by electrohydrodynamic techniques. Hydroxyapatite (HAp) and/or sodium hyaluronate (HA) can be then loaded to PCL nanofibers and/or PVP particles. The purpose of adding hydroxyapatite and sodium hyaluronate into PCL/PVP scaffolds is to increase the regenerative ability for subchondral bone and joint cartilage, respectively. Human bone marrow-derived mesenchymal stem cells (hBM-MSCs) were seeded on these biomaterials. The biocompatibility of these biomaterials in vitro and in vivo, as well as their potential to support MSC differentiation under specific chondrogenic or osteogenic conditions, were evaluated. We show here that hBM-MSCs could proliferate and differentiate both ...
The objective of the present work was to produce gastroresistant Eudragit® RS100 nanoparticles by... more The objective of the present work was to produce gastroresistant Eudragit® RS100 nanoparticles by a reproducible synthesis approach that ensured mono-disperse nanoparticles under the size of 100 nm. Batch and micromixing nanoprecipitation approaches were selected to produce the demanded nanoparticles, identifying the critical parameters affecting the synthesis process. To shed some light on the formulation of the targeted nanoparticles, the effects of particle size and homogeneity of fluid dynamics, and physicochemical parameters such as polymer concentration, type of solvent, ratio of solvent to antisolvent, and total flow rate were studied. The physicochemical characteristics of resulting nanoparticles were studied applying dynamic light scattering (DLS) particle size analysis and electron microscopy imaging. Nanoparticles produced using a micromixer demonstrated a narrower and more homogenous distribution than the ones obtained under similar conditions in conventional batch react...
For the effective management of infected chronic wounds, the incorporation of antimicrobial drugs... more For the effective management of infected chronic wounds, the incorporation of antimicrobial drugs into wound dressings can increase their local availability at the infection site. Mesoporous silicon dioxide SBA-15 is an excellent drug carrier with tunable drug release kinetics. In this work, synthesized SBA-15 loaded with the natural antimicrobial compound thymol (THY) was incorporated into polycaprolactone (PCL) electrospun nanofibers to obtain an advanced wound dressing. Rod-shaped particles with internal parallel channels oriented along the longitudinal axis (diameter: 138 ± 30 nm, length: 563 ± 100 nm) were loaded with 70.8 wt.% of THY. Fiber mats were prepared using these particles as nanofillers within polycaprolactone (PCL) electrospun fibers. The resulting mats contained 5.6 wt.% of THY and more than half of this loading was released in the first 7 h. This release would prevent an initial bacterial colonization and also inhibit or eliminate bacterial growth as in vitro shown...
Titanium dioxide (TiO2) nanoparticles have recently appeared in PET waste because of the introduc... more Titanium dioxide (TiO2) nanoparticles have recently appeared in PET waste because of the introduction of opaque PET bottles. We prepare polymer blend nanocomposites (PBNANOs) by adding hydrophilic (hphi), hydrophobic (hpho), and hydrophobically modified (hphoM) titanium dioxide (TiO2) nanoparticles to 80rPP/20rPET recycled blends. Contact angle measurements show that the degree of hydrophilicity of TiO2 decreases in the order hphi > hpho > hphoM. A reduction of rPET droplet size occurs with the addition of TiO2 nanoparticles. The hydrophilic/hydrophobic balance controls the nanoparticles location. Transmission electron microscopy (TEM_ shows that hphi TiO2 preferentially locates inside the PET droplets and hpho at both the interface and PP matrix. HphoM also locates within the PP matrix and at the interface, but large loadings (12%) can completely cover the surfaces of the droplets forming a physical barrier that avoids coalescence, leading to the formation of smaller droplets...
The development of advanced probiotic delivery systems, which preserve bacteria from degradation ... more The development of advanced probiotic delivery systems, which preserve bacteria from degradation of the gastrointestinal tract and achieve a targeted release mediated by pH-independent swelling, is of great interest to improve the efficient delivery of probiotic bacteria to the target tissue. Gram-positive and Gram-negative bacteria models (Lactobacillus acidophilus (Moro) Hansen and Mocquot (ATCC® 4356™) and Escherichia coli S17, respectively) have been successfully encapsulated for the first time in pH-independent microparticulate polymethacrylates (i.e., Eudraguard biotic) used for the targeted delivery of nutraceuticals to the colon. These bacteria have also been encapsulated within the mucoadhesive polymethacrylate Eudragit RS 100 widely used as targeted release formulation for active pharmaceutical ingredients. The enteric microparticles remained unaltered under simulated gastric conditions and released the contained viable microbial cargo under simulated intestinal conditions...
The conversion of carbon dioxide into selective hydrocarbons is vital for green energy generation... more The conversion of carbon dioxide into selective hydrocarbons is vital for green energy generation. Due to the chemical instability and lower activity, environmentally stable transition metal oxides (e.g. CuO) are unpopular for CO2 electroreduction catalysis. Here, we demonstrate substitution of Cu with isomorphic atom i.e. Ni in the CuO and utilize it for improving the hydrocarbon selectivity by 4 times as compared to pristine CuO. Hydrocarbon formation is achieved at the lowest possible applied potential (-0.2 V RHE). This gives the overpotential of about 0.37 V for methane and 0.28 V for ethylene, the lowest ever reported. Employing the ionic interaction between Ni and Cu, this catalyst suppresses the hydrogen evolution reaction (HER) to improve the hydrocarbon selectivity prominently. It is observed that current normalized by the BET surface area gives 15 to 20 times enhancement in the case of Ni substituted CuO compared to undoped CuO. The in situ experiments indicate that Ni do...
One-step synthesis of luminescent mesoporous rods with enhanced photocatalytic response as novel ... more One-step synthesis of luminescent mesoporous rods with enhanced photocatalytic response as novel metal-free peroxidase-like nanozymes.
BACKGROUND: Silver loaded hydroxyapatite nanoparticles were incorporated into poly(vinyl alcohol)... more BACKGROUND: Silver loaded hydroxyapatite nanoparticles were incorporated into poly(vinyl alcohol) (PVA) membranes obtained by supercritical CO 2 (SC-CO 2) assisted phase inversion. Ag 3 PO 4 crystals of 2.2±0.6 nm were dispersed in synthesized needle-like hydroxyapatite nanoparticles (20x65 nm) and were uniformly deposited on the internal surfaces of the PVA membranes. Operative conditions to produce membranes by SC-CO 2 , PVA concentration and the effect on membranes porosity and morphology were studied. RESULTS: Solutions at 20% w/w PVA produced membranes with cellular morphology and nanoporous walls; whereas, 30 and 50% w/w solutions produced nanostructured membranes. Silver ions were released from PVA membranes mainly by diffusion according to Peppas-Sahlin model. Membranes obtained at 20% w/w PVA showed a significant E. coli inhibition at an Ag concentration of 9 ppm, reaching the Minimal Inhibitory Concentration (MIC) and improving the bactericidal activity of the nanoparticles. CONCLUSION: A concentration of Ag 3 PO 4 crystals of about 22 ppm was calculated as capable to completely destroy these bacteria, reaching the Minimum Bactericidal Concentration (MBC).
Even though essential oils (EOs) have been used for therapeutic purposes, there is now a renewed ... more Even though essential oils (EOs) have been used for therapeutic purposes, there is now a renewed interest in the antimicrobial properties of phytochemicals and EOs in particular. Their demonstrated low levels of induction of antimicrobial resistance make them interesting for bactericidal applications, though their complex composition makes it necessary to focus on the study of their main components to identify the most effective ones. Herein, the evaluation of the antimicrobial action of different molecules present in EOs against planktonic and biofilm-forming Gram-positive () and Gram-negative () bacteria was assessed. The bactericidal mechanisms of the different molecules, as well as their cytocompatibility, were also studied. Carvacrol, cinnamaldehyde, and thymol exhibit the highest in vitro antimicrobial activities against and , with membrane disruption the bactericidal mechanism identified. The addition of those compounds (≥0.5 mg/mL) hampers biofilm formation and partially ...
International journal of biological macromolecules, Jan 23, 2018
Bovine Serum Albumin (BSA) and Horseradish Peroxidase (HRP) have been encapsulated within micropa... more Bovine Serum Albumin (BSA) and Horseradish Peroxidase (HRP) have been encapsulated within microparticulated matrices composed of Eudragit RS100 by the water-in-oil-in-water double emulsion solvent evaporation method. Good encapsulation efficiencies were achieved for BSA and HRP, 88.4 and 95.8%, respectively. The stability of the loaded proteins was confirmed by using circular dichroism and fluorescence. The gastroresistance of the protein-loaded microparticles was evaluated under simulated gastric conditions demonstrating the preservation of the structural integrity of the proteins loaded inside the particles. The enzymatic activity of HRP after being released from the enteric microparticles was evaluated by using the peroxidase substrate, revealing that the released enzyme preserved its 100% function. The high drug loadings achieved, reduced cytotoxicity and efficient gastric protection point out towards the potential use of those carriers as oral delivery vectors of therapeutic pr...
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Papers by Silvia Irusta