Highlights Photocatalytic decomposition of PFOA using a TiO 2-rGO catalyst was studied TiO 2-... more Highlights Photocatalytic decomposition of PFOA using a TiO 2-rGO catalyst was studied TiO 2-rGO catalyst (0.1 g.L-1) allowed 93±7 % PFOA removal under UV-Vis irradiation Formation of intermediate PFCAs and Felucidated the PFOA degradation mechanism Faster degradation kinetics were observed for shorter carbon-chain PFCAs ABSTRACT The inherent resistance of perfluoroalkyl substances (PFASs) to biological degradation makes necessary to develop advanced technologies for the abatement of this group of hazardous substances. The present work investigated the photocatalytic decomposition of perfluorooctanoic acid (PFOA) using a composite catalyst based on TiO2 and reduced graphene oxide (95% TiO2/5% rGO) that was synthesized using a facile hydrothermal method. The efficient photoactivity of the TiO2-rGO (0.1 g.L-1) composite was confirmed for PFOA (0.24 mmol.L-1) degradation that reached 93±7% after 12 h of UV-visible irradiation using a medium pressure mercury lamp, a great improvement compared to the TiO2 photocatalysis (24±11% PFOA removal) and direct photolysis (58±9%). These findings indicate that rGO provided the suited properties of TiO2-rGO, possibly as a result of acting as electron acceptor and avoiding the high recombination electron/hole pairs. The release of fluoride and the formation of shorter-chain perfluorocarboxilyc acids, that were progressively eliminated in a good match with the analysed reduction of total organic carbon, is consistent with a step-by-step PFOA decomposition via photogenerated hydroxyl radicals. Finally, the apparent first order rate constants of the TiO2-rGO UV-Vis PFOA decompositions, and the intermediate perfluorcarboxylic acids were found to increase as the length of the carbon chain was shorter.
This work presents the photocatalytic degradation of organic pollutants in water with TiO2 and Ti... more This work presents the photocatalytic degradation of organic pollutants in water with TiO2 and TiO2/Ag membranes prepared by immobilising photocatalysts on ceramic porous tubular supports. The permeation capacity of TiO2 and TiO2/Ag membranes was checked before the photocatalytic application, showing high water fluxes (≈758 and 690 L m−2 h−1 bar−1, respectively) and <2% rejection against the model pollutants sodium dodecylbenzene sulfonate (DBS) and dichloroacetic acid (DCA). When the membranes were submerged in the aqueous solutions and irradiated with UV-A LEDs, the photocatalytic performance factors for the degradation of DCA were similar to those obtained with suspended TiO2 particles (1.1-fold and 1.2-fold increase, respectively). However, when the aqueous solution permeated through the pores of the photocatalytic membrane, the performance factors and kinetics were two-fold higher than for the submerged membranes, mostly due to the enhanced contact between the pollutants and...
Composites of polymer and graphene-based nanomaterials (GBNs) combine easy processing onto porous... more Composites of polymer and graphene-based nanomaterials (GBNs) combine easy processing onto porous 3D membrane geometries due to the polymer and cellular differentiation stimuli due to GBNs fillers. Aiming to step forward to the clinical application of polymer/GBNs composites, this study performs a systematic and detailed comparative analysis of the influence of the properties of four different GBNs: (i) graphene oxide obtained from graphite chemically processes (GO); (ii) reduced graphene oxide (rGO); (iii) multilayered graphene produced by mechanical exfoliation method (Gmec); and (iv) low-oxidized graphene via anodic exfoliation (Ganodic); dispersed in polycaprolactone (PCL) porous membranes to induce astrocytic differentiation. PCL/GBN flat membranes were fabricated by phase inversion technique and broadly characterized in morphology and topography, chemical structure, hydrophilicity, protein adsorption, and electrical properties. Cellular assays with rat C6 glioma cells, as mode...
Background Recent advances from studies of graphene and graphene-based derivatives have highlight... more Background Recent advances from studies of graphene and graphene-based derivatives have highlighted the great potential of these nanomaterials as migrastatic agents with the ability to modulate tumor microenvironments. Nevertheless, the administration of graphene nanomaterials in suspensions in vivo is controversial. As an alternative approach, herein, we report the immobilization of high concentrations of graphene nanoplatelets in polyacrylonitrile film substrates (named PAN/G10) and evaluate their potential use as migrastatic agents on cancer cells. Results Breast cancer MCF7 cells cultured on PAN/G10 substrates presented features resembling mesenchymal-to-epithelial transition, e.g., (i) inhibition of migratory activity; (ii) activation of the expression of E-cadherin, cytokeratin 18, ZO-1 and EpCAM, four key molecular markers of epithelial differentiation; (iii) formation of adherens junctions with clustering and adhesion of cancer cells in aggregates or islets, and (iv) reorgan...
Immobilization of photocatalysts in porous materials is an approach to significantly minimize the... more Immobilization of photocatalysts in porous materials is an approach to significantly minimize the hazards of manipulation and recovery of nanoparticles. Inorganic materials, such as zeolites, are proposed as promising materials for photocatalyst immobilization mainly due to their photochemical stability. In this work, a green synthesis method is proposed to combine TiO2-based photocatalysts with commercial ZY zeolite. Moreover, a preliminary analysis of their performance as photocatalysts for the abatement of organic pollutants in waters was performed. Our results show that the physical mixture of TiO2 and zeolite maintains photocatalytic activity. Meanwhile, composites fabricated by doping TiO2–zeolite Y materials with silver and palladium nanoparticles do not contribute to improving the photocatalytic activity beyond that of TiO2.
Additional file 5: Figure S5. (A) Three-dimensional reconstruction of confocal microscope images ... more Additional file 5: Figure S5. (A) Three-dimensional reconstruction of confocal microscope images of a MCF7 cellular islet formed after growth over PAN/G10 for 5 days and co-stained with Phalloidin-FITC and DAPI. (B) Image was rotated 90º from the previous (top to bottom) to observe the vertical growth of the islet. (C) Gallery of the images used for 3D-reconstruction in (A). Note that all cross-sectional views of the islet show compact cellular aggregation. Scale bar: 30 µm.
The effect of the temperature, as a process variable in the fabrication of polymeric membranes by... more The effect of the temperature, as a process variable in the fabrication of polymeric membranes by the non-solvent induced phase separation (NIPS) technique, has been scarcely studied. In the present work, we studied the influence of temperature, working at 293, 313 and 333 K, on the experimental binodal curves of four ternary systems composed of PVDF and PES as the polymers, DMAc and NMP as the solvents and water as the non-solvent. The increase of the temperature caused an increase on the solubility gap of the ternary system, as expected. The shift of the binodal curve with the temperature was more evident in PVDF systems than in PES systems indicating the influence of the rubbery or glassy state of the polymer on the thermodynamics of phase separation. As a novelty, the present work has introduced the temperature influence on the Flory–Huggins model to fit the experimental cloud points. Binary interaction parameters were calculated as a function of the temperature: (i) non-solvent...
Photocatalytic membrane reactors (PMR), with immobilized photocatalysts, play an important role i... more Photocatalytic membrane reactors (PMR), with immobilized photocatalysts, play an important role in process intensification strategies; this approach offers a simple solution to the typical catalyst recovery problem of photocatalytic processes and, by simultaneous filtration and photocatalysis of the aqueous streams, facilitates clean water production in a single unit. The synthesis of polymer photocatalytic membranes has been widely explored, while studies focused on ceramic photocatalytic membranes represent a minority. However, previous reports have identified that the successful synthesis of polymeric photocatalytic membranes still faces certain challenges that demand further research, e.g., (i) reduced photocatalytic activity, (ii) photocatalyst stability, and (iii) membrane aging, to achieve technological competitiveness with respect to suspended photocatalytic systems. The novelty of this review is to go a step further to preceding literature by first, critically analyzing the...
The present work studies the functional behavior of novel poly(ε-caprolactone) (PCL) membranes fu... more The present work studies the functional behavior of novel poly(ε-caprolactone) (PCL) membranes functionalized with reduced graphene oxide (rGO) nanoplatelets under simulated in vitro culture conditions (phosphate buffer solution (PBS) at 37 °C) during 1 year, in order to elucidate their applicability as scaffolds for in vitro neural regeneration. The morphological, chemical, and DSC results demonstrated that high internal porosity of the membranes facilitated water permeation and procured an accelerated hydrolytic degradation throughout the bulk pathway. Therefore, similar molecular weight reduction, from 80 kDa to 33 kDa for the control PCL, and to 27 kDa for PCL/rGO membranes, at the end of the study, was observed. After 1 year of hydrolytic degradation, though monomers coming from the hydrolytic cleavage of PCL diffused towards the PBS medium, the pH was barely affected, and the rGO nanoplatelets mainly remained in the membranes which envisaged low cytotoxic effect. On the other ...
The effect of doping graphene oxide (GO) and reduced graphene oxide (rGO) into poly(ε‐caprolacton... more The effect of doping graphene oxide (GO) and reduced graphene oxide (rGO) into poly(ε‐caprolactone) (PCL) membranes prepared by solvent induced phase separation is evaluated in terms of nanomaterial distribution and compatibility with neural stem cell growth and functional differentiation. Raman spectra analyses demonstrate the homogeneous distribution of GO on the membrane surface while rGO concentration increases gradually toward the center of the membrane thickness. This behavior is associated with electrostatic repulsion that PCL exerted toward the polar GO and its affinity for the non‐polar rGO. In vitro cell studies using human induced pluripotent cell derived neural progenitor cells (NPCs) show that rGO increases marker expression of NPCs differentiation with respect to GO (significantly to tissue culture plate (TCP)). Moreover, the distinctive nanomaterials distribution defines the cell‐to‐nanomaterial interaction on the PCL membranes: GO nanomaterials on the membrane surfac...
High porosity and mass transport properties of microfiltration polymeric membranes benefit nutrie... more High porosity and mass transport properties of microfiltration polymeric membranes benefit nutrients supply to cells when used as scaffolds in interstitial perfusion bioreactors for tissue engineering. High nutrients transport is assumed when pore size and porosity of the membrane are in the micrometric range. The present work demonstrates that the study of membrane fouling by proteins present in the culture medium, though not done usually, should be included in the routine testing of new polymer membranes for this intended application. Two poly(ε-caprolactone) microfiltration membranes presenting similar average pore size (approximately 0.7 µm) and porosity (>80%) but different external surface porosity and pore size have been selected as case studies. The present work demonstrates that a membrane with lower surface pore abundance and smaller external pore size (approximately 0.67 µm), combined with adequate hydrodynamics and tangential flow filtration mode is usually more conve...
A life cycle assessment was conducted for the Zn-electroplating products passivated by different ... more A life cycle assessment was conducted for the Zn-electroplating products passivated by different processes in a small and medium enterprise. The goal was to evaluate and to compare the environmental impact associated to the conventional and alternative passivation process from a "cradle to grave" analysis. The assessment was divided into "cradle to gate", "gate to gate", and "gate to grave" steps for natural resources usage and environmental burdens. The innovative process was based on the integration of emulsion pertraction technology to the passivation bath in order to extend its lifetime. Results showed that the transferred hazardous waste from the process to the landfill was the major contributor to the environmental impact of the conventional and innovative passivation. The manufacture of the sodium hydroxide needed in the wastewater treatment process had a main role in the impacts of the "cradle to gate" cycle. This work concluded that the innovative passivation decreased most of the generated waste (92%) during the manufacture cycle of the passivated product as a consequence of the extension of the lifetime of the passivation bath. A reduction of the total environmental burdens to air and to water and the resource usage during the whole manufacture cycle of the product was stated. The environmental burdens to air and to water were mainly connected to the environmental impacts: human health effects and ecotoxicity to aquatic life, respectively.
SummaryThe effect of the surface morphology of flat poly(ϵ‐caprolactone) (PCL) scaffolds on human... more SummaryThe effect of the surface morphology of flat poly(ϵ‐caprolactone) (PCL) scaffolds on human adipose stem cell (hASC) adherence and proliferation was studied. During fabrication of the scaffolds by phase inversion, the employment of different non‐solvents (water (W), ethanol (EtOH) or isopropanol (IPA)) led to distinct surface morphologies. It was found that PCL scaffolds fabricated using IPA as a non‐solvent had a higher roughness and porosity compared to the other groups. Moreover, during culturing of hASCs under static conditions, best cell attachment, spreading and growth were observed on the PCL scaffold. Our results show the potential of PCL scaffolds prepared using IPA as a non‐solvent for especially soft tissue engineering applications.
Highlights Photocatalytic decomposition of PFOA using a TiO 2-rGO catalyst was studied TiO 2-... more Highlights Photocatalytic decomposition of PFOA using a TiO 2-rGO catalyst was studied TiO 2-rGO catalyst (0.1 g.L-1) allowed 93±7 % PFOA removal under UV-Vis irradiation Formation of intermediate PFCAs and Felucidated the PFOA degradation mechanism Faster degradation kinetics were observed for shorter carbon-chain PFCAs ABSTRACT The inherent resistance of perfluoroalkyl substances (PFASs) to biological degradation makes necessary to develop advanced technologies for the abatement of this group of hazardous substances. The present work investigated the photocatalytic decomposition of perfluorooctanoic acid (PFOA) using a composite catalyst based on TiO2 and reduced graphene oxide (95% TiO2/5% rGO) that was synthesized using a facile hydrothermal method. The efficient photoactivity of the TiO2-rGO (0.1 g.L-1) composite was confirmed for PFOA (0.24 mmol.L-1) degradation that reached 93±7% after 12 h of UV-visible irradiation using a medium pressure mercury lamp, a great improvement compared to the TiO2 photocatalysis (24±11% PFOA removal) and direct photolysis (58±9%). These findings indicate that rGO provided the suited properties of TiO2-rGO, possibly as a result of acting as electron acceptor and avoiding the high recombination electron/hole pairs. The release of fluoride and the formation of shorter-chain perfluorocarboxilyc acids, that were progressively eliminated in a good match with the analysed reduction of total organic carbon, is consistent with a step-by-step PFOA decomposition via photogenerated hydroxyl radicals. Finally, the apparent first order rate constants of the TiO2-rGO UV-Vis PFOA decompositions, and the intermediate perfluorcarboxylic acids were found to increase as the length of the carbon chain was shorter.
This work presents the photocatalytic degradation of organic pollutants in water with TiO2 and Ti... more This work presents the photocatalytic degradation of organic pollutants in water with TiO2 and TiO2/Ag membranes prepared by immobilising photocatalysts on ceramic porous tubular supports. The permeation capacity of TiO2 and TiO2/Ag membranes was checked before the photocatalytic application, showing high water fluxes (≈758 and 690 L m−2 h−1 bar−1, respectively) and <2% rejection against the model pollutants sodium dodecylbenzene sulfonate (DBS) and dichloroacetic acid (DCA). When the membranes were submerged in the aqueous solutions and irradiated with UV-A LEDs, the photocatalytic performance factors for the degradation of DCA were similar to those obtained with suspended TiO2 particles (1.1-fold and 1.2-fold increase, respectively). However, when the aqueous solution permeated through the pores of the photocatalytic membrane, the performance factors and kinetics were two-fold higher than for the submerged membranes, mostly due to the enhanced contact between the pollutants and...
Composites of polymer and graphene-based nanomaterials (GBNs) combine easy processing onto porous... more Composites of polymer and graphene-based nanomaterials (GBNs) combine easy processing onto porous 3D membrane geometries due to the polymer and cellular differentiation stimuli due to GBNs fillers. Aiming to step forward to the clinical application of polymer/GBNs composites, this study performs a systematic and detailed comparative analysis of the influence of the properties of four different GBNs: (i) graphene oxide obtained from graphite chemically processes (GO); (ii) reduced graphene oxide (rGO); (iii) multilayered graphene produced by mechanical exfoliation method (Gmec); and (iv) low-oxidized graphene via anodic exfoliation (Ganodic); dispersed in polycaprolactone (PCL) porous membranes to induce astrocytic differentiation. PCL/GBN flat membranes were fabricated by phase inversion technique and broadly characterized in morphology and topography, chemical structure, hydrophilicity, protein adsorption, and electrical properties. Cellular assays with rat C6 glioma cells, as mode...
Background Recent advances from studies of graphene and graphene-based derivatives have highlight... more Background Recent advances from studies of graphene and graphene-based derivatives have highlighted the great potential of these nanomaterials as migrastatic agents with the ability to modulate tumor microenvironments. Nevertheless, the administration of graphene nanomaterials in suspensions in vivo is controversial. As an alternative approach, herein, we report the immobilization of high concentrations of graphene nanoplatelets in polyacrylonitrile film substrates (named PAN/G10) and evaluate their potential use as migrastatic agents on cancer cells. Results Breast cancer MCF7 cells cultured on PAN/G10 substrates presented features resembling mesenchymal-to-epithelial transition, e.g., (i) inhibition of migratory activity; (ii) activation of the expression of E-cadherin, cytokeratin 18, ZO-1 and EpCAM, four key molecular markers of epithelial differentiation; (iii) formation of adherens junctions with clustering and adhesion of cancer cells in aggregates or islets, and (iv) reorgan...
Immobilization of photocatalysts in porous materials is an approach to significantly minimize the... more Immobilization of photocatalysts in porous materials is an approach to significantly minimize the hazards of manipulation and recovery of nanoparticles. Inorganic materials, such as zeolites, are proposed as promising materials for photocatalyst immobilization mainly due to their photochemical stability. In this work, a green synthesis method is proposed to combine TiO2-based photocatalysts with commercial ZY zeolite. Moreover, a preliminary analysis of their performance as photocatalysts for the abatement of organic pollutants in waters was performed. Our results show that the physical mixture of TiO2 and zeolite maintains photocatalytic activity. Meanwhile, composites fabricated by doping TiO2–zeolite Y materials with silver and palladium nanoparticles do not contribute to improving the photocatalytic activity beyond that of TiO2.
Additional file 5: Figure S5. (A) Three-dimensional reconstruction of confocal microscope images ... more Additional file 5: Figure S5. (A) Three-dimensional reconstruction of confocal microscope images of a MCF7 cellular islet formed after growth over PAN/G10 for 5 days and co-stained with Phalloidin-FITC and DAPI. (B) Image was rotated 90º from the previous (top to bottom) to observe the vertical growth of the islet. (C) Gallery of the images used for 3D-reconstruction in (A). Note that all cross-sectional views of the islet show compact cellular aggregation. Scale bar: 30 µm.
The effect of the temperature, as a process variable in the fabrication of polymeric membranes by... more The effect of the temperature, as a process variable in the fabrication of polymeric membranes by the non-solvent induced phase separation (NIPS) technique, has been scarcely studied. In the present work, we studied the influence of temperature, working at 293, 313 and 333 K, on the experimental binodal curves of four ternary systems composed of PVDF and PES as the polymers, DMAc and NMP as the solvents and water as the non-solvent. The increase of the temperature caused an increase on the solubility gap of the ternary system, as expected. The shift of the binodal curve with the temperature was more evident in PVDF systems than in PES systems indicating the influence of the rubbery or glassy state of the polymer on the thermodynamics of phase separation. As a novelty, the present work has introduced the temperature influence on the Flory–Huggins model to fit the experimental cloud points. Binary interaction parameters were calculated as a function of the temperature: (i) non-solvent...
Photocatalytic membrane reactors (PMR), with immobilized photocatalysts, play an important role i... more Photocatalytic membrane reactors (PMR), with immobilized photocatalysts, play an important role in process intensification strategies; this approach offers a simple solution to the typical catalyst recovery problem of photocatalytic processes and, by simultaneous filtration and photocatalysis of the aqueous streams, facilitates clean water production in a single unit. The synthesis of polymer photocatalytic membranes has been widely explored, while studies focused on ceramic photocatalytic membranes represent a minority. However, previous reports have identified that the successful synthesis of polymeric photocatalytic membranes still faces certain challenges that demand further research, e.g., (i) reduced photocatalytic activity, (ii) photocatalyst stability, and (iii) membrane aging, to achieve technological competitiveness with respect to suspended photocatalytic systems. The novelty of this review is to go a step further to preceding literature by first, critically analyzing the...
The present work studies the functional behavior of novel poly(ε-caprolactone) (PCL) membranes fu... more The present work studies the functional behavior of novel poly(ε-caprolactone) (PCL) membranes functionalized with reduced graphene oxide (rGO) nanoplatelets under simulated in vitro culture conditions (phosphate buffer solution (PBS) at 37 °C) during 1 year, in order to elucidate their applicability as scaffolds for in vitro neural regeneration. The morphological, chemical, and DSC results demonstrated that high internal porosity of the membranes facilitated water permeation and procured an accelerated hydrolytic degradation throughout the bulk pathway. Therefore, similar molecular weight reduction, from 80 kDa to 33 kDa for the control PCL, and to 27 kDa for PCL/rGO membranes, at the end of the study, was observed. After 1 year of hydrolytic degradation, though monomers coming from the hydrolytic cleavage of PCL diffused towards the PBS medium, the pH was barely affected, and the rGO nanoplatelets mainly remained in the membranes which envisaged low cytotoxic effect. On the other ...
The effect of doping graphene oxide (GO) and reduced graphene oxide (rGO) into poly(ε‐caprolacton... more The effect of doping graphene oxide (GO) and reduced graphene oxide (rGO) into poly(ε‐caprolactone) (PCL) membranes prepared by solvent induced phase separation is evaluated in terms of nanomaterial distribution and compatibility with neural stem cell growth and functional differentiation. Raman spectra analyses demonstrate the homogeneous distribution of GO on the membrane surface while rGO concentration increases gradually toward the center of the membrane thickness. This behavior is associated with electrostatic repulsion that PCL exerted toward the polar GO and its affinity for the non‐polar rGO. In vitro cell studies using human induced pluripotent cell derived neural progenitor cells (NPCs) show that rGO increases marker expression of NPCs differentiation with respect to GO (significantly to tissue culture plate (TCP)). Moreover, the distinctive nanomaterials distribution defines the cell‐to‐nanomaterial interaction on the PCL membranes: GO nanomaterials on the membrane surfac...
High porosity and mass transport properties of microfiltration polymeric membranes benefit nutrie... more High porosity and mass transport properties of microfiltration polymeric membranes benefit nutrients supply to cells when used as scaffolds in interstitial perfusion bioreactors for tissue engineering. High nutrients transport is assumed when pore size and porosity of the membrane are in the micrometric range. The present work demonstrates that the study of membrane fouling by proteins present in the culture medium, though not done usually, should be included in the routine testing of new polymer membranes for this intended application. Two poly(ε-caprolactone) microfiltration membranes presenting similar average pore size (approximately 0.7 µm) and porosity (>80%) but different external surface porosity and pore size have been selected as case studies. The present work demonstrates that a membrane with lower surface pore abundance and smaller external pore size (approximately 0.67 µm), combined with adequate hydrodynamics and tangential flow filtration mode is usually more conve...
A life cycle assessment was conducted for the Zn-electroplating products passivated by different ... more A life cycle assessment was conducted for the Zn-electroplating products passivated by different processes in a small and medium enterprise. The goal was to evaluate and to compare the environmental impact associated to the conventional and alternative passivation process from a "cradle to grave" analysis. The assessment was divided into "cradle to gate", "gate to gate", and "gate to grave" steps for natural resources usage and environmental burdens. The innovative process was based on the integration of emulsion pertraction technology to the passivation bath in order to extend its lifetime. Results showed that the transferred hazardous waste from the process to the landfill was the major contributor to the environmental impact of the conventional and innovative passivation. The manufacture of the sodium hydroxide needed in the wastewater treatment process had a main role in the impacts of the "cradle to gate" cycle. This work concluded that the innovative passivation decreased most of the generated waste (92%) during the manufacture cycle of the passivated product as a consequence of the extension of the lifetime of the passivation bath. A reduction of the total environmental burdens to air and to water and the resource usage during the whole manufacture cycle of the product was stated. The environmental burdens to air and to water were mainly connected to the environmental impacts: human health effects and ecotoxicity to aquatic life, respectively.
SummaryThe effect of the surface morphology of flat poly(ϵ‐caprolactone) (PCL) scaffolds on human... more SummaryThe effect of the surface morphology of flat poly(ϵ‐caprolactone) (PCL) scaffolds on human adipose stem cell (hASC) adherence and proliferation was studied. During fabrication of the scaffolds by phase inversion, the employment of different non‐solvents (water (W), ethanol (EtOH) or isopropanol (IPA)) led to distinct surface morphologies. It was found that PCL scaffolds fabricated using IPA as a non‐solvent had a higher roughness and porosity compared to the other groups. Moreover, during culturing of hASCs under static conditions, best cell attachment, spreading and growth were observed on the PCL scaffold. Our results show the potential of PCL scaffolds prepared using IPA as a non‐solvent for especially soft tissue engineering applications.
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