A comparison between gravimetric and in-situ spectroscopic methods to measure the sorption of CO₂in a biocompatible polymer

In situ ATR-IR spectroscopy was used to simultaneously measure the sorption and swelling of carbon dioxide at high pressures in a biocompatible acrylate copolymer poly(methylmethacrylate-co-ethylhexylacrylate-co-ethyleneglycoldimethacrylate), P(MMA–EHA–EGDMA). The ν3 band of CO2 dissolved in the polymer (at 2335 cm−1) was used to calculate the sorption data and the polymer swelling was determined by analyzing the changes in the absorbance of the ν(C O) band (at 1730 cm−1) of the polymer. Transmission spectroscopy in the near-IR region was also used to study the sorption of CO2 in the polymer using combinational and overtone bands. The experiments were carried out in a pressure range of 2.0–12.0MPa and in a temperature range of 27–40 ◦C. The data for CO2 sorption in this polymer obtained by in situ spectroscopic methods have been compared to the data obtained by the gravimetric technique

Planning cities with water fronts: an academic international team

The water fronts are sensitive areas, not only in environmental terms but also considering the continuity requirements with cities. Usually the spatial planning rules for the places of contact in between the urban fabric and water are focused on building issues and urban development questions rather than of ecological approaches. In this sense, this article aims to present solutions of rethinking the territories of contact in between cities and water fronts, having as pivotal concern, ecological solutions, friendly to the environment. The presented urban project is a requalification solution in order to promote the urban continuity from the buildings to the water, focused on river activities, sports and the preservation of architectural heritage. The urban project solution has as case study, a small town in the central region of Portugal, which is very well known by its thermal baths, with roman roots. The city of São Pedro do Sul is a very pleasant place for holidays, being visited for those who are looking for improving their health condition going to the Thermal Care Centre, or the contact with nature going to the water front of Vouga river. This is a low-density place, where the majority of constructions are single houses, and the main architectural landmark is the old train station, a building from the 19 th century. Nowadays, there are no more trains arriving to São Pedro do Sul and the train track line is working as an ecological corridor for pedestrians and bicycles. However, besides this effort of improving the local environmental conditions, the contact of the city with the river is yet badly considered. There are still lots of urban voids, buildings in bad status of conservation or a lack of diversity and facilities in functional terms. The urban projects were designed in an academic background, comprising several teams of international students coming from Portugal, Greece, Brazil, Slovakia, Lithuania and Poland. A pioneer teaching methodology was tested at the Urban Planning Unit of the Master Degree in Architecture at the University of Beira Interior, as a result of an agreement with the local authority. The students were organized in groups in order to propose the urban design projects to the Train Station surroundings, ensuring the continuity of the urban fabric with the Vouga water front. The best projects won several pecuniary prizes, sponsored by the city hall, which was a stimulus for students along to the designing process. The conclusions show that the presented solution was concerned with strategies to preserve and to enhance the ecological identity of the place. This article will present the contents, options and solutions of the best urban project, designed by a team of students from Brazil and Portugal considered by the jury as the most ecological proposal, friendly of the natural features.info:eu-repo/semantics/publishedVersio

Subcritical carbon dioxide foaming of polycaprolactone for bone tissue regeneration

Accepted manuscriptThe preparation of three-dimensional polycaprolactone scaffolds using dense CO2 as foaming agent, without supercritical conditions, was evaluated in this study towards future applications in bone repair. Herein, 3D foams were obtained at 5.0 MPa and 45 °C. To induce bioactivity, β-tricalcium phosphate (β-TCP, 10 wt%) and dexamethasone (5 and 10 wt%) were dispersed in the scaffolds. Foams revealed a pore size range of 164–882 μm, 73–99% porosity and 79–99% interconnectivity, assessed by micro-computed tomography, and a Young modulus of 1.76–2.92 MPa. Dexamethasone did not impair morphology of the matrices in comparison with PCL+β-TCP, which presented a water uptake of nearly 100% after 14 days. A sustained release of dexamethasone was achieved over 35 days in physiologic solution. This study reports the feasibility of using dense CO2 to produce in one-step a porous matrix loaded with active agents opening new possibilities towards injectable systems for in situ foamingEuropean Union Seventh Framework Programme (FP7/2007-2013) under grant agreement number REGPOT-CT2012-316331-POLARIS. It was also funded by the project “Novel smart and biomimetic materials for innovative regenerative medicine approaches” (RL1-ABMR-NORTE-01-0124-FEDER-000016) co-financed by North Portugal Regional Operational Programme (ON.2 – O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF) and the project NORTE‐01‐0145‐FEDER‐000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement. The authors would like to acknowledge the funding of the project Associate Laboratory ICVS/3B’s, under grant agreement number POCI-01-0145-FEDER-007038 supported by FEDER, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT)info:eu-repo/semantics/publishedVersio

Spatiotemporal assessment of particulate matter (PM10 and PM2.5) and ozone in a Caribbean urban coastal city

Air pollution has become a critical issue in urban areas, so a broad understanding of its spatiotemporal characteristics is important to develop public policies. This study analyzes the spatiotemporal variation of atmospheric particulate matter (PM10 and PM2.5) and ozone (O3) in Barranquilla, Colombia from March 2018 to June 2019 in three monitoring stations. The average concentrations observed for the Móvil, Policía, and Tres Avemarías stations, respectively, for PM10: 46.4, 51.4, and 39.7 μg/m3; for PM2.5: 16.1, 18.1, and 15.1 μg/m3 and for O3: 35.0, 26.6, and 33.6 μg/m3. The results indicated spatial and temporal variations between the stations and the pollutants evaluated. The highest PM concentrations were observed in the southern part of the city, while for ozone, higher concentrations were observed in the north. These variations are mainly associated with the influence of local sources in the environment of each site evaluated as well as the meteorological conditions and transport patterns of the study area. This study also verified the existence of differences in the concentrations of the studied pollutants between the dry and rainy seasons and the contribution of local sources as biomass burnings from the Isla Salamanca Natural Park and long-range transport of dust particles from the Sahara Desert. This study provides a scientific baseline for understanding air quality in the city, which enables policy makers to adopt efficient measures that jointly prevent and control pollution

Collagen from Atlantic cod (Gadus morhua) skins extracted using CO2 acidified water with potential application in healthcare

This work has received funding from European Union, under the scope of European Regional Development Fund (ERDF) through the Structured Project NORTE-01-0145-FEDER-000021 (Norte2020) and under the scope of the European Union Seventh Framework Programme (FP7/2007-2013) through grant agreement ERC-2012-ADG 20120216-321266 (ERC Advanced Grant ComplexiTE). PhD grant of C. O. (Norte-08-5369-000037) with financial support by Norte 2020. The authors would like to acknowledge Frigoríficos da Ermida, Lda. (Gafanha da Nazaré, Portugal) for the kind offer of Atlantic cod skins and to Dr. Manuela Pintado, Dr. Raquel Madureira and Joana Costa (Universidade Católica Portuguesa, Porto) for the use of microDSC and assistance during measurements. The authors also thank to Dr. Catarina Marques and Dr. Sandra Pina (3B’s Research Group) for assistance on XRD measurements, to Dr. Rita Lopez-Cebral (3B’s Research Group) for assistance on SEC measurements and to Dr. Alexandre Barros for discussions.The extraction of collagen from fish skins is being proposed as strategy for valorization of marine origin by-products, being a sustainable alternative to mammal collagen. The method commonly uses solutions of organic acids, but new methodologies are arising, aiming to improve process yields and/or the properties of the resulting products. In this work, skins removed from salt brine Atlantic cod (Gadus morhua) were used to extract collagen, using water acidified with CO2, obtaining an extraction yield of 13.8% (w/w). Acidified water extracted collagen (AWC) presented a total content of proline-like amino acids of 151/1000 residues, with a degree of hydroxylation of 38%, and its SDS-PAGE profile is compatible with type I collagen. Moreover, FTIR, CD and XRD results suggest the presence of preserved triple helix, having a denaturation temperature of 32.3 °C as determined by micro-DSC. AWC exhibited a typical shear thinning behavior, interesting regarding their further processing, namely in jelly-like formulations. Additionally, the presence of AWC in MRC-5 human fibroblasts culture did not affect cell viability, demonstrating the non-cytotoxic behavior. Overall, the results support the efficiency of the proposed approach for collagen extraction and further enable the design of methodologies to address AWC use in biomedical or cosmetic context.authorsversionpublishe

The role of organic solvent on the preparation of chitosan scaffolds by supercritical assisted phase inversion

The aim of this study was to evaluate the possibility of preparing chitosan porous matrixes using supercritical fluid technology. Supercritical immersion precipitation technique was used to prepare scaffolds of a natural biocompatible polymer, chitosan for tissue engineering purposes. The physicochemical and biological properties of chitosan make it an excellent material for the preparation of drug delivery systems and for the development of new biomedical applications in many fields from skin to bone or cartilage. Supercritical assisted phase inversion experiments were carried out and the effect of different organic solvents on the morphology of the scaffolds was assessed. Chitosan scaffold morphology, porosity and pore size were evaluated by SEM and micro-CT. A thermodynamic analysis of the process was carried out and insights on the solubility parameter and Flory–Huggins interaction parameters are given. The preparation of a highly porous and interconnected structure of a natural material, chitosan, using a clean and environmentally friendly technology constitutes a new processing technology for the preparation of scaffolds for tissue engineering using these materials.Ana Rita C. Duarte is grateful for financial support from Fundacao para a Ciencia e Tecnologia (FCT) through the grant SFRH/BPD/34994/2007. The support through the FCT project PTDC/QUI/68804/2006 is also acknowledged

Preparation of starch-based scaffolds for tissue engineering by supercritical immersion precipitation

The aim of this study was to evaluate the possibility of preparing starch-based porous matrixes using supercritical fluid technology. Supercritical immersion precipitation technique was used to prepare scaffolds of a polymeric blend of starch and poly(l-lactic acid) for tissue engineering purposes.Immersion precipitation experiments were carried out at different operational conditions and highly porous and interconnected scaffolds were obtained. Two organic solvents, dichloromethane and chloroform were tested, and from the results obtained chloroform was the more favourable for the process. The effect of polymer solution concentration (5 up to 20 wt%), temperature (35 up to 55 ◦C) and pressure (100 up to 200 bar) in the SPLA (50:50 wt%) membrane morphology, porosity and interconnectivity was evaluated. All the conditions tested were in the region of total miscibility between the organic solvent and carbon dioxide. Additionally, a blend with a different starch-poly(l-lactic acid) ratio (30:70 wt%) was tested. Bicontinuous structures were formed indicating that the L–L demixing process that governs the phase inversion is the spinodal decomposition.Ana Rita C. Duarte is grateful for financial support from Fundacao para a Ciencia a Tecnologia through the grant SFRH/BPD/34994/2007

Polymer processing using supercritical fluid based technologies for drug delivery and tissue engineering applications

From the use of botanical plants in early human civilizations through synthetic chemistry and biotechnology, drug research has always passionate scientists creating exciting challenges to a large number of researchers from different fields, thus, promoting a collaborative effort between polymer scientists, pharmacologists, engineers, chemists and medical researchers. Worldwide, there is an increasing concern on health care that creates a major opportunity for development of new pharmaceutical formulations. Ageing populations worried about the quality of life in the older years are actively seeking for new, more effective and patient compliant drug delivery devices. This has been the driving force for the continuous growth of the research made on delivery devices, which has become a powerful technique in health care. It has been recognized for long that simple pills or injections may not be the suitable methods of administration of a certain active compound. These medications present several problems and/or limitations, like poor drug bioavailability and systemic toxicity, derived essentially from pharmacokinetic and other carrier limitations and low solubility of the drugs in water. Therefore and to overcome these drawbacks, clinicians recommend frequent drug dosing, at high concentrations, in order to overcome poor drug bioavailability but causing a potential risk of systemic toxicity. Polymer science has open new strategies for drug delivery systems. This Chapter overviews of possible strategies involving polymer modification and processing for controlled drug delivery and drug delivery in tissue engineering.European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement number REGPOT-CT2012-316331-POLARIS and from the project “Novel smart and biomimetic materials for innovative regenerative medicine approaches” RL1 -ABMR-NORTE-01-0124-FEDER-000016 cofinanced by North Portugal Regional Operational Programme (ON.2 –O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)

Dexamethasone-loaded scaffolds prepared by supercritical assisted phase inversion

The aim of this study was to evaluate the possibility of preparing dexamethasone-loaded starch-based porous matrices in a one-step process. Supercritical phase inversion technique was used to prepare composite scaffolds of dexamethasone and a polymeric blend of starch and poly(L-lactic acid) (SPLA) for tissue engineering purposes. Dexamethasone is used in osteogenic media to direct the differentiation of stem cells towards the osteogenic lineage. Samples with different drug concentrations (5–15 wt.% polymer) were prepared at 200 bar and 55 C. The presence of dexamethasone did not affect the porosity or interconnectivity of the polymeric matrices. Water uptake and degradation studies were also performed on SPLA scaffolds. We conclude that SPLA matrices prepared by supercritical phase inversion have a swelling degree of nearly 90% and the material presents a weight loss of 25% after 21 days in solution. Furthermore, in vitro drug release studies were carried out and the results show that a sustained release of dexamethasone was achieved over 21 days. The fitting of the power law to the experimental data demonstrated that drug release is governed by an anomalous transport, i.e., both the drug diffusion and the swelling of the matrix influence the release of dexamethasone out of the scaffold. The kinetic constant was also determined. This study reports the feasibility of using supercritical fluid technology to process in one step a porous matrix loaded with a pharmaceutical agent for tissue engineering purposes.Ana Rita C. Duarte is grateful for financial support from Fundatyao para a Ciencia a Tecnologia through the Grant SFRH/BPD/34994/2007