pinecone/core-2020-05-10-deduplication huggingface dataset:
Porous hydrogels from shark skin collagen crosslinked under dense carbon dioxide atmosphere

The possibility to fabricate marine collagen porous structures crosslinked with genipin under
high pressure carbon dioxide is investigated. Collagen from shark skin is used to prepare prescaffolds
by freeze-drying. The poor stability of the structures and low mechanical properties
require crosslinking of the structures. Under dense CO2 atmosphere, crosslinking of collagen
pre-scaffolds is allowed for 16 h. Additionally, the hydrogels are foamed and the scaffolds
obtained present a highly porous structure. In vitro cell culture tests performed with a
chondrocyte-like cell line show good cell
adherence and proliferation, which is a
strong indication of the potential of
these scaffolds to be used in tissue
cartilage tissue engineering.The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. KBBE-2010-266033 (project SPECIAL) and from FEDER through POCTEP Project 0330_IBEROMARE_1_P. Portuguese Foundation for Science and Technology is also gratefully acknowledged for post-doc grants of J. Moreira-Silva and T.H. Silva
Overcoming Cancer Multidrug Resistance by Codelivery of Doxorubicin and Verapamil with Hydrogel Nanoparticles

The efficacy of chemotherapy is often inhibited by multidrug resistance (MDR). A highly engineerable hydrogel nanoparticle (NP) serves as a carrier for the optimal codelivery to tumor cells of the chemodrug, doxorubicin (Dox) and the chemosensitizer, verapamil (Vera), aiming at alleviating tumor MDR. The hydrogel NPs are prepared via the copolymerization of acrylamide and 2‐carboxyethyl acrylate. Dox and Vera are post‐loaded into the respective NPs, with drug loading around 7.7 wt% and 8.0 wt%, respectively. The codelivery of Dox‐NPs and Vera‐NPs increases the intracellular accumulation of Dox, and significantly enhances the cell killing ability of Dox with respect to NCI/ADR‐RES cells in vitro. These findings suggest that such codelivery nanoplatforms provide a promising route for overcoming tumor MDR.       A new kind of hydrogel nanoparticles  is developed as a delivery vehicle for codelivery of doxorubicin, an anti‐cancer drug (affects DNA), and verapamil, a chemosensitizer (blocks efflux pump), to tumor cells, aiming at overcoming multidrug resistance
A novel crosslinked hyaluronic Acid nanogel for drug delivery

An amphiphilic hyaluronic acid conjugate is successfully developed based on grafting a thiolated hydrophobic molecule to the polysaccharide backbone. The engineered conjugate is capable of assembling into nanostructures once dispersed in water, with average diameter of 80.2 ± 0.4 nm (n = 5), stable up to 6 months. The thiolated HyA conjugate is reticulated by dissulfide bond with a homofunctional crosslinker—1,4-Bis(3-[2-pyridyldithio]propionamido)butane (DPDPB). The drug loading efficiency of the reticulated and non-reticulated nanogel is accessed with two hydrophobic drugs, curcumin and simvastatin. Results suggest that crosslinked nanogel exhibit higher stability upon dilution and drug loading efficiency and proves to be a redox sensitive material. The nanogels hold great potential as stealth carriers of lipophilic drugs.The authors would like to acknowledge the support of FCT for the PhD grant reference SFRH/BD/61516/2009
Porous polylactic acid-silica hybrids : preparation, characterization, and study of mesenchymal stem cell osteogenic differentiation

A novel approach to reinforce polymer porous membranes is presented. In the prepared hybrid materials, the inorganic phase of silica is synthesized in-situ and inside the pores of aminolyzed polylactic acid (PLA) membranes by sol-gel reactions using tetraethylorthosilicate (TEOS) and glycidoxypropyltrimethoxysilane (GPTMS) as precursors. The hybrid materials present a porous structure with a silica layer covering the walls of the pores while GPTMS serves also as coupling agent between the organic and inorganic phase. The adjustment of silica precursors ratio allows the modulation of the thermomechanical properties. Culture of mesenchymal stem cells on these supports in osteogenic medium shows the expression of characteristic osteoblastic markers and the mineralization of the extracellular matrix.The research project is implemented within the framework of the Action "Supporting Postdoctoral Researchers" of the Operational Program "Education and Lifelong Learning'' (Action's Beneficiary: General Secretariat for Research and Technology), and is co-financed by the European Social Fund (ESF) and the Greek State, Grant No.: NARGEL-PE5(2551). J.R.R. acknowledges funding of his PhD by the Generalitat Valenciana through VALi+d grant (ACIF/2010/238). J.F.M. thanks the Portuguese Foundation for Science and Technology (FCT) for financial support through the PTDC/FIS/115048/2009 project. J.L.G.R. acknowledges the support of the Ministerio de Economia y Competitividad, MINECO, through theMAT2013-46467-C4-1-R project. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with the assistance from the European Regional Development Fund
Novel linear polymers able to inhibit bacterial quorum sensing

Bacterial phenotypes such as biofilm formation, antibiotic resistance, virulence expression are associated with Quorum Sensing (QS). QS is a density-dependent regulatory system of gene expression controlled by specific signal molecules, such as N-acyl homoserine lactones (AHLs), produced and released by bacteria. This study reports the development of linear polymers capable to attenuate QS by adsorption of AHLs. Linear polymers were synthesized using methyl methacrylate as backbone monomer and methacrylic acid and itaconic acid as functional monomers. Two different QS-controlled phenotypes, Vibrio fischeri bioluminescence and Aeromonas hydrophila biofilm formation, were evaluated to test the polymers’ efficiency. Results showed that both phenotypes were significantly affected by the polymers, with the itaconic acid-containing material more effective than the methacrylic acid one. The polymer inhibitory effects were reverted by addition of lactones, confirming attenuation of QS through sequestration of signal molecules. The polymers also showed no cytotoxicity when tested using a mammalian cell line.This work was partially supported by FEDER funding through COMPETE program and by national funds through FCT within the projects PROMETHEUS (PTDC/AGR-CFL/113831/2009 and FCOMP-01-0124-FEDER-014096) and PEst (PEst-C/MAR/LA0017/2013). FCT also financed Ph.D. and post-doctoral fellowships of Eliana Cavaleiro (BD/47502/2008), Ana Cristina Esteves (BPD/38008/2007) and Ana Sofia Duarte (BPD/46290/2008).Peer-reviewedPost-prin
A novel small-caliber bacterial cellulose vascular prosthesis: production, characterization, and preliminary in vivo testing

Vascular grafts are used to bypass damaged or diseased blood vessels. Bacterial cellulose (BC) has been studied for use as an off-the-shelf graft. Herein, we present a novel, cost-effective, method for the production of small caliber BC grafts with minimal processing or requirements. The morphology of the graft wall produced a tensile strength above that of native vessels, performing similarly to the current commercial alternatives. As a result of the production method, the luminal surface of the graft presents similar topography to that of native vessels. We have also studied the in vivo behavior of these BC graft in order to further demonstrate their viability. In these preliminary studies, 1 month patency was achieved, with the presence of neo-vessels and endothelial cells on the luminal surface of the graft.This study was supported by the Portuguese Foundation for Science and Technology (FCT) and the European Community fund FEDER, through Program COMPETE, under the scope of the Projects FCOMP-01-0124-FEDER-007025 (PTDC/AMB/68393/2006), PEST-OE/EQB/LA0023/2013, PEST-C/FIS/UI607/2013, RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and the Projects "BioEnv-Biotechnology and Bioengineering for a sustainable world" and "Matepro-Optimizing Materials and Processes". NORTE-07-0124-FEDER-000048, co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER. The authors also acknowledge the fellowship awarded to Alexandre Felipe Leitao (SFRH/BD/66094/2009) funded by the Fundacao para a Ciencia e Tecnologia (FCT). The authors also thank support by FCT through the project BCGrafts, FCOMP-01-0124-FEDER-014773 (PTDC/EBB/EBI/112170/2009) and by the People Program (Marie Curie Actions) of the European Union's Seventh Framework Program FP7/2007-2013/under REA grant agreement n317512
In vivo imaging of glycol chitosan-based nanogel biodistribution

The preclinical development of nanomedicines raises several challenges and requires a comprehensive characterization. Among them is the evaluation of the biodistribution following systemic administration. In previous work, the biocompatibility and in vitro targeting ability of a glycol chitosan (GC) based nanogel have been validated. In the present study, its biodistribution in the mice is assessed, using near-infrared (NIR) fluorescence imaging as a tool to track the nanogel over time, after intravenous administration. Rapid whole body biodistribution of both Cy5.5 labeled GC nanogel and free polymer is found at early times. It remains widespreadly distributed in the body at least up to 6 h postinjection and its concentration then decreases drastically after 24 h. Nanogel blood circulation half-life lies around 2 h with the free linear GC polymer presenting lower blood clearance rate. After 24 h, the blood NIR fluorescence intensity associated with both samples decreases to insignificant values. NIR imaging of the organs shows that the nanogel had a body clearance time of 48 h, because at this time point a weak signal of NIR fluorescence is observed only in the kidneys. Hereupon it can be concluded that the engineered GC nanogel has a fairly long blood circulation time, suitable for biomedical applications, namely, drug delivery, simultaneously allowing efficient and quick body clearance.Acknowledgements: The authors thank the FCT Strategic Project of UID/BIO/04469/2013 unit, the project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462), and the Project “BioHealth— Biotechnology and Bioengineering approaches to improve health quality,” Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. The authors also thank António Temudo, Dolores Bonaparte, and Sílvia Santos Pedrosa for the support on in vivo assays. Paula Pereira acknowledges FCT for the PhD grant SFRH/ BD/64977/2009
Designing Visible Light-Cured Thiol-Acrylate Hydrogels for Studying the HIPPO Pathway Activation in Hepatocellular Carcinoma Cells

Various polymerization mechanisms have been developed to prepare peptide-immobilized poly(ethylene glycol) (PEG) hydrogels, a class of biomaterials suitable for studying cell biology in vitro. Here, a visible light mediated thiol-acrylate photopolymerization scheme is reported to synthesize dually degradable PEG-peptide hydrogels with controllable crosslinking and degradability. The influence of immobilized monothiol pendant peptide is systematically evaluated on the crosslinking of these hydrogels. Further, methods are proposed to modulate hydrogel crosslinking, including adjusting concentration of comonomer or altering the design of multifunctional peptide crosslinker. Due to the formation of thioether ester bonds, these hydrogels are hydrolytically degradable. If the dithiol peptide linkers used are susceptible to protease cleavage, these thiol-acrylate hydrogels can be designed to undergo partial proteolysis. The differences between linear and multiarm PEG-acrylate (i.e., PEGDA vs PEG4A) are also evaluated. Finally, the use of the mixed-mode thiol-acrylate PEG4A-peptide hydrogels is explored for in situ encapsulation of hepatocellular carcinoma cells (Huh7). The effects of matrix stiffness and integrin binding motif (e.g., RGDS) on Huh7 cell growth and HIPPO pathway activation are studied using PEG4A-peptide hydrogels. This visible light poly-merized thiol-acrylate hydrogel system represents an alternative to existing light-cured hydrogel platforms and shall be useful in many biomedical applications
Gelatin-Hyaluronic Acid Hydrogels with Tuned Stiffness to Counterbalance Cellular Forces and Promote Cell Differentiation

Producción CientíficaCells interact mechanically with their environment, exerting mechanical forces that probe the extracellular matrix (ECM). The mechanical properties of the ECM determine cell behavior and control cell differentiation both in 2D and 3D environments. Gelatin (Gel) is a soft hydrogel into which cells can be embedded. This study shows significant 3D Gel shrinking due to the high traction cellular forces exerted by the cells on the matrix, which prevents cell differentiation. To modulate this process, Gel with hyaluronic acid (HA) has been combined in an injectable crosslinked hydrogel with controlled Gel–HA ratio. HA increases matrix stiffness. The addition of small amounts of HA leads to a significant reduction in hydrogel shrinking after cell encapsulation (C2C12 myoblasts). We show that hydrogel stiffness counterbalanced traction forces of cells and this was decisive in promoting cell differentiation and myotube formation of C2C12 encapsulated in the hybrid hydrogels.2018-01-01Ministerio de Economía, Industria y Competitividad (MAT2013-46467-C4-1-R)CIBER-BBN y el Instituto de Salud Carlos III mediante el Centro de Medicina Regenerativa y Terapia Celular de Castilla y Leó
Differentiation of Human Mesenchymal Stem Cells Toward Quality Cartilage Using Fibrinogen-Based Nanofibers

Mimicking the complex intricacies of the extra cellular matrix including 3D configurations and aligned fibrous structures were traditionally perused for producing cartilage tissue from stem cells. This study shows that human adipose derived mesenchymal stem cells (hADMSCs) establishes significant chondrogenic differentiation and may generate quality cartilage when cultured on 2D and randomly oriented fibrinogen/poly-lactic acid nanofibers compared to 3D sandwich-like environments. The adhering cells show well-developed focal adhesion complexes and actin cytoskeleton arrangements confirming the proper cellular interaction with either random or aligned nanofibers. However, quantitative reverse transcription-polymerase chain reaction analysis for Collagen 2 and Collagen 10 genes expression confirms favorable chondrogenic response of hADMSCs on random nanofibers and shows substantially higher efficacy of their differentiation in 2D configuration versus 3D constructs. These findings introduce a new direction for cartilage tissue engineering through providing a simple platform for the routine generation of transplantable stem cells derived articular cartilage replacement that might improve joint function
The key role of sulfation and branching on fucoidan antitumor activity

There is an urgent need for antitumor bioactive agents with minimal or no side effects over normal adjacent cells. Fucoidan is a marine-origin polymer with known antitumor activity. However, there are still some concerns about its application due to the inconsistent experimental results, specifically its toxicity over normal cells and the mechanism behind its action. Herein, three fucoidan extracts (FEs) have been tested over normal and breast cancer cell lines. From cytotoxicity results, only one of the extracts shows selective antitumor behavior (at 0.2 mg mLâ  1), despite similarities in sulfation degree and carbohydrates composition. Although the three FEs present different molecular weights, depolymerization of selected samples discardedÂ MwÂ as the key factor in the antitumor activity. Significant differences in sulfates position and branching are observed, presenting FE 2 the higher branching degree. Based on all these experimental data, it is believed that these last two properties are the ones that influence the cytotoxic effects of fucoidan extracts.The authors would like to thank the funding from projects 0687_NOVOMAR_1_P, cofunded by INTERREG 2007-2013/POCTEP, CarbPol_u_Algae (EXPL/MAR-BIO/0165/2013), and IF/00376/2014/CP1212/CT0015, funded by the Portuguese Foundation for Science and Technology, FCT, and ComplexiTE (ERC-2012-ADG 20120216-321266), funded by the European Research Council under the European Union's Seventh Framework Programme for Research and Development. The authors would also like to thank FCT, Portugal, for the scholarship of A.S.F. (SFRH/BD/102471/2014), fellowship of C.N. (SFRH/BPD/100627/2014), Investigator grants of A.M. (IF/00376/2014), R.N.-C. (IF/00373/2014), and I.P. (IF/00032/2013) and the financial support to CICECO-Aveiro Institute of Materials (POCI-01-0145-FEDER-007679, FCT UID/CTM/50011/2013) and OOPNA (UID/OUI/00062/2013), through national founds and cofinanced by the FEDER, within the PT2020 Partnership Agreement
Soluble polythiophenes as anticorrosive additives for marine epoxy paints

This study compares the resistance against corrosion of a marine epoxy primer modified with Zn-3(PO4)(2) (10 wt%) or a small concentration (0.3 wt%) of conducting polymer (CP) as inorganic or organic anticorrosive pigment, respectively. More specifically, the behavior of three different CPs has been evaluated: polyaniline (PAni) emeraldine base, poly(3-thiophen-3-yl-acrylic acid methyl ester) and poly(2-thiophen-3-yl-malonic acid dimethyl ester), the latter two being soluble polythiophene (PTh) derivatives bearing carboxylate side groups. In a first stage, the structural, thermal, and mechanical properties of all the modified epoxy coatings were characterized using infrared spectroscopy, thermogravimetric analyses and stress-strain assays, respectively. After this, accelerated corrosion assays have evidenced that the degree of protection imparted by a small concentration of PAni is higher than that obtained using 10wt% of Zn-3(PO4)(2). Indeed, PAni has been found to be more effective as anticorrosive additive than the two PTh derivatives. This fact has been attributed to the electroactivity of the former, which is higher than that of the latter. Thus, the ability to store charge has been proposed to be also responsible of protection against corrosion imparted by organic additives, based on CPs.Peer ReviewedPostprint (author’s final draft
Effects of substituting ytterbium for scandium on corrosion behaviour of Al-Sc alloy

The localized corrosion and electrochemical behaviour of Al-0.28 wt.% Sc and Al-0.24 wt.% Sc-0.07 wt.% Yb alloys have been studied in 3.5 wt.% NaCl solution. The results showed that the impurity intermetallic phases containing Fe can act as cathodes and promote localized corrosion in the surrounding matrix. Yb had strong effect on the polarization behaviour in the anodic domain of Al-Sc alloy by improving the pitting corrosion resistance of this alloy. It has been deduced that a high number density of fully coherent nano-sized Al3Sc or Al-3(Sc, Yb) precipitates in heat treated alloys can enhance the passivation tendency of these alloys.This research was supported by The Project Bridging The Gap, funded by the Erasmus Mundus External Cooperation Window Program. Acknowledgements also to the University of Minho, for the provision of research facilitiesinfo:eu-repo/semantics/publishedVersio
The effect of Sc and Yb microalloying additions and aged-hardening heat treatment on corrosion behavior of Al-Mg alloys

Sc-containing Al alloys are potentially applied in saline environment. However, the corrosion behavior and its mechanisms of Sc-containing Al alloys have not been paid much attention. In this research, the corrosion behavior of Al-4Mg, Al-4Mg-0.3Sc, and Al-4Mg-0.24Sc-0.06Yb alloys was investigated in 3.5wt% NaCl solution by immersion and potentiodynamic polarization analysis. Scanning electron microscope (SEM), transmission electron microscopy (TEM) and high-resolution TEM were used to characterize intermetallic phases and localized corrosion. The results showed that the Fe-containing intermetallic particles are cathodic with respect to the matrix and can lead to localized corrosion, whereas the high content of Mg makes the Fe-containing intermetallic particle less noble to the matrix. Yb-containing intermetallic particles did not show any dissolution of the matrix at the periphery of these particles. The results indicated that active dissolution and localized corrosion were the dominant corrosion mechanisms for Al-4Mg alloy. However the polarization curves of Al-4Mg-0.3Sc and Al-4Mg-0.24Sc-0.06Yb alloys showed spontaneous passivation followed by pitting corrosion. Results suggested that age-hardening heat treatment improved the stability of the passive film on Al-4Mg-0.3Sc and Al-4Mg-0.24Sc-0.06Yb alloys.This research was supported by The Project Bridging The Gap, funded by the Erasmus Mundus External Cooperation Window Program. Acknowledgements also to the University of Minho, for the provision of research facilities.info:eu-repo/semantics/publishedVersio
Modeling gas turbine materials’ hot corrosion degradation in combustion environments from H2‐rich syngas

Components of gas turbines (such as blades, vanes, combustor cans) exposed to combustion environments at high temperature are susceptible to hot corrosion attack. To successfully plan maintenance and to determine whether to operate in novel combustion modes (e.g., in integrated gasification combined cycles that incorporate pre-combustion carbon capture) predictions of hot corrosion component life must be made. In this paper, hot corrosion datasets relating to two alloys, MarM 509 (a cobalt-based superalloy), and Rene 80 (a nickel-based superalloy) form the basis of hot corrosion predictive lifetime models. The model framework is based on the two stages of incubation and propagation, with the transitions from incubation to propagation around the samples being based on Weibull statistics. The impact of a range of temperatures (including 700 and 900 °C), gas compositions (simulating the combustion of natural gas, H2-rich syngas, or partially cleaned syngas), and deposit chemistries/fluxes have been assessed. Predictions have been made including the expected damage spread for a range of different exposure conditions
Oxygen permeability of Fe-Ni-Cr alloys at 1100 and 1150 °C under carbon-free and carbon-containing gases

Wagner's model of internal oxidation allows the prediction of an alloy's critical concentration of oxide forming metal required to achieve a protective oxide scale at high temperatures. The model depends on oxygen permeability in the alloy, but this parameter has not been evaluated for the Fe-Ni system, and the influence of carbon-bearing gases is unknown. Oxygen permeability measurement by internal oxidation of Fe-Ni-Cr alloys, reacted at 1100 and 1150 8C is described. Exposures in Rhines packs and flowing CO-CO2 gas mixtures serve to assess the influence of carbon on oxygen permeability at the Fe-FeO equilibrium oxygen potential. Oxygen permeability in Fe-Ni increases with iron content in a non-ideal manner in both gas environments. Higher permeability is found in carbon bearing gases for iron-rich alloys, and the size of this effect increases with temperature