Co-axial printing of growth factor-laden microspheres for pancreatic islet transplantation

Type I diabetes is an autoimmune disease affecting millions of people in the world. It occurs when the pancreas cannot produce insulin, resulting in episodes of hyperglycaemia that can lead to heart attacks, renal failure, or death. The main cause is the auto destruction of beta cells that produce insulin, located in the pancreatic islets (or islets of Langerhans). Current treatments include insulin injections that decrease the blood glucose level. However, it can sometimes generate hypoglycaemia or insulin resistance on the patients. Bioprinting allows controlled engineering of pancreatic islets with hydrogel scaffolds and transplanting them into the patients. Nevertheless, immunotolerance of the grafted constructs has yet to be achieved. Currently, the islets are implanted together with immunosuppressors to avoid the rejection, but these affect the functionality of the beta cells. Co-transplanting regulatory T cells (Tregs) that regulate the autoimmune response could be the solution to immune rejection. Thus, co-axial extrusion printing is a promising approach, as it allows printing two types of bioinks. Pancreatic islets can be printed in the core of the structure and Tregs in the shell, protecting the islets. This project was mainly focused on the development of the bioink for the shell. The ink consists of a hydrogel that promotes cell growth and allows bioprinting (2% alginate/7.5% gelatin methacrylolyl (GelMA)/3.5% gelatin), and growth factors for Treg functionality (IL-2). The growth factors were encapsulated in GelMA microspheres for a sustained release inside the ink. The release rate of IL-2 was studied, as well as the ink properties and printability

Mathematical modeling for control of emulsion polymerization

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Experimental validation of a mathematical model for the evolution of the particle morphology of waterborne polymer-polymer hybrids: paving the way to the design and implementation of optimal polymerization strategies

Polymer-polymer composite nanoparticles allow both the improvement of the performance in stablished applications of waterborne polymer dispersions and targeting new applications that are out of reach of currently available products. The performance of these materials is determined by the particle morphology. To open the way to process optimization and on-line control of the particle morphology, the capability of the recently developed model to predict the evolution of the particle morphology during seeded semibatch emulsion polymerization process was evaluated. Structured polymer particles were synthesized by copolymerization of styrene and butyl acrylate (St-BA) on methyl methacrylate and butyl acrylate (MMA–BA) copolymer seeds of different Tgs. The model captured well the effect of process variables on the evolution of the particle morphology, opening the way to the design and implementation of optimal strategies.The financial support of the RECOBA project (funding from European Framework Horizon 2020, No. 636820) is gratefully acknowledged

Dynamic modeling of the morphology of multiphase waterborne polymer particles

Multiphase waterborne polymer particles provide advantages in more demanding applications, and their performance depends on particle morphology. Currently, no dynamic model for the prediction of the development of the morphology of multiphase latex particles is available. In this work, a model was developed for the prediction of the dynamic development of the morphology of multiphase waterborne systems, such as polymer-polymer and polymer-polymer- inorganic hybrids

Criminología y multiculturalismo. Medidas internacionales y propuestas de tratamiento jurídico para la erradicación de la mutilación genital femenina

[ES] El Derecho, como instrumento social, constituye el reflejo de las concepciones culturales predominantes en cada comunidad. Así, los criterios que sustentan la calificación de una conducta como “delictiva” vienen condicionados por las coordenadas sociales y políticas de cada momento histórico. Partiendo de esta afirmación, se examinan las medidas internacionales para la erradicación de la mutilación genital femenina, abordando la cuestión de la exigencia de la responsabilidad penal, a través de una reflexión sobre las diferencias culturales y la “culpabilidad jurídico-penal”.[EU] Zuzenbidea komunitate guztietako kontzeptu kulturalaren islada da. Ekintza bat delitua dela baieztatzen duten kriterioak, gizartearen koordenada sozial eta politikoengatik baldintzatuak azaltzen dira, momentu historiko bakoitzean. Afirmazio honetatik abiatuta, emakumeen genitalen mutilazioarekin amaitzeko hartzen ari diren nazioarteko neurriak aztertzen dira, erantzukizun penalari buruzko erreflexioa eginez.[FR] Le Droit, comme instrument social, constitue un reflet des conceptions culturelles prédominantes dans chaque communauté. Ainsi, les critères qui soutiennent la qualification d’une conduite comme “délictueuse“ sont conditionnés par les coordonnées sociales et politiques de chaque moment historique. En partant de cette affirmation, on examine les mesures internationales pour l’éradication de la mutilation génitale féminine, en abordant la question de l’exigence de la responsabilité pénale, à travers une réflexion sur les différences culturelles et la “culpabilité juridique-pénale“.[EN] The Law, as a social instrument, constitutes the reflection of predominant cultural conceptions in each community. Thus, the criteria to describe a conduct as “criminal” are determined by the social and political coordinates in every historical moment. Starting from this approach, the international measures to eradicate the feminine genital mutilation are examined, tackling the question of the exigency of criminal responsibility, through a reflection on the cultural differences and the “criminal culpability”

Dynamic modeling of the morphology of latex particles with in situ formation of graft copolymer

Modification of the polymer-polymer interfacial tension is a way to tailor-make particle morphology of waterborne polymer-polymer hybrids. This allows achieving a broader spectrum of application properties and maximizing the synergy of the positive properties of both polymers, avoiding their drawbacks. In situ formation of graft copolymer during polymerization is an efficient way to modify the polymer-polymer interfacial tension. Currently, no dynamic model is available for polymer-polymer hybrids in which a graft copolymer is generated during polymerization. In this article, a novel model based on stochastic dynamics is developed for predicting the dynamics of the development of particle morphology for composite waterborne systems in which a graft copolymer is produced in situ during the process

Flexible aromatic disulfide monomers for high-performance self-healable linear and cross-linked poly(urethane-urea) coatings

Implementation of the self-healing concept in coatings is challenging because they have to combine mechanical strength and chain mobility. This challenge is addressed in this work by studying the effect of the polymer microstructure on the mechanical properties and self-healing ability of waterborne poly(urethane-urea) coatings containing aromatic disulfide dynamic bonds. The structural modifications studied are the concentration and flexibility of the aromatic disulfide units and the effect of cross-linking. The effects and limits of these structural changes on the mechanical properties of the polymers and their healability were determined via a combination of DMA measurements, tensile tests, and rheological and scratch closure experiments. It was found that the flexibility of the disulfide unit was key to develop more efficient self-healing materials which offer the necessary molecular mobility for self-healing while simultaneously maintaining a level of mechanical strength that are essential for coating applications.The European Union’s Horizon 2020 research and innovation programme is accredited for the financial support through Project TRACKWAY-ITN 642514 under the Marie Sklodowska-Curie grant agreement. N.B. acknowledges the financial support obtained through the Post-Doctoral fellowship Juan de la Cierva - Incorporación (IJCI-2016-28442), from the Ministry of Economy and Competitiveness of Spai

Forces Driving the Development of Particle Morphology of Waterborne Polymer Dispersions

[EN] Particle morphology is a key characteristic of the waterborne polymer dispersions and plenty of effort has been dedicated to understand the mechanisms controlling the development of the morphology during polymerization. The availability of new characterization techniques that provide unprecedented quantitative details of the particle morphology have questioned the ideas about the driving forces ruling the development of the morphology. In this article, the case is considered of a seeded emulsion polymerization in which the second stage polymer (Polymer 2) is more hydrophobic than the seed polymer and a water-soluble initiator is used. Simulations of the effect of the different forces involved in the formation of the particle morphology carried by integrating the Navier-Stokes are compared with available experimental results. If is found that the interfacial tensions are responsible for the penetration of clusters of polymer 2 within the seed polymer and the spread of these clusters over the surface of the particle. On the other hand, van der Waals forces control coalescence of the clusters both at the surface and in the interior of the particle.The support of the partners of the Industrial Liaison Program on Polymerization in Disperse Media (Allnex, Akzo-Nobel, Arkema, Asian Paints, BASF, DSM, Elix Polymers, Inovyn, 3M, Stahl, Synthomer, Vinavil, Wacker) is acknowledged

Modeling the shear-dependent viscosity of nonionically stabilized waterborne dispersions

[EN] The performance of a rheological model that accounts for the effect of the volume fraction, the particle size distribution, and shear rate on the viscosity of water-borne dispersions stabilized with conventional nonionic surfactants and polymeric stabilizers is assessed. The model that contains three parameters fitted well the experimental data. The parameters were independent of the volume fraction, the particle size distribution, and the shear rate. Furthermore, two of them were not affected by the surfactant type and concentration, and temperature. The other parameter increased with the surfactant molecular weight and surface covering, but decreased with increasing temperature.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This study was supported by Ministerio de Ciencia e Innovacion (PID2019-107889GA-I00)

Particle Morphology

This chapter discusses the morphology of latex particles obtained mainly by (mini)emulsion polymerisation. It describes some applications of these particles, and discusses the factors that influence the particle morphology. Mathematical models that describe and predict the particle morphology as a function of polymerisation variables are presented along with some experimental examples. Structured polymer particles can be synthesized by chemical and physical methods. Among the physical methods, heterocoagulation and solvent evaporation have been used to produce capricious particle morphologies. Synthetic latexes are mainly used in applications (e.g., paints, adhesives, paper and coatings) that require the formation of a film. Film formation is described as consisting of three main processes: (i) evaporation of water to achieve the close-packing of particles, (ii) deformation of particles to fill all the void space, and (iii) interdiffusion of the polymer across particle interfaces to fuse particle boundaries