Poly(N-isopropylacrylamide) and copolymers: a review on recent progresses in biomedical applications

The innate ability of poly(N-isopropylacrylamide) (PNIPAAm) thermo-responsive hydrogel to copolymerize and to graft synthetic polymers and biomolecules, in conjunction with the highly controlled methods of radical polymerization which are now available, have expedited the widespread number of papers published in the last decade—especially in the biomedical field. Therefore, PNIPAAm-based hydrogels are extensively investigated for applications on the controlled delivery of active molecules, in self-healing materials, tissue engineering, regenerative medicine, or in the smart encapsulation of cells. The most promising polymers for biodegradability enhancement of PNIPAAm hydrogels are probably poly(ethylene glycol) (PEG) and/or poly(e-caprolactone) (PCL), whereas the biocompatibility is mostly achieved with biopolymers. Ultimately, advances in three-dimensional bioprinting technology would contribute to the design of new devices and medical tools with thermal stimuli response needs, fabricated with PNIPAAm hydrogels.Peer ReviewedPostprint (published version

PBL+CW = una combinación exitosa?

Esta comunicación analiza el proceso seguido durante los últimos años por parte del Departamento de Proyectos de Ingeniería en la Escuela Técnica Superior de Ingenierías Industrial y Aeronáutica de Terrassa (ETSEIAT) para la definición del modelo de aprendizaje en las seis asignaturas de Proyectos que imparte (y más concretamente la denominada “Fundamentos de Proyectos”). Asimismo se presenta una experiencia innovadora de aplicación de la técnica de “puzzle” para la resolución y el aprendizaje de problemas que se ha introducido en una asignatura de primer curso para Ingenieros Químicos, denominada “Enlace y Estructura”, de la Escuela Técnica Superior de Ingeniería Industrial de Barcelona (ETSEIB).Preprin

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

Puzzle-Pro: aplicación de la técnica en clases de problemas

En el presente trabajo se muestran las experiencias de aplicación de una técnica de aprendizaje cooperativo en una asignatura de quinto curso de la titulación de Ingeniería Química. La asignatura se llama “Diseño de Equipos e Instalaciones” y se imparte en la Escuela Técnica Superior de Ingenieros Industriales de Barcelona. En la asignatura de “Diseño de Equipos e Instalaciones” se ha aplicado una variante de la técnica del puzzle (rompecabezas) de Elliot Aronson (1978), denominada puzzle para problemas o puzzle-pro. Esta técnica fue desarrollado por Joan Domingo y Maria Pilar Almajano y ya ha sido aplicada en otras asignaturas como son la de “Enlace y Estructura” y “Química II”, dos asignaturas de primer curso de Ingeniería Química e Ingeniería Industrial, respectivamente. El PUZZLE-PRO es una técnica que se puede emplear en cualquier asignatura, es una técnica muy motivadora para profesores y alumnos y las claves de éxito están garantidas. La metodología, los consejos para emplear la técnica y los resultados obtenidos se muestran en la comunicación completa.Postprint (published version

Marine-friendly antifouling coating based on the use of a fatty acid derivative as a pigment

This study was devoted to examining the application of copper dodecanoate as a non-contaminant antifouling pigment due to its low copper content and fatty acid nature. For this purpose, antifouling paints with mono-component epoxy resin and rosin matrixes were formulated, and their antifouling efficiency was evaluated. Before its incorporation into the different formulations, the synthesized pigment was characterized. Immersion tests in a marine environment were carried out for 12 months to evaluate the antifouling efficiency of the developed paints; the results were compared with those from a commercial paint. The antifouling efficiency of the new epoxy formulation was found to be considerably higher than that of the rosin formulation and very similar to that of the commercial paint. Most importantly, the release of copper from the epoxy paint formulated with copper dodecanoate was 73.5% lower than that of the commercial paint, suggesting prolonged activity of the developed paint.Peer ReviewedPostprint (published version

Modified tannin extracted from black wattle tree as an environmentally friendly antifouling pigment

The use of modified black wattle tannin as an antifouling pigment is reported in this work. A mixture of tannin adsorbed in activated carbon (soluble fraction of tannin) and low soluble fraction of tannin was used as an antifouling pigment. The soluble rosin resin was used as a paint matrix. C-13 NMR analysis confirm the modification of black wattle tannin through the cleavage of tannin interflavonoid bonds. FTIR spectra indicate the presence of tannin in the formulated antifouling coating even after 7 months of its exposure in a marine environment. Water contact angle analysis shows the hydrophilic characteristic of the tannin antifouling coating surface. Immersion tests at Badalona Port in the Mediterranean Sea shows the high antifouling efficiency of the TAN coating, comparable to commercial paint, until 7 months. The use of a natural black wattle tannin, without its complexation with metals, can eliminate the release of metals and other toxic biocides to the marine environment. (C) 2014 Elsevier B.V. All rights reserved.Peer ReviewedPostprint (author’s final draft

Designing stainless steel surfaces with anti-pitting properties applying laser ablation and organofluorine coatings

Long-lasting and superhydrophobic stainless steel with anti-pitting properties is achieved by modifying conventional AISI 304L through a two-step strategy: 1) application of a femtosecond surface laser ablation treatment to generate micro-nano structures on the surface; and 2) deposition of organofluorine nanometric coating. Samples with two different patterns, namely paraboloid- and cauliflower-like, are approached and investigated by means of contact angle hysteresis, X-ray photoelectron spectroscopy, and electrochemical techniques. Results indicate that the stainless steel surface acquires efficient anticorrosive properties due to the homogenization and refinement of the patterned microstructure into a magnetite rich phase, in combination with the formation of a carbonaceous and sol–gel layer. The adherent semiconducting oxide layer is stable over time in presence of an aggressive chloride environment. The prepared superhydrophobic surfaces prevent the steel substrates from getting wet with water, protecting them from the pitting corrosion caused by the electrolyte intrusion. The corrosion resistance is explained by a mechanism in which, in addition of the silane coating, the air trapped into the micro-nano patterned surfaces plays an important role.Peer ReviewedPostprint (author's final draft

Assembly of Conducting Polymer and Biohydrogel for the Release and Real-Time Monitoring of Vitamin K3

In this work, we report the design and fabrication of a dual-function integrated system to monitor, in real time, the release of previously loaded 2-methyl-1,4-naphthoquinone (MeNQ), also named vitamin K3. The newly developed system consists of poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles, which were embedded into a poly-¿-glutamic acid (¿-PGA) biohydrogel during the gelling reaction between the biopolymer chains and the cross-linker, cystamine. After this, agglomerates of PEDOT nanoparticles homogeneously dispersed inside the biohydrogel were used as polymerization nuclei for the in situ anodic synthesis of poly(hydroxymethyl-3,4-ethylenedioxythiophene) in aqueous solution. After characterization of the resulting flexible electrode composites, their ability to load and release MeNQ was proven and monitored. Specifically, loaded MeNQ molecules, which organized in shells around PEDOT nanoparticles agglomerates when the drug was simply added to the initial gelling solution, were progressively released to a physiological medium. The latter process was successfully monitored using an electrode composite through differential pulse voltammetry. The fabrication of electroactive flexible biohydrogels for real-time release monitoring opens new opportunities for theranostic therapeutic approaches.Peer ReviewedPostprint (published version

Effect of corrosion-induced damage on microstructure and residual strenght of WC-Co,Ni cemented carbide

Postprint (published version

3D-printed polymer-infiltrated ceramic network: mechanical properties and biocompatibility

The current study focuses on the manufacture and characterization of emerging polymer-infiltrated ceramic networks (PICN) produced by 3D-printing technologies, which show a potential to be used as dental implant material. The advantage in comparison with currently used materials is the combination of organic and inorganic phases and therefore similarity to natural teeth. Porous zirconia (3Y-TZP) scaffolds with 50 % infill and cubic geometry were designed. Samples were extruded from 30:70 Pluronic® hydrogel and 3Y-TZP powder paste through 800 μm nozzle employing robocasting technique. Following the sintering process the scaffolds were infiltrated with a copolymer mixture of bisphenol A glycerolate dimethacrylate (Bis-GMA) and tri(ethylenglycol) dimethacrylate (TEGDMA) in 40:60 ratio and copolymerized in vacuum to avoid the formation of bubbles. To ensure proper infiltration and the attachment of copolymer to zirconia surface the samples were functionalized with 3-(trimethoxysilyl)propyl methacrylate (γ-MPS). As the material is predetermined to be used as biomaterial, the chemical, microstructural, mechanical, and cytotoxic properties were evaluated. The adherence of copolymer to zirconia surface was supported by x-ray photoelectron spectroscopy analysis and visualized by scanning electron microscopy. To observe the mechanical performance of PICN, the crack resistance of the material under compression stress was characterized and recorded by Vic 2DTM camera. The novel composite also shows a reduction of proliferation of 2 lines of bacteria, Gram-negative Escherichia coli and Gram-positive Streptococcus salivarius, and the MG-63 cell viability assays confirmed the biocompatibility of the composite material