Progression of regional lung strain and heterogeneity in lung injury: assessing the evolution under spontaneous breathing and mechanical ventilation

Indexación ScopusBackground: Protective mechanical ventilation (MV) aims at limiting global lung deformation and has been associated with better clinical outcomes in acute respiratory distress syndrome (ARDS) patients. In ARDS lungs without MV support, the mechanisms and evolution of lung tissue deformation remain understudied. In this work, we quantify the progression and heterogeneity of regional strain in injured lungs under spontaneous breathing and under MV. Methods: Lung injury was induced by lung lavage in murine subjects, followed by 3 h of spontaneous breathing (SB-group) or 3 h of low Vt mechanical ventilation (MV-group). Micro-CT images were acquired in all subjects at the beginning and at the end of the ventilation stage following induction of lung injury. Regional strain, strain progression and strain heterogeneity were computed from image-based biomechanical analysis. Three-dimensional regional strain maps were constructed, from which a region-of-interest (ROI) analysis was performed for the regional strain, the strain progression, and the strain heterogeneity. Results: After 3 h of ventilation, regional strain levels were significantly higher in 43.7% of the ROIs in the SB-group. Significant increase in regional strain was found in 1.2% of the ROIs in the MV-group. Progression of regional strain was found in 100% of the ROIs in the SB-group, whereas the MV-group displayed strain progression in 1.2% of the ROIs. Progression in regional strain heterogeneity was found in 23.4% of the ROIs in the SB-group, while the MV-group resulted in 4.7% of the ROIs showing significant changes. Deformation progression is concurrent with an increase of non-aerated compartment in SB-group (from 13.3% ± 1.6% to 37.5% ± 3.1%), being higher in ventral regions of the lung. Conclusions: Spontaneous breathing in lung injury promotes regional strain and strain heterogeneity progression. In contrast, low Vt MV prevents regional strain and heterogeneity progression in injured lungs. © 2020, The Author(s).https://annalsofintensivecare.springeropen.com/articles/10.1186/s13613-020-00725-

Strategies to Fabricate Polypeptide-Based Structures via Ring-Opening Polymerization of N-Carboxyanhydrides

In this review, we provide a general and clear overview about the different alternatives reported to fabricate a myriad of polypeptide architectures based on the ring-opening polymerization of N-carbonyanhydrides (ROP NCAs). First of all, the strategies for the preparation of NCA monomers directly from natural occurring or from modified amino acids are analyzed. The synthetic alternatives to prepare non-functionalized and functionalized NCAs are presented. Protection/deprotection protocols, as well as other functionalization chemistries are discussed in this section. Later on, the mechanisms involved in the ROP NCA polymerization, as well as the strategies developed to reduce the eventually occurring side reactions are presented. Finally, a general overview of the synthetic strategies described in the literature to fabricate different polypeptide architectures is provided. This part of the review is organized depending on the complexity of the macromolecular topology prepared. Therefore, linear homopolypeptides, random and block copolypeptides are described first. The next sections include cyclic and branched polymers such as star polypeptides, polymer brushes and highly branched structures including arborescent or dendrigraft structures.The authors acknowledge financial support given by FONDECYT Grant No. 1170209. M.A. Sarabia acknowledges the financial support given by CONICYT through the doctoral program Scholarship Grant. J. Rodríguez-Hernández acknowledges financial support from Ministerio de Economía y Competitividad (MINECO) (Project MAT2016-78437-R, FEDER-EU). Finally, this study was funded by VRAC Grant Number L216-04 of Universidad Tecnológica MetropolitanaWe acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

Advances in the Fabrication of Antimicrobial Hydrogels for Biomedical Applications

This review describes, in an organized manner, the recent developments in the elaboration of hydrogels that possess antimicrobial activity. The fabrication of antibacterial hydrogels for biomedical applications that permits cell adhesion and proliferation still remains as an interesting challenge, in particular for tissue engineering applications. In this context, a large number of studies has been carried out in the design of hydrogels that serve as support for antimicrobial agents (nanoparticles, antibiotics, etc.). Another interesting approach is to use polymers with inherent antimicrobial activity provided by functional groups contained in their structures, such as quaternary ammonium salt or hydrogels fabricated from antimicrobial peptides (AMPs) or natural polymers, such as chitosan. A summary of the different alternatives employed for this purpose is described in this review, considering their advantages and disadvantages. Finally, more recent methodologies that lead to more sophisticated hydrogels that are able to react to external stimuli are equally depicted in this review.We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

Polymers for additive manufacturing and 4D-printing: Materials, methodologies, and biomedical applications

Additive manufacturing (AM), also known as additive manufacturing, permits the fabrication of fully customized objects with a high level of geometrical complexity at reduced fabrication time and cost. Besides metals and ceramics, polymers have become a widely researched class of materials for applications in AM. The synthetic versatility and adaptability, as well as the wide range of properties that can be achieved using polymer materials, have rendered polymers the most widely employed class of materials for AM methodologies. In this review, the basic principles, considering the printing mechanism as well as the advantages and disadvantages, of the most relevant polymer AM technologies are described. The particular features, properties and limitations of currently employed polymer systems in the various AM technology areas are presented and analyzed. Subsequently, 4D printing, that is the fabrication of 3D printed structures that are cabable to change with time, is discussed. A brief description of the polymeric materials and technologies under development for 4D printed structures as well as the different shape changes explored are presented. Finally, based on the characteristics of the polymers employed for each technology illustrative examples of the principal applications are discussed.AcknowledgmentsThe authors acknowledge financial support given by FONDECYTGrant N◦1170209. M.A. Sarabia acknowledges the financial supportgiven by CONICYT through the doctoral program Scholarship Grant.J. Rodriguez-Hernandez acknowledges financial support from the Spanish National Science Foundation (CSIC) and the Ministerio de Economia y Competitividad (MINECO) (Project MAT2016-78437-R, FONDOS FEDER). Finally, this study was funded by VRAC GrantNumber L216-04 of Universidad Tecnológica Metropolitana.Peer Reviewe

Antimicrobial Polymers for Additive Manufacturing

Three-dimensional (3D) printing technologies can be widely used for producing detailed geometries based on individual and particular demands. Some applications are related to the production of personalized devices, implants (orthopedic and dental), drug dosage forms (antibacterial, immunosuppressive, anti-inflammatory, etc.), or 3D implants that contain active pharmaceutical treatments, which favor cellular proliferation and tissue regeneration. This review is focused on the generation of 3D printed polymer-based objects that present antibacterial properties. Two main different alternatives of obtaining these 3D printed objects are fully described, which employ different polymer sources. The first one uses natural polymers that, in some cases, already exhibit intrinsic antibacterial capacities. The second alternative involves the use of synthetic polymers, and thus takes advantage of polymers with antimicrobial functional groups, as well as alternative strategies based on the modification of the surface of polymers or the elaboration of composite materials through adding certain antibacterial agents or incorporating different drugs into the polymeric matrix.This research was funded by FONDECYT NO 1170209 and Project MAT2016-78437-R, FONDOS FEDERWe acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)Peer reviewe

Innovaciones tecnológicas en la impresión 3D basada en extrusión de materiales

La manufactura aditiva (MA), o más conocida coloquialmente como impresión 3D, ha experimentado importantes avances en los últimos años debido a las innovaciones tecnológicas en las áreas de la ingeniería e informática. Es más, se espera que con la llegada de la cuarta revolución industrial y con el “internet de las cosas”, la tecnología de la MA cobre mayor relevancia de la que ya tiene actualmente, sirviendo como un puente mucho más directo entre el productor y el consumidor de los bienes. El objetivo de este artículo es resumir y revisar de manera concisa los avances más recientes de la tecnología MA, desde una perspectiva tecnológica y de materiales con el fin de solucionar una serie de problemas pendientes en la MA relativa principalmente al uso de materiales poliméricos por extrusión. Para esto, se analizarán y discutirán las ventajas, desventajas y limitaciones actuales de la MA. Además, se presenta una descripción detallada de los esfuerzos realizados para mejorar la técnica, estudiando aspectos como el tamaño de la pieza, la posibilidad de producir piezas de forma continua y automática, la disminución en el tiempo de fabricación, la reducción del uso de soportes y la fabricación de componentes utilizando más de un material.Additive manufacturing (AM), or more colloquially known as 3D printing, has experienced significant advances in recent years due to technological innovations in the areas of engineering and computing. Moreover, it is expected that with the arrival of the fourth industrial revolution and with the “internet of things”, AM technology will become more relevant than it already has today, serving as a much more direct bridge between the producer and the consumer of the goods. The objective of this article is to concisely summarize and review the most recent advances in AM technology, from a technological and materials perspective, in order to solve a series of pending problems in AM related mainly to the use of polymeric materials by extrusion. For this purpose, the current advantages, disadvantages and limitations of MA will be analyzed and discussed. In addition, a detailed description of the efforts made to improve the technique is presented, studying aspects such as the size of the part, the possibility of producing parts continuously and automatically, the reduction in manufacturing time, the reduction in the use of supports and the manufacture of components using more than one material.Peer reviewe

Innovation in Additive Manufacturing Using Polymers: A Survey on the Technological and Material Developments

This review summarizes the most recent advances from technological and physico-chem-ical perspectives to improve several remaining issues in polymeric materials’ additive manufacturing (AM). Without a doubt, AM is experimenting with significant progress due to technological innovations that are currently advancing. In this context, the state-of-the-art considers both research areas as working separately and contributing to developing the different AM technologies. First, AM techniques’ advantages and current limitations are analyzed and discussed. A detailed overview of the efforts made to improve the two most extensively employed techniques, i.e., material extrusion and VAT-photopolymerization, is presented. Aspects such as the part size, the possibility of producing parts in a continuous process, the improvement of the fabrication time, the reduction of the use of supports, and the fabrication of components using more than one material are ana-lyzed. The last part of this review complements these technological advances with a general overview of the innovations made from a material perspective. The use of reinforced polymers, the preparation of adapted high-temperature materials, or even the fabrication of metallic and ceramic parts using polymers as supports are considered. Finally, the use of smart materials that enable the fabrication of shape-changing 3D objects and sustainable materials will also be explored.The authors recognize the financial support given by FONDECYT Grant No. 1170209 and No. 1220251. M.A. Sarabia-Vallejos acknowledges financial support from Universidad San Sebastián (USS) via its project No. VRID FAI 21/17. J. Rodriguez-Hernandez acknowledges financial support from Ministerio de Ciencia, Innovación y Universidades (Project MAT2016-78437-R, FONDOS FEDER, and RTI2018-096328-B-I00). Finally, we would like to thank the PIT FAB3D, PTI + Salud Gobal and the PTI + SUSPLAST from CSIC for their support

Formation of responsive hierarchical wrinkled patterns on hydrogel films via multi-step methodology

In this article, a simple protocol based on a multi-step methodology is used to form flat, first-generation (G1) or second-generation (G2) wrinkled patterns. Different concentrations of DMAEMA were used to synthesize hydrogel films. The multi-step method used to form the wrinkled pattern involves vacuum, argon plasma, and UV exposure. This methodology allows creating different morphologies, which are intimately related to both the kind of treatment as well as the order employed in each case. The G1 and G2 patterns involve three essential steps. First, water removal via vacuum, generating a deswelling gradient in the films triggering the formation of a G1 pattern on top. Secondly, a frontal vitrification process was induced by argon plasma, which generates a rigid top layer, thus triggering the formation of a G2 pattern. Finally, UV irradiation for fixing the pattern. From these, we obtained the roughness, area increase percentage, undulation wavelength, and amplitude.The authors acknowledge the financial support given by FONDECYT Grant N° 1170209 and N° 3160217. To FONDEQUIP N° EQM150101 for the use of FE-SEM facilities. M.A. Sarabia acknowledges the financial support given by CONICYT through the doctoral program Scholarship Grant. J. Rodriguez-Hernandez acknowledges financial support from Ministerio de Economia y Competitividad (MINECO) (Project MAT2016-78437-R, FONDOS FEDER, and RTI2018-096328-B-I00).Peer Reviewe

Effect of annealing and UV-radiation time over micropore architecture of self-assembled block copolymer thin film

Block copolymers have been recognized as versatile materials to prepare nanoporous polymer films or membranes, but their potential has not been completely explored. This study focuses on the formation and characterization of nanoporous polymer films based on poly(styrene)-block-(methylmethacrylate/methacrylic acid); (PS-b-MMA/MAA) were obtained through atom transfer radical polymerization (ATRP), by using two different protocols: annealing and annealingirradiation; for improving the formation of microporous surface. The composition, crystallinity and structural order of the films were studied by Raman spectroscopy. The film polymer thickness was obtained through very high resolution ellipsometry (VHRE). Finally, atomic force microcopy (AFM) and scanning electron microscopy (SEM) techniques were used to detect changes in the porous-structure. These results show that the morphological properties of the block copolymer were affected via the modification of two variables, UV-radiation time and annealing. SEM and AFM micrographs showed that the morphology exhibit a porous ordered structure. Contact angle measurement suggests additional interactions between hydrophilic functional groups that influence the film wettability