Imine bonding self-repair hydrogels after periodate-triggered breakage of their cross-links

The development of new materials with smart properties is currently expanding the development of new technologies. Therefore, the design of materials with novel sensitivities and smart behavior is important for the development of smart systems with automated responsivity. We have recently reported the synthesis of hydrogels, cross-linked by N,N´-diallyltartardiamide (DAT). The covalent DAT-crosslinking points have vicinal diols which can be easily cleaved with periodate, generating changes in the hydrogel properties, as well as generating valuable α-oxo-aldehyde functional groups useful for further chemical modification. Based on those findings, we envisioned that a self-healable hydrogel could be obtained by incorporation of primary amino functional groups, from 2-aminoethyl methacrylate hydrochloride (AEMA), coexisting with DAT into the same network. Herein, α-oxo-aldehyde groups generated after the reaction with periodate would arise in the immediate environment of amine groups to form imine cross-links. For this purpose, DAT-crosslinked hydrogels were synthesized and carefully characterized. The cleavage of DAT-crosslinks with periodate promoted changes in the mechanical and swelling properties of the materials. As expected, a self-healing behavior was observed, based on the spontaneous formation of imine covalent bonds. In addition, we surprisingly found a combination of fast vicinal diols cleavage and a low speed self-crosslinking reaction by imine formation. Consequently, it was found a time-window in which a periodate-treated polymer was obtained in a transient liquid state, which can be exploited to choose the final shape of the material, before automated gelling. The singular properties attained on these hydrogels could be useful for developing sensors, actuators, among other smart systems.Fil: Wolfel Sánchez, Alexis. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Alvarez Igarzabal, Cecilia Ines. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Romero, Marcelo Ricardo. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; Argentin

Válvulas rígidas

Carcinoid syndrome is a rare disease. The cardiologist must suspect it in the presence of a compatible clinical picture and an echocardiogram with characteristic findings. The following is the clinical case of a patient with carcinoid syndrome with cardiac involvement. After a long period with typical symptoms (erythema, diarrhea, bronchospasm) she evolved with right heart failure. Doppler echocardiography was essential to assess valvular involvement and repercussion in the cardiac cavities.El síndrome carcinoide es una enfermedad poco frecuente. El cardiólogo tiene que sospecharlo ante la presencia de un cuadro clínico compatible y un ecocardiograma con hallazgos característicos. A continuación, se presenta el caso clínico de una paciente con síndrome carcinoide con compromiso cardíaco. Luego de un largo período con los síntomas típicos (eritema, diarrea, broncoespasmo) evolucionó con insuficiencia cardíaca derecha. El eco Doppler fue fundamental para valorar el compromiso valvular y la repercusión en las cavidades cardíaca

upramolecular complex based on MWNTs/Boltorn H40 provides fast response to a Sandwich-type amperometric lactate biosensor

Most sandwich-type biosensors can be used several times, since their long-time stability generally ranges from weeks to several months. However, the response-time of this kind of sensors is typically slow because reagents and products have to diffuse through filtering membranes and the enzymatic matrix. In this manuscript, multiwalled carbon nanotubes (MWNTs) have been used for wiring the enzymatic matrix to the electrode surface. To achieve this, the hyperbranched polymer Boltorn H40 (BH40) has been self-assembled at the surface of MWNTs. After the assembling, the suspension of BH40-MWNTs became stable and its functionality was tested by replacing mucin in the enzymatic matrix of a previously reported sandwich-type lactate biosensor. The inclusion of BH40-MWNTs in the biosensor: increased the diffusion coefficient of soluble species by decreasing the elastic properties of the enzymatic matrix, kept the characteristics of the microenvironment where the enzyme is stored, and wired the enzymatic matrix through a 13 μm thick polycarbonate membrane to the electrode surface. It is important to understand that the superstructure of BH40-MWNTs does not increase the active surface of the electrode. Instead of this, it is a conductive 3D network that connects the enzymatic matrix to the electrode. As a result, the response-time of this novel sandwich-type lactate biosensor is much shorter than that of conventional biosensors because the mediator of the enzyme (oxygen) can be regenerated at the enzymatic matrix and it does not have to diffuse to the electrode surface.Fil: Romero, Marcelo Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Peralta, Damian Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Alvarez Igarzabal, Cecilia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Strumia, Miriam Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Garay, Fernando Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Crosslinked casein-based micelles as a dually responsive drug delivery system

New types of biodegradable nanocarriers for drug delivery were prepared using casein (CAS) micelles as particle templates and glyceraldehyde (GAL) as a crosslinking agent. We found that highly crosslinked casein micelles (CCM) maintained their structural integrity at pH 7.4 (plasma conditions) but were easily degraded in the presence of proteases at pH 5 (lysosomal conditions). Nile red (NR) was chosen as a hydrophobic model drug inspired by the natural role of casein as lipophilic nutrient nanotransporter. The cumulative release of the NR-loaded micelles showed marginal dye leakage at pH 7.4 but was significantly accelerated by protease and pH-mediated degradation of the nanocarriers in a dual-responsive fashion. The prepared nanocarriers possess many favorable features for drug delivery: excellent biocompatibility and biodegradability, high stability in physiological conditions, remarkable capacity for the encapsulation of hydrophobic drugs, minimal drug leakage under extracellular conditions, and rapid drug release in response to the endo-lysosomal levels of pH and proteases. In this regard, the prepared CCM represent a promising candidate for the delivery and triggered release of anti-cancer drugs in lysosomal environments.Fil: Picchio, Matías Luis. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Cuggino, Julio César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Nagel, Gregor. Freie Universitat Berlin; AlemaniaFil: Wedepohl, Stefanie. Freie Universitat Berlin; AlemaniaFil: Minari, Roque Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Alvarez Igarzabal, Cecilia Ines. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; Argentina. Freie Universitat Berlin; AlemaniaFil: Gugliotta, Luis Marcelino. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Calderon, Marcelo. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Freie Universitat Berlin; Alemani

Exploiting cyanine dye J-aggregates/monomer equilibrium in hydrophobic protein pockets for efficient multi-step phototherapy: An innovative concept for smart nanotheranostics

After several decades of development in the field of near-infrared (NIR) dyes for photothermal therapy (PTT), indocyanine green (ICG) still remains the only FDA-approved NIR contrast agent. However, upon NIR light irradiation ICG can react with molecular oxygen to form reactive oxygen species and degrade the ICG core, losing the convenient dye properties. In this work, we introduce a new approach for expanding the application of ICG in nanotheranostics, which relies on the confinement of self-organized J-type aggregates in hydrophobic protein domains acting as monomer depots. Upon the fast photobleaching, while the dye is irradiated, this strategy permits the equilibrium-driven monomer replacement after each irradiation cycle that radically increases the systems' effectivity and applicability. Gadolinium-doped casein micelles were designed to prove this novel concept at the same time as endowing the nanosystems with further magnetic resonance imaging (MRI) ability for dual-modal imaging-guided PTT. By teaching a new trick to a very old dog, the clinical prospect of ICG will undoubtedly be boosted laying the foundation for novel therapeutics. It is anticipated that future research could be expanded to other relevant J-aggregates-forming cyanine dyes or nanocrystal formulations of poorly water-soluble photosensitizers.Fil: Picchio, Matías Luis. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Bergueiro, Julian. Freie Universität Berlin; AlemaniaFil: Wedepohl, Stefanie. Freie Universität Berlin; AlemaniaFil: Minari, Roque Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Alvarez Igarzabal, Cecilia Ines. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Gugliotta, Luis Marcelino. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Cuggino, Julio César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Calderón, Marcelo. Polymat; Españ

Unraveling the gallol-driven assembly mechanism of thermoreversible supramolecular hydrogels inspired by ascidians

Polyphenols-based supramolecular hydrogels have recently attracted much attention as smart materials for applications in several technologies. Although great advances have been made in this field, there is a challenging need for creating new versatile materials that combine synthesis simplicity and suitable functional properties. In this work, inspired by the hydrogen bonding ability of pyrogallol-bearing proteins found in ascidians, we explored a small gallol analog, gallic acid (GA), as a dynamic crosslinker of poly(vinyl alcohol) (PVA). The fundamentals of the supramolecular assembly mechanism of PVA/GA hydrogels are studied for understanding the final properties of the obtained thermo-reversible hydrogels. The polymer deacetylation degree was a key factor to control the gelation kinetics, morphology, and properties of the supramolecular materials. Furthermore, the intercalation of GA molecules between PVA chains produced polymer crystals with a new spatial arrangement, modifying the elastic modulus of the supramolecular network and increasing its stability in water. With remarkable fast gelation ability, ascidian-inspired PVA-GA hydrogels may provide a promising platform for a wide range of biomedical applications including topical drug delivery of therapeutic proteins, wearable electronic devices, and 3D printing.Fil: Wolfel Sánchez, Alexis. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Euti, Esteban. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Picchio, Matías Luis. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Romero, Marcelo Ricardo. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Galván Josa, Víctor Martín. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Martinelli, Marisa. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Minari, Roque Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Alvarez Igarzabal, Cecilia Ines. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; Argentin

Crosslinked casein micelles bound paclitaxel as enzyme activated intracellular drug delivery systems for cancer therapy

Nanomedicine for cancer therapy is a successful tool to diminish the side effect of chemotherapeutics such as paclitaxel (PTX). In this regard, Abraxane®, a human serum albumin (HSA)-based nanomedicine system has shown lesser side effects than Taxol®. However, the large-scale production of HSA protein is limited and expensive, which is traduced in a high cost of the treatments in clinical applications. Thus, the use of easily-available alternative nanocarriers could increment the accessibility of patients to nanomedicine for cancer treatments. Casein is a low-cost protein able to self-assemble into micelles which could efficiently encapsulate PTX into their structure. In this work, the synthesis of chemically crosslinked casein micelles (CCM), used to prepare PTX-based nanoformulations, is presented. CCM@PTX nanoformulations showed promising results in vitro to be applied as nanomedicine for cancer therapy. Thus, the obtained nanoformulations are great candidates to be parenterally administered, accumulate in tumor by passive targeting without leakage of PTX in plasma, and release the drug within the tumor microenvironment, in response to overexpressed proteases such as trypsin.Fil: Cuggino, Julio César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Picchio, Matías Luis. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Gugliotta, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bürgi Fissolo, María de Los Milagros. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ronco, Ludmila Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Calderón, Marcelo. Polymat; EspañaFil: Etcheverrigaray, Marina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; ArgentinaFil: Alvarez Igarzabal, Cecilia Ines. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Minari, Roque Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Gugliotta, Luis Marcelino. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Post-synthesis modification of polymers for the development of functional dynamic covalent hydrogels

The development of hydrogels to perform specific functions in complex environments requires a detailed refinement of their physicochemical properties and responsiveness to environmental changes. Accordingly, the conventional hydrogel synthesis methods have found an insurmountable barrier when the achievement of fully-functional structures at different scales is intended.Thus, in response to the growing requirements, post-synthesis modifications appear as essential strategies to achieve the desired characteristics. Due to the impulse provided by these methods, progress has been made in materials engineering to allow the development of smart hydrogels that predictably change their properties in response to environmental stimuli. Consequently, in addition to changes in the swelling behavior, the range of possible intelligent response has tremendously expanded to self-healing capacity, shape memory, the release of a bioactive, and/or on-demand degradation in biological tissues, to name a few.In the last years, the incorporation of reversible covalent bonds, supramolecular bonds, or other types of reversible interactions has prompted the study of the self-healing capacity and the shape memory property. The presence of dynamic/reversible bonds into a hydrogel provides it the particularity to self-repair after mechanical damage. Besides, shape-memory makes it possible to modify the hydrogel morphology through external mechanical forces and temporarily fix the new desired geometry by making use of the reversible bonds. Subsequently, the material can return to its original form applying a specific external stimulus. Furthermore, the growing interest in the biological applications of hydrogels has driven efforts in the adjustment of the mechanical properties by controlling polymer-polymer interactions and the degree and type of cross-linking. Another highly required characteristic is the insertion of functional groups in situ, with low toxicity and in the absence of side reactions. Numerous works aimed to yield macrogels with dynamic covalent bonds, the formation of gels with sol-gel behavior, self-curing properties, and/or shape memory and gelation under adequate physiological conditions. In this context, post-synthesis modifications of polymers to the development of functional dynamic covalent hydrogels are presented in this chapter. The polymer composition is usually selected to allow post-synthetic modification to achieve control over morphology, mechanical and swelling properties, and chemical functionality. Herein, we focused on the obtainment of Schiff base crosslinked dynamic covalent networks as a robust strategy to obtain smart materials by bio-orthogonal reactions. Different presented methodologies constitute useful tools for the development of functional materials that could be applied in various lines of research: from the production of devices for the controlled release of drugs to the development of soft actuators, surface modification, the anchoring of biomolecules in chromatographic supports, among others.Fil: Wolfel Sánchez, Alexis. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Romero, Marcelo Ricardo. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Alvarez Igarzabal, Cecilia Ines. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; Argentin

Imine Based Self-Healing Hydrogel Triggered by Periodate

Design of materials with novel sensitivities and smart behaviour is important for the development of smart systems with automated responsiveness. We have recently reported the synthesis of hydrogels, cross-linked by N,N\u27-diallyltartardiamide (DAT). The covalent DAT-crosslinking points have vicinal diols which can be easily cleaved with periodate, generating valuable a-oxo-aldehyde functional groups, useful for further chemical modification. Based on those findings, we envisioned that a self-healable hydrogel could be obtained by incorporation of primary amino functional groups, from 2-aminoethyl methacrylate hydrochloride (AEMA), coexisting with DAT into the same network. The a-oxo-aldehyde groups generated after the reaction with periodate would arise in the immediate environment of amine groups to form imine cross-links. For this purpose, DAT-crosslinked hydrogels were synthesized and carefully characterized. The cleavage of DAT-crosslinks with periodate promoted changes in the mechanical and swelling properties of the materials. As expected, a self-healing behavior was observed, based on the spontaneous formation of imine covalent bonds. In addition, we surprisingly found a combination of fast vicinal diols cleavage and a low speed self-crosslinking reaction by imine formation. Consequently, it was found a time-window in which a periodate-treated polymer was obtained in a transient liquid state, which can be exploited to choose the final shape of the material, before automated gelling. The singular properties attained on these hydrogels could be useful for developing sensors, actuators, among other smart systems.</p

Smart valve. Polymer actuator to moisture soil control

The adequate use of water for irrigation in agriculture is a widespread concern. In this study, we developed an autonomous smart system consisting of a new hydrogel into a valve, which regulates the flow of water according to soil moisture. The main objective was to find an alternative to avoid waste of water. Yet, hydrogel development and study of the quantitative relationship between its properties and soil moisture were also important to achieve this aim. The hydrogel was synthesized from tris[(hydroxymethyl) methyl]acrylamide (NAT) copolymerized with methyl methacrylate (MMA) and crosslinked with N, N´-methylene bis(acrylamide) (BIS). The use of cellulose (2% w/v) avoids hydrogel breakage during swelling-deswelling. The relation between swelling ratio, force of expansion and moisture was evaluated for the novel hydrogel. It was found that as soil moisture increases, the gel swells, while expansion force diminishes. These properties showed linear relationship in the range studied. The three-dimensional network formed by flexible chains has the attribute of exerting a great force when it expands (15 N for a hydrogel disc of 1 cm2). When the material was put in contact with the ground, it swelled and deswelled without breaking. The hydrogel within the valve was able to open and close the passage of water. The valve prototype was tested during four months with a plant. During this period, only three liters of irrigation water was used monthly, instead of about half a liter daily. Hence, an autonomous actuator capable of controlling soil moisture was developed based on a new hydrogel.Fil: Romero, Marcelo Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Wolfel, Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Alvarez Igarzabal, Cecilia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin