An experimental study on pumpless extracorporeal membrane oxygenation (ECMO) support in a canine model.

This study was carried out to determine whether an extracorporeal membrane oxygenation (ECMO) support could be sufficiently conducted by the right ventricle alone from the viewpoint of the hemodynamics and blood gas state. Six infant dogs underwent a bypass between the left pulmonary artery and left atrium with an in-line oxygenator after a left pneumonectomy. Partial ECMO support was conducted simply by opening the circuit, and total ECMO support was conducted by ligating the right pulmonary artery. After the establishment of partial ECMO, approximately one-third of the right ventricular output was passively shunted through the bypass circuit, and the cardiac index and central venous pressure did not change. The mean pulmonary arterial pressures increased significantly. After a complete ligation of the right pulmonary artery, all 6 dogs survived for 12 h, but the cardiac output and blood pressure decreased significantly. The blood gas state was sufficiently maintained throughout the experiment. The results suggest the possibility of using the pumpless ECMO support. However, the flow resistance of the membrane oxygenator proved to still be too high for use in a total pumpless ECMO. Further studies on long-term ECMO and the development of a membrane oxygenator with a considerably low flow-resistance are needed.</p

A Novel Grafting of Polymers onto the Surface of Graphene Oxide

A simple grafting of polymers onto graphene oxide (GO) was achieved by polymer radical trapping, ligand-exchange reaction, and surface initiated cationic and anionic graft polymerization. Grafting of poly(ethylene glycol) (PEG) onto GO was successfully achieved by trapping of PEG radicals formed by thermal decomposition of PEG macroazo initiator to give PEG-grafted GO. The grafting of copolymers containing vinyl ferrocene moieties onto GO surfaces was also successfully achieved by the ligand-exchange reaction between ferrocene moieties of these copolymers and GO. Carboxyl groups on GO have an ability to initiate the cationic polymerizations of vinyl monomers, such as N-vinylcarbazole and isobutyl vinyl ether. The corresponding vinyl polymers were grafted onto GO, during the cationic polymerization, based on the termination of growing polymer cation by counter anion (carboxylate) groups on GO. It was found that the anionic ring-opening alternating copolymerization of epoxides with cyclic acid anhydrides was successfully initiated by potassium carboxylate groups on GO, introduced by neutralization of carboxyl groups with KOH, to give the corresponding polyester-grafted GO. The dispersibility of GO in organic solvents was remarkably improved by the grafting of the above polymers onto GO. In addition, easy preparation of reduced GO-based conducting polyaniline composite organogel will be discussed

Indirect Adhesion of Hydrogels via the Radical Polymerization Mediated by <i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′‑Tetramethylethylenediamine and Ammonium Persulfate

Recently, developing superior adhesive hydrogel systems is in demand because it is important when hydrogel materials are used for applications in engineering, medical, and other fields. Among the adhesive gel systems, the ones for which adhesion can be controlled indirectly have high potential for various applications in the medical and engineering fields because they have merits compared to the systems that need to be regulated directly at the adhesive interfaces when we need to make materials adhere at places that are difficult to touch. In this manuscript, we report the adhesive system which can be regulated indirectly by the reaction of N,N,N′,N′-tetramethylethylenediamine (TMEDA) and ammonium persulfate (APS) inside the gel networks. Applying this system, a step-by-step adhesion, in which adhesive timing can be controlled, and a multiple adhesion, which can adhere multiple gel pieces at once, are constructed. These indirect and continuous adhesions will help us use hydrogels for constructing artificial biomaterials and other various applications

Preparation and Permeation Properties of a pH-Responsive Polyacrylic Acid Coated Porous Alumina Membrane

A pH-responsive membrane is expected to be used for applications such as drug delivery, controlling chemical release, bioprocessing, and water treatment. Polyacrylic acid (PAA) is a pH-responsive polymer that swells at high pH. A tubular α-alumina porous support was coated with PAA by grafting to introduce appropriate functional groups, followed by polymerization with acrylic acid. The permeances of acetic acid, lactic acid, phenol, and caffeine were evaluated by circulating water inside the membrane, measuring the concentration of species that permeated into the water, and analyzing the results with the permeation model. The permeance of all species decreased with increasing pH, and that of phenol was the largest among these species. At high pH, the PAA carboxy group in the membrane dissociated into carboxy ions and protons, causing the swelling of PAA due to electrical repulsion between the negative charges of the PAA chain, which decreased the pore size of the membrane and suppressed permeation. Furthermore, the electrical repulsion between negatively charged species and the PAA membrane also suppressed the permeation. The results of this study demonstrated that the PAA-coated α-alumina porous support functioned as a pH-responsive membrane

Highly Tolerant and Durable Adhesion between Hydrogels Utilizing Intercalation of Cationic Substituents into Layered Inorganic Compounds

Adhering hydrogel systems are important particularly in the medical field because they can be used as adhesives cross-linking between living tissues. In this research, hydrogels including cationic substituents prepared via free-radical polymerization were brought into contact after applying an aqueous dispersion of the layered inorganic compound Micromica to their surfaces. As a result, the hydrogels adhered to each other due to the intercalation of cationic substituents included in the gel networks into the interlayers of Micromica. As the water content ratio of hydrogels decreased, the adhesive strength came to be higher, and finally the adhesively bonded joint supported a tensile load of 10 kg. Moreover, it was confirmed that the adhered hydrogels have high tolerance toward various environments, such as high or low temperatures and solvents

Adhesive Gel System Growable by Reversible Addition–Fragmentation Chain Transfer (RAFT) Polymerization

Gel materials are materials with high elasticity that deform when stressed and then return to their original shapes once the stress is removed. Gel materials are expected to be used in artificial living tissues, soft robotics, sensors, and so on. On the other hand, humans grow and change their bodies and characteristics over time. In this research, we developed an adhesive gel system that can grow and change its characteristics like our humans after adhesion through reversible addition–fragmentation chain transfer (RAFT) polymerization, a class of living radical polymerization. The adhesive joint grown by RAFT polymerization had higher adhesive strength than the non-RAFT-polymerized adhesive joint and a function, i.e., thermal responsiveness of adhesive strength. The environment around us changes over time. These growable adhesive gel systems should enable us to use gel materials for a long time while adapting their structures and characteristics to environmental changes

Linear versus Dendritic Molecular Binders for Hydrogel Network Formation with Clay Nanosheets: Studies with ABA Triblock Copolyethers Carrying Guanidinium Ion Pendants

ABA-triblock copolyethers <b>1a</b>–<b>1c</b> as linear polymeric binders, in combination with clay nanosheets (CNSs), afford high-water-content moldable supramolecular hydrogels with excellent mechanical properties by constructing a well-developed crosslinked network in water. The linear binders carry in their terminal A blocks guanidinium ion (Gu⁺) pendants for adhesion to the CNS surface, while their central B block comprises poly­(ethylene oxide) (PEO) that serves as a flexible linker for adhered CNSs. Although previously reported dendritic binder <b>2</b> requires multistep synthesis and purification, the linear binders can be obtained in sizable quantities from readily available starting materials by controlled polymerization. Together with dendritic reference <b>2</b>, the modular nature of compounds <b>1a</b>–<b>1c</b> with different numbers of Gu⁺ pendants and PEO linker lengths allowed for investigating how their structural parameters affect the gel network formation and hydrogel properties. The newly obtained hydrogels are mechanically as tough as that with <b>2</b>, although the hydrogelation takes place more slowly. Irrespective of which binder is used, the supramolecular gel network has a shape memory feature upon drying followed by rewetting, and the gelling water can be freely replaced with ionic liquids and organic fluids, affording novel clay-reinforced iono- and organogels, respectively