Reaction of Amino-Terminated PAMAM Dendrimers with Carbon Dioxide in Aqueous and Methanol Solutions

Polyamines have been used as active materials to capture carbon dioxide gas based on its well-known reaction with amines to form carbamates. This work investigates the reactions between three amino-terminated poly(amidoamine) (PAMAM) dendrimers (G1, G3 and G5) and CO2(g) in aqueous (D2O) and methanolic (CD3OD) solutions. The reactions were monitored using 1H NMR spectroscopy, and yielded dendrimers with a combination of terminal carbamate and terminal ammonium groups. In aqueous media the reaction was complicated by the generation of soluble carbonate and bicarbonate ions. The reaction was cleaner in CD3OD, where the larger G5 dendrimer solution formed a gel upon exposure to CO2(g). All reactions were reversible, and the trapped CO2 could be released by treatment with N2(g) and mild heating. These results highlight the importance of the polyamine dendrimer size in terms of driving changes to the solution’s physical properties (viscosity, gel formation) generated by exposure to CO2(g).

Rheo-SAXS study of shear-induced orientation and relaxation of cellulose nanocrystal and montmorillonite nanoplatelet dispersions

The shear-induced orientation in the flow direction increases with increasing shear rate. The relaxation of the CNC:MNT in comparison to CNC-only dispersion was found to be strongly retarded due to the addition of MNT, which promotes gel formation.

GEL FORMATION IN THE KAOLIN SYSTEM - SODIUM ALGINATE - CALCIUM SULFATE - SODIUM PYROPHOSPHATE

Представлены результаты исследований изменений происходящих при формировании наполненных альгинатных гелей при внутреннем диффузионном гелеобразовании. Исследование проводилось для систем, состоящих из каолина и альгината натрия с системой отверждения из сульфата кальция и пирофосфата натрия. Установлено, что применение реологических методов исследования позволяют получать данные о показателях качества альгинатных гелей и их составе, и механизме гелеобразования. Установлено, что для системы каолин – альгинат натрия – сульфат кальция – пирофосфат натрия при формировании альгинатного геля целесообразно использовать сульфат кальция с массовой долей от 5 до 6,5, а пирофосфат натрия с массовой долей от 1,5 до 3 % при гидромодуле 1 к 3 и температуре воды 20 °С.Эти данные можно использовать при разработке рецептуры альгинатных масок и подготовки нормативной технической документации. The results of studies of changes occurring during the formation of filled alginate gels during internal diffusion gelation are presented. The study was carried out for systems consisting of kaolin and sodium alginate with a curing system of calcium sulfate and sodium pyrophosphate. It has been established that the use of rheological research methods makes it possible to obtain data on the quality indicators of alginate gels and their composition, and the mechanism of gelation. It was found that for the system kaolin-sodium alginate-calcium sulfate-sodium pyrophosphate when forming an alginate gel, it is advisable to use calcium sulfate with a mass fraction of 5 to 6.5, and sodium pyrophosphate with a mass fraction of 1.5 to 3% at a hydromodule 1 to 3 and a water temperature of 20 °C. This data can be used in the development of the formulation of alginate masks and the preparation of regulatory technical documentation.

Polyureas Versatile Polymers for New Academic and Technological Applications

Polyureas (PURs) are a competitive polymer to their analogs, polyurethanes (PUs). Whereas PUs’ main functional group is carbamate (urethane), PURs contain urea. In this revision, a comprehensive overview of PUR properties, from synthesis to technical applications, is displayed. Preparative routes that can be used to obtain PURs using diisocianates or harmless reagents such as CO2 and NH3 are explained, and aterials, urea monomers and PURs are discussed; PUR copolymers are included in this discussion as well. Bulk to soft components of PUR, as well as porous materials and meso, micro or nanomaterials are evaluated. Topics of this paper include the general properties of aliphatic and aromatic PUR, followed by practical synthetic pathways, catalyst uses, aggregation, sol–gel formation and mechanical aspects.

Interaction of two MADS-box genes leads to growth phenotype divergence of all-flesh type of tomatoes

All-flesh tomato cultivars are devoid of locular gel and exhibit enhanced firmness and improved postharvest storage. Here, we show that SlMBP3 is a master regulator of locular tissue in tomato fruit and that a deletion at the gene locus underpins the All-flesh trait. Intriguingly, All-flesh varieties lack the deleterious phenotypes reported previously for SlMBP3 under-expressing lines and which preclude any potential commercial use. We resolve the causal factor for this phenotypic divergence through the discovery of a natural mutation at the SlAGL11 locus, a close homolog of SlMBP3. Misexpressing SlMBP3 impairs locular gel formation through massive transcriptomic reprogramming at initial phases of fruit development. SlMBP3 influences locule gel formation by controlling cell cycle and cell expansion genes, indicating that important components of fruit softening are determined at early pre-ripening stages. Our findings define potential breeding targets for improved texture in tomato and possibly other fleshy fruits.

Mechanism of Amyloid Gel Formation by Several Short Amyloidogenic Peptides

Under certain conditions, many proteins/peptides are capable of self-assembly into various supramolecular formations: fibrils, films, amyloid gels. Such formations can be associated with pathological phenomena, for example, with various neurodegenerative diseases in humans (Alzheimer’s, Parkinson’s and others), or perform various functions in the body, both in humans and in representatives of other domains of life. Recently, more and more data have appeared confirming the ability of many known and, probably, not yet studied proteins/peptides, to self-assemble into quaternary structures. Fibrils, biofilms and amyloid gels are promising objects for the developing field of research of nanobiotechnology. To develop methods for obtaining nanobiomaterials with desired properties, it is necessary to study the mechanism of such structure formation, as well as the influence of various factors on this process. In this work, we present the results of a study of the structure of biogels formed by four 10-membered amyloidogenic peptides: the VDSWNVLVAG peptide (AspNB) and its analogue VESWNVLVAG (GluNB), which are amyloidogenic fragments of the glucantransferase Bgl2p protein from a yeast cell wall, and amyloidogenic peptides Aβ(31–40), Aβ(33–42) from the Aβ(1–42) peptide. Based on the analysis of the data, we propose a possible mechanism for the formation of amyloid gels with these peptides.

Gel Formation in Low Concentrated Solutions of Glycyram and Amino Acids in the Presence of Silver Nitrate

Research relevance: low molecular weight supramolecular hydrogels are unique objects that can solve many pressing problems in medicine, food industry and other sectors of the national economy. Research objectives: in recent past, it was discovered that low-concentration solutions of L-cysteine and silver nitrate (CSN) can form, when electrolyte solutions are added to hydrogels. We were faced with the task of obtaining hydrogels from dilute solutions of glycyram (GC) by adding CSN, since GC, due to its poor solubility, has low bioavailability. Materials and research methods: using the method of isomolar series, a comparative study of the formation of hydrogels by dilute GC solutions with the addition of CSN and GCP was carried out. It has been found that most durable hydrogels were obtained using CSN. Thus, GC hydrogels were obtained at a concentration of 10−3 M after adding CSN and GCP, which have a supramolecular character and combine the properties of GC, amino acids, and silver ions. Research results: glycyram hydrogels were obtained at its concentration equal to 10−3 M by mixing it with silver amino acids L-cysteine (CSN) and L-glutamic acid (GCP) solutions in same low concentrations. Conclusions: hydrogels with glycyram form silver solutions of those amino acids that are capable of giving frame structures at a ratio of amino acid: silver nitrate of 1.25.

Investigation of Thermal Gel Formation of Methylcellulose in Glycols Using DSC and XRD

Novel compositions of methylcellulose in ethylene, propylene and butylene glycol were investigated for their thermal gel formation. These compositions have previously been found useful for inkjet-printing-based additive manufacturing processes as support materials. Experimental techniques such as viscosity measurements between 20 °C–150 °C–20 °C, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used and the results showed that the gel formation upon cooling is caused by polymer–polymer association. The results also show that, for methylcellulose, propylene glycol is a better solvent than ethylene glycol and butylene glycol. Since no chemical reaction is involved, these gels can be used as support materials for jetting-based additive manufacturing processes.