The Synthesis of Poly(Vinyl Alcohol) Grafted with Fluorinated Protic Ionic Liquids Containing Sulfo Functional Groups

There has been an ongoing need to develop polymer materials with increased performance as proton exchange membranes (PEMs) for middle- and high-temperature fuel cells. Poly(vinyl alcohol) (PVA) is a highly hydrophilic and chemically stable polymer bearing hydroxyl groups, which can be further altered. Protic ionic liquids (proticILs) have been found to be an effective modifying polymer agent used as a proton carrier providing PEMs’ desirable proton conductivity at high temperatures and under anhydrous conditions. In this study, the novel synthesis route of PVA grafted with fluorinated protic ionic liquids bearing sulfo groups (–SO3H) was elaborated. The polymer functionalization with fluorinated proticILs was achieved by the following approaches: (i) the PVA acylation and subsequent reaction with fluorinated sultones and (ii) free-radical polymerization reaction of vinyl acetate derivatives modified with 1-methylimidazole and sultones. These modifications resulted in the PVA being chemically modified with ionic liquids of protic character. The successfully grafted PVA has been characterized using 1H, 19F, and 13C-NMR and FTIR-ATR. The presented synthesis route is a novel approach to PVA functionalization with imidazole-based fluorinated ionic liquids with sulfo groups.

Deciphering the structural attributes of protein–heparan sulfate interactions using chemo-enzymatic approaches and NMR spectroscopy

Heparan sulfates (HS) is a polysaccharide found at the cell surface, where it mediates interactions with hundreds of proteins and regulates major pathophysiological processes. HS is highly heterogeneous and structurally complex and examples that define their structure–activity relationships remain limited. Here, in order to characterize a protein–HS interface and define the corresponding saccharide-binding domain, we present a chemo-enzymatic approach that generates 13C-labeled HS-based oligosaccharide structures. Nuclear magnetic resonance (NMR) spectroscopy, which efficiently discriminates between important or redundant chemical groups in the oligosaccharides, is employed to characterize these molecules alone and in interaction with proteins. Using chemokines as model system, docking based on NMR data on both proteins and oligosaccharides enable the identification of the structural determinant involved in the complex. This study shows that both the position of the sulfo groups along the chain and their mode of presentation, rather than their overall number, are key determinant and further points out the usefulness of these 13C-labeled oligosaccharides in obtaining detailed structural information on HS–protein complexes.

Comparison of the Interactions of Different Growth Factors and Glycosaminoglycans

Most growth factors are naturally occurring proteins, which are signaling molecules implicated in cellular multiple functions such as proliferation, migration and differentiation under patho/physiological conditions by interacting with cell surface receptors and other ligands in the extracellular microenvironment. Many of the growth factors are heparin-binding proteins (HBPs) that have a high affinity for cell surface heparan sulfate proteoglycans (HSPG). In the present study, we report the binding kinetics and affinity of heparin interacting with different growth factors, including fibroblast growth factor (FGF) 2,7,10, hepatocyte growth factor (HGF) and transforming growth factor (TGF β-1), using a heparin chip. Surface plasmon resonance studies revealed that all the tested growth factors bind to heparin with high affinity (with KD ranging from ~0.1 to 59 nM) and all the interactions are oligosaccharide size dependent except those involving TGF β-1. These heparin-binding growth factors also interact with other glycosaminoglycans (GAGs), as well as various chemically modified heparins. Other GAGs, including heparan sulfate, chondroitin sulfates A, B, C, D, E and keratan sulfate, showed different inhibition activities for the growth factor-heparin interactions. FGF2, FGF7, FGF10 and HGF bind heparin but the 2-O-sulfo and 6-O-sulfo groups on heparin have less impact on these interactions than do the N-sulfo groups. All the three sulfo groups (N-, 2-O and 6-O) on heparin are important for TGFβ-1-heparin interaction.

ДОСЛІДЖЕННЯ ВПЛИВУ ХІМІЧНОЇ БУДОВИ КИСЛОТНИХ БАРВНИКІВ НА СВІТЛОСТІЙКІСТЬ ЗАБАРВЛЕНЬ

The purpose of the work is to determine the dependence of the lightfastness of colours obtained on wool fabric with acid dyes on their chemical structure, namely, the chemical class, the structure of chromophore and the number of sulfo groups.

Chemical grafting of sulfo groups onto carbon fibers

We proposed the brominated carbon cloth that made of polyacrylonitrile-based activated carbon fibers (PAN-ACFs) as a precursor to chemically and uniformly graft SO3H groups to prepare the solid acid catalyst. The thermal and catalytic properties of the sulfonated PAN-ACFs were examined by IR controlled catalytic measurements and thermal analysis. The catalytic test results showed that the sulfonated surface remarkably improved the operating efficiency in isopropanol dehydration by decreasing the reaction temperature. All PAN-ACFs with grafted SO3H groups prepared through brominated precursors can converse 100% of isopropanol into propylene at moderate temperature. They showed the highest catalytic activity compared to PAN-ACFs sulfonated with oleum and chlorosulfonic acid, which conversed only 40% and 70% of isopropanol into propylene and deactivated at the higher temperatures in the reaction medium.

Changes in Surface Condition during Fabrication Process of Bioactive Apatite Nuclei Incorporated PEEK

We aimed to clarify the effect of sulfuric acid treatment and oxygen plasma treatment on changes in surface condition of PEEK substrates during fabrication process of bioactive apatite nuclei (AN) precipitated PEEK. We treated PEEK substrate by sulfuric acid treatment. This treatment contributed to provide micropores and sulfo groups on the surface of the PEEK. Next, we treated the PEEK with oxygen plasma at 200 W for 4 minutes. By this treatment, both generation of carboxyl groups and increase of sulfo groups were occurred and significant improvement of hydrophilicity of the surface of the PEEK was occurred. Finally, we precipitated AN on the surface of the PEEK. By this treatment, high apatite-forming ability was achieved.