Redox- and glucose-responsive hydrogels from poly(vinyl alcohol) and 4-mercaptophenylboronic acid

Novel redox- and glucose-responsive hydrogels have been synthesized by simple mixing of poly(vinyl alcohol) (PVA) and 4-mercaptophenylboronic acid (MPBA) in aqueous solutions (pH > 9) in an oxidative aqueous media. These hydrogels are produced through the formation of disulfide linkages between MPBA molecules in an oxidative environment (oxygen dissolved in solution or hydrogen peroxide added to the reaction mixture) and complexation via dynamic covalent bonds between PVA and MPBA dimer. These hydrogels show degradation in solutions of l-glutathione and d-glucose

Phosphorylation of cotton cellulose with baker’s yeast hexokinase

Here we report for the first time on phosphorylation of cotton cellulose using baker’s yeast hexokinase and phosphoryl donor adenosine-50-triphosphate. An enzymatic assay was adopted for determination of the degree of hosphorylation of cellulose. This functional modification of cellulose resulted in improved colorability and flame resistance

Synthesis of fluorescently-labelled poly(2-ethyl-2-oxazoline)-protected gold nanoparticles

Gold nanoparticles (GNPs) protected by poly(2-ethyl-2-oxazoline) (POZ) of different molecular weights (Mw = 5, 50, 200 and 500 kDa) were synthesised and characterised by dynamic light scattering, nanoparticle tracking analysis, zeta potential measurement and transmission electron microscopy. It was established that the use of POZ with 50 kDa resulted in formation of GNPs with low polydispersity while POZ with greater molecular weights led to formation of more polydisperse GNPs. Fluorescent labelling of these nanoparticles was achieved through their reaction with polyethyleneglycol dithiol (8-12 kDa) as a linker molecule with subsequent reaction with 6-(iodoacetamido) fluorescein. The fluorescent nature of obtained GNPs was confirmed by the appearance of the fluorescence peak at 510 nm that is typical for fluorescein molecules and glowing of the aqueous solution under the UV irradiaton. The fluorescently-labelled GNPs are promising tool in biomedical application to monitor the biological systems using fluorescent microscopy

Effect of Electric Field on the Swelling Behavior of Cross-linked Copolymers of Poly(ethylene oxide) Bis-macromonomers with Methacrylic Acid

The hydrogels capable to interpolymer complex formation have been synthesized by direct radical copolymerization of methacrylic acid with poly(ethylene oxide) bis-macromonomer bearing methacrylate terminal groups. The swelling behavior of these hydrogels in electric field has been studied. The hydrogels were shown to undergo contraction or additional swelling depending on solution pH. In weakly acidic region (pH 5.1) the contraction of the network was observed. In these conditions the swelling behavior of the hydrogel is affected by the complex formation between unionized carboxylic groups and oxyethylene units within the networks and the gel sample has relatively low swelling degree and network charge. In basic region (pH 9.18) the polycomplex is destroyed and the network has higher charge density and higher swelling degree. Under the action of electric field such hydrogel swells additionally. An increase in ionic strength of  solution decreases the amplitude of hydrogels contraction