Combining polymers with the functionality of proteins: new concepts for atom transfer radical polymerization, nanoreactors and damage self-reporting materials.

Proteins are macromolecules with a great diversity of functions. By combining these biomolecules with polymers, exciting opportunities for new concepts in polymer sciences arise. This highlight exemplifies the aforementioned with current research results of our group. We review our discovery that the proteins horseradish peroxidase and hemoglobin possess ATRPase activity, i.e. they catalyze atom transfer radical polymerizations. Moreover, a permeabilization method for polymersomes is presented, where the photo-reaction of an α-hydroxyalkylphenone with block copolymer vesicles yields enzyme-containing nanoreactors. A further intriguing possibility to obtain functional nanoreactors is to enclose a polymerization catalyst into the thermosome, a protein cage from the family of chaperonins. Last but not least, fluorescent proteins are discussed as mechanoresponsive molecular sensors that report microdamages within fiber-reinforced composite materials.

Differences in surface behaviour of galactolipoids originating from different kind of wheat tissue cultivated in vitro.

The aim of presented researches was to investigate the physicochemical properties of Langmuir monolayer of galactolipids extracted from two different kinds of plastids: immature embryos and inflorescences. Differences between the physicochemical properties of the plastid membranes may help to explain different physiological processes, such as plant regeneration. Surface pressure (pi) vs. molecular area (A) isotherms of the monogalactosyldiacylglycerol (MGDG)/digalactosyldiacylglycerol (DGDG) monolayers of various molar ratios were measured at 15 degrees C. Galactolipids were extracted from two different types of tissue: inflorescences and embryos. Based on the analysis of the pi-A isotherms, the properties of monolayers, such as collapse pressure (pi(coll)), limiting area (A(lim)), compressibility modulus (C(s)(-1)), excess free energy of mixing (DeltaG(EXC)) and free energy of mixing (DeltaG(MIX)), were calculated. The results show that pure MGDG and DGDG and their mixtures form liquid-expanded monolayers, independently on the kind of tissue. Galactolipids originating from inflorescences produce more compressible films at the air/water interface, with larger limiting area per molecule and lower stability against the collapse process. MGDG and DGDG are miscible and form non-ideal mixed monolayers at the air/water interface. Negative values of DeltaG(EXC) were calculated for the mixture of galactolipids originating from inflorescences, with the content of MGDG, x(MGDG)>0.6. In the case of embryos, the negative values of DeltaG(EXC) were found for x(MGDG) approximately 0.5. Therefore, the attractive interactions between MGDG and DGDG exist in the mixtures of these compositions. As it is shown by negative values of DeltaG(MIX), mixed monolayers are more stable compared with unmixed ones.

Fluorescent protein senses and reports mechanical damage in glass-fiber-reinforced polymer composites.

Yellow fluorescent protein (YFP) is used as a mechanoresponsive layer at the fiber/resin interface in glass-fiber-reinforced composites. The protein loses its fluorescence when subjected to mechanical stress. Within the material, it reports interfacial shear debonding and barely visible impact damage by a transition from a fluorescent to a non-fluorescent state.

The linoleic acid influence on molecular interactions in the model of biological membrane.

The present work explores the properties for binary (LA/DPPC), (cholesterol/DPPC) and also ternary (LA/cholesterol/DPPC) mixed Langmuir monolayers, at the air-water interface, treated as the simplest models of a half of the biological membranes. In ternary monolayers both cholesterol and DPPC were mixed at constant molar ratios that correspond to the proportions occuring in different natural membranes, among which fibroblast membrane (where the amount of phospholipid predominates) and also erythrocyte membrane (where the amount of sterol predominates) were taken into consideration. Our researches were conducted by using the Langmuir film balance, by means of which we registered the surface pressure (pi) as a function of the area of water surface available to each molecule (A). It was found that LA and DPPC also cholesterol and DPPC are miscible in binary as well as LA, cholesterol and DPPC in ternary mixed monolayers, however in ternary mixed monolayers, at higher content of fatty acid (for molar fraction X(LA)=0.6, 0.8) these components were miscible only at the surface pressure below approximately 27 mN/m. Furthermore the results of our measurements show that LA reveals very strong influence on the membrane composition. Depending on various amounts of this fatty acid within the models of biological membranes it seems to affect different stability of natural bilayer.