The use of mild conditions to perform the entrapment of biomolecules in polymeric matrices is a crucial step in a broad range of applications as biosensors, biocarrier-mediated facilitated transport membranes, and drug-controlled release devices. In this study, we investigated the crosslinking of poly(vinyl alcohol) (PVA) by glutaraldehyde in the absence of an acid catalyst and organic solvents to improve the water resistance of the hydrophilic biocompatible polymer. Glutaraldehyde was chosen as the crosslinking agent because it favors the intermolecular reaction with PVA and is able to bind nonspecifically to proteins. The effects of the temperature and glutaraldehyde content on the thermal and structural properties of the PVA films were examined. Membranes prepared at 40C showed a maximum crosslinking density for low glutaraldehyde content namely, 0.04 wt % in the spreading solution. Higher amounts of the crosslinker led to the branching of PVA. The increase in membrane thermal properties and reduction in crystallinity were ascribed to the crosslinking treatment, which was confirmed by Fourier transform infrared analysis. The oxygen permeability of the films was reduced up to 2.7 times, which indicated that the crosslinking of the polymer was successfully accomplished. V

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-The fractionation of apitoxin (bee venom) by means of a commercial 10 kDa ultrafiltration membrane was investigated aiming at the removal of phospholipase A 2 , the main allergenic substance. The feed content was varied from 1 to 50 g apitoxin/L, in deionized water, and caused changes in membrane flux and rejection, due to concentration polarization. The increase in pressure difference and stirring rate improved the flux through the membrane. The best result was achieved for 1 g apitoxin/L in feed stream, with a pressure difference of 220 kPa, and 750 rpm, with a permeate flux of 103 kg/m 2 h. The use of ultrafiltration was efficient to improve the permeate safety since biological tests revealed that the remaining enzyme lost its ability to catalyze the hydrolysis of phospholipids.

We report the preparation of centimeter‐scale composite membranes formed by monolayer or bilayer graphene and polydimethylsiloxane (PDMS). Graphene was synthesized on copper foils by chemical vapor deposition (CVD), and two methods for transferring the graphene layers from the Cu to the PDMS were tested. The method based on the use of poly(methyl methacrylate) as a sacrificial support layer was more effective in producing membranes with significant gas‐barrier properties, in which the gas permeability values for CO2 and N2 were reduced by up to 30% as compared to blank PDMS membranes. Raman spectroscopy maps and atomic force microscopy revealed that, on the microscopic scale, graphene is preserved upon transfer, but the presence of extended defects such as folds and tears still limits further increases in the composite barrier properties. The deleterious effect of such defects is reduced by using more than one graphene layer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45521.

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