A Comparative Study Using Small-Angle X-ray Scattering and Solid-State NMR of Microdomain Structures in Poly(styrene−butadiene−styrene) Triblock Copolymers

Largely improved electromechanical properties of thermoplastic dielectric elastomers by grafting carboxyl onto SBS through thiol–ene click chemistry

Modified SBS with largely improved electromechanical properties is prepared by grafting carboxyl groups onto the polybutadiene domains using a simple, effective and controllable photochemical thiol-ene click reaction.

Clinical characterization of a new polymeric membrane for use in renal replacement therapy

Renal replacement therapy makes extensive use of semi-permeable membranes, ideal requirements for such membranes are good solute transport characteristics and a low reactivity with blood. Membranes manufactured from synthetic polymers fulfil these requirements. Such membranes have asymmetric and anisotropic structures characterized by a dense layer with which the blood is in contact supported by a thicker solid structure with containing interlinked voids, providing support. The nature of the structures are critically dependent upon the polymer blend and the control of parameters during manufacture such as the temperature or additive concentrations. In this prospective study, we have evaluated the clinical performance of a new membrane manufactured from a blend of polyamide, polyarylethersulfone and polyvinylpyrrolidone (Polyflux, Gambro GmbH, Hechingen, Germany), and compared it with that of polysulfone blended with polyvinylpyrrolidone (Fresenius Polysulfone, Fresenius Medical Care, Bad Homburg, Germany), a material widely acknowledged as providing an optimal biocompatibility in terms of solute removal and complement activation. The clearance of small molecules (urea, creatinine, phosphate) for both membranes was comparable. Both membranes removed beta2 microglobulin during treatment (50.2% reduction with Polyflux and 54.5% reduction with polysulfone. This removal due to the non-selectivity of the membranes was associated with protein loss during therapy which was similar for both the membranes (7.7 g). The biocompatibility profiles of the membranes indicated slight neutropenia and platelet adhesion and minimal C3a, C5a and SC5b-9 generation which were independent of the membrane material. These findings indicate that despite the differences in microstructure of the membranes, their functional performance in the clinical setting is comparable.

Clinical performance of a new high-flux synthetic membrane

The clinical performance during first use of a new membrane manufactured from a blend of polyarylethersulfone and polyvinylpyrrolidone (Arylane; Hospal Renal Care, Lyon, France), in which the microstructure of the membrane has been tailored by the manufacturing process and polymer blend, has been compared with Fresenius Polysulfone (Fresenius Medical Care, Bad Homburg, Germany) in a prospective, randomized, crossover study. Small-molecular clearances were similar. A reduction in plasma beta(2)-microglobulin levels was present using both membranes, with a significantly greater removal by Arylane such that the mean postdialysis plasma level difference between the membranes at the end of dialysis was 8. 7 mg/L (95% confidence interval, 3.9 to 13.5; P = 0.004). Recovery of beta(2)-microglobulin from the dialysis fluid was similar: 170 +/- 70 mg for Arylane and 110 +/- 60 mg for Fresenius Polysulfone (P = 0.04). Both membranes were impermeable to albumin but allowed the passage of low-molecular-weight proteins, with 10,046 +/- 3,239 mg for Arylane and 7,285 +/- 2,353 mg for Fresenius Polysulfone recovered from the dialysis fluid (P = 0.07). Neutropenia and platelet adhesion to the membrane were minimal, and time-averaged complement levels during dialysis for C3a and C5b-9 were 207 +/- 92 and 62 +/- 24 ng/mL for Arylane and 223 +/- 68 and 45 +/- 24 ng/mL for Fresenius Polysulfone, respectively, and were membrane independent. This study indicates that the membrane using polyarylethersulfone in conjunction with PVP has complement-activation potential and neutropenia similar to Fresenius Polysulfone but has an enhanced capacity to remove beta(2)-microglobulin. This enhanced removal arises from transmembrane transport augmented by adsorption within the membrane matrix.