Polymeric membranes with antioxidant activity based on cellulose esters and poly(vinylidene fluoride)/cellulose ester blends

Abstract

A series of novel cellulose membranes with antioxidant activity was prepared and characterized. Microcrystalline cellulose was functionalized with lipoic acid, ferulic acid and alpha-tocopherol moieties. These materials were characterized by FT-IR and NMR spectroscopy and their degree of substitution (DS) was determined by volumetric analysis. The manuscript discusses the antioxidant activity of cellulose derivatives in inhibiting lipid peroxidation in rat-liver microsomal membranes, induced in vitro by two different sources of free radicals: 2,2′-azobis-(2-amidinopropane) (AAPH), which exogenously produces peroxyl radicals by thermal decomposition, and tert-butyl hydroperoxide (tert-BOOH), which endogenously produces alkoxyl radicals by Fenton reactions. Membranes were prepared by the nonsolvent-induced phase inversion technique. Membranes of the pure cellulose derivatives were thin, mechanically weak and generally unsuitable for practical application. As an alternative, mechanically resistant poly(vinylidene fluoride)/cellulose ester blend membranes were obtained by direct phase inversion of the polymer/polymer/solvent mixture. These membranes were characterized by means of water permeability measurements, optical and scanning electron microscopy, determination of the antioxidant activity in comparison with starting materials. The membranes exhibited a good preservation of peroxidation inhibition and the performance of this kind of cellulose membrane as a scavenger of Reactive Oxygen Species (ROS) offers interesting perspectives for an effective control of intradialytic oxidative stress.