BACKGROUNDComplex polysaccharides are important in the pharmaceutical industry, yet, due to their large molecular weight and reduced charges, their purification is a highly demanding process that requires binding matrices with unique properties. This work demonstrates for the first time that complex polysaccharides biosynthesized by microalga Porphyridium purpureum can be adsorbed onto Q fibrous anion exchangers. RESULTSWhen the polysaccharides were characterized, the extent of sulfation was higher in native polysaccharides than in ethanol- or alkali-extracts. The zeta potentials increased with increasing pH and the highest charge was observed at pH 8, while the Z-average diameters of the polysaccharide at pH 6 were highest for alkali-extracts. Instead of pellicular resins, Q fibrous adsorbents were used to determine Langmuir thermodynamic properties and dynamic binding capacities. The parameters included static binding capacity and dissociation constant of 13.47 1.02 mg g(-1) and 0.141 +/- 0.027 mg mL(-1), and 10 and 50% breakthrough capacities of 4.46 +/- 0.22 and 5.51 +/- 0.28 mg g(-1), respectively. The antiviral activity of the polysaccharides was demonstrated by minimizing bacteriophage lysis of Streptococcus thermophilus. CONCLUSION This work demonstrates that polysaccharide extraction can be optimized and the adsorption and desorption of a complex polysaccharide onto Q fibrous matrix is feasible. These parameters could be exploited for up-scaling of polysaccharides for nutraceutical and pharmaceutical applications. (c) 2013 Society of Chemical Industry