Alginate dialdehyde meets nylon membrane: a versatile platform for facile and green fabrication of membrane adsorbers

Alginate dialdehyde (ADA), a biocompatible polymer, was used as an intermediate layer on a nylon membrane to readily fabricate cation exchange (CEX), metal-affinity (Me-affinity), histidine-affinity (His-affinity) and peptide-affinity (Pep-affinity) membrane adsorbers without any organic solvent usage. All the membrane adsorbers exhibited a high selectivity in the fractionation of a IgG (immunoglobulin)/HSA (human serum albumin) mixture. Along with a high purity of 100%, a high IgG binding capacity of 30, 24, 21 and 28 mg mL^-1 (membrane volume) was achieved by the CEX, Me-affinity, His-affinity and Pep-affinity membrane adsorbers in flow-through mode respectively, which is superior to those of the reported membrane adsorbers. Furthermore, the CEX and Pep-affinity adsorbers were tested for the separation of IgG from human plasma solution. The carboxylic groups along with the peptides on the Pep-affinity adsorber captured IgG synergistically with a higher recovery and purity (99% and 98.6%). This synergetic adsorber showed a q_max and dynamic binding capacity (DBC) of 138.4 and 38.7 mg mL^-1 respectively for IgG binding which was somewhat higher than that of the reported protein A agarose (having q_max and DBC of 84 and 24.4 mg g^-1 respectively). The present work indicated that the ADA layer not only activated the membrane surface to attach various adsorptive ligands under mild conditions, but also reduced non-specific adsorption. Due to the versatile linking function and green reaction conditions, the ADA coating on the nylon membrane is promising for the preparation of diverse membrane adsorbers.