Bioactive cellulose nanofibrils for specific human IgG binding.

Bioactive films were produced by conjugation of a short peptide onto modified cellulose nanofibrils (CNF). Specifically, a hydrophilic copolymer, poly(2-aminoethyl methacrylate hydrochloride-co-2-hydroxyethylmethacrylate) (poly(AMA-co-HEMA)), was grafted via surface initiated polymerization from an initiator coupled to CNF. The poly(AMA-co-HEMA) was used as a spacer and support layer for immobilization of the peptide, acetylated-HWRGWVA, which has specific affinity with human immunoglobulin G (hIgG). Two methods for peptide grafting were compared: modification of CNF in aqueous suspension followed by assembly into a bioactive film and peptide grafting on a preformed CNF film. The CNF-based networks were examined on solid supports via atomic force microscopy (AFM) and extreme resolution imaging with ultralow electron landing energies (scanning low energy electron microscopy). The specific binding capability of hIgG and nonspecific protein resistance of the resultant peptide-modified CNF were evaluated by using quartz crystal microgravimetry (QCM). The effects of initiator concentration and thickness of poly(AMA-co-HEMA) layer on hIgG adsorption were investigated in the developed systems, which exhibited high signal-to-noise response.