Modification of cellulose films by adsorption of CMC and chitosan for controlled attachment of biomolecules.

The adsorption of human immunoglobulin G (hIgG) and bovine serum albumin (BSA) on cellulose supports were investigated. The dynamics and extent of related adsorption processes were monitored by surface plasmon resonance (SPR) and quartz crystal microbalance with dissipation monitoring (QCM-D). Amine groups were installed on the cellulose substrate by adsorption of chitosan from aqueous solution, which allowed for hIgG to physisorb from acid media and produced a functionalized substrate with high surface density (10 mg/m(2)). hIgG adsorption from neutral and alkaline conditions was found to yield lower adsorbed amounts. The installation of the carboxyl groups on cellulose substrate via carboxymethylated cellulose (CMC) adsorption from aqueous solution enhanced the physisorption of hIgG at acidic (adsorbed amount of 5.6 mg/m(2)) and neutral conditions. hIgG adsorption from alkaline conditions reduced the surface density. BSA was used to examine protein attachment on cellulose after modification with chitosan or carboxymethyl cellulose. At the isoelectric point of BSA (pI 5), both of the surface modifications enhanced the adsorption of this protein when compared to that on unmodified cellulose (a 2-fold increase from 1.7 to 3.5 mg/m(2)). At pH 4, the electrostatic interactions favored the adsorption of BSA on the CMC-modified cellulose, revealing the affinity of the system and the possibility of tailoring biomolecule binding by choice of the surface modifier and pH of the medium.