Characterization of CMC-modified cellulose biointerface for antibody immobilization by QCM-D

A novel method to modify cellulosic surfaces to enhance protein binding was developed. This would be beneficial in a search of more affordable and environmentally friendly biointerfaces based on cellulosic materials. Cellulose-based surfaces could offer new platforms for immunoassays or filter-based assays. For sensitive and reliable immunoassay sufficient and stable binding of antibodies without nonspecific binding on the surface is a prerequisite. To achieve this we have employed surface deposition of carboxymethyl cellulose (CMC) on model cellulose. By CMC adsorption the number of carboxyl groups of cellulose for antibody immobilization was increased. Antibodies were co-valently immobilized through carboxyl groups of CMC. CMC adsorption, linkage of the antibodies and the level of antigen binding and nonspecific binding were monitored in situ by quartz crystal microbalance with dissipation (QCM-D). Our QCM-D experiments showed that CMC adsorbed irreversibly onto the cellulose surface. Specific change in frequency, corresponding to the antigen concentration, was observed. Regeneration of the immobilized surface after antigen binding implied that the CMC modified cellulose surface can act as a renewable immunochemical assay platform.