Aging effect and antibody immobilization on -COOH exposed surfaces designed for dengue virus detection

Polymethylmethacrylate-co-methacrylic acid, poly(MMA-co-MAA) coatings were produced with different initial molar ratios of monomers (MMA and MAA) in free-radical polymerization reaction. Polymeric platforms were specifically designed with controlled concentration of surface-exposed carboxyl (-COOH) groups that can be used as a desirable functionality for protein immobilization. Spin-coated chips were used for antibody (Ab) immobilization in order to investigate the influence of -COOH surface concentration on dengue virus detection efficiency in enzyme-linked immunosorbent assay (ELISA) experiment. Successful immobilization of Ab was achieved by two different techniques: (1) physical adsorption; and (2) covalent immobilization by carbodiimide coupling between the surface -COOH groups and amine functionalities of dengue Ab molecules. Produced polymer coatings were characterized with surface spectroscopy techniques (Raman and X-ray photoelectron spectroscopy, XPS) and water-in-air contact angle (WCA) measurements. In particular, this research concentrated on the aging effect on the availability and activity of surface -COOH groups. For that reason, WCA and Ab immobilization (ELISA) experiments were repeated on coated biochips after 3,6 and 9 months of storage. Results in this paper describe the robust and sustainable functionalized polymeric platform that can be used effectively for protein activation and development of novel biosensors.