Synthesis and characterization of methacrylic microspheres for biomolecular recognition: Ultrasensitive biosensor for Dengue virus detection

In this paper we report methacrylic microspheres (MMS), produced via free-radical polymerization between methyl methacrylate (MMA) and methacrylic acid (MAA), cross-linked with triethylene glycol dimethacrylate (TEGDMA). In particular, MAA monomer was chosen for structural carboxyl functionalities that exist on the surface of produced microspheres. Two different MMA/MAA molar ratios of MMA–TEGDMA–MAA microspheres were processed effectively and both compositions of MMS were analyzed with scanning electron microscopy (SEM), optical microscopy and X-ray photoelectron spectroscopy (XPS). Results confirmed uniform surface morphology and two ranges of particle size distributions for different macromolecular structures. Surface carboxyl groups (generated from MAA polymer units) were used as polymeric platforms for immobilization of Dengue antibody molecules. In order to examine the efficiency of antibody surface immobilization we have performed fluorescence enzyme-linked immunosorbent assay (ELISA). Dengue antigens were used for specific recognition of template proteins (antibodies) and results show more than 20 times higher fluorescence intensity in comparison to conventional ELISA assay used in contemporary clinical practice. Furthermore, our results show that the physical adsorption of template antibodies is almost as effective as covalent attachment through carbodiimide chemistry and formation of amide bonds between amine peptide groups and surface carboxyl groups on microspheres.