Cells are the fundamental structural and functional units of living organisms. The cell membrane is comprised of phospholipid and gycolipids; glycoproteins are located on the cell membrane surface. The sugar residues of glycoproteins combine with biological molecules such as antibodies, hormones and enzymes. [1][2][3] Bacteria and viruses also recognize the structure and sequence of sugar residues and invade the host by binding to them. 4 Lectins are proteins that interact with specific sugar residues. Binding between lectin and sugar residues causes cell agglutination and precipitation of polysaccharides. 5Because many lectins are commercially available and are easy to handle, they are well-suited for the study of protein-sugar residue binding. 6 For example, one type of lectin wheat germ agglutinin (WGA) is a 36000 molecular weight protein consisting of two identical sub-units.WGA specifically binds the sugar, N-acetylglucosamine, which is comprised of glucosamine and glucose. Generally, the terminal sugar residue on the cell surface is either glucose, N-acetylglucosamine, mannose or xylose. Therefore, the binding between WGA and glucose plays an important role in various physiological processes. 7 For example, the time dependence of agglutination and the spreading of human erythrocytes induced by cell-cell contact involve WGA-glucose binding. 8 The importance of WGA-glucose binding for the sexual development of dictyostelium discoideum also has been reported. 9WGA-glucose has also been applied to affinity chromatography, using glycoconjugates and WGA as the ligands. 10Various models of biological cells have been used to study living cells. Bilayer lipid membranes are widely used because they replicate the electric and hydrophobic properties of the cell membrane.11 Liposomes also have been used as a model of the cell.12 Magnetic microbeads are the same size as living cells; thus, magnetic microbeads are used as cell models in medical, biological and environmental research. Furthermore, functional molecules can be immobilized onto the surface of magnetic beads via cross-linking. The beads can be easily isolated from solutions containing protein or from bacterial cultures by application of a magnetic field.Magnetic beads have been used in a variety of immunologic and electrochemical assays. Kim et al. detected abnormal prion proteins using a magnetic bead-based immunoassay coupled with laser-induced fluorescence spectrofluorometry. 13 In addition, immunomagnetic beads have been used in the detection of bacillus stearothermophilus spores in food and environmental samples.14 Microbeads with fluorogenic 15 and chemiluminescence reagents 16 have been developed to evaluate protein-sugar residue binding. Thomas et al. established an electrochemical procedure for the evaluation of the antigen-antibody reaction on the magnetic bead surface using an enzyme reaction. 17 Our group previously reported a method for the evaluation of lectin-sugar binding on sugar-modified beads. 18 In this method, the sugar was labeled with a...