Binding assay of human IgG to mannosylerythritol-A attached onto poly (2-hydroxyethyl methacrylate) beads. Human IgG or human serum albumin (1.0 mg) was added to the mixture of MEL-polyHEMA composite (0.35±0.05 g) bearing different amounts of MEL-A and 50 mM phosphate buffer (3 ml) in a polypropylene tube. The tube was incubated for 1 hr and then centrifuged. The amount of bound protein was calculated by subtracting the unbound protein from the total added; the unbound protein was estimated by measuring the UV absorbance of the supernatant. human IgG (-??-), human serum albumin (-??-). Each plot is the mean of triplicate. MEL-A, mannosylerythritol lipid-A; polyHEMA, poly (2-hydroxyethyl methacylate).