Attachment of MEL-A onto poly (2-hydroxyethyl methacrylate) beads. Different amounts of MEL-A in methanol were charged to the mixture of polyHEMA beads (0.35 ± 0.05 g) and methanol (20 ml). After the solvent was evaporated, the obtained residue was washed with water and filtrated. The amount of MEL-A attached onto the beads was determined by anthrone method after being extracted with a mixture of chloroform-methanol (2:1). Each plot is the mean of triplicate. MEL-A, mannosylerythritol lipid-A; polyHEMA, poly (2-hydroxyethyl methacrylate).