“…In ELISA, the classic technique involves passive adsorption of antigen in alkaline diluents such as carbonate, bicarbonate, carbonate-bicarbonate, glycine, or borate buffers (9,13,38,65). Alternatively, antigen may be bound at physiological pH values by using diluents such as PBS (12,53) or water (55,72). Fixative and coupling agents for improving antigen retention on support media, such as formaldehyde (12,25), glutaraldehyde (1,55,64), acetone (57), and poly-L-lysine (14,37) have also been used.…”