Homogeneous immunoassay based on dihexadecyl-dimethylammonium bilayer membranes.
We describe a rapid, highly sensitive, simple immunoassay based on cationic bilayer membranes prepared from dihexadecyl-dimethylammonium bromide. This detergent was dispersed in water to give a slightly turbid solution which contained lamellar (not vesicular) bilayer membranes with a gel to liquid crystal phase transition (Tc, 28 degrees C). An anionic hapten (N,N'-bis(2,4-dinitrophenyl)-L-lysine) combined electrostatically with this cationic membrane to induce aggregation of membranes, making the solution turbid. This aggregation was suppressed by antibodies to the hapten. The aggregation rate was rapid at a temperature above Tc, and the amount of antibodies was quantified by measuring absorbance or light scattering of the aqueous solution with a detection limit of 0.1 ng/ml of the antibodies. Anionic and zwitterionic bilayer membranes from di(tetradecyl)phosphate and phosphocholine derivatives, respectively, were less sensitive as detectors of the hapten-antibody reaction. Ionic interactions between cationic bilayer membranes and anionic haptens are important for successful assay performance.
Ihara
H
H
Department of Applied Chemistry, Faculty of Engineering, Kumamoto University, Japan.
Imamura
T
T
Kunitake
T
T
Hirayama
C
C
D000371:Agglutination; D003902:Detergents; D007118:Immunoassay / Q000379:methods*; D008051:Lipid Bilayers; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D013696:Temperature
D003902:Detergents; D008051:Lipid Bilayers; D000644:Quaternary Ammonium Compounds; C046417:dihexadecyldimethylammonium