Regulation of anti-LDL immobilization on self-assembled protein G layer using CHAPS and its application to immunosensor

In antibody-based immunoassay, it is important to fabricate a structured base plate with high activity for antibody immobilization. To prevent the reduction of anti-LDL binding capacity due to protein G aggregation, detergent was introduced to control the size of protein G aggregate. The self-assembled monolayer of 11-mercaptoundecanoic acid (11-(MUA)) and hexanethiol mixture was fabricated to form the stable protein G layer. 3-[(cholamidopropyl)dimethyl-ammonio]-1-propane sulfonate (CHAPS) was used for the regulation of protein G aggregate immobilized on the 11-(MUA) surface. The effect of various CHAPS concentrations on the amount of anti-low density lipoprotein (LDL) immobilized on protein G layer was investigated. Twelve millimolars of CHAPS were determined as the optimal concentration to maximize the binding capacity of anti-LDL due to the control of protein G density on the surface. The anti-LDL layer on self-assembled protein G using CHAPS was applied to surface plasmon resonance immunosensor for detection of LDL and its detection limit was 100 pM.