Immobilization of Anti-hCG Antibody to Nitrocellulose via Protein G

Recently, biosensors have been widely studied and applied in disease diagnosis. Many factors affect the sensitivity of biosensors, two of which are the concentration and orientation of captured antibodies immobilization on the test region of the biosensors. Therefore, choosing an appropriate and efficient immobilization method is one of the top priority tasks in fabricating highly sensitive biosensors. In this paper, the specific hCG-capturing antibody (β1-mAb) was immobilized onto a nitrocellulose membrane via protein G. The resulting color signal in the test line was the basis for determining the effect of this immobilization. The investigation of β1-mAb antibody immobilization onto nitrocellulose membrane via protein G showed that protein G had a good binding ability to the nitrocellulose membrane, and the color signal of protein G on nitrocellulose membranes was still good when different washing solutions treated it. This result proved that protein G could link the antibody and the nitrocellulose membrane. Investigation of the molecular ratios of the mixture of protein G and mouse IgG antibody showed that the ratio of 1:2 gave the most optimal efficiency of antibody immobilization on nitrocellulose membrane. When testing with the hCG sample, the protein G-associated biosensors gave a better color signal on the test line than the biosensors without protein G. The results proved the potential application of antibody immobilization via protein G in the fabrication of highly sensitive biosensors.