Field-effect-transistor type C-reactive protein sensor using cysteine-tagged protein G

A BioFET (biological field effect transisor) for detection of C-reactive protein has been characterised using cysteine-tagged protein G capable of site-specific immobilisation of antibody to enhance antigen detection. Drain current of the BioFET with immobilised protein G on the gate surface has been measured in different pH solutions to investigate charge effect of the protein. Antibody-antigen interaction was observed through variation of the drain current of the BioFET. The current differential ratio was linearly related to the concentration of the C-reactive protein in the range 3-20 mug/ml.