Detection of cytochrome C by means of surface plasmon resonance sensor

We have studied the detection of cytochrome C by the use of surface plasmon resonance sensor on gold surfaces modified by alkyl thiols with different tail groups such as CH3, NH2 and CH2OH. When the hexadecanethiol film was coated on gold surface, the incident angle changed from 23.1° to 53.2°. Moreover, the incident angle was changed from 53.2° to 63.6° by adding the phosphate buffer (PB) solution (pH=7.06), followed by contacting the cytochrome C solution (10 μM) to 64.6°. The highest sensitivity was obtained on the thiol film having the hydrophobic group. The sensitivity decreased in the order CH3>NH2>CH2OH. As a result of examining the reproducibility, the incident angle returned at about 90% immediately, when the absorbed surface was washed in the imidazole solution (3 mM, pH=7.8).