A practical and simple DNA sensor based on surface plasmon resonance (SPR) has been developed to determine the interferon gamma (IFN-γ). This SPR instrument was designed on the basis of simultaneous multi- wavelength detection. IFN-γ oligonucletide DNA chemically labeled with biotin was used as the probe. Biotin-avidin system was used to immobilize the bio-DNA on the sensor surface. The assembling process and condition of the DNA sensor were examined in detail. The SPR sensor can be used to monitor the process of the immobility of the bio-DNA and DNA hybridization in real-time. The determination range of IFN-γ oligonucleotide (24 bases) is 50-400ng/mL. The determination range of polymerase chain reaction (PCR) product of IFN- γ (247 bases) is 5-40ng/mL. The stability, reversibility and specificity of the DNA sensor were also investigated. It is found from the experiment that the sensor can be applied for longer time (about 100 times). The relative standard deviation (RSD) for determination DNA and PCR product of DNA was 1.2% and 1.4%, respectively. The interference of noncomplementary DNA sequence with the determination of DNA was examined. It is found that noncomplementary 20-mer and 21-mer DNA (ICE-F and ICE-R) do not affect the determination of DNA.

Key words: INTERFERON, DEOXYRIBONUCLEIC ACID, SENSORS, PROBES