Abstract: The surface plasmon resonance (SPR)-based optical biosensor assay for detecting the ampicilllin residues in milk is developed. The assay is based on the bio-molecular interaction analysis (BIA) and the high sensitivity to the refractive index of the sensor. Combining with the monoclonal antibody anti-ampicillin binding on the sensor surface, the assay could be performed based on the capability of quantitative detection for ampicillin. The analysis system was equipped wih miniature integrated SPR sensor. The method of the preparation of the sensor surface was introduced, and the assay was designed to cover the ampicillin concentration range from 0 ng/ml to 100 ng/ml. With analyzing the detecting results, the sensorgrams of milk samples with different concentrations of ampicillin were obtained. The limit of detection for ampicillin can reach 50 ng/ml. It is sure that this assay based on the SPR technology can be applied to the detection of the antibiotics residues in milk.

Key words: biosensor, surface plasmon resonance, milk, antibody, ampicillin