Improved Methods And Experiments For The Detection Of Antibiotics Residues Based On Surface Plasmon Resonance Sensor

With the occurrence of food security problem, people pay more and more attention to residues issues. Antibiotics and illegal additives residues in milk are harmful to human health. In the field of antibiotics residues detection, the impracticality of forcible testing due to the shortcomings of current popular detection methods.So it is necessary to develop new detection methods.The surface plasmon resonance (SPR) biosensors were used to detect antibiotics and melamine residues in milk in the thesis. With the technique based on SPR biosensors being simple with some disadvantage in application of the residues detection field, new detection methods are proposed and studied in the thesis. The study will develop and enrich the theory of detecting low molecular residues by using SPR biosensor.First, signal amplification assay based on the SPR biosensor is developed. In an attempt to improve the sensitivity and lower the limit of detection (LOD), second antibodies are introduced to use for second detection analyte after the competitive inhibition assay. The second analyte can magnify the first detection analyte signals obviously. The detection assays of ampicillin, kanamycin and streptomycin in water solution are carried out. The results show that the LODs of the residues using the competitive inhibition assays are 0.346ng/mL, 11.89ng/mL and 24.29ng/mL respectively, while the LODs using the signal amplification assays are 0.346ng/mL, 11.89ng/mL and 24.29ng/mL respectively. So the signal amplification detection are not only satisfy the regulation of EU's maximum residue limit (MRL), but better than the competitive inhibition method.Next, in order to solve the problem that the sensors are special for the detection of residues in current methods, a new method based on SPR biosensors for the detection of various residues is proposed. Marking the residues with special moleculars, the analyte was transformed from residues in the sample to general markers after twice competitive inhibition. Thus, the biosensor with ligand immobilized once could dectect various residues. In the assay, bovine serum albumin (BSA) was used as molecular-marker, and kanamycin, melamine, ampicillin and streptomycin are marked with BSA separately. Water solution with a series concentration of residueds is detected respectively by the same biosensor in this paper. The LODs reach to 14.3ng/mL, 7.89ng/mL, 0.51ng/mL and 8.08ng/mL respectively, being much lower than MRLs accordingly. The method has solved the problem that sensors are special for the detection of residues in the competitive assay, and then the sensors will be more available.To sum up, two new methods of detecting residues in milk based on SPR biosensor are developed. The feasibility of the new methods are tested by experiments, and the standarized assays procedure, excluding pretreating of samples, preprocessing of the sensor surface and detecting of the analyte, are established. Furthermore, the methods can be applied to other fields of food and drug residues detection.