| Porcine pseudorabies is an fatal epidemic disease and caused enormous economic losses to animal husbandry in the world. Until now, the porcine pseudorabies is still frequently outbreak in many developing countries. Therefore, developing sensitive and quantitative detection methods for porcine pseudorabies is very important for the early diagnosis and controling the outbreak of the disease.Signal amplification based on quantum dots as a common method to improve the sensitivity has many advantages such as high sensitivity, broad detection range, high specificity and varies detection approach. Now, signal amplification method has been widely used for the environment detection, bioassay and clinical diagnose. In this paper, we used the signal amplification based on quantum dots to detect the porcine pseudorabies virus (PRV) antibody. The CdSe quantum dots and CdSe modified SiO2nanoparticles was synthesized and used as the labels to amplify the signal for developing new method to detect the PRV antibody, the detail contents and results of the paper are as follow:1. A method with potential advantages and wide application in the bioassay to detect CdSe quantum dots by Rhod-5N was investigated. The detection condition was investigated, under the optimal condition, the detection linearity range of CdSe quantum dots was10.0to500pmol/L, the linear equation was Y=0.1538+0.00134X, with a liner correlation0.9943, the limit of detection was10.0pmol/L. The florescence intensity obtained form Rhod-5N after the cation exchange and signal amplification was45fold of the CdSe synthesized in organic phase and370fold of water-soluble CdSe quantum dots. There is no strict requirement to the optical or other quality of the quantum dots, so the current synthesis technology is quite adequate for the detection. The proposed method provide a simple and sensitive assay to the quantum dots labels in the bioassay. This method also can be used to detect other nanomaterial by change the florescence dye.2. A novel immunoassay for PRV antibody that is based on fluorescence signal amplification induced by silver (I) ion exchange in CdSe quantum dots was reported. In the assay, the large amount of Cd (II) ions in the CdSe labels was used for signal amplification. After the immunoassay, the Cd (II) ions in the CdSe was released by a cation exchange reaction with Ag (I) and detected by the Rhod-5N. Under the optimal condition, the methhod has a limit of detection as low as1.2ng/mL and can response to the positive serum with a1024fold dilution. Compared with the traditional ELISA, the good sensitivity, the broad linear range, the low costs and good speficity in this method provide a well prospect in the clinical diagnosis.3. The stable SiO2@QDs@SiO2microsphere was synthesized and used to label the Rabbit anti Pig IgG, then the probe was used to detect the PRV antibody. We used the improved Stober method to prepare the SiO2microsphere and then sulfhydrylation with (3-Mercaptopropyl)trimethoxysilane. After the sulfhydrylation, the CdSe was modified on the surface of the microsphere directly. Lastly, the QDs@SiO2was further silica coating and labeled with Rabbit anti Pig IgG Due to the large amount of Cd2+in CdSe and the hundreds of CdSe carried by microsphere, the signal obtained from Rhod-5N was dual amplified. The result of the PRV antibody detection indicated that the SiO2@QDs@SiO2microsphere probe has great potential in bioassay. The SiO2@QDs@SiO2microsphere provide a well functional nanomaterial for the signal amplification in bioassay. |
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