Cadimium Sulfate Quantum Dots Synthesized and Coupled with Listeria Monocytogenes Antibody IgG
The CdS quantum dots were synthesized by using the precursors including CdCl2 and Na2S and thioglycoli acid (TGA) as stabilizing agent in aqueous solution. The optimal conditions for synthesis of CdS quantum dots were as follows: reaction time of 3 h, 2∶1 of ratio of [Cd2+] to [S2-], TGA volume of 50 μL, system pH value of 8.0 and reaction temperature of 30 ℃ for preparing the CdS quantum dots. The Listeria monocytogenes antibody IgG was successfully coupled to the CdS quantum dots by using the EDC·HCl and the NHS as coupling reagents. The fluorescence intensity of Listeria monocytogenes antibody IgG coupled with the CdS quantum dots was enhanced significantly and was four times of that coupled before. The results of serum agglutination reaction and direct immunofluorescence test showed that the characteristics of Listeria monocytogenes antibody coupled with CdS quantum dots did not changed, and the Listeria monocytogenes could be detected quickly and sensitively by fluorescence microscope. This method can be effectively used in the rapid detection of pathogens in the food because of its high specificity, stability and repeatability.