The Detection Of DNA Using CdTe Quantum Dots And Gold Nanoparticles

DNA detection has played an important role in life science. It has been widely used in many fields such as medical diagnose, environment monitoring and medicine research. So it becomes a hot topic to develop new assay methods with high sensitivity, good selectivity and simple. Owing to the outstanding characteristics of semiconductor nanomaterials, it plays an increasingly important role in DNA detection. In this work, we developed three methods to detect DNA based on the optics properties of gold nanoparticles and quantum dots. The main content and results of research are as following:1. A method has been developed for the rapid determination of calf thymus (ct) DNA that is based on the photoinduced electron transfer (PET) that occurs between CdTe quantum dots (QDs) and the ruthenium(II)tris-bipyridyl complex [Ru(bpy)32+]. The latter quenches the photoluminescence (PL) of the QDs through PET. The Stern-Volmer quenching constant is 2,500 L mol-1. The intensity of the PL the system is recovered in the presence of ct DNA, and relative recovered PL intensity is linearly proportional to the concentration of ct DNA. The dynamic range is from 17 uM to 1.5 mM of DNA, and the detection limit (at S/N= 3) is 5.7 uM.2. A label-free method to detect the Nopaline synthase (NOS) terminator sequence has been developed based on the color change of gold naoparticles. The detection limit of this method isl.0 x 10-8 mol L-1. The method is simple, in-expensive and fast. It has a good application prospect.3. The detection of transgenic products is of great significance for the development of transgenic technique. We developed a simple, rapid and ultrasensitive method for the detection of sequence-specific Nopaline synthase (NOS) gene from the transgenic plants using label-free gold nanoparticle (NP) probe and dynamic light scattering (DLS) technology. Gold NPs were stable in NaCl solution with the presence of NOS gene probe. On the contrary, they were aggregated in NaCl solution when the probe sequence was hybridized with target sequence. The change in the size of gold NPs can be detected by DLS technology with high sensitivity. Under the optimal conditions, the average hydrodynamic diameter of gold NPs was linear with the concentration of the target sequence ranging from 1.0 x 10-13 mol L-1 to 5.0 x 10-9 mol L-1, with a detection limit of 3.0 x 10-14 mol L-1 (S/N= 3). The relative standard deviation (at 1.0 x 10"9 mol L-1 of target sequence) was 4.8%(n= 11). The result shows that gold Nps-based DLS method has great potential in the analysis of transgenic products.