Construction Of Nucleic Acid Sensors Based On Quantum Dots And Their Applications In Biomedical Analysis

As a new semiconductor fluorescent nano-material, quantum dots expected to be widely used inthe biomedical field application since it exhibited a broad excitation, narrow emission, tunableemission wavelength, larger Stokes shift, good light stability and biocompatibility. A great deal ofscientific research proved that the occurrence and development of tumors are often associated withabnormal expression of a variety of nucleic acid markers related. Therefore, we directly preparedCdTe/CdS core-shell quantum dots in the aqueous phase via microwave-assisted process. Weconstruct the QDs-DNA bioconjugate by ligand exchange and further use as high sensitivity andselectivity suitable nucleic acid sensor for the early detection of lung cancer. The main topics of thisthesis are as follows:(1) Preparation of the QDs-DNA probe.First, we prepared the QDs-DNA via ligand exchange of DNA that is substituted with thequantum dots surface mercapto acid ligand mercapto group. Corresponding QDs-DNA nucleic acidprobe showed unique excellent optical properties and specifically recognizes the configuration ofthe sensor.(2) Preparation of the quantum dots-based sensor.Second, we propose a "signal off" strategy to achieve high selectivity and sensitivity detection ofthe DNA and miRNA through controlling the fluorescence resonance energy transfer betweenfluorescence quantum dots and BHQ2. QDs-DNA nucleic acid sensor exhibited high and excellentsensitivity to the target DNA and miRNA-21molecules. And the detection limit of the sensor isreached1fM and10fM respectively. The sensor has four orders of magnitude in the range oflinearity and a good specificity.(3) Preparation of the quantum dots and magnetic nanoparticles-based sensor for detection ofnucleic acid.Consideration of the excellent fluorescence properties of the quantum dots and thesuperparamagnetic properties of magnetic nanoparticles, the separation of quantum dots andmagnetic nanoparticles under magnetic field, and further analysis the concentration-dependentluminance property of quantum dots. The experimental result suggests that it exhibited excellentsensitivity and efficiency. The detection limit of the sensor is reached10fM.