| It have been demonstrated that the gene mutation is the biologicalbasis of the tumor. Gastric cancer is a kind of tumor with high incidencerate in China. Therefore, it is significant to develop new methods for thedetection of gastric cancer-related genes. The development ofnanotechnology brings important opportunity for the development ofgene detection. This research combined nanotechnology withhigh-throughput gene detection in the liquid phase. In this article, thequantum dots encoded microspheres, the separation of magneticnanoparticles and the signal amplification of bar-code DNA wereintegrated to achieve a high-throughput, fast, high sensitivity detectionmethod for the assay of gastric cancer related DNA. The main contentsinclude:1) Preparation and analysis of Fe3O4magnetic nanoparticles: Fivekinds of Fe3O4magnetic nanoparticles (10nm,15nm,20nm,30nm and50nm) was synthesized and then characterized by X-ray diffractionspectra, transmission electron microscopy (TEM) and the analysis of themagnetic (VSM). The results showed that the magnetic Fe3O4nanoparticles were superparamagnetic when their particle sizes were lessthan30nm. While the magnetic particles superparamagnetism when theparticle size increased to50nm. The saturation magnetization of50nmFe3O4magnetic particles are75.92emu/g, which is much higher than thatof Fe3O4nanoparticles below30nm.2) Synthesis and characterization of quantum dots (QDs): Thewater-soluble CdTe QDs were prepared by hydrothermal method. Anumber of CdTe QDs with different fluorescence spectra were fabricatedunder different reflux time. The as-prepared QDs were characterized byfluorescence spectroscopy and TEM. The results showed that thefluorescence emission peaks of quantum dots red shift accompanyingwith the increase of reflux time, and the fluorescent colors of QDschanged gradually from green to red. The QDs is spherical, of gooddispersibility and high fluorescence intensity. 3) Preparation and characterization of QD encoded microspheres:Quantum dots encoded microspheres were prepared by the couplingreaction of amino (-NH2) and carboxyl (-COOH). With the couplingagent of ((1-[3-(Dimethylamino) propyl]-3-ethylcarbodiimide methiodide(EDC), N-Hydroxysuccinimide(NHS)), coupling reaction was carried onbetween the amino on the surface of polystyrene microspheres and thecarboxyl on the surface of CdTe Different QD encoded microsphereswere fabricated by coupling QDs with different fluorescence emissionpeaks on the surface of polystyrene microspheres, and determined byfluorescence spectroscopy and TEM. The results showed that the QDencoded microspheres with different fluorescence characteristics weresuccessfully structured by adjusting the ratio of different QDs, whichprovides a general platform for the conjugation of biomolecules in liquidbiochip.4) Detection of gastric cancer related DNA based on magneticnanoparticles and QD encoded microspheres: The DNA detection wasperformed by bio-bar code technique. At first, two DNA probes wereimmobilized on the surface of QD coded microsphere, and the third DNAprobe was immobilized on the surface of Fe3O4magnetic nanoparticles.Then the detection of target gastric cancer related DNA was carried on by"sandwich" hybridization with the probes immobilized on the surface ofQD coded microsphere and Fe3O4magnetic nanoparticles. The resultsshowed that the fluorescence detection can be achieved by one excitationlight source, and the fluorescence peaks of encoded microspheres andDNA detection signal appeared simultaneously. This method can detect atarget DNA concentration of50nM, and the complementary andmismatched sequences can be distinguished effectively. |
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