Detection Techniques Based On Colloidal Gold And Aptamers And Their Preliminary Application

Colloidal gold particles are nanoscale materials with a diameter of 1-100 nm and belong to ultrafine gold nanometers.Colloidal gold particles have two characteristics,both the chemical nature of the metal and the unique physical properties,but also has the characteristics of surface effects.The morphology,size,and aggregation state of colloidal gold particles are closely related to their unique optical effects.Nucleic acid probes have a series of advantages,such as: they are very simple in synthesis,easier to design,and have better sensitivity and specificity in detection.Therefore,it is used as an important detection tool in nucleic acid detection.It is precisely because of the above advantages that many scientific researchers have conducted in-depth research and designed many new types of detection nucleic acid probes with different functions.Has a very important role,such as: molecular medicine,disease and other areas have made significant contributions.An aptamer is a piece of DNA sequence,usually an oligonucleotide fragment obtained from a library of nucleic acid molecules using an in vitro screening technique(SELEX).Nucleic acid aptamers have a wide range of uses in various fields,such as biopharmaceuticals,biosensing,nanotechnology,etc.;in this paper,a novel detection method based on aptamers,nucleic acid probes and cross-linked gold technology is constructed.This method can detect nucleic acid molecules,ions and proteins with high sensitivity.In response to these,the work has mainly started in two areas:1.Based on cross-linked gold and aptamer technology,a general colloidal gold system for the detection of multiple target substances was constructed.In this system,we developed a method for high-sensitivity detection of ATP small molecules,potassium ions,and thrombin.Based on the principle of cross-linked colloidal gold particles,we can use only one kind of UV spectrophotometer with this colloidal gold technology.The target substance is simply detected with high sensitivity,and the presence or absence of the target substance can be judged directly by visual observation of the color.Compared with other colorimetric detection methods,the advantage of this method is that only a functional colloidal gold particle is used.The lowest lower limit of thrombin is 5 fM,the lowest limit of potassium ion is 50 nM,and the lower limit of ATP molecule is 0.2 nM..The method is simple and convenient,does not require the presence of enzymes,does not require complicated equipment,has low cost,and has good potential application value.2.Based on the principle of polymerase displacement of target substances,an ultra-sensitive universal colloidal gold detection protein system was constructed.In this system,by designing aptamers,based on the use of cross-linked gold and aptamers,a polymerase-polymerized displacement target amplification reaction was further added.When there is no target substance,colloidal gold and nucleic acid aptamers hybridize with nucleic acid probes to make colloidal gold not agglomerate and the peak of colloidal gold does not shift.When the target substance is present,under the action of the polymerase,a well-designed nucleic aptamer can specifically bind to the target substance to perform a cyclic amplification reaction,so that the target substance can be rapidly detected at a very low concentration.And can reach the detection limit of 0.5aM.