DNA-tetrahedron-mediated Nanobiosensor Dual-Mode Detection Of MiRNA-21

With the continuous development of self-assembly technology,nanoparticle assemblies have shown great prospects in the fields of optoelectronics,biosensing,etc.,while noble metal nanomaterial assemblies exhibit superior stability compared to other nanoparticle assemblies.With biocompatibility and unique optical properties,it has received extensive attention and research.Among them,DNA structure-mediated precious metal nanomaterial self-assembly technology has been favored by many researchers,mainly because of the unique self-identification and programmable properties of DNA structure,by controlling the distance between particles and the spatial configuration of nano-components.A highly complex and multi-layered nanoassembly can be constructed.At present,nano biosensors based on DNA technology are increasingly applied to various fields such as bioimaging,tumor therapy,and drug targeting.Therefore,a nanobiosensor mediated by DNA tetrahedron was constructed,and the detection of miRNA-21 by fluorescence and SERS-based bimodal optical signals was realized.The main research work is as follows:Construct a gold nanoparticle dimer(Au^I-Au^II)structure mediated by DNA tetrahedral structure.Gold nanoparticles with ss-DNA single modification were obtained by covalent binding of gold particles to thiol bonds.The gold nanoparticle dimer structure with uniform morphology,high yield,good dispersion and stability was successfully prepared based on the principle of base pairing pairing with the other two chains.Detecting the detection of miRNA-21 by constructing a nano-bioprobe mediated by DNA tetrahedral structure.Based on the previously prepared gold nanoparticle dimer structure,the Cy5-labeled miRNA-21 Aptamer strand was partially complementary to the DNA and assembled to form a tetrahedral nanobioprobe containing a hairpin structure.When miRNA-21 is present,the target molecule is complementary to the Aptamer chain and detached from the tetrahedral structure and away from the gold nanoparticles.The fluorescence intensity of the probe is significantly enhanced,and the fluorescence intensity value and miRNA-21 are within a certain concentration range.The concentration is linear and the detection limit of the probe can be as low as 56 pM.In addition,based on the detection performance of the probe in human serum samples,it is indicated that the nanobioprobe can realize the quantitative detection of the marker miRNA-21 of lung cancer in a complex environment.Quantitative detection of miRNA-21 by constructing a SERS bioprobe mediated by DNA tetrahedral structure.The experiment was based on a previously prepared nanobioprobe,replacing the fluorophore with ss-DNA-4-MBA-Au^INPs.When miRNA-21 is present,the target molecule can hybridize with the Aptamer-Cy5 chain and detach it.The ss-DNA-4-MBA-Au^INPs is completely complementary to the DNA tetrahedral vacant part,making the nanobioprobe(Au^I-Au^II)The polymer structure forms a gold nanoparticle trimer(Au^I-Au^II-Au^I)structure,and the concentration of the target molecule is quantitatively determined by the enhancement of the SERS spectrum.Then,by optimizing the experimental conditions,the SERS bioprobe has a linear relationship between the Raman signal intensity and the concentration of miRNA-21 in the concentration range of 0.05 aM to0.4 aM.