Construction And Analytical Application Of DNA-Based Photonic Wires

Molecular photonic wires(MPWs)are formed by multiple fluorophores in series,and achieve the directional transfer of photonic energy at the nanometer scale by F(?)rster resonance energy transfer(FRET),which has the potential application of light harvest,biological transmission,sensor and molecular electronics.Deoxyribonucleic acid(DNA)can be designed,synthesized easily and modified easily,which is a novel nanomaterial with highly controllable structure.The method of locating and modifying fluorophores on DNA can strictly control the fluorophore spacing.This DNA-based molecular photonic wires(DNA PWs)has a controllable structure and a controllable fluorophore array,which has more excellent energy transfer efficiency and effective transmission distance.However,the current research on DNA PWs mainly focuses on light capture.In order to pursue high efficiency,the fluorescence peak spectral crosstalk of most DNA PWs is serious,and it is difficult to carry out practical applications of their fluorescence.Therefore,this dissertation takes DNA PWs as the research object.Aiming at the current deficiencies in fluorescence analysis research,the following research contents are carried out:1.Construction of long-range FRET DNA PWs.Cascade energy transfer between fluorophores on DNA is the basis for efficient photon transfer.However,when too much fluorophore modification is involved,it will cause crosstalk of the DNA PWs spectrum.We introduced nucleic acid dyes and used them to self-assemble with DNA to construct photonic wires based on three fluorophores.However,the effective spectral overlap between fluorophores and the binding efficiency of nucleic acid dyes are two important factors that affect the energy transfer efficiency of DNA PWs.Here,we used fluorescence spectroscopy to study the photonic wires constructed by different nucleic acid dyes(Acridine orange,Acridine yellow)and different donor-acceptors.It was found that the energy transfer efficiency of dye groups with higher spectral overlap is not necessarily high,and it is also compared with fluorescence.The orientation of the group is related and conforms to the F(?)rster’s theory.Therefore,for the construction of photonic wires,the selection of fluorophores is conducive to obtaining a better photon line energy transfer system after a variety of combination comparisons.At the same time,the limited use of three dyes greatly improves the problem of spectral crosstalk.Finally,the study found that the appropriate dye combination is 7-amino-4-methyl-3-coumarinylacetic acid(AMCA)→Acridine Orange(AO)→Texas Red(TR),laying a certain foundation for further expanding the application of DNAPWs in the field of fluorescence analysis.2.Research on the optical properties of DNA PWs.In order to further explore the energy transfer properties and fluorescence characteristics of DNA PWs,they are better applied to the field of fluorescence analysis.Here,we used fluorescence spectroscopy to systematically explore the cascade energy transfer characteristics and long–distance energy transfer performance of DNA PWs by increasing and changing DNA length and nucleic acid dye concentration.The study found that the fluorescence spectrum of the DNA PWs we designed has independent three primary colors(RGB)emission,which are the blue light of the donor(AMCA),the green light of the nucleic acid dye(AO)and the red light of the acceptor(TR).The relative intensity value can be changed by adjusting the energy transfer effect,confirming that DNA PWs have fluorescence pleochroism.On the other hand,we calculated the fluorescence anisotropy to prove that the nucleic acid dye binds to DNA and forms Homo-FRET by itself.Due to the low loss of photon energy in the transfer process through Homo-FRET,the designed DNA PWs have high energy transfer efficiency,and the donor and acceptor fluorescence do not interfere with each other,making it an excellent energy transfer probe.3.DNA PWs are used for information encryption and nuclease activity detection probes.The current research on DNA PWs is mainly focused on improving the light trapping ability and simulating the photon energy transfer of photosynthesis,but there are few reports in the field of analysis.The DNA PWs we designed not only can achieve high-efficiency long-distance energy transfer,but also have three primary colors of fluorescence emission.The emission spectra between the donor and receiver fluorophores are not overlapped,and at the same time,they have FRET sensitivity to fluorophore spacing,so they are expected to become excellent optical sensors Original.Based on this,we use DNA PWs as the original fluorescent color toning,and the fluorescent color of DNA PWs as the output signal.We use different dye ratios to change the RGB value to achieve the purpose of changing the fluorescent color.We have modulated 36 fluorescent colors according to the different ratios.Use it as the parent to encode it,and the encoded content contains all English capital letters and Arabic numerals,which finally realizes the purpose of information encryption.Secondly,we also use the energy transfer properties of photon rays.Based on the fact that deoxyribonuclease I(Deoxyribonuclease I,DNase I)will hydrolyze the DNA scaffold,the nucleic acid dye will have no assembly sites,energy transfer will be blocked,the donor fluorescence will be restored,and the acceptor fluorescence will decrease.We have designed DNase I activity detection system.This research has enriched the research content of the optical properties of DNAPWs,expanded ideas for its research and development,and laid a certain foundation for the research and development of photon wires as fluorescent probes.In summary,this article takes DNA PWs as the research object,with the help of fluorescence analysis technology,studies the energy transfer and fluorescence properties related to the fluorophore combination,dye ratio,size,etc.of DNA PWs.On this basis,DNA PWs are used as Color original,realize 36-color information encryption coding,and successfully used for information encryption.At the same time,we also use its energy transfer properties to successfully apply it to the detection of DNase I activity.The above experiments have deeply studied the fluorescence properties of photonic wires,provided a certain experimental basis and new direction for the development of DNA PWs,and also expanded the application of DNA PWs in the field of fluorescence analysis.