Research On DNA Defect Detection Based On Terahertz Wave

The vibrational modes(torsion,translation,collective and skeletal vibrations,etc.)between DNA molecules are mainly in the terahertz band.DNA molecules exhibit many unique absorption properties in the terahertz band compared to the infrared band.THz spectroscopy detection in the conformational changes of the active biomolecules has been restrained as the strong absorption of water in biological solutions,but microfluidic chip can reduces the absorption of water effectively and enhances the characteristic signal of biomolecules.In this thesis,Terahertz Time-Domain Spectroscopy(THz-TDS)is combined with microfluidic chip to achieve label-free detection of DNA molecules.The main research work is as follows:1)The microfluidic chip carrying liquid DNA samples was prepared,and the absorption spectra of seven mutated DNA molecules in the 0.2-2.5 THz band were studied by combining THz-TDS with the microfluidic chip,and the Savitzky-Golay(S-G)algorithm was applied to noise reduction of the spectrograms.The possibility of THz-TDS for DNA spectral detection was explored,and the relationship between different DNA sequences and their characteristic spectra was revealed.This work provides a new idea of combining THz-TDS with the microfluidic chip for label-free detection of gene mutations.2)THz-TDS is combined with the microfluidic chip to detect cell DNA samples.By selecting the DNA of normal liver cells,liver cancer cells,normal gastric cells,gastric cancer cells and breast cancer cells,the differences between the two groups of normal cell DNA and their cancerous cell DNA were analyzed;the correlation of the DNA absorption spectra of the three cancer cells was compared;the fingerprint spectrum of cancer cell DNA was obtained,and the Principal Component Analysis(PCA)method was applied to achieve the automatic identification of three kinds of cancer cell DNA samples.This work confirms the potential value of THz-TDS technology combined with microfluidic chip for clinical disease diagnosis.All the research work in this text has made further contributions to the development of the pathogenesis of genetic diseases,cancer and other complex diseases and related preventive measures.