Breast Cancer-related MiRNA Detection Based On Surface Enhanced Raman Spectroscopy Technology

Surface Enhanced Raman Scattering(SERS)is an ultra-sensitive molecular vibrational spectroscopy technology,which is widely used in various analyses,such as in chemistry,materials,life sciences,and other applications.SERS spectral detection generally involves loading the target analyte on a SERS substrate,performing SERS spectral detection on that substrate,then processing the data obtained from the detection,and finally achieving quantitative or qualitative analysis of the target analyte.Based on the characteristics of high sensitivity and strong specificity light of SERS spectrum detection technology,the application of SERS in biomedical field has become a research hotspot in recent years.miRNA is non-coding RNA with only dozens of bases.Studies have shown that miRNA participate in the activity process of different types of cells by controlling the gene expression of RNA after transcription.Since the amount of healthy persons and patients expressing the miRNA significant difference,thus miRNA can be used as a tumor marker for early screening of breast cancer.In this thesis,SERS technology was used as a detection tool for miRNA,a tumor marker associated with breast cancer,and two different SERS probes were constructed to achieve specific detection of miRNA and to explore a early detection tool for breast cancer with high specificity,high sensitivity and rapid and low cost.The main research contents are as follows:(1)Using Au nanoparticles with SERS enhancement effect,by modifying the gold nanoparticles and based on the feature that miRNA is endogenous non-coding small RNA,a DNA strand that can specifically bind to the detection target miRNA was designed so that one end of the DNA strand has a Raman report molecule and the other end has a sulfhydryl modification.The Au-S bond was used to connect the end with sulfhydryl group to the gold nanoparticles to complete the modification of the gold nanoparticles so that they can be used as SERS sensors for specific detection of miRNA.(2)A sandwich-like structure of SERS sensor was constructed,and core-shell nanoparticles with Raman label molecules and silicon wafers with gold nanoparticle loading were prepared as two-dimensional substrates.The target miRNA was specifically bound to the hairpin DNA strand by a cyclic amplification system to generate a DNA double strand,and the core-shell nanoparticles were bound to the two-dimensional substrate to achieve quantitative detection of tumor markers according to the intensity change of the detected signal molecules.(3)Using the prepared SERS sensor with similar sandwich structure,the serum miRNAs of breast cancer patients and healthy individuals were investigated.Through the processing and analysis of the SERS data,the SERS characteristic peaks of the two serum specimens were significantly different,thus achieving an accurate differentiation between patients and healthy individuals.At the same time,compared with the non-labeled breast cancer SERS detection method,the comparison of statistical results can reveal that the labeled detection method designed in this experiment has higher sensitivity and specificity,and our constructed miRNA SERS sensor has great potential for application as an early detection tool for breast cancer.In this thesis,two miRNA SERS sensors were constructed and applied them to the detection of breast cancer miRNA with good results.In addition,we also conducted a study of the latter miRNA 2D SERS sensor on actual serum samples,and the experimental results showed that the miRNA 2D SERS sensor has higher sensitivity and high specificity,which may provide a fast,simple and accurate detection solution for early diagnosis of breast cancer.