| The integration of microelectronics,materials and biological sciences will greatly promote the development of the bio-microelectronics and biomedical fields.It is of great significance to apply biochips and biosensing technology to the diagnosis and treatment of cancers,viral epidemics and other major diseases which lead to human deaths.In particular,with the rapid development of modern medical technology,many diseases can be effectively treated and even cured if treated in the early stage.However,the diagnostic techniques currently used in clinical practice are not sufficient for the rapid and efficient early diagnosis of diseases.Therefore,it is urgent to find new biomarkers,establish a rapid and sensitive early diagnosis platform,and make early diagnosis and treatment for patients after rapid diagnosis to improve the survival rate.Studies have shown that RNA molecules play an important role in regulating cell state,and a variety of RNA molecules can be used as markers for disease diagnosis.Aiming at the important needs of rapid nucleic acid detection technology for medical care,health and major infectious diseases,and uses the advantages of electronics,materials,biology,chemistry and other multidisciplinary cross-discipline to construct a new type of biosensing detection technology to achieve rapid quantitative detection of RNA molecules.In this dissertation,a high-throughput microfluidic fluorescent chip cover was designed by using micro-nano processing technology in microelectronics.By integrating with self-assembled polylysine glass substrate,a microfluidic fluorescent chip for the specific detection of breast cancer related miRNAs was prepared.Then the three-segment hybridization system is used to detect multiple miRNAs in which one end of the capture probe is complementary to the other end of the target miRNA and the detection probe with fluorescence is partially complementary to the other end of the target miRNA.The three-segment structure realizes label-free miRNA detection.The microfluidic fluorescence chip we proposed can not only the accurate quantification of sample loading volume,but also economic material cost.The chip is capable of sensing multiple miRNAs at the same time,without amplification,and the detection limit is 1 pM in 30 min which is of great application value in the early diagnosis of breast cancer.Secondly,we use nanomaterial technology and photoelectric detection technology to construct a three-signal(colorimetry,fluorescence and Raman)biosensing system based on Au NPs,which can quickly and quantitatively detect the specific RNA genes of COVID-19 within 40 minutes.The construction of the system combines the unique optical properties and excellent Raman enhancement properties of Au NPs,as well as the different affinities for single-stranded and double-stranded nucleic acid molecules,which can achieve colorimetric sensing with the naked eye.At the same time,after centrifugation of the solution,the free double-stranded nucleic acid molecules in the supernatant provide a response to a fluorescent signal,and the aggregation of Au NPs provides a sensitive Raman detection signal,thus successfully realizing the triple signal detection of viral RNA.Finally,through the coupling of multi-point probes in the sensor system,the detection accuracy and sensitivity of the three-signal biosensing system are improved,and the generation of false signals is greatly reduced.The sensing system achieves femtomolar detection sensitivity in triple mode,with a detection limit of 160 fM in absorption mode,259 fM in fluorescence mode,and 395 fM in SERS mode.The work shows potential application in screening of COVID-19,as well as accurate early diagnosis and real-time monitoring.Finally,the main research content and results of the dissertation are summarized and analyzed,and related research directions in the future are prospected. |
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