| Surface acoustic wave(SAW)sensor is a kind of new sensors which adapt to the development of the MEMS and micro manufacturing technology.It mainly includes Rayleigh Wave sensor,Shear Horizontal Wave sensor,Love Wave sensor and so on.Among these,Love Wave has attracted many attentions in recent years due to its advantages of good output stability in liquid media and high sensitivity.Therefore,it leads extensive applications in clinical detection,environmental monitoring and food analysis.This dissertation.mainly discusses about the research on Love Wave SAW sensor,based on sensor fabrication,signal measurement and biochemical detection technologies,the Love Wave sensor and its system are established for lung cancer biomarker and toxin detection.A novel and sensitive Love Wave sensor is designed and fabricated,and combined with microfluidic chips,the multi-channel and portable flow detection system and cell monitoring system are realized.In this dissertation,immunoassay technology based on specific binding between antigen and antibody is utilized to detect lung cancer biomarker protein in exhaled breath condensate and shellfish toxins.Furthermore,cells are used as the sensing element and a novel cell-based biosensor is realized to detect shellfish toxins.With the development of Love Wave sensor,this kind of sensing technology together with the portable detection system can provide a utility and rapid platform for the biochemical detection and analysis.The main content and innovations of this dissertation are given as the following aspects.1.A high-sensitivity Love Wave sensor,together with the microfluidic chips were proposed.And a high throughput and accurate sensor signal detection system,which could measure the amplitude and phase responses of sensors,was designed and implemented.This study chose ST-cut quartz as the piezoelectric substrate,SiO2 as the guiding layer,and Au as the sensing layer.And a high-sensitivity Love Wave sensor was designed and fabricated based on these parameters.Combined with the specific microfluidic chips,the stability of sensors for biochemical detection was improved.Besides,the detection system,which consists of automatic injection,detection circuit and mobile software,was developed.This system could reduce the experimental error brought by manual operation.Analog multichannel switches were added to realize the high throughput detection.2.A Love Wave immunosensor which was based on gold nanoparticle enhancement strategy was designed,and could be used for the sensitive detection of the lung cancer biomarker detection in exhaled breath condensate.Coating antibodies were immobilized onto the sensitive area of Love Wave sensors through protein A.Markers to.be detected were captured by coating antibodies.The specificity of immunosensor resulted from the specific recognition between antibody and antigen.In addition,the detecting antibodies were labeled by gold nanoparticles.A"sandwich" immunoassay was performed on a Love Wave sensor.Subsequently,gold staining solution was introduced,which resulted in catalyzed deposition of gold(III)on to the gold nanoparticles.The deposition amplified the mass loading on immunosensor and made it possible to detect tumor markers in EBC.The limits of detection was 0.967 ng/ml for CEA,which was lower than the diagnostic threshold of lung cancer screening.This showed that the described Love Wave immunosensor had a potential to detect lung cancer in clinic.3.A novel Love Wave sensor based on indirect competitive immunoassay was realized.And it could be utilized for OA detection with a high specify.Indirect competitive immunoassay was selected in this assay for molecular weight of OA is small.Gold staining solution was introduced and gold was deposited onto gold nanoparticles,which resulted in amplification of gravimetrical signals.And the results showed that the sensor signals were linear to the concentrations of OA in range of 10-150 ng/mL with a detection limit of 5.45 ng/mL.The accuracy of this method was compared with the ELISA assay,and the result showed that this immunosensors is accurate and reliable in the analysis of practical samples.4.Detection of Okadaic acid(OA)using liver cancer cell-based Love Wave biosensor was proposed,and this method could reduce the cost and simplify the detection processes.A HepG2 cell-based surface acoustic wave biosensor was introduced in Okadaic acid(OA)detection.The cell culture density was optimized for the toxin detection,and the optimal density was 10,000 cells/well.The insertion loss shifts of sensor had a good relationship with OA concentrations(10-100 ng/mL),the correlation coefficient was 0.9834 and the limit detection was 10.91 ng/mL.Besides,other toxins were also tested to demonstrate the specificity and repeatability of this biosensor.And this research showed that this method needs less reagents than traditional immunoassay.Comparing with animal experiments,the process of this method is much more convenient and fast. |
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