Fabrication Of Novel Surface Acoustic Wave Sensors And Its Application In Detecting Exosomes With High Sensitivity

The detection principle of the surface acoustic wave sensor is based on the propagation of surface acoustic waves.According to the changes in the quality and viscoelasticity of the platform surface,the quantitative detection of biological macromolecules can be achieved.Surface acoustic wave sensors are increasingly applied in the field of medical testing due to their advantages of high operating frequency,high sensitivity,label-free,easy operation,and real-time detection.Constructing a signal amplification system is an important way to further improve the detection sensitivity of surface acoustic wave sensors.Since the surface acoustic wave can detect the dynamic change of the chip surface while passing through the chip surface,the signal amplification system can significantly improve the detection effect of the platform.In this paper,the signal amplification system of gold nanoparticles and horseradish peroxidase-catalyzed polydopamine were constructed,the amplification principle and detection conditions were also discussed,and discussed its practical application.Exosomes,as a subtype of extracellular vesicles(EVs),have the advantages of more uniform size,higher biological fluid content,and better specificity of markers(RNA,DNA,lipids and proteins).Exosomes have been widely recognized in clinical medicine.As the latest generation of tumor markers,it is considered to be a better detection method than liquid biopsy.In order to achieve high-sensitivity quantitative detection of exosomes and make the detection method suitable for clinical use,we have constructed a double antibody sandwich system on the surface acoustic wave platform.The topic consists of the following two parts:Part ?:AuNPs Amplified Surface Acoustic Wave Sensor for Quantification of ExosomesThe platform is based on a gold film,and a layer of self-assembled Au-S bond is modified on the surface of the chip using mercaptoacetic acid.The anti-CD63 antibody is modified after activating the carboxyl group on the chip surface using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride(EDC)and N-hydroxysuccinimide;1-hydroxypyrrolidine-2,5-dione(NHS).The membrane protein CD63 is presented on the surface of the exosomes,which can be captured on the SAW chip immobilized with the anti-CD63antibody.In order to amplify the detection signal,a biotin-conjugated epithelial cell adhesion molecule(EpCAM)antibody is used as a secondary antibody on the SAW chip,and streptavidin modified gold nanoparticles are added and assembled on the chip by biotin-avidin recognition.Through the signal amplification system,the detection line of the platform can reach 1.1×10~3 particles/mL,the anti-interference ability of the platform and the ability to detect actual samples have been fully verified.Similarly,if the signal amplification strategy is not used,the detection limit of the surface acoustic wave platform is 8.4×104 pieces/ml by calculation,which is two orders of magnitude higher than the detection limit using signal amplification.This fully demonstrates the importance of signal amplification for surface acoustic wave detection platforms.In addition,the platform also has good anti-interference ability,and can be initially used for the detection of clinical actual samples.In this article,we tested ten healthy samples,five liver cancer patient samples,and five lung cancer patient samples,and the results also reflected the platform's good differentiation and actual detection capabilities.In summary,these advantages make our platform an impressive new technology for the quantitative detection of exosomes in clinical samples,which can be combined with existing clinical treatment diagnosis to achieve individualized treatment and administration of cancer patients.Part ?:Discussion on the effect of polydopamine solution on surface acoustic wave sensor and its application in quantitative detection of exosomesAccording to the literature,horseradish peroxidase(HRP)can greatly accelerate the self-polymerization of dopamine to form polydopamine particles,and the excellent adsorption and biocompatibility of polydopamine can make the surface quality and viscoelasticity of the chip change dramatically,so as to play an excellent signal amplification effect.In this study,biotinylated thiol polyethylene glycol(PEG)was modified on the chip,and the streptavidin-modified HRP enzyme was connected to the surface of the chip through the biotin avidin linking system.The results show that HRP catalyzed polydopamine has a significant signal amplification effect on the surface acoustic wave platform.The newly constructed surface acoustic wave sensor based on the polydopamine signal amplification system quantitatively detects exosomes,and the results show that it has an excellent linear relationship and can be initially used for the detection of exosomes in clinical samples.