Research On The Capture And Detection Of Exosomes

Breast cancer is the most common cancer among women in China,which ranks the second leading cause of cancer death among women.Since breast cancer can induce salivary glands to secrete specific exosomes,early detection of breast cancer can be achieved by detecting specific exosomes in saliva.The immunoassay based on SERS technology has attracted much attention due to its high sensitivity,excellent multiplexing capability and high light stability.In this thesis,we achieved the detection of exosomes based on a "sandwich" immunoassay by using a hydrophobic substrate and SERS probe.First,the organic silane self-assembled monolayer hydrophobic substrate was prepared though vapor deposition method.By adjusting the ratio between the hydrophilic molecule(APTES)and the hydrophobic molecule(TPFS),supplemented by lubricant,a substrate with hydrophobicity was prepared.The experimental results show that the substrate has excellent slipperiness and targeted adhesion,as well as the advantages of preventing blood clotting and decreasing the non-specific adhesion.Second,we prepared a core-shell SERS nanoprobe as Au@CA+4-Mpy@Ag NPs.In this probe,the gold core has a good stability and a strong biocompatibility;the silver shell helps to provide further enhanced SERS signals.In addition,two kinds of materials as CA and 4-Mpy sandwiched between gold core and silver shell,respectively have the functions of assisting shell growth and providing Raman signals.By placing Raman reporter of 4-Mpy sandwiched between the core and shell layer,the signal stability of such a SERS probe can be greatly improved in a complex biological environment.Finally,using the as-prepared hydrophobic substrate and SERS nanoprobe,the capture and detection of exosomes was realized.To verify the integrity and reliability of the this immunoassay,the specificity of the probe and the reliability of the substrate were verified.The results proved that the probe has a high SERS activity and specificity,which can be used in the detection and quantitative analysis of exosomes.Besides,we found that the hydrophobic substrate can effectively inhibit the non-specific adhesion,which is more reliable and accurate than hydrophilic(100% APTES)substrates.We have classified two types of breast cancer exosomes subtypes,agreed well with the previously reported results.Thus,the substrates and the SERS probes that we demonstrated can be effectively used for typing breast cancer exosomes.