Stable Graphene Isolated Au Nanocrystal For Accurate And Rapid SERS Analysis And Target Imaging

It is known to all that metal-graphene compound integrates the fantastic features of both expensive gold and graphene.So such a material is very popular in chemists and biologists.Researchers has utilized metal-graphene compound for various purpose in biomedicine and other areas.The study of SERS has encountered some challenges such as the accuracy of quantification,due to the heterogeneity and unstability of substrate itself so it causes the poor reproducibility therefore a poor accuracy.It is also readily influenced by the conditions of measurement and interference from co-existed substances.Though there are numerous efforts exerted to solve it like a variety of substrates have been designed and introduction of internal standard,however,these internal standards are either unstable enough or time and labor consuming when synthesis it.Occasionally,there is interference of fluorescence background while imaging bio-samples.Conventional methods used for CV detection has some drawbacks such as high cost,low sensitivity and a trivial extraction process is needed.Fluorescence is quite a severe problem in imaging.Lung cancer is a disease of high lethality.So finding a powerful way to diagnose the cancer in early time is quite important in clinical medicine.To handle these problems mentioned above,we choose GIAN as a substrate for accurate SERS quantification and rapid bio-sample detection.Simultaneously,we functionalized GIAN with aptamer which can target to A549 that can express nucleolin.By using functionalized GIAN,we can image cancer cell clearly with low background.All these researches show that GIAN has giant potential in biomedicine application.Our major work showed as following:1)In the second chapter,we synthesized the gold-isolated-graphene nanocrystal(GIAN),then conducted some characterization experiments.Then the advantages as a SERS substrate were also studied.GIAN was fabricated by CVD by depositing graphene on the gold catalyst.It shaped with a core-shell structure with a gold as a core which can drastically improve the Raman signal.The graphene layer outside can not only protect the inner gold,but also anti-fight harsh conditions such as laser,oxide and bio-enzyme.Furthermore,it has the ability to cancellation fluorescence,decrease the interference of fluorescence.All these experiments demonstrate that GIAN can be an ideal substrate.2)In the third chapter,we utilized GIAN for SERS quantification,we tested different measurement conditions such as laser,depth of focus,coexisted substance and the state of substrate itself to show the ability of GIAN for improving the accuracy of detection.We used GIAN with its 2D signal as an internal standard to quantify CV.As a consequence,the linear relation was quite good.At the same time we applied GIAN for detection of CV directly on fish and fish scale without trivial extraction process which was more rapid and convenient than conventional methods.3)In the fourth episode,we functionalized GIAN with apamater-AS1411 by hydrophobic interaction.This kind of GIAN was full of advantages.Firstly,aptamer has powerful recognition ability that can target a certain cell,here A549 which express nucleoin can bind with AS 1411.Moreover,the 2D signal from graphene can achieve a low background imaging which located in Raman silent region.If such functionalized GIAN loaded with DOX,photosentisizer can be used for chemotherapy and phototherapy which are new methods in biomedicine.