Preparation Of Novel Graphite Nanomaterials And The Application In Multimodal Imaging And Raman Quantitative Detection

Because of unique physical and chemical properties and excellent biocompatibility, nanomaterials have been widely used in biomedical applications. For example, detection methods and imaging technology based on various nanomaterials in biochemistry, diagnosis and treatment of diseases are widely used. Metal-graphite composite nanomaterial, which combines the excellent properties of metal nanoparticles and graphene, has been used in biochemical analysis. But its further application still has some challenges, such as the size of the control, stability, the preparation of high-quality graphene and so on. In order to solve these problems, AuNR-encapsulated graphitic (AuNR@G) nanocapsule and gold nanoparticles (AuNPs) decorated on a multilayered graphitic magnetic nanocapsules (AGNs) were prepared by chemical vapor deposition (CVD). AuNR@G has not only Raman properties of graphene, but also has characteristics of gold nanorods, and therefore can achieve multi-modal imaging. The AGNs graphite has a unique and strong Raman peaks and SERS effect, Raman 2D signal can be used as an internal standard for quantitative analysis, achieving high sensitivity detection and analysis.This paper introduced the preparation, characterization and detection, and multi-modality imaging applications of AuNR@G; and introduced the Raman quantitative determination of AGNs based on graphite as an internal standard. Details are as follows:(1) In the second chapter, the preparation, characterization and detection of graphite nanomaterials-AuNR@G was reported. AuNR@G was prepared by depositing graphene on AuNR@SiO2 surface according to CVD method, which obtains a core of AuNR, a shell of graphite. Such particles have characteristics of Raman graphite and a two-photon nature of AuNR. Graphene shell can increase the stability of the particles; AuNR is a good substrate to enhance the Raman signal. AuNR@G can not only quench the fluorescence of R6G, but can greatly enhance the Raman signal of R6G and improve the detection limit. In addition, AuNR@G has a strong absorption in the near infrared, which can quickly transfer light energy into heat, with good photothermal effect and the high effect of hyperthermia in cells.(2) The third chapter shows the dual-mode Raman and two-photon imaging of AuNR@G. FDTD simulation shows the local field strength of AuNR@G and Au@G, and the strength of AuNR@G is greater than Au@G. No matter two-photon imaging or Raman imaging, the experimental result and the theoretical study is matched. Further SYL3C aptamer modified AuNR@G can achieve a dual-mode target identification imaging in breast tissue.(3) In the fourth chapter, we designed and fabricated another novel nanomaterial AGNs. During the synthesis of the particles, changing the size of gold particles can obtain the nanomaterials having higher Raman signal enhancement. Further, such magnetic core particles are liable to collect and store. The presence of gold nanoparticles greatly enhances the strength of the Raman signal, forming a SERS effect. AGNs gain typical unique 2D peaks, which is in Raman silence region of cells, therefore AGN is as ideal Raman internal standard. AGN exhibit excellent stability and significantly improve the accuracy of Raman analysis. AGN has far-reaching significance in the study of living cells because AGNs can image using D, G and 2D vibration peaks for co-localization.