Research Of Graphene Nanomaterials And Nanoceria-Based Optical Sensors

As one of important analytical methods, the optical sensing technology has been widely applied in various fields, including bio-imaging, molecular recognition and security monitoring etc. The rapid development of nanomaterials provides the possibility for miniaturization application of optical sensing. Graphene and graphene derivatives, gold nanoparticles and cerium oxide nanoparticles have attracted much attention due to their excellent optical, mechanical, electronic and thermodynamic properties. They have a good application prospect in the fields of bio-or chemical sensing, bio-imaging, clinical diagnosis and treatment.This paper has mainly researched about the preparation of graphene-nanoparticles hybrid and cerium based nanomaterials, investigated the morphology, component and valence state of the composite materials in details, and assessed the performance of nanocomposites in sensing with optical methods. We also try to apply the mentioned optical sensors to the detection of the environment pollutants and metabolin.Chapter 1 OverviewIn this chapter, we gave an outline of the optical properties of graphene, gold nanoparticles and cerium doped nanomaterials, and selected some examples of relevant sensing applications. At the end, we proposed the research content and significance.Chapter 2 Surface enhance Raman scatting detection of lead ions with AuNPs/rGO colloid as substrateIn this chapter, the preparation process of AuNPs/rGO colloid is described in detail. We obtained the information about the morphology and chemical components of materials by characterizing with TEM, SEM, XRD and XPS. The Raman spectra indicated the strong SERS signal of AuNPs/rGO. Considering of the rapid gold dissolution reaction with lead ions as the catalyst, we established a SERS sensor for lead ions detection based on the AuNPs/rGO. This method has shown a good selectivity and sensitivity for lead ions detection. The detection range is from 5 nM to 4 μM, and the limit of detection is 1 nM.Chapter 3 Colorimetric sensing of hydrogen peroxide and superoxide based on the double enzyme activity of CeO2/rGO hybridIn this chapter, we synthesized the CeO2/rGO nanocomposite by a simple ultrasonic-hydrothermal method. After carefully analyzing the properties of CeO2/rGO, we found it could obviously exhibit peroxidase and superoxide dismutase-like activity in neutral pH. By taking advantage of the reaction between 3, 3’,5,5’-tetramethyl benzidine and hydrogen peroxide, we established a colorimetric sensing system to determine the concentration of hydrogen peroxide and superoxide in vitro. The limit detection for hydrogen peroxide is 2.5 μM, but for surperoxide is 1.1 μM.Chapter 4 CeO2@BSA nanocluster-based fluorescence sensor for alkaline phosphatase detectionIn this chapter, we introduced the morphology, composition and optical properties of the bovine serum albumin stabilized cerium nanocluster (CeO2@BSA). Copper ions can induce the aggregating of CeO2@BSA to cause the fluorescence quenching, the strong combination of pyrophosphoric acid with copper ions can inhibit the aggregating of CeO2@BSA to induce the fluorescence discovery, however, after the hydrolyzation of pyrophosphate by alkaline phosphatase, the fluorescence is quenching again. Based on this principle, we ensured the fluorescence detection relationship between the fluorescent intensity of CeO2@BSA and the concentration of alkaline phosphatase. The linear detection range for alkaline phosphatase is from 20 U/L to 400 U/L, and the limit detection is 2.66 U/L.