| The optical response of gold nanorods is typically characterized by the presence of strong absorption and scattering peaks that are not present in the spectrum of the bulk metal, a phenomenon named localized surface plasmon resonance (LSPR), due to the coupling of conduction electrons to the electromagnetic field of the incident light. On the other hand, Gold nanorods have attracted much attention as biosensors because of their unique optical properties biocompatibility.In this thesis, The LSPR properties of gold nanorods were tuned by tailoring their size with a new method, then the biosensors based on the LSPR properties of gold nanorods were fabricated.(1) A approach of adjusting the LSPR properties of gold nanorods has been developed. Gold naorods were prepared according to the method of seed-growth, then the synthesized gold nanorods reacted with nitrate acid to tailor the size and shape of gold nanorods, resulting in the changes of LSPR properties.(2) An enhanced sensitive biosensor has been developed to detect biological targets by tailoring the LSPR property of core-shell gold nanorods. A shell layer is produced on gold nanorods by generating a layer of chalcogenide on the gold nanorod surface after attachment of the recognition reagent, namely, goat IgG and antigen of schistosomiasis japonica. The bioactivity of these attached biomolecules is retained and the sensitivity of this biosensor is thus enhanced significantly. The plasmonic properties of the gold nanorods attached with the biomolecules can be adjusted and the plasmon resonance wavelength can be red-shifted up to several hundred nanometers in the visible or near infrared (NIR) region, which is extremely important to biosensing applications. This leads to a lager red-shift in the localized surface plasmon resonance absorption compared to the original gold nanorod-based sensor and hence offers greatly enhanced sensitivity in the detection of schistosomiasis japonica.(3) A rapid, simple, and sensitive immunoassay based on localized surface plasmon resonance (LSPR) of gold nanorods has been developed to identify Schistosoma japonicum and tuberculosis. 43 human serum samples infected by Schistosoma japonicum and 39 healthy ones are analyzed and compared using the optimized sensing technique. Similarly, 52 human serum samples infected by tuberculosis patients'serum have been analyzed. Almost the infected human serum samples show positive response.(4) The fluorescence resonance energy transfer between the core-shell gold nanorods and Rhodamine B. The spherical gold nanoparticals have been obtained from gold nannorods by heating, and the influnce of spherical gold nanoparticals to the fluorescence of Rhodamine B have been investigated.Then a core-shell structre nanoparticals have acquired by being dealed with Na2S2O3 solution.With a Lambda 35 spectrophotometer and Fluorescence spectrometer,we can observed that the fluorescence of Rhodamine B enhanced with the enlarge of surface plasmon resonance band exactly the increase of the thickness of shell. |
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