Development Of Novel Gold Nanorods-based Non-aggregation Colorimetric Sensor And Applications In Biological Analysis

Anisotropic gold nanorods （AuNRs） possess longitudinal surface plasmon resonance（LSPR） and transverse surface plasmon resonance （TSPR） absorption bands in visible lightregion. In this dissertation, AuNRs were synthesized by silver ion-assisted seed-mediatedmethod. The colorimetric sensors have been developed based on the strong correlationbetween the LSPR absorption band of AuNRs and their aspect ratio （length/diameter）, andapplication study and mechanism analysis were carried out.In AuNRs solution, Vitamin C （Vc） and dopamine （DA） could reduce Hg²⁺and Ag+to Hg⁰and Ag⁰, respectively. And then Hg⁰would selectively deposit on the tips of AuNRs to formgold amalgamation, while Ag⁰deposit on the surface of AuNRs to form Au core-Ag shellnanorods （Au@Ag NRs）. As a result, the aspect ratio of AuNRs decreased, LSPR absorptionband blue shifted with the color of the solution changing obviously. Thus, thenon-aggregation colorimetric sensors for the determination of Vc and DA were developed.The proposed sensors have been applied to the detection of Vc and DA in real samples andthe results agreed well with those of aggregation colorimetric sensor and fluorscence method.Besides, the structures of AuNRs, gold amalgamation and Au@Ag NRs were characterizedby transmission electron microscope （TEM）, and the sensing mechanism of Vc and DA hasbeen discussed.Fe³⁺could catalyze the reaction of H2O2selectively oxidizing the tips of AuNRs, causingthe aspect ratio of AuNRs to decrease, the LSPR absorption band of AuNRs to blue shift （λ）and the color of the solution to change. Thus, a signal amplification non-aggregationcolorimetric sensor has been developed for online analysis of Fe³⁺in water samples, and theresults were consistent with those of inductively coupled plasma-mass spectroscopy（ICP-MS）. Meanwhile, the sensing mechanism of Fe³⁺catalysis in H2O2oxidizing AuNRs hasbeen discussed.