Study On Preparation Of One-dimensional Monodisperse Gold Nanorod And Its Application In Sensor

The one-dimensional gold nanoparticles refers to a gold material with two dimensions inthe nanoscale. Gold nanorods and gold nanowires are the most representativeone-dimensional gold nanomaterials. Especially the special morphology and structure of goldnanorods make them have anisotropic, localized surface plasmon resonance wavelengthtunable, and surface electromagnetic field enhancement effect. Gold nanorods with light,electricity, heat and other unique properties which are different from the conventionalmaterials, have gradually become the focus of the scientific field. However, the traditionalpreparation methods of gold nanorods have many problems. For example, the preparedproducts cannot meet the application requirements of special field of biological analysis.Preparation size adjustable, monodisperse and low toxicity of gold nanorod are crucial to itswide application. We use anionic surfactants as additives to prepare good monodisperse goldnanorods by seed growth. And the gold nanorods successfully apply to construct optical andelectrochemical sensors.Sodium dodecyl sulfonate (SDS) and sodium dodecyl benzene sulfonate (SDBS) wereemployed as additives for synthesis of gold nanorods. When CTAB was reduced to0.05mol·L-1, only in the SDBS reaction system, monodisperse gold nanorods can still besynthesized. On the one hand, the hydrophilic head groups of CTAB are separated from eachother by rigid benzene structure of the SDBS, which reduces mutual exclusion of hydrophilichead groups of the CTAB and improves surface activity of the reaction system. Meanwhile,biological toxicity of CTAB in the product is also reduced. On the other hand, the interactionof long alkyl chain of the SDBS with hydrophobic alkyl chains of the CTAB as well as strongaffinity between the sulfonic acid group with hydrophilic head groups of the CTAB willenhance stability of the CTAB micelles. Thus, as-prepared gold nanorods provided singleshape, narrow particle size distribution and stable optical property. Moreover, the use of sucha low CTAB concentration greatly decreases the inhibition of bromine ion on the surfacegrowth of gold crystal, thus the growth of gold nanorods can complete within30minutes. Inaddition, the experiment shows that the size of gold nanorods is easily regulated andcontrolled by changing the concentration of silver nitrate in the growth solution.Based on the plasmon resonance light scattering effect of the gold nanorods, weestablished methods of determining the allergen Ara h1in peanut food by preparing goldnanorods and annular peanut allergens DNA self-assembly biosensor. The experimentalresults show that hybridization reaction of peanut allergen DNA can reduce surface charge ofgold nanorods and the repulsive force between gold nanorods, which leads to aggregation ofthe gold nanorods and results in a linear increase of the RLS intensity. With the increase of peanut allergen-Ara h1concentration, the RLS intensity of gold nanorods increases linearlyin the range from0.0002to50nmol·L-1The detection limit of the proposed method was0.06pmol·L-1(S/N=3). This method with the advantages of simple operation, and high sensitivityhas been successfully used for the determination of trace amounts of peanut allergens in thepeanut milk.Gold nanorods and graphite oxide were mixed to form gold nanorods/graphenecomposite materials by electrostatic attraction. A certain amount of the composite dispersionwas dropped onto the surface of a glassy carbon electrode. Then, it was subjected in situreduction to obtain gold nanorods/graphene modified electrode. The composite materials onthe electrode surface were characterized by SEM, IR and Raman spectroscopy.Electrochemical characterization of the sensor were investigated by cyclic voltammetry andelectrochemical impedance spectroscopy, respectively. The research shows that thecombination of gold nanorods and graphene not only reduces the electrode surface transferresistance and enhance the electron transfer rate but also improves the electrochemicalresponse of the sensor signal. We simultaneously detect catechol (CA) and hydroquinone (HQ)in wastewater. When the concentrations of CA and HQ are in the ranges of4×10-7to1×10-4mol·L-1, differential the oxidation peak current of the sensor linearly increases. The methodhas the advantages of simple operation, high stability and reliability, and lays the foundationfor the practical application of gold nanorods/graphene composite materials.