A key frontier in nanomaterial fabrication is the integration of different materials within the same structure as a means to increase functionality. Herein, a facile solution route for the synthesis of nanocomposites consisting of PbSe and gold is reported. It has been found that the molar ratio of PbSe/Au has great influence on the morphologies of the PbSe–Au nanocomposites. The evolution from nanocomposites with multiple Au deposition on the particle surface to those with a single Au domain, and further to pineapple-like morphologies has been illustrated by increasing the molar ratio of Au/PbSe during the synthesis. Surprisingly, the experimental observations show that the growth of Au on the surface of PbSe has an upper limit size. Upon the achievement of this size, addition of more Au precursors only results in the deposition of Au on extra sites over the surface of PbSe instead of continuous growth of the Au domain, termed ‘pineapple-like’ nanocomposites. This thereby extends an opportunity for the fabrication and control of nanostructures, in particular for nanocrystals composed of different materials.
Yuyun Sui,Aigui Xu,Xiaorui Jin,Jiao Zheng,Xin He,Yan Cheng,Qingji Xie,Rushi Liu
Procalcitonin (PCT) is an important indicator for bacterial inflammatory diseases, and its sensitive, accurate and rapid detection has important clinical value. On the basis of sandwich immunoassay , glucose oxidase-catalyzed gold deposition and in-situ microliter-droplet anodic stripping voltammetry (ASV) of the enzyme-generated gold directly on the immunoelectrode, the ultrasensitive electrochemical detection of PCT is achieved. A new method of the chemical dissolution of gold by an appropriately diluted aqua regia and the simultaneous cathodic preconcentration of gold on the immunoelectrode is suggested, which gives the better performance for the ASV analysis of gold than the reported one. Under optimized conditions, the ASV peak current is linear with the common logarithm of PCT concentration from 0.05 fg mL −1 to 500 ng mL −1 , with a limit of detection (LOD, S / N = 3) as low as 0.04 fg mL −1 . Our method has also been used for detection of PCT in serum samples with satisfactory results.
Gold deposition on Au nanoparticles is a common method to control the shape and further modify the properties of nanoparticles as their properties have a strong correlation with their nanostructures. For Au nanobipyramid (Au NBP), it has advantages such as the enhancement of electric field and a higher tunability in plasmon wavelength than the Au nanorod and thus owns a greater potential in shape control. In this paper, we demonstrate a scheme of depositing Au on the surface of Au NBP with the presence of a type of ligand 2-mercaptobenzoimidazole-5-carboxylic acid (MBIA) to synthesize Au NBP@Au dimers. The growth mode of Au depositing on Au NBP can be controlled by the coverage of MBIA. As the coverage is low, with a concentration of MBIA below 0.4 mM, the rough core–shell nanostructure is synthesized; However, as the coverage is high, with a concentration of MBIA over 0.8 mM, gold deposition may form islands on the surface of Au NBP. The SERS performance of Au depositing on Au NBP can also be enhanced by growth mode. For the rough-surface core–shell growth mode, the enhancement is more significant as the EF is improved from 3.5 × 10 5 to 1.06 × 10 6 than the islands-growing growth mode due to the coupling between core and shell. And our results show that with multiple types of nanosturctures easy to obtained by changing modified ligand coverage, the controlled growth has a great potential in the dimer design and SERS enhancement using Au NBP.
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