Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another "bad" ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.
After analyzing protein surface structure, the opposite side of the activity site of esterase BioH was observed to be hydrophilic. Hence subsequently, a hydrophilic-modified solid support was selected to immobilize enzyme through oriented adsorption. The immobilized enzyme remained 86% of its original activity under the acylation of 1-phenylethanol, much more than those immobilized on other solid supports with low hydrophilicity (20–35.6%), as the mode of the immobilization could facilitate enzyme to expose its active site to the substrate. This demonstrated that the strategy to select solid support based on the analysis of protein surface structure was successful. It was also noticed that the substrate of the reaction was obviously adsorbed onto the support, therefore the adsorption effect could not be ignored and it was necessary to obtain the adsorption isotherm of the substrate for a more authentic result. The parameter K m shifted from 884.56 to 296.09 mM after immobilization. This was possibly mainly caused by the increment of substrate concentration around the enzyme due to the substrate adsorbing on the support. It could be another explanation for why those parameters were changed after enzyme immobilization in addition to some existing proposed reasons such as stabilizing conformation, facilitating dispersion of enzyme, etc.
危险品化学品经营许可证（带存储）