Shengqiang Zhou,Tianliang Lu,Lipeng Zhou,Xiaomei Yang
Glycerol, as the main byproduct in biodiesel production, is attractive for the synthesis of value-added chemicals with the rapid increase of the biodiesel market in recent years. In this study, we developed a bifunctional Au/Sn-Beta catalyst via a molecule linkage strategy for the one-pot catalytic conversion of glycerol to methyl lactate (MLA) with molecular oxygen as the oxidant. Bifunctional Au/Sn-Beta was constructed using β-mercaptoethylamine as a linkage molecule to anchor negative Au species on the negative surface of Sn-Beta zeolites. β-Mercaptoethylamine with a well-defined structure of head and tail functional groups was anchored on Sn-Beta zeolite through the interaction of amine groups with the framework Sn sites and weakly acidic silanols. Gold species with negative charge were captured by thiol groups of β-mercaptoethylamine anchored on Sn-Beta. Upon calcination, highly dispersed Au nanoparticles (∼2 nm) were confined in the crystal of Sn-Beta zeolite, which was proved by Tomogram-section TEM images. Linkage molecules with different structures were employed. The role of the linkage molecule was revealed by XPS, FTIR, and Raman spectroscopy. It was observed that electrons were transferred from Au sites to Sn sites, which facilitated the dispersion and stabilization of Au sites. A yield of 79.3% to MLA with 100% of glycerol conversion was achieved over the prepared Au/Sn-Beta at 160 °C for 1.5 h, which was much higher than that over Au/Sn-Beta prepared by the wet impregnation method. The positive charge on Au sites decreased the catalytic oxidation ability of the catalyst. The catalyst showed good catalytic activity and stability in ten batch reaction runs.
Xuemei Li,Wenhua Ji,Rongyu Wang,Lidan Zhang,Ran Miao,Shenling Wang
Covalent organic framework molecularly imprinted polymers (CMIPs) was prepared using the thiol-ene click post-synthetic modification. The morphological, chemical characteristics and porosity were systematically characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and N 2 adsorption–desorption. Isothermal adsorption, kinetic adsorption, and selective adsorption were used to evaluate the binding property of CMIPs. After being prepared as a solid-phase microextraction (SPME) fiber coating, the CMIPs-SPME pretreatment process for the extraction of six aminoglycosides was established after optimizing parameters such as desorption solvent and time, extraction time, pH value of the sample, and ion concentration. Under the optimized conditions, the CMIPs-SPME was combined with UPLC-MS/MS for the determination of trace aminoglycosides in milk and honey samples. The limits of quantification (S/N = 10) in milk and honey samples were 0.007–0.07 μg kg −1 and 0.04–0.1 μg kg −1 , respectively. The relative recoveries at three different spiked levels (1, 10, and 100 μg kg −1 ) for milk and honey are in the ranges of 86.2 %–115.3 % (RSD ≤ 9.6 %) and 88.1 %–114.3 % (RSD ≤ 10.4 %), respectively. The results indicated that the CMIPs-SPME pretreatment method for the determination of aminoglycosides in real samples is accurate, sensitive, and reliable.
Yunyan Li,Tong Yan,Wenya Chang,Chongjiang Cao,Dawei Deng
Cancer metastasis is a major cause of high mortality in breast cancer. Despite the progress achieved in nanomaterial-based treatments, the cure rate remains unsatisfactory, owing to their poor biocompatibility and non-specific recognition. Inspired by the cell-mimetic strategy, in this work, we fabricated an intelligent cell-like nano-prodrug (Dox-MPK@MDL) for lung metastasis of breast cancer. Specifically, a DNA tetrahedron dendrimer was selected to act as a rigid internal cytoskeleton, and then sequentially coated with a liposome and macrophage membrane to form cell-like Dox-MPK@MDL via hierarchical self-assembly. Here, it should be noted that pH-sensitive Dox-MPK prodrugs were synthesized and inserted into the DNA-based cytoskeleton (the Dox group is an intercalator of double stranded DNA) in advance for the next anti-metastatic therapy. Our results show that Dox-MPK@MDL specifically targeted the sites of lung metastasis via the biomimetic metastasis-homing effects and intelligently triggered Dox release at the metastatic cancer cells, thereby leading to the significant inhibition of lung metastasis. All these features help to enhance the anti-metastatic therapy efficiency of Dox while maximally reducing side-effects.
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