Organic polymer‐based monolithic capillary columns and their applications in food analysis

In recent years, the use of organic polymer monolithic capillary columns in separation science has gained popularity due to the fact that they are easy to fabricate and do not require retaining frits. These materials have been applied in different fields including foods, proteomics, and pharmaceuticals. The interest in food analysis still needs to develop in order to increase the sensitivity towards micro/nano‐scale food applications for food samples of < 5 μg (e.g., foodomics). In this regard, polymer monolithic capillary columns offer great separation capability in the food analytical separation science. We review the most important applications in food analysis using polymer monolithic capillary columns. In addition, several examples of the use of capillary separation methods combined with mass spectrometry detection in food analysis are summarized.     

Nano‐MoO3 for highly selective enrichment of polycyclic aromatic hydrocarbons in in‐tube solid‐phase microextraction

Nano‐molybdenum trioxide was prepared from nano‐molybdenum disulfide by simple firing in muffle furnace. Nano‐molybdenum trioxide was used as the extraction coating on the stainless steel wire. Four wires were filled in a polyetheretherketone tube to get an extraction tube. The tube was connected to the six‐port valve of a high performance liquid chromatograph, and the online analysis system was constructed. Extraction selectivity of the tube for different types of compounds, including polycyclic aromatic hydrocarbons, plasticizers, estrogens, anilines and neonicotinoids, was studied. Good enrichment ability for polycyclic aromatic hydrocarbons, but the extraction efficiency of others was not satisfactory. Using eight polycyclic aromatic hydrocarbons as the targets, an analytical method was established after optimizing main factors such as sampling volume, sampling rate, methanol content, and desorption time. The established method exhibited wide linear range to 0.016–20.00 μg/L and low limits of detection to 0.005 μg/L, and the enrichment factors can be up to 2443. The method was applied to the detection of trace polycyclic aromatic hydrocarbons in tap water and river water, and a good recovery was obtained. The tube showed good durability and chemical stability, and it still remained good extraction effect after more than 140 run.     

四针状纳米氧化锌电磁波吸收特性

将四针状纳米ZnO作为吸收剂、环氧树脂为粘结剂制备成吸波涂层,分析了吸波涂层中的四针状纳米氧化锌含量及涂层厚度对吸波性能的影响,当涂层厚度为15mm时,吸收主要集中在15—18GHz波段;当涂层厚度增加到35mm后,样品的吸波性能提高明显,特别在6—11GHz之间的吸波性能提高显著,样品反射率小于-5dB的频率宽度达到136GHz(44—18GHz),其吸波性能相比较微米级ZnO有显著提高. 最后对四针状纳米氧化锌的吸波机理进行了讨论. 所研究的涂层在电磁波屏蔽方面具有较大的应用价值. 关键词： 四针状纳米ZnO 吸波性能 反射率 吸波机理     

Self‐assembled polyurea macromer nanodispersion and resulting hybrid polyurea‐acrylic emulsions and films

A polyurea macromer (PUM) was synthesized and dispersed in basic conditions to form self‐assembled nanoparticles (<20 nm dispersions, up to 30 wt % aq. soln.). These nanoparticles enabled surfactant‐free emulsion polymerization to form hybrid polyurea‐acrylic particles despite the absence of a measureable water‐soluble fraction. The T_g of the starting PUM material was a strong function of the PUM's extent of neutralization and hydration (varying between 100 °C and >175 °C) due to changes in hydrogen and ionic bonding. Two separate hybrid polyurea‐acrylic emulsion systems were prepared: one by direct polymerization of (meth)acrylic monomers in the presence of the nanodispersion and a second by a physical blend of PUM nanodispersion with an acrylic latex control. The direct polymerization method resulted in a hybrid emulsion particle size that developed by a mechanism resembling conventional emulsion polymerization and was unlike that described for seeded polyurethane dispersion systems. Film hardness was shown to increase with increasing coating thickness for the hybrid film prepared by direct polymerization. The resulting mechanical properties could be explained by applying mechanical models for a composite foam structure. These results were unprecedented for normal elastomer films. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1373–1388     

Synthesis of boronic acid‐functionalized poly(glycerol‐oligoγ‐butyrolactone): Nano‐networks for efficient electrochemical sensing of biosystems

Despite the outstanding properties of hyperbranched polyglycerols such as biocompatibility and multifunctionality, enough attention has not been paid to the synthesis of their functional copolymers. This problem has limited the structural diversity of hyperbranched polyglycerols and hampers further developments and their practical usage. In this work, butyrolactone segments were incorporated into the backbone of polyglycerols by one‐pot ring‐opening copolymerization of a mixture of glycidol and γ‐butyrolactone in the presence of tin(II) 2‐ethylhexanoate. Poly(glycerol‐oligoγ‐butyrolactone)s were then crosslinked by 2,5‐thiophenediylbisboronic acid to obtain polymeric nanonetworks with 140 nm average size. Afterwards, the gold electrode was modified by the polymeric nano‐networks, and it was used for the determination of glucose, glycated hemoglobin, and Escherichia coli in phosphate buffer solution (pH = 9.0) through cyclic voltammetry and impedance spectroscopic. Taking advantage of the straightforward synthesis, cheap precursors and multifunctionality of poly(glycerol‐oligoγ‐butyrolactone)s, they could be used for real‐time sensing of a wide range of biosystems. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1430–1439     

Nanocrystalline TiO2, via green combustion synthesis,as an efficient and reusable catalyst for the preparation of 1,8‐dioxooctahydroxanthenes and 1,8‐dioxodecahydroacridines

Nanocrystalline TiO₂ is synthesized using a green combustion method and used as a recyclable catalyst for the one‐pot multicomponent synthesis of 1,8‐dioxodecahydroacridines and 1,8‐dioxooctahydroxanthenes, under solvent‐free conditions. This method is mild, environmentally friendly, inexpensive and highly effective for obtaining good to excellent yields of the products. Copyright © 2015 John Wiley & Sons, Ltd.     

Artificial nano‐pin as a temporal molecular glue for the targeting of acidic tumor cells

Highly precise control of molecular structure for developing efficient anticancer drug delivery is challenging. Our method reported herein can satisfy the need for building novel hybrid molecule; this molecule serves as a built‐in transformer that changes its molecular configuration from a pin‐shaped arrangement to a dog bone‐shaped arrangement. This approach led to a significant increase in the efficiency of tumor inhibition. Copyright © 2014 John Wiley & Sons, Ltd.     

A Universal Nano‐capillary Based Method of Catalyst Immobilization for Liquid‐Cell Transmission Electron Microscopy

A universal nano‐capillary based method for sample deposition on the silicon nitride membrane of liquid‐cell transmission electron microscopy (LCTEM) chips is demonstrated. It is applicable to all substances which can be dispersed in a solvent and are suitable for drop casting, including catalysts, biological samples, and polymers. Most importantly, this method overcomes limitations concerning sample immobilization due to the fragility of the ultra‐thin silicon nitride membrane required for electron transmission. Thus, a straightforward way is presented to widen the research area of LCTEM to encompass any sample which can be externally deposited beforehand. Using this method, Ni_xB nanoparticles are deposited on the μm‐scale working electrode of the LCTEM chip and in situ observation of single catalyst particles during ethanol oxidation is for the first time successfully monitored by means of TEM movies.     

Synthesis,Hirshfeld surface analysis,luminescence and thermal properties of three first-row transition metal complexes containing 4′-hydroxy-2,2′:6′,2″-terpyridine: Application for preparation of nano metal oxides

A series of new mono- and bis-terpyridine complexes [Mn(tpyOH)Cl₂] ( 1 ), [Ni(tpyOH)₂](PF₆)₂ ( 2 ) and [Zn(tpyO)(η¹-OCOCH₃)(H₂O)]⋅3H₂O ( 4 ) containing 4′-hydroxy-2,2′:6′,2″-terpyridine (tpyOH) were synthesized and structurally characterized using elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction. The reaction of MnCl₂ with tpyOH in a mixture of methanol and CH₂Cl₂ resulted in the formation of 1 . The X-ray crystal structure of 1 reveals that Mn(II) is penta-coordinated by three nitrogen atoms from tpyOH and two Cl⁻ in a slightly distorted trigonal bipyramidal geometry. Complex 2 was also prepared by the reaction of nickel(II) chloride with tpyOH in a methanolic medium in the presence of NH₄PF₆. Notably, the complex [Ni(tpyOH)(tpyO)]PF₆ ( 3 ), obtained during the crystallization of 2 from dichloromethane, was characterized using X-ray crystallography which shows that six nitrogen atoms from terpyridine ligands occupy the coordination sites around the Ni(II) centre in a distorted octahedral geometry with four longer bonds and two shorter Ni N bonds. The reaction of zinc(II) acetate with tpyOH in a mixture of methanol and CH₂Cl₂ led to the formation of 4 . The crystal structure of 4 reveals the formation of penta-coordinated Zn(II) complex containing three nitrogen atoms from tpyO, a monodentate acetate ligand and one coordinated water molecule. Hirshfeld surface analyses and two-dimensional fingerprint plots show that the main interactions are O…H/H…O contacts in 1 , 3 and 4 . The thermal decomposition reactions of 1 , 2 and 4 were studied using thermogravimetric analysis in detail due to their different structures. The solution luminescence features of 1 , 2 and 4 include high-energy intense π → π* intraligand and low-energy metal-to-ligand charge transfer transitions at room temperature. The calcination of the coordination complexes led to the formation of corresponding nano metal oxides. The products were structurally characterized using infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The average particle size using Scherrer's equation was calculated to be below 50 nm.