One-pot synthesis of pillar[5]quinone-amine polymer coated silica as stationary phase for high-performance liquid chromatography.

To expand the application of pillararene in chromatographic separation, we designed and fabricated a pillar[5]quinone-amine polymer coated silica through quinone-amine reaction by facile one-pot synthesis method, which was applied as a stationary phase for high-performance liquid chromatography. Separation of hydrophobic compounds, hydrophilic compounds, halogenated aromatic compounds, and 11 aromatic positional isomers was achieved successfully in this stationary phase. Reverse-phase separation mode and hydrophilic-interaction separation mode were proved to exist, indicating the potential application of the mix-mode stationary phase. Studies of chromatographic retention behavior and molecular simulation showed that multiple interactions might play an important role in the separation process, including hydrophobic interaction, hydrogen-bonding interaction, aromatic π-π interaction, electron donor-acceptor interaction, and host-guest interaction. Column repeatability and stability were tested, which showed relative standard deviations of retention time less than 0.2% for continuous 11 injections, and the durability relative standard deviations of retention time were less than 0.91% after 90 days. This novel design strategy would broaden the application of pillararene-based covalent organic polymer in chromatography and separation science.

Rapid and quantitative detection of tear MMP-9 for dry eye patients using a novel silicon nanowire-based biosensor.

Dry eye disease (DED) is the most common chronic eye disease characterized by ocular surface inflammation that affects hundreds of millions of people worldwide. The diagnosis and monitoring of DED require fast and reliable tools in the clinical setting. Matrix metalloproteinase 9 (MMP-9) has been proven to be a reliable indicator of DED owing to its close relationship with inflammation. A novel biosensor based on silicon nanowire-based field-effect transistor (SiNW FET) devices was fabricated for the quantitative measurement of MMP-9 in human tears. A modified controllable process was applied to improve the uniformity of the SiNWs in size and stabilize their performance with optical calibration at low salt concentrations for clinical application. With this protocol, correlation analysis proved the high agreement between the biosensor and enzyme-linked immunosorbent assay (correlation coefficient of 0.92 for DED patients and 0.90 for healthy controls). A diagnostic sensitivity of 86.96% and specificity of 90% were achieved in human tear samples from DED patients and healthy subjects in real-world clinical settings. Furthermore, the tear MMP-9 concentrations monitored using the device correlated with the therapeutic response of the patients with DED. Our enhanced SiNW biosensor device demonstrated its potential as an alternative tool for real-time diagnosis and monitoring for prognostic prediction toward point-of-care testing for DED.

Simultaneous enrichment of bisphenols and polyfluoroalkyl substances by cyclodextrin-fluorinated covalent organic frameworks membrane in food packaging samples.

Efficient separation and preconcentration of trace harmful substances in food samples is a prerequisite for reliable analysis. Most of harmful substances with different properties coexist in the food samples, which is difficult to achieve simultaneously extraction through traditional adsorbents. In this work, a new adsorbent based on cyclodextrin- fluorinated covalent organic frameworks (CD-F-COF) was prepared. The mechanism of the CD-F-COF recognizing polyfluoroalkyl substances (PFASs) and bisphenols (BPs) were validated by molecular simulation. The CD-F-COF showed strong fluorophilic and host-guest interactions for polyfluoroalkyl substances (PFASs) and bisphenols (BPs), respectively. The CD-F-COF coated membranes were immobilized on the syringe filter and coupled with multi-channel syringe pump to achieve high-throughput sample pretreatment. After that, a sensitive analytical method for the simultaneous enrichment and determination of trace BPs and PFASs was established followed by HPLC-MS/MS. The results indicated that the limits of detection for the seven BPs and three PFASs were in the range of 0.006-0.050 ng/g and 0.001-0.008 ng/g. This method has great potential for application in sample preparation as it can fulfill fast and high-throughput for enrichment of trace multiple targets.

In situ fabrication of chiral covalent triazine frameworks membranes for enantiomer separation.

Rapid and high-flux enantiomer separation is significant for drug development. Membrane separation technology provides promising approaches for enantiomer separations. Porous membrane with good selectivity and high permeability is an ideal choice for enantiomer separations. Herein, we demonstrate the preparation of a novel two-dimensional chiral covalent triazine frameworks (CCTF) membrane by "in situ growth" method. Inheriting the strong chirality and specific interactions from CCTF, the CCTF membranes exhibited good enantioselectivity for drug intermediates and drug, including (R)/(S)-1-phenylethanol, (R)/(S)-1,1'-binaphthol and (R)/(S)-ibuprofen. Under optimal separation conditions, the enantiomeric excess value (e.e %) was above 21.7 % for (R)/(S)-1-phenylethanol, 12.0% for (R)/(S)-1,1'-binaphthol and 9.7 % for (R)/(S)-ibuprofen. The mechanism of the CCTF recognizing enantiomers were simulated by quantum mechanical calculations. In addition, the mechanism was also proved by the separation of enantiomers using this CCTF-modified silica column in liquid chromatography. The CCTF membrane may bring about the potentially application for large-scale production of chiral compounds. Meanwhile, this work provides a theoretical guidance for the application of CCOFs in enantiomer separation.

A Theoretical and Simulation Analysis of the Sensitivity of SiNWs-FET Sensors.

Theoretical study and software simulation on the sensitivity of silicon nanowires (SiNWs) field effect transistor (FET) sensors in terms of surface-to-volume ratio, depletion ratio, surface state and lattice quality are carried out. Generally, SiNWs-FET sensors with triangular cross-sections are more sensitive than sensors with circular or square cross-sections. Two main reasons are discussed in this article. Firstly, SiNWs-FET sensors with triangular cross-sections have the largest surface-to-volume ratio and depletion ratio which significantly enhance the sensors' sensitivity. Secondly, the manufacturing processes of the electron beam lithography (EBL) and chemical vapor deposition (CVD) methods seriously affect the surface state and lattice quality, which eventually influence SiNWs-FET sensors' sensitivity. In contrast, wet etching and thermal oxidation (WETO) create fewer surface defects and higher quality lattices. Furthermore, the software simulation confirms that SiNWs-FET sensors with triangular cross-sections have better sensitivity than the other two types of SiNWs-FET sensors under the same conditions, consistent with the theoretical analysis. The article fully proved that SiNWs-FET sensors fabricated by the WETO method produced the best sensitivity and it will be widely used in the future.

Research progress on sample pretreatment methods for migrating substances from food contact materials.

Excessive absorption of migrating substances from food contact materials can affect human health. Thus, it is essential to analyze the migration of contaminant from food contact materials. However, comprehensive analysis has been challenged by low concentration of migrating substances, manifold and complex matrix interference of food contact materials. Therefore, appropriate sample pretreatment methods should be applied before instrumental detection, which is essential to improve the analytical efficiency, sensitivity, and reliability. This paper systematically reviews the development of sample pretreatment methods for analysis of migrating substances from food contact materials in the past decade. To extract volatile and semi-volatile substances, headspace extraction, headspace solid phase microextraction, and purge and trap technique are discussed. For non-volatile substances, solid-liquid extraction and field-assisted extraction are usually used to extract them from food contact materials, while liquid-liquid extraction, solid phase extraction, and their corresponding microextraction techniques play important roles on enrichment process. In addition, new progress in developments of sample pretreatment methods of food contact materials is summarized, covering new devices, specific adsorbents, and sample preparation methods for rapid detection. An outlook of future prospect of sample pretreatment, especially for non-targeted analysis of non-intentionally added substances is briefly discussed.

ß-Cyclodextrin porous polymers with three-dimensional chiral channels for separation of polar racemates.

The recognition and separation of polar chiral compounds are important technological challenges in separation science. Taking full advantage of the intrinsically chiral environment and multiple interactions featured by macrocycles, we designed the first example of porous methylated cyclodextrins-containing polymers (MP-CDPs) with three-dimensional (3D) chiral channels. The enantioselective recognition of (R)/(S)-1-phenylethylamine mixtures was realized with enantiomer excess (e.e.) >73% in only 3 min by using MP-CDPs as the adsorbent. The obtained MP-CDPs also serve as highly efficient liquid chromatographic stationary phases for separation of polar chiral compounds. The stationary phase can separate racemic alcohols and acids successfully. These chiral compounds can be separated within 8 min under normal-phase mode, and the resolution (RS) range from 1.76 to 3.00. Molecular simulations suggest that chiral recognition is a cooperative interaction based on multiple effects such as host-guest interaction, H-bond and size selection. These findings will provide novel chiral stationary phases for recognition and separation of polar chiral compounds in the fields of separation science and pharmaceutical industry.

Aptamer-gold nanoparticle doped covalent organic framework followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for selective enrichment and detection of human insulin.

In this work, we introduced an aptamer modified Au nanoparticles doped covalent organic frameworks composite (IBAs-AuNPs/COF) to improve the property of selective enrichment of insulin from serum samples. The Au nanoparticles were immobilized on imine-based COF by in-situ reduction reaction via mussel inspired polydopamine coating, and then sulfhydryl-containing aptamers were bonded to the surface of AuNPs through an Au-S linkage. Due to the excellent adsorption property of COF and specific recognition between insulin and IBAs, the IBAs-AuNPs/COF composites show selective and satisfactory extraction property to insulin in serum samples. Excellent specifity was obtained for insulin in the presence of 50-fold interfering substances including human immunoglobulin, lysozyme and biotin. The concentrations of insulin in the range of 1.0 to 50.0 µg L-1 show good linear relationship (R2 = 0.9917) with limit of detection and limit of quantitation of 0.28 µg L-1 and 0.93 µg L-1, respectively. Then, the IBAs-AuNPs/COF composites were applied to enrich insulin in serum samples followed by analysis with matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). After the recovery experiment, the developed method shows good recoveries in range of 91.6%-112.4% with low RSD value (2.4%-9.4%, n = 3) for diabetic and healthy serum samples. The developed IBAs-AuNPs/COF composites propose a new perspective for selective and efficient enrichment of biomarkers in serum samples by functionalized COF.

Effects of mutual grafting on the cadmium accumulation characteristics of two ecotypes of Solanum photeinocarpum.

The effects of mutual grafting on the cadmium (Cd) accumulation characteristics of two ecotypes (farmland and mining) of the potential Cd-hyperaccumulator Solanum photeinocarpum were studied through a pot experiment for one month. Four treatments were used in the experiment: ungrafted farmland ecotype (F-CK), ungrafted mining ecotype (M-CK), the farmland ecotype as the scion grafted onto rootstocks of the mining ecotype (F-Scion), and the mining ecotype as the scion grafted onto rootstocks of the farmland ecotype (M-Scion). Mutual grafting increased the rootstock biomass of both S. photeinocarpum ecotypes. However, mutual grafting decreased the scion biomass of F-Scion compared with F-CK and M-CK, and the scion biomass of M-Scion was higher than that of M-CK and lower than that of F-CK. The Cd content in the rootstock of M-Scion increased compared with F-CK, and the Cd content in the rootstock of F-Scion increased compared with M-CK, but mutual grafting decreased the Cd content in scions of both S. photeinocarpum ecotypes. Mutual grafting increased Cd extraction by rootstocks of both S. photeinocarpum ecotypes, but decreased extraction by scions. Therefore, mutual grafting can increase Cd accumulation in S. photeinocarpum rootstocks but not increase Cd accumulation in S. photeinocarpum scions in a short period.