Preparation and chromatographic performance of chiral peptide-based stationary phases for enantiomeric separation.

This study presents the development of three new chiral stationary phases. They are based on silica modified with peptides containing phenylalanine and proline. Successful analyses and characterizations were conducted using Fourier transform infrared spectra, elemental analysis, and thermogravimetric analysis. After this, the enantioselective performance of the three chiral peptide-based columns was evaluated. The evaluation used 11 racemic compounds under normal-phase high performance liquid chromatography mode. Optimized enantiomeric separation conditions were established. Under these conditions, the enantiomers of flurbiprofen and naproxen were successfully separated on CSP-1 column: the separation factor of these was 1.27 and 1.21, respectively. In addition, the reproducibility of the CSP-1 column was also investigated. The results of the investigation illustrated that the stationary phases have good reproducibility (RSD = 0.73%, n = 5).

Label-Free Small Extracellular Vesicles Capturing Strategy for Lung Cancer Diagnosis and Typing Based on a Natural Polyphenol-Metal Three-Dimensional Network.

Small extracellular vesicles (sEVs) have been increasingly recognized as circulating biomarkers and prognosticators for disease diagnosis. However, the clinical applications of sEVs are seriously limited by the lack of a robust and easy scale-up isolation technique. Herein, the feasibility of a polyphenol-metal three-dimensional (3D) network for label-free sEV isolation was explored. As a proof-of-concept, with tannic acid (TA) as the polyphenolic ligand and Fe(III) as the coordinated metal, the TA-Fe(III) 3D network coating mesoporous silica beads (SiO2@BSA@Fe-TA6) was designed and fabricated via a coordination-driven layer-by-layer self-assembly approach. The successful fabrication of SiO2@BSA@Fe-TA6 was validated by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. With the low-cost TA (as low as US$ 0.18/g) as the probe, SiO2@BSA@Fe-TA6 achieved universal capture toward sEVs in different cells and plasma samples. The capture efficiency reached 85.4 ± 1.5%, which is comparable to the antibody-based capture techniques and significantly higher than the ultracentrifugation (UC) method. The purity of sEVs isolated by SiO2@BSA@Fe-TA6 from the H1299 cell culture supernatant was measured as (1.07 ± 0.14) × 1011 particles/µg, which is 3.1 times higher than that via the UC method. Another important superiority of SiO2@BSA@Fe-TA6 is the facile self-assembly approach, which can harvest a yield of up to grams, allowing simultaneous processing of more than 500 plasma samples. The SiO2@BSA@Fe-TA6-based strategy was further successfully employed to distinguish nonsmall cell lung cancer (NSCLC) and small cell lung cancer (SCLC) with an accuracy of 87.1%. The developed SiO2@BSA@Fe-TA6 is a label-free, universal, low cost, and easy scale-up technique for sEV-based liquid biopsy in lung cancer diagnosis and typing.

Polymerized phosphonium ionic liquid functionalized silica microspheres as mixed-mode stationary phase for liquid chromatographic separation of phospholipids.

There is a large and growing demand for the vigorous development of new high performance liquid chromatography stationary phases in order to solve complex phospholipids separation. Herein, phosphonium-based ionic liquid trioctyl(allyl)phosphonium bromide ([P888Allyl]Br) was first synthesized with trioctylphosphine and allyl bromide. With [P888Allyl]Br as the polymerizable monomer, polymerized phosphonium ionic liquid functionalized silica microsphere (PIL@SiO2) was further synthetized via click chemistry reaction. Significantly, based on the inherent amphiphilic nature of the introduced [P888Allyl]Br, the packed PIL@SiO2 column displayed hydrophilic/hydrophobic mixed-mode retention mechanisms. The PIL@SiO2 column can achieve separation of nucleic acid bases and nucleosides, sulfonamides, amides and anilines with excellent selectivity in a shorter separation time. The column efficiency reached 109,700 N/m for 2-iodoacetamide. One of the important characteristics of the PIL@SiO2 column is that both phospholipid classes and species can be efficiently separated via the same column, outperforming that of the commercial amino column. Furthermore, the application potential of the PIL@SiO2 column was further verified via separation of phospholipids extracted from soy lecithin. The proposed PIL@SiO2 column provides a promising candidate for separation of complex phospholipid samples.

Superhydrophobic conjugated microporous polymers grafted silica microspheres for liquid chromatographic separation.

Vigorously developing new high performance liquid chromatography (HPLC) stationary phases to meet the versatile separation requirements is still an important issue in the field of analytical chemistry. Conjugated microporous polymers (CMPs) are a new type of three-dimensional network porous material with high specific surface area, good chemical stability and superhydrophobicity. Herein, we firstly report the synthesis and applications of CMPs@SiO2 material for HPLC stationary phase. The CMPs@SiO2 material can be in situ fabricated via Sonogashira coupling of 1,3,5-triethynylbenzene and 1,4-diiodobenzene on the surface of spherical silica. The morphology and physicochemical properties of the synthesized stationary phase material were investigated by a series of characterization methods. Due to the superhydrophobic nature of the CMPs@SiO2 material, the packed CMPs@SiO2 HPLC column displays ultrastrong chromatographic retention and can be used for separation of both hydrophobic and hydrophilic compounds with good selectivity. Significantly, CMPs@SiO2 column can be performed for separation with pure acetonitrile as the eluent. Thus, the new column was successfully exploited for monitor and analysis of the hydrolysis of silane coupling agents. Furthermore, based on its oleophilicity, this report firstly utilized the CMPs@SiO2 material to identify and analyze the quality of cooking oils through one-step enrichment and subsequent HPLC separation. We will further exploit to fabricate versatile CMPs-based stationary phases, highlighting their potential applications in different separation scopes.

Precipitates in Nb and Nb-V microalloyed X80 pipeline steel.

Precipitates in two X80 pipeline steels were studied by transmission electron microscopy equipped with an energy filtering system. The steels are microalloyed with niobium and niobium-vanadium (Nb-V), respectively, and produced by continuous hot rolling. Besides the precipitates TiN and (Ti, Nb) (C, N), which were 10-100 nm in size, a large number of precipitates smaller than 10 nm distributed in the two steels have been observed. In the Nb-V microalloyed steel, only a few titanium nitrides covered by vanadium compounds on the surface have been observed. It is inferred that the vanadium exists mainly in the matrix as a solid solution element. The fact has been accepted that there was no contribution to the precipitation strengthening of the X80 steel by adding 0.04-0.06% vanadium under the present production process. By contrast, the toughness of the Nb-V steel is deteriorated. Therefore, a better toughness property of the Nb microalloyed X80 results from the optimum microalloying composition design and the suitable accelerating cooling after hot rolling.

Features of the ISO-25498: method of selected area electron diffraction analysis in transmission electron microscopy.

International standard ISO-25498 specifies the method of selected area electron diffraction (SAED) analysis in TEM. It is applicable to the acquisition of SAED patterns, indexing the patterns and calibration of diffraction constant. Several features of this standard are introduced. As an example of the applications, phosphide with nanometer scale in a low-carbon steel produced by compact strip production process was analyzed by SAED and EDX. The phosphide precipitates in the steel are identified as M x P, where x is 2-3 and M is Fe, Ti, Cr, or Ni. It possesses a hexagonal lattice with lattice parameter a = 0.609 nm and c = 0.351 nm.