Junjie Ou

•Thiol-maleimide click reaction was firstly adopted to prepare capillary monoliths.•Ultra-high column efficiency (180,500 N/m) was acquired on poly(BMI-co-3SH).•The tryptic digests of BSA and HeLa were positively identified in cLC–MS.One-step thiol-maleimide polymerization reaction was firstly adopted for direct preparation of polymeric monoliths via alkaline-catalyzed reaction of 4,4′-bis(maleimidophenyl)methane (BMI) and trimethylolpropane tris(3-mercaptopropionate) (3SH)/pentaerythriol tetra(3-mercaptopropionate) (4SH) in the presence of a small amount of triethylamine (TEA). The polymerization could be performed within 3 h, which was faster than thermal-initiated free radical polymerization. Two kinds of monoliths, poly(BMI-co-3SH) (marked as I) and poly(BMI-co-4SH) (marked as II), were characterized with scanning electron microscopy (SEM), attenuated total reflection Fourier-transformed infrared spectroscopy (ATR-FTIR), thermal gravimetric analysis (TGA) and mercury intrusion porosimetry (MIP). Satisfactory chromatographic separation ability and column efficiency were gained for analysis of small molecular compounds such as alkylbenzenes, polynuclear aromatic hydrocarbons (EPA 610) and phenols in reversed-phase capillary liquid chromatography (cLC). High column efficiency (180,500 N/m) for butylbenzene was acquired on poly(BMI-co-3SH) column I-2, which was higher than those on most reported polymeric monoliths. A retention-independent efficient performance of small molecules was obtained by plotting of plate height (H) of alkylbenzenes versus the linear velocity (u). A term values in van Deemter equation of I-2 (1.72-0.24 μm) and poly(BMI-co-4SH) column II-2 (5.28-4.14 μm) were smaller than those of traditional organic/hybrid monoliths. Finally, as a practical application, 53 and 2184 unique peptides from the tryptic digests of bovine serum albumin (BSA) and HeLa cell proteins were positively identified with poly(BMI-co-3SH) monolith in cLC–MS.

Preparation and characterization of hydrophilic hybrid monoliths via thiol-ene click polymerization and their applications in chromatographic analysis and glycopeptides enrichment

Co-reporter:Jingyao Bai, Zhongshan Liu, Hongwei Wang, Xin You, Junjie Ou, Yehua Shen, Mingliang Ye

Journal of Chromatography A 2017 Volume 1498(Volume 1498) pp:

Publication Date(Web):19 May 2017

DOI:10.1016/j.chroma.2016.12.031

•A hydrophilic hybrid monolith was synthesized via thiol-ene click reaction.•The obtained columns exhibited good separation ability for neutral polar compounds.•The matrix was modified into hydrazide material for glycopeptides enrichment.A macroporous hydrophilic organic-silica hybrid monolithic column was synthesized via photoinitiated thiol-ene click polymerization reaction of 1-thioglycerol-modified polyhedral oligomeric vinylsilsesquioxane (vinylPOSS) and dithiothreitol (DTT) in a binary porogenic system consisting of tetrahydrofuran (THF) and dodecanol. 1-Thioglycerol was used to modify vinylPOSS in order to form a precursor with good solubility in the binary porogenic system. The influences of both the ratio of 1-thioglycerol/vinylPOSS and the porogenic solvents on the morphology and permeability of hybrid monoliths were studied in detail. The physical properties of hybrid monolith were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and nitrogen adsorption/desorption measurement. The chromatographic performance was evaluated by separation of neutral polar compounds in capillary liquid chromatography (cLC). The resulting column possessed homogeneous macroporous structure and showed hydrophilic interaction liquid chromatography (HILIC) separation mechanism with high efficiency of 65,000 N m−1 for formamide. Ultimately, the hybrid matrix was grafted with hydrazine groups and then exhibited the ability of glycopeptides enrichment.

Facile preparation of polysaccharide functionalized macroporous adsorption resin for highly selective enrichment of glycopeptides

Co-reporter:Xudong Sun, Jing Dong, Jinan Li, Mingliang Ye, Weibing Zhang, Junjie Ou

Journal of Chromatography A 2017 Volume 1498(Volume 1498) pp:

Publication Date(Web):19 May 2017

DOI:10.1016/j.chroma.2016.12.045

•Hydrophilic MAR was modified with polysaccharides through LbL self-assembly methods.•The preparation method is facile, low cost and easy to expand production.•The resulting hydrophilic MAR exhibited great specificity to low-abundance N-linked glycopeptide.A facile approach for preparation of hydrophilic polysaccharide-functionalized macroporous adsorption resin (MAR) was presented. Polydisperse MAR with approximately 250 μm in diameter was synthesized via suspension polymerization and then modified with polysaccharides, sodium hyaluronate (HA) and chitosan (CS), through layer-by-layer (LbL) self-assembly process. The preparation method was facile, low cost and easy to expand production from tens of grams to one kilogram. The resulting MAR@(HA/CS)20 possesses highly hydrophilic property and rapid adsorption behavior. The specificity and efficiency of MAR@(HA/CS)20 to glycopeptide was demonstrated by trapping N-linked glycopeptide from tryptic digests of human immunoglobulin G (IgG) and horseradish peroxidase (HRP) with a homemade solid-phase extraction (SPE) column. The detection sensitivity for glycopeptide determined by MALDI-TOF MS was as low as 5 fmol for standard tryptic digest of human IgG. The enrichment recoveries were higher than 73%. Furthermore, in the analysis of real biological sample, 745 unique N-glycosylation sites in 1353 unique glycopeptides mapped to 379 N-glycosylated proteins were identified in three replicate analyses of protein sample extracted from mouse liver, showing the great potential of MAR@(HA/CS)20 in the enrichment and identification of low-abundance N-linked glycopeptides in complicated biological samples.

Functionalization of hybrid monolithic columns via thiol-ene click reaction for proteomics analysis

Co-reporter:Zhongshan Liu, Jing Liu, Zheyi Liu, Hongwei Wang, Junjie Ou, Mingliang Ye, Hanfa Zou

Journal of Chromatography A 2017 Volume 1498(Volume 1498) pp:

Publication Date(Web):19 May 2017

DOI:10.1016/j.chroma.2017.01.029

•Vinyl-functionalized monolithic columns with 75 and 150 μm i.d. were prepared.•The monolithic columns were facilely modified via thiol-ene click reaction.•The effect of flow rate on cLC–MS/MS performance was investigated.•The SCX and RP monolithic columns were applied in two-dimensional separation.The vinyl-functionalized hybrid monolithic columns (75 and 150 μm i.d.) were prepared via sol-gel chemistry of tetramethoxysilane (TMOS) and vinyltrimethoxysilane (VTMS). The content of accessible vinyl groups was further improved after the monolithic column was post-treated with vinyldimethylethoxysilane (VDMES). The surface properties of monolithic columns were tailored via thiol-ene click reaction by using 1-octadecanethiol, sodium 3-mercapto-1-propanesulfonate and 2,2′-(ethylenedioxy)diethanethiol/vinylphosphonic acid, respectively. The preparing octadecyl-functionalized monolithic columns were adopted for proteomics analysis in cLC–MS/MS. A 37-cm-long × 75-μm-i.d. monolithic column could identify 3918 unique peptides and 1067 unique proteins in the tryptic digest of proteins from HeLa cells. When a 90-cm-long × 75-μm-i.d. monolithic column was used, the numbers of unique peptides and proteins were increased by 82% and 32%, respectively. Furthermore, strong cation exchange (SCX) monolithic columns (4 cm in length × 150 μm i.d.) were also prepared and coupled with the 37-cm-long × 75-μm-i.d. octadecyl-functionalized monolithic column for two-dimensional SCX-RPLC–MS/MS analysis, which could identify 17114 unique peptides and 3211 unique proteins.

Preparation of open tubular capillary columns by in situ ring-opening polymerization and their applications in cLC-MS/MS analysis of tryptic digest

Co-reporter:Hongwei Wang, Yating Yao, Ya Li, Shujuan Ma, Xiaojun Peng, Junjie Ou, Mingliang Ye

Analytica Chimica Acta 2017 Volume 979(Volume 979) pp:

Publication Date(Web):1 August 2017

DOI:10.1016/j.aca.2017.05.004

•It was the first time to prepare OT column by ring-opening polymerization.•The ratio of ethanol/H2O at 13/1 (v/v) was used in the synthesis of the OT phases.•The OT column was successfully applied in cLC-MS/MS analysis of tryptic digest.An open tubular (OT) column (25 μm i.d.) was prepared by in situ ring-opening polymerization of octaglycidyldimethylsilyl polyhedral oligomeric silsesquioxanes (POSS-epoxy) with 4-aminophenyl disulfide (APDS) in a binary porogenic system of ethanol/H2O. It was found that porogenic composition played an important role in the formation of OT stationary phases. The ratio of ethanol/H2O at 6/1 (v/v) would lead to the fabrication of hybrid monoliths, while the ratio of ethanol/H2O at 13/1 (v/v) would result in the synthesis of OT phases. In addition, the effects of precursor content and reaction duration on the thickness of OT stationary phases were investigated. Either lower precursor content or shorter reaction duration would produce thinner layer of OT column. The repeatability of OT columns was evaluated through relative standard deviation (RSD%) with benzene as the analyte. The run-to-run, column-to-column and batch-to-batch repeatabilities were 1.7%, 4.8% and 5.6%, respectively, exhibiting satisfactory repeatability of the OT column. Then tryptic digest of mouse liver proteins was used to evaluate the performance of the resulting OT columns (25 μm i.d. × 2.5 m in length) by cLC-MS/MS analysis, demonstrating their potential in proteome analysis.Download high-res image (147KB)Download full-size image

Tailor-Made Stable Zr(IV)-Based Metal–Organic Frameworks for Laser Desorption/Ionization Mass Spectrometry Analysis of Small Molecules and Simultaneous Enrichment of Phosphopeptides

Co-reporter:Lianfang Chen, Junjie Ou, Hongwei Wang, Zhongshan Liu, Mingliang Ye, and Hanfa Zou

ACS Applied Materials & Interfaces 2016 Volume 8(Issue 31) pp:20292

Publication Date(Web):July 18, 2016

DOI:10.1021/acsami.6b06225

Although thousands of metal–organic frameworks (MOFs) have been fabricated and widely applied in gas storage/separations, adsorption, catalysis, and so on, few kinds of MOFs have been used as adsorption materials while simultaneously serving as matrixes to analyze small molecules for laser desorption/ionization mass spectrometry (LDI-MS). Herein, a new concept is introduced to design and synthesize MOFs as both adsorption materials and matrixes according to the structure of ligands and common matrixes. The proof of concept design was demonstrated by selection of 2,5-pyridinedicarboxylic acid (PDC) and 2,5-dihydroxyterephthalic acid (DHT) as ligands for synthesis of MOFs. Two Zr(IV)-based MOFs of UiO-66-PDC and UiO-66-(OH)2 were synthesized and applied for the first time as new matrixes for analysis of small molecules by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Both of them showed low matrix interferences, high ionization efficiency, and good reproducibility when used as matrixes. A variety of small molecules, including saccharides, amino acids, nucleosides, peptides, alkaline drugs, and natural products, were analyzed. In addition, UiO-66-(OH)2 exhibited potential for application in the quantitative determination of glucose and pyridoxal 5′-phosphate. Furthermore, thanks to its intrinsically large surface area and highly ordered pores, UiO-66-(OH)2 also showed sensitive and specific enrichment of phosphopeptides prior to MS analysis. These results demonstrated that this strategy can be used to efficiently screen tailor-made MOFs as matrixes to analyze small molecules by MALDI-TOF-MS.Keywords: LDI-MS; metal−organic frameworks; small molecules; UiO-66-(OH)2; UiO-66-PDC

Synthesis and Characterization of Hydrazide-Linked and Amide-Linked Organic Polymers

Co-reporter:Zhongshan Liu, Junjie Ou, Hongwei Wang, Xin You, and Mingliang Ye

ACS Applied Materials & Interfaces 2016 Volume 8(Issue 46) pp:32060

Publication Date(Web):November 3, 2016

DOI:10.1021/acsami.6b11572

Four kinds of either hydrazide-linked or amide-linked polymers were facilely synthesized by using hydrazine, tetrakis(4-aminophenyl)methane (TAPM), terephthaloyl chloride (TPC), and trimesoyl chloride (TMC) as building blocks. The morphology, porosity, composition, and surface property of polymers were characterized by scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption measurement, 13C/CP-MAS NMR, X-ray photoelectron spectroscopy, etc. The results indicated that building blocks had important effects on morphology and porosity. Poly(TMC–TAPM) synthesized with TMC and TAPM showed the highest surface area of 241.9 m2 g–1. In addition, note that a hollow structure with ∼20 nm wall thickness was formed in poly(TMC–hydrazine) prepared with TMC and hydrazine. Further study indicated that both carboxyl groups (−COOH) and hydrazide groups (−CONH–NH2) existed on the surface of poly(TMC–hydrazine), besides the mainly hydrazide linkage (−CONH–NHOC−). Taking advantages of good hydrophilicity and special functional groups on the surface, we finally adopted poly(TMC–hydrazine) to enrich glycopeptides from tryptic digest via both hydrophilic interaction chromatography method with identification of 369 unique N-glycosylation sites and hydrazide chemistry method with identification of 88 unique N-glycosylation sites, respectively.Keywords: amide; enrichment of glycopeptide; hollow structure; hydrazide; porous organic polymer

Rapid “one-pot” preparation of polymeric monolith via photo-initiated thiol-acrylate polymerization for capillary liquid chromatography

Co-reporter:Jingyao Bai, Hongwei Wang, Junjie Ou, Zhongshan Liu, Yehua Shen, Hanfa Zou

Analytica Chimica Acta 2016 Volume 925() pp:88-96

Publication Date(Web):21 June 2016

DOI:10.1016/j.aca.2016.04.012

•A highly crosslinked polymeric monolith was fast prepared with a multi-acrylate monomer as crosslinker within 5 min.•The addition of thiol eliminated the major obstacle of oxygen inhibition in the thiol-ene (acrylate/methacrylate) polymerization.•Poly(ODT-co-DPEPA) monolith exhibited efficient chromatographic performance for separation of alkylbenzenes and tryptic digest of proteins.A facile approach was exploited for fast preparation of polymer-based monoliths in UV-transparent fused-silica capillaries via “one-pot” photo-initiated thiol-acrylate polymerization reaction of dipentaerythritolpenta-/hexaacrylate (DPEPA) and 1-octadecanethiol (ODT) in the presence of porogenic solvents (1-butanol and ethylene glycol). Due to relative insensitivity of oxygen inhibition in thiol-ene free-radical polymerization, the polymerization could be performed within 5 min. The effects of composition of prepolymerization solution on the morphology and permeability of poly(ODT-co-DPEPA) monoliths were investigated in detail by adjusting the content of monomer and binary porogen ratio. The physical properties of poly(ODT-co-DPEPA) monoliths were characterized by Fourier transform infrared spectroscopy (FT-IR), mercury intrusion porosimetry (MIP) and nitrogen adsorption/desorption measurement. The evaluation of chromatographic performance was carried out by capillary liquid chromatography (cLC). The results indicated that the poly(ODT-co-DPEPA) monolith was homogeneous and permeable, and also possessed a typical reversed-phase retention mechanism in cLC with high efficiency (∼75,000 N m−1) for separation of alkylbenzenes. Eventually, the further separation of tryptic digest of proteins by cLC tandem mass spectrometry (cLC-MS/MS) demonstrated its potential in the analysis of biological samples.

Improving permeability and chromatographic performance of poly(pentaerythritol diacrylate monostearate) monolithic column via photo-induced thiol-acrylate polymerization

Co-reporter:Hongwei Wang, Junjie Ou, Jingyao Bai, Zhongshan Liu, Yating Yao, Lianfang Chen, Xiaojun Peng, Hanfa Zou

Journal of Chromatography A 2016 Volume 1436() pp:100-108

Publication Date(Web):4 March 2016

DOI:10.1016/j.chroma.2016.01.063

•Thiol-acrylate photopolymerization was adopted to prepare poly(PEDAS-co-TPTM) column.•The column possessed bicontinuous structure.•The column exhibited better permeability (1.68 × 10−14 m2) than poly(PEDAS) column (9.2 × 10−15 m2).•The column exhibited lower plate heights (15.7–17.7 μm) than poly(PEDAS) column (19.1–37.9 μm).A simple approach was developed for rapid preparation of polymeric monolithic columns in UV-transparent fused-silica capillaries via photoinitiated thiol-acrylate polymerization of pentaerythritol diacrylate monostearate (PEDAS) and trimethylolpropane tris(3-mercaptopropionate) (TPTM) within 10 min, in which the acrylate homopolymerized and copolymerized with the thiol simultaneously. The morphology, permeability and chromatographic performance of the resulting poly(PEDAS-co-TPTM) monoliths were studied. It could be observed from SEM that the morphology of poly(PEDAS-co-TPTM) monolith was rather different from that of poly(PEDAS) monolith, which was fabricated via photo-induced free radical polymerization using PEDAS as the sole monomer. Compared with poly(PEDAS) monolith, poly(PEDAS-co-TPTM) monolith possessed better permeability when they were fabricated under the same preparation conditions. By adjusting the composition of porogenic solvents, poly(PEDAS-co-TPTM) monolith exhibited lower plate heights (15.7–17.7 μm) than poly(PEDAS) monolith (19.1–37.9 μm) in μLC. In addition, 66 unique peptides were positively identified on poly(PEDAS-co-TPTM) monolith when tryptic digest of four proteins was separated by μLC-MS/MS, demonstrating its potential in proteome analysis.

Preparation of cyclodextrin-modified monolithic hybrid columns for the fast enantioseparation of hydroxy acids in capillary liquid chromatography

Co-reporter:Kamila Szwed;Guang Huang;Hui Lin;Zhongshan Liu;Hongwei Wang ;Hanfa Zou

Journal of Separation Science 2016 Volume 39( Issue 6) pp:1110-1117

Publication Date(Web):

DOI:10.1002/jssc.201501157

Cyclodextrins and their derivatives are one of the most common and successful chiral selectors. However, there have been few publications about the use of cyclodextrin-modified monoliths. In this study, organic hybrid monoliths were prepared by the immobilization of derivatized β-cyclodextrin alone or with l-2-allylglycine hydrochloride to the polyhedral oligomeric silsesquioxane methacryl substituted monolith. The main topic of this study is a combined system with dual chiral selectors (l-2-allylglycine hydrochloride and β-cyclodextrin) as monolithic chiral stationary phase. The effect of l-2-allylglycine hydrochloride concentration on enantioseparation was investigated. The enantioseparation of the four acidic compounds with resolutions up to 2.87 was achieved within 2.5 min on the prepared chiral monolithic column in capillary liquid chromatography. Moreover, the possible mechanism of enantioseparation was discussed.

Synthesis of a stationary phase based on silica modified with branched octadecyl groups by Michael addition and photoinduced thiolyne click chemistry for the separation of basic compounds

Co-reporter:Guang Huang;Hongwei Wang;Yongsheng Ji;Hao Wan;Zhang Zhang;Xiaojun Peng;Hanfa Zou

Journal of Separation Science 2016 Volume 39( Issue 8) pp:1461-1470

Publication Date(Web):

DOI:10.1002/jssc.201501403

A novel silica-based stationary phase with branched octadecyl groups was prepared by the sequential employment of the Michael addition reaction and photoinduced thiol–yne click chemistry with 3-aminopropyl-functionalized silica microspheres as the initial material. The resulting stationary phase denoted as SiO₂-N(C18)₄ was characterized by elemental analysis, FTIR spectroscopy and Raman spectroscopy, demonstrating the existence of branched octadecyl groups in silica microspheres. The separations of benzene homologous compounds, acid compounds and amine analogues were conducted, demonstrating mixed-mode separation mechanism on SiO₂-N(C18)₄. Baseline separation of basic drugs mixture was acquired with the mobile phase of acetonitrile/H₂O (5%, v/v). SiO₂-N(C18)₄ was further applied to separate Corydalis yanhusuo Wang water extracts, and more baseline separation peaks were obtained for SiO₂-N(C18)₄ than those on Atlantis dC18 column. It can be expected that this new silica-based stationary phase will exhibit great potential in the analysis of basic compounds.

Click polymerization for preparation of monolithic columns for liquid chromatography

Co-reporter:Zhongshan Liu, Junjie Ou, Hanfa Zou

TrAC Trends in Analytical Chemistry 2016 Volume 82() pp:89-99

Publication Date(Web):September 2016

DOI:10.1016/j.trac.2016.05.016

•Click polymerization was used for direct construction of monolithic columns.•Monolithic columns can generate plate height with smaller than 10 µm in LC.•The phase separation process of click polymerization was discussed.In recent years, polymerizations based on click reactions (thiol-ene, thiol-yne, thiol-Michael, thiol-epoxy and amine-epoxy) have been utilized to prepare monolithic columns. These polymerization systems are easily carried out under mild conditions. Either hybrid or organic monolithic columns fabricated by click polymerization demonstrated homogeneous network structures. For separation of small molecules, the column efficiencies, such as plate height with less than 10 µm, have been greatly improved comparing with organic monolithic columns prepared with free radical polymerization. In this review, we will summarize recent progress on the preparation of monolithic columns and their chromatographic performances.

Thiol-Epoxy Click Polymerization for Preparation of Polymeric Monoliths with Well-Defined 3D Framework for Capillary Liquid Chromatography

Co-reporter:Hui Lin, Junjie Ou, Zhongshan Liu, Hongwei Wang, Jing Dong, and Hanfa Zou

Analytical Chemistry 2015 Volume 87(Issue 6) pp:3476

Publication Date(Web):February 13, 2015

DOI:10.1021/acs.analchem.5b00006

A facile approach was developed for direct preparation of organic monoliths via the alkaline-catalyzed thiol-epoxy click polymerization. Two organic monoliths were prepared by using tetraphenylolethane glycidyl ether as a multiepoxy monomer, and trimethylolpropane tris(3-mercaptopropionate) and pentaerythritol tetrakis(3-mercaptopropionate) as the multithiol monomer, respectively, in the presence of a ternary porogenic system (DMSO/PEG200/H2O). The obtained organic monoliths showed high thermal, mechanical and chemical stabilites. Benefiting from the step-growth polymerization process, two organic monoliths possessed well-defined 3D framework microstructure, and exhibited high permeabilities and column efficiencies in capillary liquid chromatography. A series of neutral, basic and acidic small molecules were used to comprehensively evaluate the separation abilities of these monoliths, and satisfactory chromatographic performance with column efficiencies ranged from 35 500 to 132 200 N/m was achieved, demonstrating good separation abilities of these organic monoliths prepared via thiol-epoxy click polymerization approach. Besides, multiple retention mechanisms, including hydrophobic, hydrophilic and π–π conjugate interactions were observed during the separation of analytes on these monoliths, which would make them promising for more extensive applications in capillary liquid chromatography.

Preparation of Hybrid Monolithic Columns via “One-Pot” Photoinitiated Thiol–Acrylate Polymerization for Retention-Independent Performance in Capillary Liquid Chromatography

Co-reporter:Haiyang Zhang, Junjie Ou, Zhongshan Liu, Hongwei Wang, Yinmao Wei, and Hanfa Zou

Analytical Chemistry 2015 Volume 87(Issue 17) pp:8789

Publication Date(Web):July 30, 2015

DOI:10.1021/acs.analchem.5b01707

A novel “one-pot” approach was developed for ultrarapid preparation of various hybrid monolithic columns in UV-transparent fused-silica capillaries via photoinitiated thiol–acrylate polymerization of an acrylopropyl polyhedral oligomertic silsesquioxane (acryl-POSS) and a monothiol monomer (1-octadecanethiol or sodium 3-mercapto-1-propanesulfonate) within 5 min, in which the acrylate not only homopolymerizes, but also couples with the thiol. This unique combination of two types of free-radical reaction mechanisms offers a simple way to fabricate various acrylate-based hybrid monoliths. The physical characterization, including scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and thermal gravimetric analysis was performed. The results indicated that the monothiol monomers were successfully incorporated into acryl-POSS-based hybrid monoliths. The column efficiencies for alkylbenzenes on the C18-functionalized hybrid monolithic column reached to 60 000–73 500 plates/m at the velocity of 0.33 mm/s in capillary liquid chromatography, which was far higher than that of previously reported POSS-based columns prepared via thermal-initiated free-radical polymerization without adding any thiol monomers. By plotting the plate height (H) of the alkylbenzenes versus the linear velocity (u) of the mobile phase, the results revealed a retention-independent efficient performance of small molecules in the isocratic elution. These results indicated that more homogeneous hybrid monoliths formed via photoinitiated thiol–acrylate polymerization; particularly, the use of the multifunctional cross-linker possibly prevented the generation of gel-like micropores, reducing mass transfer resistance (C-term). Another sulfonate-containing hybrid monolithic column also exhibited hydrophobicity and ion-exchange mechanism, and the dynamic binding capacity was calculated as 71.1 ng/cm (75 μm i.d.).

A novel polymeric monolith prepared with multi-acrylate crosslinker for retention-independent efficient separation of small molecules in capillary liquid chromatography

Co-reporter:Haiyang Zhang, Junjie Ou, Yinmao Wei, Hongwei Wang, Zhongshan Liu, Lianfang Chen, Hanfa Zou

Analytica Chimica Acta 2015 Volume 883() pp:90-98

Publication Date(Web):9 July 2015

DOI:10.1016/j.aca.2015.04.001

•A crosslinker with multiple acrylate groups was first used for preparing polymeric monoliths.•The poly(LMA-co-DPEPA) monoliths exhibited the column efficiencies of 111,000–165,000 N m−1 for alkylbenzenes in cLC.•Highly crosslinked monoliths also exhibited retention-independent efficient chromatographic performance.Low column efficiency for small molecules in reversed-phase chromatography is a major problem commonly encountered in polymer-based monoliths. Herein, a novel highly crosslinked porous polymeric monolith was in situ prepared by using a multi-acrylate monomer, dipentaerythritol penta-/hexa-acrylate (DPEPA), as crosslinker, which copolymerized with lauryl methacrylate (LMA) as functional monomer in a UV-transparent fused-silica capillary via photo-initiated free-radical polymerization within 5 min. The mechanical stability and permeability of the resulting poly(LMA-co-DPEPA) monolith were characterized in detail. One series of highly crosslinked poly(LMA-co-DPEPA) columns were prepared with relatively higher content of crosslinker (63.3%) in the precursor. Although they exhibited lower permeability, high column efficiency for alkylbenzenes was acquired in cLC, and the minimum plate height (column B) was in the range of 6.04–9.00 μm, corresponding to 111,000–165,000 N m−1. Meanwhile, another series of poly(LMA-co-DPEPA) columns prepared with relatively lower content of crosslinker (52.7%) in the precursor exhibited higher permeability, but the minimum plate height (column E) was relatively low in the range of 10.75–20.04 μm for alkylbenzenes, corresponding to 50,000–93,000 N m−1. Compared with common poly(LMA-co-EDMA) columns previously reported, the highly crosslinked poly(LMA-co-DPEPA) columns using a multi-acrylate monomer as crosslinker possessed remarkably high column efficiency for small molecules in cLC. By plotting of plate height (H) of alkylbenzenes versus the linear velocity (u) of mobile phase, the results revealed a retention-independent efficient performance of small molecules in the isocratic elution, indicating that the use of multi-functional crosslinker possibly prevents the generation of gel-like micropores in the poly(LMA-co-DPEPA) monolith, reducing the mass transfer resistance (C-term).

Preparation of well-controlled three-dimensional skeletal hybrid monoliths via thiol–epoxy click polymerization for highly efficient separation of small molecules in capillary liquid chromatography

Co-reporter:Hui Lin, Lianfang Chen, Junjie Ou, Zhongshan Liu, Hongwei Wang, Jing Dong, Hanfa Zou

Journal of Chromatography A 2015 Volume 1416() pp:74-82

Publication Date(Web):16 October 2015

DOI:10.1016/j.chroma.2015.09.011

•Two hybrid monoliths were facilely prepared via thiol–epoxy click polymerization reaction.•The obtained monoliths possess high thermal and chemical stabilities.•The highest column efficiency of ca. 182,700 N/m was achieved.•The obtained monoliths exhibited high separation capabilities for various simple and complicated samples.Two kinds of hybrid monoliths were first prepared via thiol–epoxy click polymerization using a multi-epoxy monomer, octaglycidyldimethylsilyl POSS (POSS-epoxy), and two multi-thiols, trimethylolpropanetris(3-mercaptopropionate) (TPTM) and pentaerythritoltetrakis(3-mercaptopropionate) (PTM), respectively, as the precursors. The resulting two hybrid monoliths (assigned as POSS-epoxy–TPTM and POSS-epoxy–PTM) not only possessed high thermal, mechanical and chemical stabilities, but also exhibited well-controlled 3D skeletal microstructure and high efficiency in capillary liquid chromatography (cLC) separation of small molecules. The highest column efficiency reached 182,700 N/m (for butylbenzene) on the monolith POSS-epoxy–PTM at the velocity of 0.75 mm/s. Furthermore, the hybrid monolith POSS-epoxy–PTM was successfully applied for cLC separations of various samples, not only standard compounds such as alkylbenzenes, PAHs, phenols and dipeptides, as well as intact proteins, but also complex samples of EPA 610 and BSA digest.

Facile construction of macroporous hybrid monoliths via thiol-methacrylate Michael addition click reaction for capillary liquid chromatography

Co-reporter:Hui Lin, Junjie Ou, Zhongshan Liu, Hongwei Wang, Jing Dong, Hanfa Zou

Journal of Chromatography A 2015 Volume 1379() pp:34-42

Publication Date(Web):30 January 2015

DOI:10.1016/j.chroma.2014.12.031

•Three hybrid monoliths were facilely prepared via thiol-methacrylate Michael addition click reaction.•The obtained monoliths possess high thermal and chemical stabilities.•The highest column efficiency of ca. 190,000 N/m was achieved.•The obtained monoliths exhibited high separation capabilities for various simple and complicated samples.A facile approach based on thiol-methacrylate Michael addition click reaction was developed for construction of porous hybrid monolithic materials. Three hybrid monoliths were prepared via thiol-methacrylate click polymerization by using methacrylate-polyhedral oligomeric silsesquioxane (POSS) (cage mixture, n = 8, 10, 12, POSS-MA) and three multi-thiol crosslinkers, 1,6-hexanedithiol (HDT), trimethylolpropane tris(3-mercaptopropionate) (TPTM) and pentaerythritol tetrakis(3-mercaptopropionate) (PTM), respectively, in the presence of porogenic solvents (n-propanol and PEG 200) and a catalyst (dimethylphenylphosphine, DMPP). The obtained monoliths possessed high thermal and chemical stabilities. Besides, they all exhibited high column efficiencies and excellent separation abilities in capillary liquid chromatography (cLC). The highest column efficiency could reach ca. 195,000 N/m for butylbenzene on the monolith prepared with POSS-MA and TPTM (monolith POSS-TPTM) in reversed-phase (RP) mode at 0.64 mm/s. Good chromatographic performance were all achieved in the separations of polycyclic aromatic hydrocarbons (PAHs), phenols, anilines, EPA 610 as well as bovine serum albumin (BSA) digest. The high column efficiencies in the range of 51,400–117,000 N/m (achieved on the monolith POSS-PTM in RP mode) convincingly demonstrated the high separation abilities of these thiol-methacrylate based hybrid monoliths. All the results demonstrated the feasibility of the phosphines catalyzed thiol-methacrylate Michael addition click reaction in fabrication of monolithic columns with high efficiency for cLC applications.

Fast preparation of a highly efficient organic monolith via photo-initiated thiol-ene click polymerization for capillary liquid chromatography

Co-reporter:Lianfang Chen, Junjie Ou, Zhongshan Liu, Hui Lin, Hongwei Wang, Jing Dong, Hanfa Zou

Journal of Chromatography A 2015 Volume 1394() pp:103-110

Publication Date(Web):15 May 2015

DOI:10.1016/j.chroma.2015.03.054

•A fast approach was successfully developed to prepare an organic monolith via thiol-ene click polymerization.•Effects of the compositions of prepolymerization mixture and reaction time were investigated.•The obtained organic monolith exhibited a very high column efficiency of ∼133,000 plates per meter.A novel organic monolith was firstly prepared in a UV-transparent fused-silica capillary by a single-step approach via photo-initiated thiol-ene click polymerization reaction of 1,2,4-trivinylcyclohexane (TVCH) and pentaerythriol tetra(3-mercaptopropionate) (4SH) within 10 min. The effects of both composition of prepolymerization solution and polymerization time on the morphology and permeability of monolithic column were investigated in detail. Then, the optimal condition was acquired to fabricate a homogeneous and permeable organic monolith. The chemical groups of the monolithic column were confirmed by Fourier transform infrared spectroscopy (FT-IR). The SEM graphs showed the organic monolith possessed a uniform porous structure, which promotes the highest column efficiency of ∼133,000 plates per meter for alkylbenzenes at the linear velocity of 0.65 mm/s in reversed-phase liquid chromatography. Finally, the organic monolithic column was further applied for separation of basic compounds, pesticides and EPA610, indicating satisfactory separation ability.

Photoinduced thiol–ene polymerization reaction for fast preparation of macroporous hybrid monoliths and their application in capillary liquid chromatography

Co-reporter:Zhongshan Liu, Junjie Ou, Hui Lin, Zheyi Liu, Hongwei Wang, Jing Dong and Hanfa Zou

Chemical Communications 2014 vol. 50(Issue 66) pp:9288-9290

Publication Date(Web):12 Jun 2014

DOI:10.1039/C4CC03451A

Hybrid monoliths with a macroporous structure were prepared within a few minutes via a photoinduced thiol–ene polymerization reaction, the surfaces of which showed hydrophobic character. The monolithic column demonstrated good separation performance towards alkylbenzenes, peptides, proteins and BSA tryptic digest in cLC.

Preparation of Monolithic Polymer Columns with Homogeneous Structure via Photoinitiated Thiol-yne Click Polymerization and Their Application in Separation of Small Molecules

Co-reporter:Zhongshan Liu, Junjie Ou, Hui Lin, Hongwei Wang, Zheyi Liu, Jing Dong, and Hanfa Zou

Analytical Chemistry 2014 Volume 86(Issue 24) pp:12334

Publication Date(Web):November 18, 2014

DOI:10.1021/ac503626v

Two monolithic polymer columns were directly prepared in the UV-transparent fused-silica capillaries via photoinitiated thiol-yne click polymerization of 1,7-octadiyne (ODY) with a dithiol (1,6-hexanedithiol, 2SH) or a tetrathiol (pentaerythriol tetrakis(3-mercaptopropionate), 4SH) within 15 min. The rapid polymerization provided a time-saving approach to optimize preparation conditions. Then, two porogenic systems of diethylene glycol diethyl ether (DEGDE)/tetrahydrofuran (THF) and DEGDE/poly(ethylene glycol) (PEG, Mn = 200) were found to effectively control the porous structure of two kinds of polymeric monoliths (O2SH and O4SH), respectively. The almost disappearance of thiol and alkynyl vibrations (2560 and 2115 cm–1, respectively) in infrared spectra and Raman spectra indicated a high conversion of the thiol-yne polymerization reaction. The thiol-yne polymerization was further proved by analyzing the energy-dispersive X-ray spectrum (EDS), MALDI-TOF mass spectrum, and elemental data. Scanning electron microscopy (SEM) images showed the monolithic polymer columns with homogeneous porous structure and macropore size of 0.5–1.0 μm, which facilitated the minimum plate heights of 10.0–12.0 μm for alkylbenzenes in reversed-phase liquid chromatography (RPLC). The low values of the A and C terms (<1.0 μm and <15.5 ms, respectively) in the van Deemter equation were similar to those obtained by some monolithic silica columns. The BSA tryptic digest was also separated on the monolithic polymer column by cLC-MS/MS. The result with 85% protein coverage was better than those given by some hybrid monolithic columns. The monolithic polymer columns were further applied for separation of phenols, natural products, and standard proteins and demonstrated satisfactory separation ability.

Synthesis of zwitterionic polymer brushes hybrid silica nanoparticles via controlled polymerization for highly efficient enrichment of glycopeptides

Co-reporter:Guang Huang, Zhichao Xiong, Hongqiang Qin, Jun Zhu, Zhen Sun, Yi Zhang, Xiaojun Peng, Junjie ou, Hanfa Zou

Analytica Chimica Acta 2014 Volume 809() pp:61-68

Publication Date(Web):27 January 2014

DOI:10.1016/j.aca.2013.11.049

•Silica nanoparticles modified with uniform PMSA brushes (SiO2-RAFT@PMSA) via RAFT technique were successfully synthesized.•The SiO2-RAFT@PMSA nanoparticles were successfully applied for glycopeptide enrichment.•SiO2-RAFT@PMSA nanoparticles performed better glycopeptide enrichment than monolayer materials & PMSA brushes nanoparticles.Zwitterionic hydrophilic interaction chromatography (ZIC-HILIC) materials have been increasingly attractive in glycopeptide enrichment. However, the traditional ZIC-HILIC materials are modified with monolayer zwitterionic molecules on the surface, therefore, the hydrophilicity, detection sensitivity and loading capacity are limited. In this work, we synthesized novel silica nanoparticles with uniform poly(2-(methacryloyloxy)ethyl)dimethyl-(3-sul-fopropyl)ammonium hydroxide (PMSA) brushes grafted onto the surface via reversible addition-fragmentation chain transfer (RAFT) polymerization (denoted as SiO2-RAFT@PMSA). The resulting SiO2-RAFT@PMSA nanoparticles demonstrated low detection limit (10 fmol) and high recovery yield (over 88%) for glycopeptide enrichment from tryptic digest of human IgG. The SiO2-RAFT@PMSA nanoparticles were further applied for the analysis of mouse liver glycoproteome, a total number of 303 unique N-glycosylation sites corresponding to 185 glycoproteins was reliably profiled in three replicate nano-LC–MS/MS runs. Significantly, more glycopeptides were identified than those of nanoparticles, monolayer MSA molecules modified SiO2@single-MSA and nonuniform multi-layer PMSA brushes coated SiO2@PMSA, as well as commercial ZIC@HILIC beads and Click Maltose beads. The excellent performance of SiO2-RAFT@PMSA nanoparticles results from the non-fouling property, a large quantity of functional molecules and suitable link arms provided by uniform PMSA brushes, as well as efficient interaction between glycopeptides and uniform PMSA brushes. It is concluded that the synthesized SiO2-RAFT@PMSA nanoparticles exhibit great potential in glycoproteome analysis. Moreover, this strategy to modify nanopaticles with uniform polymer brushes via RAFT polymerization can also be explored to design other types of materials for bioseparation application.

Preparation of hydrazine functionalized polymer brushes hybrid magnetic nanoparticles for highly specific enrichment of glycopeptides

Co-reporter:Guang Huang, Zhen Sun, Hongqiang Qin, Liang Zhao, Zhichao Xiong, Xiaojun Peng, Junjie Ou and Hanfa Zou

Analyst 2014 vol. 139(Issue 9) pp:2199-2206

Publication Date(Web):27 Jan 2014

DOI:10.1039/C4AN00076E

Hydrazide chemistry is a powerful technique in glycopeptides enrichment. However, the low density of the monolayer hydrazine groups on the conventional hydrazine-functionalized magnetic nanoparticles limits the efficiency of glycopeptides enrichment. Herein, a novel magnetic nanoparticle grafted with poly(glycidyl methacrylate) (GMA) brushes was fabricated via reversible addition-fragmentation chain transfer (RAFT) polymerization, and a large amount of hydrazine groups were further introduced to the GMA brushes by ring-opening the epoxy groups with hydrazine hydrate. The resulting magnetic nanoparticles (denoted as Fe3O4@SiO2@GMA–NHNH2) demonstrated the high specificity of capturing glycopeptides from a tryptic digest of the sample comprising a standard non-glycosylated protein bovine serum albumin (BSA) and four standard glycoproteins with a weight ratio of 50:1, and the detection limit was as low as 130 fmol. In the analysis of a real complex biological sample, the tryptic digest of hepatocellular carcinoma, 179 glycosites were identified by the Fe3O4@SiO2@GMA–NHNH2 nanoparticles, surpassing that of 68 glycosites by Fe3O4@SiO2-single-NHNH2 (with monolayer hydrazine groups on the surface). It can be expected that the magnetic nanoparticles modified with hydrazine functionalized polymer brushes via RAFT technique will improve the specificity and the binding capacity of glycopeptides from complex samples, and show great potential in the analysis of protein glycosylation in biological samples.

Chromatographic assessment of two hybrid monoliths prepared via epoxy-amine ring-opening polymerization and methacrylate-based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer

Co-reporter:Hongwei Wang, Junjie Ou, Hui Lin, Zhongshan Liu, Guang Huang, Jing Dong, Hanfa Zou

Journal of Chromatography A 2014 Volume 1367() pp:131-140

Publication Date(Web):7 November 2014

DOI:10.1016/j.chroma.2014.09.072

•Two hybrid monoliths were prepared by different polymerization techniques.•Two hybrid monoliths were investigated on the morphology and chromatographic assessment.•Both hybrid monoliths showed satisfactory tailorability.Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65 °C for 12 h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60 °C for 12 h. Two hybrid monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA–DAD monolith possessed higher column efficiencies (25,000–34,000 plates/m) for the separation of alkylbenzenes than the epoxy-MA–EDMA monolith (12,000–13,000 plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine monoliths, the epoxy-MA–EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA–DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA–DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA–DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA–EDMA monolith when compared with that on pristine epoxy-MA–EDMA monolith. The enhancement of the column efficiency of epoxy-MA–DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC.

Preparation of polyhedral oligomeric silsesquioxane-based hybrid monolith by ring-opening polymerization and post-functionalization via thiol-ene click reaction

Co-reporter:Zhongshan Liu, Junjie Ou, Hui Lin, Hongwei Wang, Jing Dong, Hanfa Zou

Journal of Chromatography A 2014 Volume 1342() pp:70-77

Publication Date(Web):16 May 2014

DOI:10.1016/j.chroma.2014.03.058

•A facile approach was successfully developed to prepare a POSS-based hybrid monolith possessing disulfide bonds.•Functionalization of POSS-based hybrid monolith was performed with methylacrylate via thiol-ene reaction at room temperature.•The column efficiency was obviously enhanced after SMA-modification of hybrid monolithic column.•A 1-m-long column of 75 μm i.d. was prepared and exhibited the highest column efficiency of ∼70,000 plates.A polyhedral oligomeric silsesquioxane (POSS) hybrid monolith was simply prepared by using octaglycidyldimethylsilyl POSS (POSS-epoxy) and cystamine dihydrochloride as monomers via ring-opening polymerization. The effects of composition of prepolymerization solution and polycondensation temperature on the morphology and permeability of monolithic column were investigated in detail. The obtained POSS hybrid monolithic column showed 3D skeleton morphology and exhibited high column efficiency of ∼71,000 plates per meter in reversed-phase mechanism. Owing to this POSS hybrid monolith essentially possessing a great number of disulfide bonds, the monolith surface would expose thiol groups after reduction with dithiothreitol (DTT), which supplied active sites to functionalize with various alkene monomers via thiol-ene click reaction. The results indicated that the reduction with DTT could not destroy the 3D skeleton of hybrid monolith. Both stearyl methylacrylate (SMA) and benzyl methacrylate (BMA) were selected to functionalize the hybrid monolithic columns for reversed-phase liquid chromatography (RPLC), while [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide (MSA) was used to modify the hybrid monolithic column in hydrophilic interaction chromatography (HILIC). These modified hybrid monolithic columns could be successfully applied for separation of small molecules with high efficiency. It is demonstrated that thiol-ene click reaction supplies a facile way to introduce various functional groups to the hybrid monolith possessing thiol groups. Furthermore, due to good permeability of the resulting hybrid monoliths, we also prepared long hybrid monolithic columns in narrow-bore capillaries. The highest column efficiency reached to ∼70,000 plates using a 1-m-long column of 75 μm i.d. with a peak capacity of 147 for isocratic chromatography, indicating potential application in separation and analysis of complex biosamples.

Ring-opening polymerization reaction of polyhedral oligomeric silsesquioxanes (POSSs) for preparation of well-controlled 3D skeletal hybrid monoliths

Co-reporter:Hui Lin, Junjie Ou, Zhenbin Zhang, Jing Dong and Hanfa Zou

Chemical Communications 2013 vol. 49(Issue 3) pp:231-233

Publication Date(Web):09 Oct 2012

DOI:10.1039/C2CC36881A

A novel, facile, highly flexible process was developed for the first preparation of well-controlled 3D skeletal polyhedral oligomeric silsesquioxane (POSS)-based functionalizable porous hybrid monoliths via ring-opening polymerization. This approach represents an ideal pathway for easy access to a series of hybrid monoliths with high separation efficiency in cLC.

Polyhedral oligomeric silsesquioxanes as functional monomer to prepare hybrid monolithic columns for capillary electrochromatography and capillary liquid chromatography

Co-reporter:Junjie Ou, Zhenbin Zhang, Hui Lin, Jing Dong, Hanfa Zou

Analytica Chimica Acta 2013 Volume 761() pp:209-216

Publication Date(Web):25 January 2013

DOI:10.1016/j.aca.2012.11.052

A simple approach to fabricate hybrid monolithic column within the confines of fused-silica capillaries (75 μm i.d.) was introduced. A polyhedral oligomeric silsesquioxanes (POSS) reagent containing a methacrylate group was selected as functional monomer, and copolymerized with bisphenol A dimethacrylate (BPADMA) or ethylene dimethacrylate (EDMA) in the presence of porogenic solvents via thermally initiated free radical polymerization. After optimization of the preparation conditions, two POSS-containing hybrid monoliths were successfully prepared and exhibited good permeability and stability. By comparison of the separation efficiencies of the resulting poly(POSS-co-BPADMA) and poly(POSS-co-EDMA) monoliths in capillary electrochromatography (CEC) and capillary liquid chromatography (cLC), it was indicated the former has better column efficiencies for alkylbenzenes, phenols, anilines and PAHs in CEC and cLC than the latter. Particularly, the hybrid poly(POSS-co-BPADMA) monolith is more suitable for separation of PAHs due to π–π interaction between the analytes and aromatic rings in the surface of monolithic stationary phase.Graphical abstract.Highlights► A POSS reagent was selected as monomer to prepare hybrid monolithic column. ► Two resulting hybrid monoliths were successfully applied for CEC and cLC. ► The hybrid poly(POSS-co-BPADMA) monolith exhibits better selectivity for PAHs.

Facile preparation of a stable and functionalizable hybrid monolith via ring-opening polymerization for capillary liquid chromatography

Co-reporter:Hui Lin, Junjie Ou, Shouwan Tang, Zhenbin Zhang, Jing Dong, Zhongshan Liu, Hanfa Zou

Journal of Chromatography A 2013 Volume 1301() pp:131-138

Publication Date(Web):2 August 2013

DOI:10.1016/j.chroma.2013.05.069

•A POSS-based functionalizable hybrid monolith was successfully prepared via ring-opening polymerization.•The obtained hybrid monolith possesses well-controlled 3D skeleton.•A column efficiency of 110,000 N/m was achieved for isocratic separation of alkylbenzenes.•The obtained hybrid monolith showed high stability and good surface tailorability.An organic–inorganic hybrid monolith was prepared by a single-step ring-opening polymerization of octaglycidyldimethylsilyl polyhedral oligomeric silsesquioxane (POSS) with poly(ethylenimine) (PEI). The obtained hybrid monoliths possessed high ordered 3D skeletal microstructure with dual retention mechanism that exhibits reversed-phase (RP) mechanism under polar mobile phase and hydrophilic-interaction liquid chromatography (HILIC) retention mechanism under less polar mobile phase. The high column efficiencies of 110,000 N/m can be achieved for separation of alkylbenzenes in capillary reversed-phase liquid chromatography (cLC). Due to the robust property of hybrid monolith and the rich primary and secondary amino groups on its surface, the resulting hybrid monolith was easily modified with γ-gluconolactone and physically coated with cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC), respectively. The former was successfully applied for HILIC separation of neutral, basic and acidic polar compounds as well as small peptides, and the latter for enantioseparation of racemates in cLC. The high column efficiencies were achieved in all of those separations. These results demonstrated that the hybrid monolith (POSS–PEI) possessed high stability and good surface tailorbility, potentially being applied for other research fields

Preparation of polyhedral oligomeric silsesquioxane based hybrid monoliths by ring-opening polymerization for capillary LC and CEC

Co-reporter:Hui Lin;Zhenbin Zhang;Jing Dong;Zhongshan Liu;Hanfa Zou

Journal of Separation Science 2013 Volume 36( Issue 17) pp:2819-2825

Publication Date(Web):

DOI:10.1002/jssc.201300417

A new organic–inorganic hybrid monolith was prepared by the ring-opening polymerization of octaglycidyldimethylsilyl polyhedral oligomeric silsesquioxane (POSS) with 1,4-butanediamine (BDA) using 1-propanol, 1,4-butanediol, and PEG 10 000 as a porogenic system. Benefiting from the moderate phase separation process, the resulting poly(POSS-co-BDA) hybrid monolith possessed a uniform microstructure and exhibited excellent performance in chromatographic applications. Neutral, acidic, and basic compounds were successfully separated on the hybrid monolith in capillary LC (cLC), and high column efficiencies were achieved in all of the separations. In addition, as the amino groups could generate a strong EOF, the hybrid monolith was also applied in CEC for the separation of neutral and polar compounds, and a satisfactory performance was obtained. These results demonstrate that the poly(POSS-co-BDA) hybrid monolith is a good separation media in chromatographic separations of various types of compounds by both cLC and CEC.

Preparation of a butyl–silica hybrid monolithic column with a “one-pot” process for bioseparation by capillary liquid chromatography

Co-reporter:Zhenbin Zhang;Fangjun Wang;Hui Lin

Analytical and Bioanalytical Chemistry 2013 Volume 405( Issue 7) pp:2265-2271

Publication Date(Web):2013 March

DOI:10.1007/s00216-012-6589-z

A butyl–silica hybrid monolithic column for bioseparation by capillary liquid chromatography (cLC) was prepared with butyl methacrylate and alkoxysilanes through a “one-pot” process. The effects of polycondensation temperature, volume percentage of N,N′-dimethylformamide, and content of cetyltrimethylammonium bromide and butyl methacrylate on the morphologies of the hybrid monolithic columns prepared were investigated in detail. Baseline separations of proteins and small peptides on the hybrid monolithic column were achieved by cLC with gradient elution. In addition, the resulting hybrid column was also applied for analysis of tryptic digests of bovine serum albumin by cLC coupled with tandem mass spectrometry. The results demonstrate its potential application in separation of complex biological samples.

Facile Preparation of Zwitterionic Organic-Silica Hybrid Monolithic Capillary Column with an Improved “One-Pot” Approach for Hydrophilic-Interaction Liquid Chromatography (HILIC)

Co-reporter:Hui Lin, Junjie Ou, Zhenbin Zhang, Jing Dong, Minghuo Wu, and Hanfa Zou

Analytical Chemistry 2012 Volume 84(Issue 6) pp:2721-2728

Publication Date(Web):February 22, 2012

DOI:10.1021/ac3001429

A simple single-step thermal-treatment “one-pot” approach for the preparation of organic-silica hybrid capillary monolithic columns is described. In this improved method, the cross-linker vinyltrimethoxysilane (VTMS) was replaced by 3-methacryloxypropyltrimethoxysilane (γ-MAPS), which is more active in polymerization reactions, and only one thermal treatment step was required in the preparation of hybrid monoliths. Two zwitterionic organic-silica monolithic columns were successfully synthesized by using [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (MSA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) as the organic monomers. The effects of the tetramethoxysilane (TMOS)/γ-MAPS molar ratio, content of monomer, composition of porogenic solvent, and reaction temperature on the morphologies of the hybrid monoliths were investigated. The MSA-silica and MPC-silica hybrid monolithic columns exhibited good permeability and good mechanical stability. The monolithic columns were used for the separation of polar compounds by capillary hydrophilic-interaction chromatography (cHILIC). A typical HILIC retention mechanism was observed at higher organic solvent contents (>50% ACN). The MSA monoliths were further investigated in the separation of various neutral, basic, and acidic analytes, as well as small peptides, by capillary liquid chromatography (cLC), and high efficiency and satisfactory reproducibility were achieved. In addition, the analysis of a tryptic digest of bovine serum albumin (BSA) by cLC tandem mass spectrometry (cLC-MS/MS) with an MSA monolith further demonstrated its potential in the separation of biological samples.

Hybrid monolithic columns coated with cellulose tris(3,5-dimethylphenyl-carbamate) for enantioseparations in capillary electrochromatography and capillary liquid chromatography

Co-reporter:Junjie Ou, Hui Lin, Shouwan Tang, Zhenbin Zhang, Jing Dong, Hanfa Zou

Journal of Chromatography A 2012 Volume 1269() pp:372-378

Publication Date(Web):21 December 2012

DOI:10.1016/j.chroma.2012.09.022

A hybrid monolithic capillary column synthesized with (3-chloropropyl)-trimethoxysilane (CPTMS) and tetramethoxysilane (TMOS) via sol–gel chemistry was in situ coated with cellulose tris(3,5-dimethylphenyl-carbamate) (CDMPC) for enantioseparations in capillary electrochromatography (CEC) and capillary liquid chromatography (CLC). Prior to coating, the prepared CP-silica hybrid monolith was straightforwardly modified with diethylenetriamine (DETA) to introduce NH2 functionalities via the nucleophilic substitution reaction, which generate the stronger EOF for CEC. The coating condition was optimized to obtain a stable and reproducible chiral stationary phase for enantioseparation. The results indicated that racemic benzoin was baseline separated on the resulting hybrid monolith coated with 30 mg/mL CDMPC in CEC, while several racemates were successfully enantioseparated on the resulting CP-silica hybrid monolithic column coated with 60 mg/mL CDMPC in CLC with RP and NP modes.Highlights► A hybrid monolith was synthesized with CPTMS and TMOS via sol–gel chemistry. ► The hybrid monolith was straightforwardly modified to introduce NH2 functionality. ► Cellulose deriviative was coated on monolith for enantioseparations in CEC and CLC.

Preparation of phenyl-silica hybrid monolithic column with “one-pot” process for capillary liquid chromatography

Co-reporter:Zhenbin Zhang, Hui Lin, Junjie Ou, Hongqiang Qin, Ren’an Wu, Jing Dong, Hanfa Zou

Journal of Chromatography A 2012 Volume 1228() pp:263-269

Publication Date(Web):9 March 2012

DOI:10.1016/j.chroma.2011.07.048

A phenyl-silica hybrid monolithic column for capillary liquid chromatography (cLC) was prepared through “one-pot” process by con-currently using benzyl methacrylate and alkoxysilanes. The effects of the molar ratio of tetramethoxysilane/vinyltrimethoxysilane (TMOS/VTMS), polycondensation temperature, content of supramolecule template (cetyltrimethylammonium bromide, CTAB), ratio of N,N′-dimethylformamide/methanol (v/v), the volume of benzyl methacrylate on the morphologies of the prepared phenyl-silica hybrid monolithic columns were investigated in detail. The permeability of the hybrid monolithic column was calculated as 3.23 × 10−13 m2, and the minimum plate height was determined as 8.38 μm which corresponding to 119,000 theoretical plates per meter. Separation of various neutral, polar and basic analytes as well as small peptides on the hybrid monolithic column was achieved by cLC and showed high efficiency and satisfactory reproducibility. Moreover, the prepared hybrid monolithic column was also applied for the analysis of tryptic digests of bovine serum albumin (BSA), ovalbumin, α-casein, cytochrome C and myoglobin by cLC tandem mass spectrometry (cLC–MS/MS), and the results showed that the separation performance was close to that of the octadecylsilane (C18) packed capillary column which demonstrating its potential in proteome analysis. Moreover, since the prepolymerization system was mainly consisted of organic solvents (methanol and N,N′-dimethylformamide), various hydrophobic monomers could be potentially used to prepare organic-silica hybrid monolithic columns through “one-pot” approach.

Photoinduced thiol–ene polymerization reaction for fast preparation of macroporous hybrid monoliths and their application in capillary liquid chromatography

Co-reporter:Zhongshan Liu, Junjie Ou, Hui Lin, Zheyi Liu, Hongwei Wang, Jing Dong and Hanfa Zou

Chemical Communications 2014 - vol. 50(Issue 66) pp:NaN9290-9290

Publication Date(Web):2014/06/12

DOI:10.1039/C4CC03451A

Ring-opening polymerization reaction of polyhedral oligomeric silsesquioxanes (POSSs) for preparation of well-controlled 3D skeletal hybrid monoliths

Co-reporter:Hui Lin, Junjie Ou, Zhenbin Zhang, Jing Dong and Hanfa Zou

Chemical Communications 2013 - vol. 49(Issue 3) pp:NaN233-233

Publication Date(Web):2012/10/09

DOI:10.1039/C2CC36881A