Inner Surface Of Capillary Research Articles

Directed alignment of graphene-oxide liquid crystals in confined spaces: Effects of flow, pickering stabilization, and phase transition

Because of its versatility for processing, graphene oxide (GO) serves as a superior substance for two-dimensional carbon-based materials. Controlling GO alignment is crucial to augment its inherent anisotropic nature. Here, we report the controlled alignment of GO confined in the rectangular and circular capillary tubes. GO aligns in contrasting orientations according to the phase of GO dispersion during loading into a capillary. Upon GO liquid crystal (LC) loading, GO-layers are oriented tangential to the inner surface of capillary, resulting in a concentric organization of the GO-layers. In the LC phase, the GO orientation is mainly influenced by the flow so that the GOs are aligned tangential to the hydraulic shear plane. However, GO self-assembles parallel to the capillary cross-section when loaded in the isotropic phase and then concentrated into the LC phase. Surprisingly, by excluding flow-induced effects, the GO layer is aligned perpendicular to the inner surface throughout the capillary. This unexpected alignment of the GO-layers is initiated in the meniscus region by the “Pickering effect” (i.e., tangential adsorption of GO along the Air-Liquid interface). Upon solvent evaporation, GO dispersions experience a sequential isotropic to nematic phase transition from the meniscus to the central region. During the phase transition, the orientation of the GO layer is determined by the long-range ordering of the LC phase. As a result, the alignment effect caused by the Air-Liquid interface determines the GO alignment throughout the capillary. Our results provide useful insight into the delicate control of GO alignment in a confined space. Precise control of GO alignment in a confined space can be achieved based on the appropriate directional design of the Air-Liquid interface and the corresponding sequential phase transition.

Homomesoporous Metal-Organic Framework for High-Performance Electrochromatographic Separation.

Metal-organic frameworks (MOFs) have exhibited tremendous potential in the area of separation science. However, most of the developed MOF-based stationary phases contained only microporous structures and suffer from limited separation performance. Herein, homomesoporous MOFs with excellent mass transfer capability and strong thermodynamic interactions are first explored as the novel stationary phase for high-performance capillary electrochromatographic separations. As a proof of concept, noninterpenetrated mesoMOF-1 with uniform mesopore sizes (22.5 × 26.1 Å) and good stability was facilely grown on the inner surface of capillaries and applied as a homomesoporous MOF coating-based stationary phase for high-efficiency electrochromatographic separation. Seven types of analytes with different molecular dimensions were all baseline separated on a mesoMOF-1 coated column with high theoretical plate numbers and excellent repeatability, exhibiting significantly improved separation selectivity and column efficiency in comparison to a microporous HKUST-1 coated column. The maximum column efficiencies of the mesoMOF-1 coated column for substituted benzenes and halobenzenes reached up to 1.4 × 105 plates/m, and its mass loadability was also much higher than that of the HKUST-1 coated column. In addition, based on the analysis of adsorption kinetics and chromatographic retention behaviors, the interaction and retention mechanisms of different molecular-weight analytes on mesoMOF-1 coated stationary phases were systematically explored and disclosed in detail. These results indicate that the homomesoporous MOF-based stationary phase can effectively balance the kinetic diffusion (mass transfer capability) and thermodynamic interactions (the strength of adsorption interaction), having great potential for high-performance chromatographic separation.

Preparation and Evaluation of 2 m Long Open Tubular Capillary Columns of 50 μm Internal Diameter for Separation of Peptides in Liquid Chromatography

A 2 m long open tubular column with a copolymer layer fabricated on the inner surface of silica capillary of 50 μm id has been prepared. A ligand with a terminal halogen was bound to the capillary inner surface via silanol-isocyanate reaction and an initiator moiety was introduced by reacting with the terminal halogen. Then a thick layer of linear copolymer chains was generated on the inner surface of capillary by reversible addition-fragmentation transfer polymerization of styrene and N-phenyl acrylamide. The resultant open tubular column exhibited a remarkably high separation efficiency for the separation of a synthetic mixture of five peptides in liquid capillary chromatography (in the pressure mode). The effect of monomer mixing ratio (styrene versus N-phenyl acrylamide) on the chromatographic separation efficiency has been studied. The column prepared with the optimum mixing ratio produced the number of theoretical plates (N) of 391,200 per column under the optimized elution pressure. The column to column repeatability estimated as relative standard deviation in plate count, retention factor, asymmetry factor, and resolution was found better than 3.0%.

Covalent Biofunctionalization of the Inner Surfaces of a Hollow-Fiber Capillary Bundle Using Packed-Bed Plasma Ion Implantation.

Hollow-fiber capillary bundles are widely used in the production of medical devices for blood oxygenation and purification purposes such as in cardiopulmonary bypass, hemodialysis, and hemofiltration, but the blood interfacing inner surfaces of these capillaries provide poor hemocompatibility. Here, we present a novel method of packed-bed plasma ion implantation (PBPII) for the modification of the inner surfaces of polymeric hollow-fiber bundles enclosed in a cassette. The method is simple and can be performed on an intact hollow-fiber bundle cassette by the placement of a hollow cylindrical electrode, connected to a negative high-voltage pulse generator, around the cassette. The method does not require the insertion of electrodes inside the capillaries or the cassette. Nitrogen gas is fed into the capillaries inside the cassette by connecting the inlet of the cassette to a gas source. Upon the application of negative high-voltage bias pulses to the electrode, plasma is ignited inside the cassette, achieving the surface modification of both the internal and external surfaces of the capillaries. Fourier transform infrared-attenuated total reflectance spectroscopy of the PBPII-treated capillaries revealed the formation of aromatic C═C bonds, indicating the progressive carbonization of the capillary surfaces. The PBPII treatment was found to be uniform along the capillaries and independent of the radial position in the cassette. Atomic force microscopy of cross sections through the capillaries revealed that the increased stiffness associated with the carbonized layer on the inner surface of the PBPII-treated capillary has a depth (∼40 nm) consistent with that expected for ions accelerated by the applied bias voltage. The modified internal surfaces of the capillary bundle showed a greatly increased wettability and could be biofunctionalized by covalently immobilizing protein directly from the buffer solution. The direct, reagent-free protein immobilization was demonstrated using tropoelastin as an example protein. Covalent binding of the protein was confirmed by its resistance to removal by hot sodium dodecyl sulfate detergent washing, which is known to disrupt physical binding.

A novel diazoresin/polystyrene-poly(ethylene oxide) covalent capillary coating for the analysis of proteins by capillary electrophoresis

A novel method for the preparation of covalently linked capillary coatings of polystyrene-poly (ethylene oxide) (PS-PEO) was demonstrated by using photosensitive diazoresin (DR) as coupling agents. Layer by layer (LBL) self-assembly membrane of DR and PS-PEO based on hydrogen bonding firstly was fabricated on the inner wall of capillary, then with the treatment of UV light through the unique photochemistry reaction of DR, the hydrogen bonding was converted into covalent bonding. The covalently bonded coatings have the ability of inhibiting protein adsorption on the inner surface of capillary, and thus a baseline separation of Lysozyme (Lys), cytochrome c (Cyt-c), bovine serum albumin (BSA), ribonuclease A (RNase A) and myoglobin (Mb) was achieved by using capillary electrophoresis (CE). Compared with bare capillary or non-covalently bonded DR/PS-PEO coatings, the covalently linked DR/PS-PEO capillary coatings improved the CE separation performance for proteins; what’s more, it exhibited good stability and repeatability. This method can provide a green and easy way to make the covalently coated capillaries for CE, replacing of the old way which using highly toxic and moisture sensitive silane coupling agent by DR in the covalent coating preparation.

Preparation of hydroxypropyl cellulose-poly (2-Methacryloyloxyethyl phosphorylcholine) coating for the analysis of proteins by capillary electrophoresis

We reported a new method for preparing coated capillaries in this paper. First, we combined hydroxypropyl cellulose (HPC) and 2-Methacryloyloxyethyl phosphorylcholine (MPC) to form hydroxypropyl cellulose-poly (2-Methacryloyloxyethyl phosphorylcholine) (HPC-PMPC) by atom transfer radical polymerization (ATRP). Then the photosensitive polymer diazoresin (DR) was used as a linker to the inner wall of the capillary, and finally exposed to ultraviolet light to form a stable covalent bond coating. Protein adsorption on the inner surface of capillary was effectively inhibited. The cytochrome c (Cyt-c), lysozyme (Lys), ribonuclease A (RNase A) and bovine serum albumin (BSA) were separated obviously using capillary electrophoresis (CE) within 15 minutes and showed good stability and repeatability.

Preparation of diazoresin/graphene oxide covalent coated capillary for separation of proteins by capillary electrophoresis

Protein adsorption on the inner surface of capillary is the main reason for the poor separation performance of capillary electrophoresis. Currently, many ways have been reported to inhibit protein adsorption, while they have numerous disadvantages, such as complicated, toxic and unstable. Here, by using photosensitive diazoresin (DR) as coupling agents and graphene oxide (GO) as coating, we found a simple, economic and environmental friendly approach to inhibit protein adsorption. Through layer by layer (LBL) self-assembly technique and unique photochemistry reaction of DR, a stable and efficient capillary coating could be obtained. The bare capillary, non-covalently GO coated capillary and covalently GO coated capillary were all characterized. Results indicated that the DR/GO covalently linked capillary coatings showed great separation performance of proteins with excellent stability and repeatability. Compared with bare capillary and non-covalent, better separation efficiency was achieved by covalent GO capillary column.

Quantitative analysis of liquid crystal-based immunoassay using rectangular capillaries as sensing platform.

In past studies, liquid crystal (LC)-based immunoassays were accomplished by fabricating an LC cell with two pieces of glass slides after immunobinding, which makes the determination of the immunoassay not in real-time and requires trained personnel. Herein, we developed the LC-based immunoassay by using rectangular capillaries as the substrate for immunobinding. The inner surface of rectangular capillaries was decorated with a long alkyl saline, dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP), followed by immobilization of human serum albumin (HSA) as the probe. In this situation, the orientation of LC was homeotropic and dark LC image was observed under polarized light. When the solution containing anti-human serum albumin (anti-HSA) were dispensed into the capillary through capillary action, the specific immunobinding between HSA and anti-HSA formed an immunocomplex on the inner surface of capillary, which disrupted the original orientation of LC and led to a dark-to-bright transition of the LC images. The quantification of anti-HSA can be achieved by measuring the length of the bright LC image in the rectangular capillary. By using this immunoassay, the limit of detection (LOD) for anti-HSA is 1 μg/mL, and it did not respond to HSA and anti-human immunoglobulin G (anti-h-IgG). On the other hand, the diversity of the LC-based immunoassay can be extended for HSA detection when we immobilized anti-HSA in the capillary. Because the post-fabrication of LC cell was waived by using rectangular capillaries to develop the LC-based immunoassay, it is more convenient for users to handle and collect more reliable data. Moreover, the results of the immunoassay were visualized through naked-eye and could be recorded by a smartphone; it is more suitable for portable and point-of-care applications.

Using open-tubular capillary electrochromatography with part-coating column for binding constants determination of β2 -adrenergic receptor with seven drugs.

An open-tubular capillary electrochromatography method has been developed for the determination of binding constants between β2 -adrenergic receptor (β2 -AR) and seven drugs. β2 -AR was oriented immobilized onto one part of inner surface of capillary via microwave-assisted technical synthesis. According to the linear relationship between coating length and the apparent mobility of analyte, the binding constant (Kb ) can be obtained by related theories and equations. The order of Kb values between drugs such as adrenaline hydrochloride, norepinephrine bitartrate, and propranolol hydrochloride with β2 -AR is well consistent with that reported in the literature. By the method, Kb values between four extracts of Radix Paeoniae Rubra and β2 -AR were also successfully obtained. Subsequently, computer models were applied to interpret the CEC experiments. And the results proved to be in good agreement with the method. The work, herein, demonstrates the potential of the method in drug-receptor affinity interactions evaluation and screening of lead compounds from natural sources.

Substantiation of the mechanism of interaction between the carbohydrates of rye­wheat flour and nanoparticles of the polyfunctional food additive "Magnetofооd"

Moisture-retaining capacity (MRC) is one of the most important functional-technological properties. The food additive Magnetofood produces a comprehensive effect, including MRC. That explains the importance of studying the MRC mechanism of Magnetofood. We have established the mechanism of interaction between nanoparticles (NP) of the food additive Magnetofood and the functional groups of biopolymers of the carbohydrate complex of rye-wheat flour. A cluster-capillary MRC model of Magnetofood with dough carbohydrates is proposed. Water molecules are initially adsorbed, particularly at the surface of starch grains and in micro capillaries. The Magnetofood NP, due to their nano dimensions, active and ionized surface, biocompatibility with the polymeric molecules of carbohydrates, easily penetrate their pores (micro-capillaries). The Magnetofood NP possess a high chemical potential; they, consequently, activate, for example, the surface of starch grains and the inner surface of capillaries. The nanoparticles of Magnetofood form complexes with the ОН-groups and ether of oxygen of amylose and amylopectin of starch through coordination bonds. There emerge the supramolecular ensembles Magnetofood-carbohydrate of the cluster type. The Magnetofood NP electrostatically interact also with the dipoles of water. Strong aqua complexes thereby form. The Н2О molecules then penetrate the least organized sections of chains of polysaccharide macromolecules. They are retained there by the hydrogen bonds with the Magnetofood dipoles and the ionogenic groups of carbohydrates: atoms of hydrogen and oxygen of the ОН-groups of D- glucopyranose residues. Aqua complexes form around the Magnetofood NP; solvato associates form in the clusters. Polymer chain diverge thereby improving the penetration of Н2О dipoles inside the carbohydrate. Such water absorption weakens the intra-macro-molecular bonds in the dense layers of the polysaccharide and contributes to the penetration of moisture inside. We have experimentally determined that the food additive Magnetofood produces a comprehensive effect: sorption, complexing, moisture- and fat-retaining. That leads to an increase in yield and improves quality of bakery products. In this context, the research results are of interest not only for Ukraine but also for the scientific community in other countries.

A covalent capillary coating of diazoresin and polyglycerol dendrimer for protein analysis using capillary electrophoresis.

Overcoming proteins adsorption on the inner surface of capillary has attracted increasing attention recently. By using the unique photochemistry reaction of diazoresin (DR), a new covalent capillary coating was prepared on the fused-silica capillary through layer-by-layer self-assembly of DR with polyglycerol (PG) dendrimer. The separation performance of covalently DR/PG-dendrimer coated capillary noticeably exceeded the bare capillary and the noncovalently linked DR/PG-dendrimer capillary. A baseline separation of lysozyme, myoglobin, bovine serum albumin, and ribonuclease A was achieved using CE within 20min. Besides, the covalently linked DR/PG-dendrimer coating has the remarkable stability and reproducibility. Especially, compared with the traditional method which use highly toxic and moisture-sensitive silane coupling agent, this method seems to be a simple and environmental friendly way to prepare the covalently coated capillaries for CE.

Preparation of polydopamine-hyaluronic acid capillary coating for the analysis of proteins by capillary electrophoresis

ABSTRACTA novel method to prepare capillary coatings using dopamine (DA) and hyaluronic acid (HA) was mentioned in this paper. Firstly, dopamine was oxidized to form polydopamine and attached to the inner wall of the capillary spontaneously. HA attached to the polydopamine by electrostatic interaction to form a polydopamine-hyaluronic acid (PDA-HA) coating. Protein adsorption on the inner surface of capillary was suppressed, and the proteins of lysozyme (Lys), cytochrome c (Cyt-c), bovine serum albumin (BSA) and ribonuclease A (RNase A) were baseline separated obviously using capillary electrophoresis (CE) within 20 minutes.

Poly(glycidyl methacrylate) nanoparticle-coated capillary with oriented antibody immobilization for immunoaffinity in-tube solid phase microextraction: Preparation and characterization

A combination between modification with nanoparticles (NP) and oriented antibody immobilization (OAI) on the inner face of capillary was for the first time developed for immunoaffinity in-tube solid-phase microextraction (SPME) to promise high antigen extraction capacity. β2-microglobin (β2MG) and cystatin C (Cys-C) were selected as model antigens. Poly(glycidyl methacrylate) (PGMA) NPs were chemically immobilized onto the capillary by a ring-opening reaction. Antibodies for β2MG and Cys-C were immobilized on the NPs through OAI. Scanning electron micrograph of the OAI capillary clearly showed that the PGMA NPs were coated onto the inner surface of capillary in a dense monolayer. In addition, random antibody immobilized (RAI) capillaries and OAI capillaries without NP were also prepared as controls. The extraction capacities of OAI capillaries were 2.02 and 2.18mgm−1 for β2MG and Cys-C, and were about 5 and 6 times as many as RAI capillaries and OAI capillaries without NP, respectively. The resultant capillaries were used as in-tube SPME materials to enrich β2MG and Cys-C for particle-enhanced turbidimetric immunoassay. When using 1.0mgL−1 standard solutions, the recoveries of OAI capillaries, RAI capillaries and OAI capillaries without NP were 103.6% and 96.8%, 48.5% and 31.5%, and 24.2% and 25.7% for β2MG and Cys-C, respectively. Furthermore, the method quantitation limit by OAI capillaries was 5 and 10 times lower than that by RAI capillaries and OAI capillaries without NP, respectively. This result indicated that the NP-coated capillaries with OAI are more suitable for using as immunoaffinity in-tube SPME materials than that with RAI.

Open tubular capillary column of 50μm internal diameter with a very high separation efficiency for the separation of peptides in CEC and LC.

A specially designed long open tubular capillary column (50μm internal diameter and 112cm effective length) was prepared by fabrication of a thin three-component co-polymer layer on the inner surface of silica capillary. A pretreated silica capillary was reacted with 4-(chloromethyl)phenyl isocyanate in the presence of dibutyltin dichloride as catalyst followed by sodium diethyl dithiocarbamate. Then a thin polymer layer was made on the inner surface of capillary by reversible addition-fragmentation transfer polymerization of styrene, N-phenylacrylamide, and methacrylic acid. A carefully adjusted formulation of reaction mixture and elaborated procedures were adopted to secure formation of the co-polymer layer of enhanced separation performance. The co-polymer immobilized open tubular capillary column was used for the separation of a synthetic mixture of five peptides and excellent separation efficiency (over 1.7 million per column) was obtained in the capillary electrochromatography mode. Such excellent separation efficiencies of ca. 1m column have not been obtained in the isocratic elution mode so far. The column was also used for separation of the peptides in the liquid chromatography mode to show very good separation efficiency (average 286 700 per column).

Polydopamine-assisted immobilization of zeolitic imidazolate framework-8 for open-tubular capillary electrochromatography.

In this work, we developed a capillary column modified with zeolitic imidazolate framework-8 as a novel stationary phase for open-tubular capillary electrochromatography. To immobilize zeolitic imidazolate framework-8 onto the inner surface of silica capillary, a bio-inspired polydopamine functionalization was used to functionalize the capillary surface with polydopamine. First, a polydopamine layer was assembled inside the capillary. Second, due to noncovalent adsorption and covalent reaction ability, polydopamine could attract and anchor zeolitic imidazolate framework-8 onto the inner surface of capillary. It has been demonstrated that zeolitic imidazolate framework-8 was successfully grafted on the inner wall of the capillary by scanning electron microscopy, and Fourier transform infrared spectroscopy. The electro-osmotic flow characteristics of capillaries were also investigated by varying the pH value and acetonitrile content of mobile phase. The zeolitic imidazolate framework-8 coating not only increased the phase ratio of open-tubular column, but also improved the interactions between tested analytes and the stationary phase. Three groups of isomers including acidic, basic, and neutral compounds were well separated on the zeolitic imidazolate framework-8 bonded column, with theoretic plate numbers up to 1.9 × 105 N for catechol. The repeatability of the prepared columns was also studied, and the relative standard deviations for intra- and interday runs were less than 5%.

Photosensitive diazotized poly(ethylene glycol) covalent capillary coatings for analysis of proteins by capillary electrophoresis

A new method for the fabrication of covalently cross-linked capillary coatings of poly(ethylene glycol) (PEG) is described using diazotized PEG (diazo-PEG) as a new photosensitive coating agent. The film of diazo-PEG depends on ionic bonding and was first prepared on the inner surface of capillary by self-assembly, and ionic bonding was converted into covalent bonding after reaction of ultraviolet light with diazo groups through unique photochemical reaction. The covalently bonded coating impedance adsorption of protein on the central surface of capillary and hence the four proteins ribonuclease A, cytochrome c, bovine serum albumin, and lysosome can be baseline separated by using capillary electrophoresis (CE). The covalently cross-linked diazo-PEG capillary column coatings not only improved the CE separation performance for proteins compared to non-covalently cross-linked coatings or bare capillary but also showed a remarkable chemical solidity and repeatability. Because photosensitive diazo-PEG took the place of the highly noxious and silane moisture-sensitive coating reagents in the fabrication of covalent coating, this technique shows the advantage of being environment-friendly and having a high efficiency for CE to make the covalently bonded capillaries.

Self-assembled and covalently linked capillary coating of diazoresin and cyclodextrin-derived dendrimer for analysis of proteins by capillary electrophoresis

Self-assembled and covalently linked capillary coatings of cyclodextrin-derived (CD) dendrimer were prepared using photosensitive diazoresin (DR) as a coupling agent. Layer by layer (LBL) self-assembled DR/CD-dendrimer coatings based on ionic bonding was fabricated first on the inner surface of capillary, and subsequently converted into covalent bonding after treatment with UV light through a unique photochemistry reaction of DR. Protein adsorption on the inner surface of capillary was suppressed by the DR/CD-dendrimer coating, and thus a baseline separation of lysozyme (Lys), myoglobin (Mb), bovine serum albumin (BSA) and ribonuclease A (RNase A) was achieved using capillary electrophoresis (CE). Compared with the bare capillary, the DR/CD-dendrimer covalently linked capillary coatings showed excellent protein separation performance with good stability and repeatability. Because of the replacement of highly toxic and moisture sensitive silane coupling agent by DR in the covalent coating preparation, this method may provide an environmentally friendly and simple way to prepare the covalently coated capillaries for CE.

Evaluation of affinity interaction between small molecules and platelets by open tubular affinity capillary electrochromatography.

In this paper, an open tubular affinity capillary electrochromatography (OT-ACEC) was developed by physical adsorption of rabbit platelets on the inner surface of capillary. The interactions between small molecules include adenosine diphosphate (ADP) (positive control), protocatechuic acid (negative control) and seven natural products (salvianolic acid B, salvianic acid A sodium, hydroxysafflor yellow A, ferulic acid, chlorogenic acid, sinapic acid, caffeic acid) and platelets were evaluated by their retention factors and binding constants obtained based on peak-shift assay. Then, the activities of anti-platelet aggregation induced by thrombin (THR), ADP and arachidonic acid (AA) for those small molecules (except ADP) were evaluated by turbidimetric method. The results indicate that: (i) ADP, a platelet aggregation inducer, had strong interaction with platelet, while protocatechuic acid that had no inhibition on platelet aggregation behaved no specific interaction; (ii) there was a positive correlation between the anti-platelet aggregation activities of small molecules and their interactions with platelet, generally those compounds with higher binding constants with platelet exhibited higher activities. Therefore, the OT-ACEC method developed in the present study can be a potential method to evaluate affinity interactions between small molecules and platelets, so as to predict the biological activities such as anti-platelet aggregation for the small molecules.

Open tubular capillary electrochromatography with an N-phenylacrylamide-styrene copolymer-based stationary phase for the separation of anomers of glucose and structural isomers of maltotriose.

A ligand with a terminal halogen (4-chloromethylphenyl isocyanate) was chemically bound on the inner surface of pretreated silica capillary with 50 μm internal diameter and 58 cm total and 50 cm effective length in the presence of dibutyl tin dichloride as a catalyst through isocyanate-hydroxyl reaction. Attachment of initiator (sodium diethyl dithiocarbamate) to the bound ligand was carried out and followed by in situ polymerization. Reversible addition-fragmentation chain transfer polymerization was used for the immobilization of N-phenylacrylamide-styrene copolymer on the inner surface of capillary column. The resultant open tubular column showed excellent separation performance for derivatized saccharide isomers in capillary electrochromatography. D-Glucose was separated into α- and β-anomers while five structural isomers were separated for derivatized maltotriose with separation efficiency above one million theoretical plates per meter. The effects of pH and acetonitrile composition on the electrochromatographic performance of the derivatized saccharides were studied and the optimized elution condition was found to be 90:10 v/v% acetonitrile/30 mM sodium acetate at pH 6.6. UV absorption at 214 nm was used as detection mode in open tubular capillary electrochromatography separations.

Room temperature fabrication of post-modified zeolitic imidazolate framework-90 as stationary phase for open-tubular capillary electrochromatography

Metal–organic frameworks (MOFs) are attractive as porous stationary phase for open-tubular capillary electrochromatography (OT-CEC) due to their fascinating structures and unusual properties. Here we report a directly covalent bonding approach to prepare uniform and dense MOF film on the inner wall of fused silica capillary at room temperature for OT-CEC. Zeolitic imidazolate framework-90 (ZIF-90) as a model MOF because it not only possesses large surface area and high stability but also provides the free aldehyde groups to bond to the inner surface of capillary via covalent bond. X-ray diffraction, scan electron microscopy, and UV–vis spectrophotometry were used to confirm the bonding of the ZIF-90 to the inner wall of the silica capillary. The ZIF-90 coating not only increased the phase ratio of open-tubular column, but also improved the interactions of tested analytes and the coating. Owing to the porous structure of ZIF-90 and hydrophobic interactions between the analytes and the organic ligands of ZIF-90, three groups of isomers, neutral and basic compounds and nonsteroidal anti-inflammatory drugs were well separated on the ZIF-90 bonded column. The precisions (relative standard deviation, RSD) of retention time, half peak width and peak area for three consecutive runs were 0.3–1.2%, 1.3–6.0% and 1.5–5.2%, respectively. The run-to-run, day-to-day, and column-to-column precisions (RSDs) for the electroosmotic flow of the ZIF-90 bonded column were 0.2%, 0.4%, and 1.9%, respectively. Moreover, the ZIF-90 bonded column could stand more than 230 runs without observable change in the separation efficiency.