Shu-Jing Yang

A novel diazoresin/polyethylene glycol covalent capillary coating for analysis of proteins by capillary electrophoresis

A novel method for the preparation of covalently linked capillary coatings of polyethylene glycol (PEG) was demonstrated using photosensitive diazoresin (DR) as the coupling agent. Layer by layer (LBL) self-assembly film of DR and PEG based on hydrogen bonding was first fabricated on the inner wall of capillary, then the hydrogen bonding was converted into covalent bonding after treatment with UV light through a unique photochemistry reaction of DR. The covalently bonded coatings suppressed protein adsorption on the inner surface of the capillary, and thus a baseline separation of lysozyme (Lys), cytochrome c (Cyt-c), bovine serum albumin (BSA) and ribonuclease A (RNase A) was achieved using capillary electrophoresis (CE). Compared with the bare capillary or non-covalently bonded DR/PEG coatings, the covalently linked DR/PEG capillary coatings not only improved the CE separation performance for proteins, but also exhibited good stability and repeatability. Due to the replacement of highly toxic and moisture sensitive silane coupling agents by DR in the covalent coating preparation, this method may provide a green and easy way to make the covalently coated capillaries for CE.

A novel diazoresin/poly(N‐vinyl aminobutyric acid) covalent capillary coating for the analysis of proteins by capillary electrophoresis

A novel method for the preparation of covalently linked capillary coatings of poly(N-vinyl aminobutyric acid) (PVAA) obtained from hydrolyzed polyvinylpyrrolidone was demonstrated using photosensitive diazoresin (DR) as a coupling agent. A layer-by-layer self-assembled film of DR and PVAA based on ionic bonding was first fabricated on the inner wall of capillary, then ionic bonding was converted into covalent bonding after treatment with UV light through a unique photochemical reaction of DR. The covalently bonded coatings suppressed protein adsorption on the inner surface of the capillary, and thus a baseline separation of lysozyme, cytochrome c, BSA, amyloglucosidase, and myoglobin was achieved using CE. Compared with bare capillary or noncovalently bonded DR/PVAA coatings, the covalently linked DR/PVAA capillary coatings not only improved the CE separation performance for proteins, but also exhibited good stability and repeatability. Due to the replacement of the highly toxic and moisture-sensitive silane coupling agent by DR in the covalent coating preparation, this method may provide a green and easy way to make covalently coated capillaries for CE.

Fabrication of anisotropic silica hollow microspheres using polymeric protrusion particles as templates

Anisotropic polystyrene/poly(styrene-co-divinylbenzene) (PS/P(S-DVB)) protrusion particles with various morphologies such as eyeball-like, snowman-like, and raspberry-like were synthesized using a modified seeded polymerization method by dynamically controlling and stabilizing the phase separation. The effects of swelling agent, crosslinker, and monomer concentrations on the particle morphologies were studied. Using the PS/P(S-DVB) protrusion particles as templates, anisotropic silica (SiO2) hollow microspheres were fabricated facilely. The obtained anisotropic silica hollow spheres had a potential application in rapid waste removal and detoxification extraction with a very simple procedure.

Synthesis and modification of monodisperse silica microspheres for UPLC separation of C60 and C70

Monodisperse silica microspheres with average diameters from 1 μm to 2 μm were synthesized by a modified Stober method, in which an ethanolic solution of tetraethyl orthosilicate (TEOS) was continuously supplied to the reaction mixture containing KCl electrolyte, water, ethanol and ammonia. The effects of reactant amounts, supply rate, and reaction temperature on the microsphere morphology were investigated. After surface modification with octadecyl trichlorosilane, the obtained monodisperse C18-silica microspheres with an average diameter of 1.5 μm were applied to ultra performance liquid chromatography (UPLC) separation of fullerenes. Because of having a smaller size, the 1.5 μm monodisperse C18-silica UPLC stationary phase shows ultra high efficiency compared with the commercial C18-silica HPLC stationary phase with average diameters from 5 to 50 μm.

A Recipe Research of PAN Hollow Fiber Ultrafiltration Membranes

Polyacrylonitrile (PAN) hollow fiber ultrafiltration (UF) membranes were prepared via wet spinning method using lithium chloride (LiCl) and calcium chloride (CaCl2) as pore-foaming agent. Influences of PAN, LiCl and CaCl2 contents to water flux, rejection rate, breaking strength and breaking elongation of the membrane were discussed. Results indicated that the comprehensive performance of the membrane was the best when the PAN/LiCl and PAN/CaCl2 ratios in the spinning solution equaled to 18:1.

Self-cleaning superhydrophobic coatings based on PDMS and TiO2/SiO2 nanoparticles

ABSTRACT Superhydrophobic coatings based on PDMS and TiO2-NPs/SiO2-NPs were prepared. Due to the photocatalytic property of TiO2-NPs, the PDMS/TiO2-NPs coatings could remove the organic pollutes efficiently, and showed an excellent self-cleaning properties. The superhydrophobicity of the PDMS/TiO2-NPs coatings was still remained after 6 months in the open air, which is much better than the PDMS/SiO2-NPs coatings.

Advanced Modified Polyacrylonitrile Membrane with Enhanced Adsorption Property for Heavy Metal Ions

Advanced modified polyacrylonitrile (PAN) membrane with high adsorption property for heavy metal ions was designed and fabricated for the first time. The introduced diazoresin-ethylenediaminetetraacetic acid (DR-EDTA) layer could effectively absorb the metal ion, such as Cu2+, Pb2+, Hg2+ in the waste water. The effects of layers, metal ion concentration, pH, temperature and cycle time were investigated. The results showed that the adsorption isotherms for Cu2+ were well fitted by Langmuir model. The maximum adsorption capacity of the modified membrane for Cu2+ was approximately 47.6 mg/g. In addition, the prepared PAN-(DR-EDTA)3 membrane could be regenerated more than 720 h based on their adsorption/desorption cycles. The results demonstrated that the modified PAN membrane could be used as effective adsorbents for heavy metal removal from waste water.

Preparation of Humidity-Sensitive Poly(Ethylene Glycol) Inverse Opal Micropatterns Using Colloidal Lithography

Humidity-sensitive poly(ethylene glycol) (PEG) inverse opals with micropatterns of 2 μm wide anti-swell-broken grooves were prepared using polystyrene (PS) colloidal crystals as templates and colloidal lithography. Monodisperse PS colloids were deposited in an ordered manner onto glass slides using a double-substrate vertical deposition method to form colloidal crystal templates. Poly(ethylene glycol) diacrylate (PEGDA) with photoinitiator was infiltrated into the interspaces of the colloidal crystals and photo-crosslinked by UV irradiation through a photomask. After removal the PS templates and unexposed PEGDA by tetrahydrofuran (THF), PEG hydrogel micropatterns with three-dimensional ordered porous structures were obtained. The band gaps of the PS colloidal crystals and corresponding PEG hydrogel inverse opals were measured by UV-VIS reflection spectrometer, calculated by Bragg law and simulated by Band SOLVE. The obtained PEG hydrogel inverse opal micropatterns can be used as sensors for humidity sensing due to absorption and desorption of moisture in the band gap structures. The sensor had a very reliable performance after repeated humidity sensing, and could be mass produced facilely with very low cost. The photopatterned anti-swell-broken grooves play an important role in the reliability of the sensors.

Preparation of hydrophilic polypropylene hollow fiber membranes by UV modification

abstract A polypropylene hollow fiber membrane (PPHFM) was obtained by UV grafting polyacrylic acid (PAA) on the surface. The hydrophilicity of PPHFM was improved with water contact angle reduced from 82.3° to 73.6°. The photoinitiator and monomer concentration conditions had significant effects on the grafting rates. After modification, the pure water flux decreased, but the rejection rate was improved.

Facile Preparation of Litchi-Like Polystyrene-Silica Hybrid Particles via Dispersion Polymerization

The composite particles with litchi-like morphologies attributing to the combination of inorganic silica seed and polymer nodules were synthesized successfully using a modified dispersion polymerization method. Dispersion polymerization of styrene was achieved in the presence of silica particles and the formed polystyrene nanoparticles were absorbed onto the surface of silica particles. The effects of the adding amount of St monomer on the particle morphologies was investigated.