| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- He, M., et al.
(författare)
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A versatile approach towards multi-functional surfaces via covalently attaching hydrogel thin layers
- 2016
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Ingår i: Journal of Colloid and Interface Science. - : Academic Press. - 0021-9797 .- 1095-7103. ; 484, s. 60-69
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a robust and straightforward method to covalently attach multi-functional hydrogel thin layers onto substrates was provided. In our strategy, double bonds were firstly introduced onto substrates to provide anchoring points for hydrogel layers, and then hydrogel thin layers were prepared via surface cross-linking copolymerization of the immobilized double bonds with functional monomers. Sulfobetaine methacrylate (SBMA), sodium allysulfonate (SAS), and methyl acryloyloxygen ethyl trimethyl ammonium chloride (METAC) were selected as functional monomers to form hydrogel layers onto polyether sulfone (PES) membrane surfaces, respectively. The thickness of the formed hydrogel layers could be controlled, and the layers showed excellent long-term stability. The PSBMA hydrogel layer exhibited superior antifouling property demonstrated by undetectable protein adsorption and excellent bacteria resistant property; after attaching PSAS hydrogel layer, the membrane showed incoagulable surface property when contacting with blood confirmed by the activated partial thromboplastin time (APTT) value exceeding 600 s; while, the PMETAC hydrogel thin layer could effectively kill attached bacteria. The proposed method provides a new platform to directly modify material surfaces with desired properties, and thus has great potential to be widely used in designing materials for blood purification, drug delivery, wound dressing, and intelligent biosensors.
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| 3. |
- He, Min, et al.
(författare)
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Super-Anticoagulant Heparin-Mimicking Hydrogel Thin Film Attached Substrate Surfaces to Improve Hemocompatibility
- 2017
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Ingår i: Macromolecular Bioscience. - : WILEY-V C H VERLAG GMBH. - 1616-5187 .- 1616-5195. ; 17:2
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Tidskriftsartikel (refereegranskat)abstract
- In this study, heparin-mimicking hydrogel thin films are covalently attached onto poly(ether sulfone) membrane surfaces to improve anticoagulant property. The hydrogel films display honeycomb-like porous structure with well controlled thickness and show long-term stability. After immobilizing the hydrogel films, the membranes show excellent anticoagulant property confirmed by the activated partial thromboplastin time values exceeding 600 s. Meanwhile, the thrombin time values increase from 20 to 61 s as the sodium allysulfonate proportions increase from 0 to 80 mol%. In vitro investigations of protein adsorption and blood-related complement activation also confirm that the membranes exhibit super-anticoagulant property. Furthermore, gentamycin sulfate is loaded into the hydrogel films, and the released drug shows significant inhibition toward E. coli bacteria. It is believed that the surface attached heparin-mimicking hydrogel thin films may show high potential for the applications in various biological fields, such as blood contacting materials and drug loading materials.
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| 4. |
- Shi, Wenbin, et al.
(författare)
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Redox-responsive polymeric membranes via supermolecular host-guest interactions
- 2015
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 480, s. 139-152
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Tidskriftsartikel (refereegranskat)abstract
- Redox-responsive materials have attracted much attention, and redox-responsive membrane is strongly desired since enormous numbers of redox reactions carry out in living systems. Herein, a novel polymeric membrane with redox-resposive hydraulic permeability is fabricated by introducing a reversible redox-responsive system based on the host guest complex between ferrocene (Fc) and beta-cyclodextrin (1 CD) into polyethersulfone (PES) membrane. As the result of reversible radox-responsive formation or deformation of the complex, the water flux for the membrane with 18.3 wt% redox-responsive materials was 270 mL/m(2) mmHg h in original state, while increased to 1022 mL/m(2) mmHg h in oxidation state and decreased to 538 mL/m(2) mmHg h in reduction state. In addition, the results of water contact angle, surface zeta potential and the gas flow/liquid displacement confirmed that the origin of the reclox-responsive hydraulic permeability were the change of the pore size and porosity for the modified membranes. The redox-responsive membranes have great potential to be utilized in the Fields of chemical detection, drug delivery, biological treatments and so On.
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| 5. |
- Sun, C., et al.
(författare)
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A facile approach toward multifunctional polyethersulfone membranes via in situ cross-linked copolymerization
- 2015
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Ingår i: Journal of Biomaterials Science. Polymer Edition. - : Taylor & Francis. - 0920-5063 .- 1568-5624. ; 26:15, s. 1013-1034
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Tidskriftsartikel (refereegranskat)abstract
- In this study, multifunctional polyethersulfone (PES) membranes are prepared via in situ cross-linked copolymerization coupled with a liquid-liquid phase separation technique. Acrylic acid (AA) and N-vinylpyrrolidone (VP) are copolymerized in PES solution, and the solution is then directly used to prepare PES membranes. The infrared and X-ray photoelectron spectroscopy testing, scanning electron microscopy, and water contact angle measurements confirm the successful modification of pristine PES membrane. Protein adsorption, platelet adhesion, plasma recalcification time, and activated partial thromboplastin time assays convince that the modified PES membranes have a better biocompatibility than pristine PES membrane. In addition, the modified membranes showed good protein antifouling property and significant adsorption property of cationic dye. The loading of Ag nanoparticles into the modified membranes endows the composite membranes with antibacterial activity.
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| 6. |
- Xiang, T., et al.
(författare)
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Zwitterionic polymer functionalization of polysulfone membrane with improved antifouling property and blood compatibility by combination of ATRP and click chemistry
- 2016
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Ingår i: Acta Biomaterialia. - : Elsevier. - 1742-7061 .- 1878-7568. ; 40, s. 162-171
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Tidskriftsartikel (refereegranskat)abstract
- The chemical compositions are very important for designing blood-contacting membranes with good antifouling property and blood compatibility. In this study, we propose a method combining ATRP and click chemistry to introduce zwitterionic polymer of poly(sulfobetaine methacrylate) (PSBMA), negatively charged polymers of poly(sodium methacrylate) (PNaMAA) and/or poly(sodium p-styrene sulfonate) (PNaSS), to improve the antifouling property and blood compatibility of polysulfone (PSf) membranes. Attenuated total reflectance-Fourier transform infrared spectra, X-ray photoelectron spectroscopy and water contact angle results confirmed the successful grafting of the functional polymers. The antifouling property and blood compatibility of the modified membranes were systematically investigated. The zwitterionic polymer (PSBMA) grafted membranes showed good resistance to protein adsorption and bacterial adhesion; the negatively charged polymer (PNaSS or PNaMAA) grafted membranes showed improved blood compatibility, especially the anticoagulant property. Moreover, the PSBMA/PNaMAA modified membrane showed both antifouling property and anticoagulant property, and exhibited a synergistic effect in inhibiting blood coagulation. The functionalization of membrane surfaces by a combination of ATRP and click chemistry is demonstrated as an effective route to improve the antifouling property and blood compatibility of membranes in blood-contact.
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| 7. |
- Zhang, Man, et al.
(författare)
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Multi-responsive, tough and reversible hydrogels with tunable swelling property
- 2017
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Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 322, s. 499-507
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Tidskriftsartikel (refereegranskat)abstract
- A novel family of multi-responsive, tough, and reversible hydrogels were prepared by the combination of dipole-dipole interaction, hydrogen bonding interaction and slightly chemical cross-linking, using monomers of acrylonitrile, sodium allylsulfonate and itaconic acid. Reversible gel-sol transition was achieved by the flexible conversion of the dipole-dipole interactions between acrylonitrile-acrylonitrile and acrylonitrile-sodium thiocyanate, and the hydrogels could freely form desired shapes. The dipole dipole and hydrogen bonding interactions improved the mechanical strength of the hydrogels with a compressive stress of 2.38 MPa. Meanwhile, the hydrogels sustained cyclic compressive tests with 60% strain, and exhibited excellent elastic property. The hydrogels were sensitive to pH and ionic strength, and could keep their perfect spherical structures without any obvious cracks even after immersing in strong ionic strength (or pH) solution for several reversible cycles. Furthermore, the hydrogels were recycled for environmental pollution remediation, and showed great potential to be applied in water treatments and other related fields.
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| 8. |
- Zhang, Xiang, et al.
(författare)
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Graphene oxide-based polymeric membranes for broad water pollutant removal
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 5:122, s. 100651-100662
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Tidskriftsartikel (refereegranskat)abstract
- Graphene oxide (GO) and its derivatives display excellent removal abilities of water contaminants; however, the complex preparation process of GO-based adsorbents and difficult collection of GO sheets during the adsorption process limit their practical applications. Hence, three kinds of GO-based polymeric membranes with specific adsorption characteristics were fabricated by a facile blending method, including GO/PES membrane, reduced GO (RGO)/PES membrane, and polyethyleneimine (PEI) coated GO membrane of GO@PEI/PES membrane. The GO/PES membrane exhibited selective adsorption for cationic dyes, the RGO/PES membrane exhibited selective adsorption for endocrine disruptors, and the GO@PEI/PES membrane exhibited selective adsorption for anionic dyes. The adsorption data fitted the pseudo-second-order kinetic model and the Langmuir isotherm well, and the adsorption process was controlled by the interparticle diffusion. The thermodynamic studies indicated that the adsorption reactions were spontaneous and exothermic processes. The dynamic adsorption results indicated that the prepared membranes could be used in wastewater filtration. The study indicated that GO-based polymeric membranes with broad water pollutant removal could be fabricated by facile strategies, and the problem of difficult collection of GO sheets during and after adsorption process was solved.
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| 9. |
- Zhao, Weifeng, et al.
(författare)
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A recyclable and regenerable magnetic chitosan absorbent for dye uptake
- 2016
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 150, s. 201-208
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Tidskriftsartikel (refereegranskat)abstract
- A recyclable and regenerable magnetic polysaccharide absorbent for methylene blue (MB) removal was prepared by coating magnetic polyethyleneimine nanoparticles (PEI@MNPs) with sulfonated chitosan (SCS) and further cross -linked with glutaraldehyde. The driving force for coating is the electrostactic interaction between positively charged PEI and negatively charged SCS. Infrared spectra, zeta potential, thermal gravimetric analysis and X-ray diffraction demonstrated the successful synthesis of magnetic polysaccharide absorbent. The self-assembly of polysaccharide with magnetic nanopartices did not alter the saturation magnetization value of the absorbent confirmed by vibrating sample magnetometer. The nanoparticles showed fast removal (about 30 min reached equilibrium) of MB. In particular, the removal ability of MB after desorption did not reduce, demonstrating an excellent regeneration ability. Our study provides new insights into utilizing polysaccharides for environmental remediation and creating advanced magnetic materials for various promising applications.
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| 10. |
- Zhao, Weifeng, et al.
(författare)
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In Situ Cross-Linking of Stimuli-Responsive Hemicellulose Microgels during Spray Drying
- 2015
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:7, s. 4202-4215
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Tidskriftsartikel (refereegranskat)abstract
- Chemical cross-linking during spray drying offers the potential for green fabrication of microgels with a rapid stimuli response and good blood compatibility and provides a platform for stimuli-responsive hemicellulose microgels (SRHMGs). The cross-linking reaction occurs rapidly in situ at elevated temperature during spray drying, enabling the production of microgels in a large scale within a few minutes. The SRHMGs with an average size range of similar to 1-4 mu m contain O-acetyl-galactoglucomannan as a matrix and poly(acrylic acid), aniline pentamer (AP), and iron as functional additives, which are responsive to external changes in pH, electrochemical stimuli, magnetic field, or dual-stimuli. The surface morphologies, chemical compositions, charge, pH, and mechanical properties of these smart microgels were evaluated using scanning electron microscopy, IR, zeta potential measurements, pH evaluation, and quantitative nanomechanical mapping, respectively. Different oxidation states were observed when AP was introduced, as confirmed by UV spectroscopy and cyclic voltammetry. Systematic blood compatibility evaluations revealed that the SRHMGs have good blood compatibility. This bottom-up strategy to synthesize SRHMGs enables a new route to the production of smart microgels for biomedical applications.
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