| 1. |
- Hajizadeh, Solmaz, et al.
(författare)
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Cryogelation of molecularly imprinted nanoparticles: A macroporous structure as affinity chromatography column for removal of β-blockers from complex samples.
- 2013
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Ingår i: Journal of chromatography. A. - : Elsevier BV. - 1873-3778 .- 0021-9673. ; 1274, s. 6-12
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a new macroporous molecularly imprinted cryogel (MIP composite cryogel) was synthesized by glutaraldehyde cross-linking reaction of poly(vinyl alcohol) (PVA) particles and amino-modified molecularly imprinted core-shell nanoparticles. The MIP core-shell nanoparticles were prepared using propranolol as a template by one-pot precipitation polymerization with sequential monomer addition. The characteristics of the MIP composite cryogel were studied by scanning electron microscopy (SEM) and texture analyzer. The macroporous structure of the composite (with the pore size varying from a few micrometers to 100μm) enabled high mass transfer of particulate-containing fluids. In a solid phase extraction (SPE) process, the efficiency and selectivity of the MIP composite cryogel were investigated, where the cryogel was used as an affinity matrix to remove propranolol from aqueous solution as well as from complex plasma sample without prior protein precipitation. The MIP composite cryogel maintained high selectivity and stability and could be used repeatedly after regeneration.
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| 2. |
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| 3. |
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| 4. |
- Kamra, Tripta, et al.
(författare)
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Covalent immobilization of molecularly imprinted polymer nanoparticles on a gold surface using carbodiimide coupling for chemical sensing.
- 2016
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 461, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- One challenging task in building (bio)chemical sensors is the efficient and stable immobilization of receptor on a suitable transducer. Herein, we report a method for covalent immobilization of molecularly imprinted core-shell nanoparticles for construction of robust chemical sensors. The imprinted nanoparticles with a core-shell structure have selective molecular binding sites in the core and multiple amino groups in the shell. The model Au transducer surface is first functionalized with a self-assembled monolayer of 11-mercaptoundecanoic acid. The 11-mercaptoundecanoic acid is activated by treatment with carbodiimide/N-hydroxysuccinimide and then reacted with the core-shell nanoparticles to form amide bonds. We have characterized the process by studying the treated surfaces after each preparation step using atomic force microscopy, scanning electron microscopy, fluorescence microscopy, contact angle measurements and X-ray photoelectron spectroscopy. The microscopy results show the successful immobilization of the imprinted nanoparticles on the surface. The photoelectron spectroscopy results further confirm the success of each functionalization step. Further, the amino groups on the MIP surface were activated by electrostatically adsorbing negatively charged Au colloids. The functionalized surface was shown to be active for surface enhanced Raman scattering detection of propranolol. The particle immobilization and surface enhanced Raman scattering approach described here has a general applicability for constructing chemical sensors in different formats.
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| 5. |
- Kamra, Tripta, et al.
(författare)
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Covalent immobilization of molecularly imprinted polymer nanoparticles using an epoxy silane.
- 2015
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 445, s. 277-284
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Tidskriftsartikel (refereegranskat)abstract
- Molecularly imprinted polymers (MIPs) can be used as antibody mimics to develop robust chemical sensors. One challenging problem in using MIPs for sensor development is the lack of reliable conjugation chemistry that allows MIPs to be fixed on transducer surface. In this work, we study the use of epoxy silane to immobilize MIP nanoparticles on model transducer surfaces without impairing the function of the immobilized nanoparticles. The MIP nanoparticles with a core-shell structure have selective molecular binding sites in the core and multiple amino groups in the shell. The model transducer surface is functionalized with a self-assembled monolayer of epoxy silane, which reacts with the core-shell MIP particles to enable straightforward immobilization. The whole process is characterized by studying the treated surfaces after each preparation step using atomic force microscopy, scanning electron microscopy, fluorescence microscopy, contact angle measurements and X-ray photoelectron spectroscopy. The microscopy results show that the MIP particles are immobilized uniformly on surface. The photoelectron spectroscopy results further confirm the action of each functionalization step. The molecular selectivity of the MIP-functionalized surface is verified by radioligand binding analysis. The particle immobilization approach described here has a general applicability for constructing selective chemical sensors in different formats.
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| 6. |
- Kamra, Tripta, et al.
(författare)
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Photoconjugation of Molecularly Imprinted Polymer Nanoparticles for Surface-Enhanced Raman Detection of Propranolol
- 2015
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:49, s. 27479-27485
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Tidskriftsartikel (refereegranskat)abstract
- We report a simple and versatile method to covalently immobilize molecularly imprinted polymer (MIP) nanoparticles on a Raman active substrate (Klarite) using a disulfide-derivatized perfluorophenylazide (PFPA-disulfide). Gold-coated Klarite was functionalized with PFPA-disulfide via a gold sulfur bond. Upon light radiation, the available azido groups were converted to highly reactive singlet perfluorophenyl nitrene that undergoes a CH insertion reaction and form covalent bonds with the MIP nanoparticles. The resulting surfaces were characterized using scanning electron microscopy and surface enhanced Raman spectroscopy to study the morphology and template affinity of the surfaces, respectively. The Raman measurements clearly show a dose-responsive signal when propranolol binds to the MIP surface. Because the MIP particles were covalently attached to the Raman active substrate, the sensing surface was stable and could be reused after regeneration in acetic acid solution. The MIP-based Raman sensor was used successfully to detect propranolol in urine samples (7.7 X 10(-4) M). Our results show that the high selectivity of MLPs and the fingerprint Raman identification can be integrated into a compact sensing unit using high-efficiency photoconjugation. Thus, the method proposed is reliable, efficient and fast for fabricating label-free chemical sensors.
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| 7. |
- Shen, Xiantao, et al.
(författare)
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Imprinted polymer beads enabling direct and selective molecular separation in water
- 2012
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 8:27, s. 7169-7176
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we describe the synthesis of water-compatible Molecularly Imprinted Polymer (MIP) microspheres by nanoparticle-stabilized emulsion (Pickering emulsion) polymerization. During the polymerization, the amount of the porogen used not only affected the stability of the Pickering emulsion but also the specific molecular recognition of the obtained MIP microspheres. Under optimized conditions, the MIP microspheres synthesized had a porous and hydrophilic surface. Scanning electron microscopy and fluorescent labeling experiments indicated that the MIP microspheres had particle sizes of 165 +/- 38 mu m. Selective molecular recognition with the MIP microspheres was studied through equilibrium binding analysis and liquid chromatography experiments under pure aqueous conditions. Using the new MIP microspheres as solid phase extraction (SPE) absorbents, low concentration organic pollutants (beta-blockers) were effectively enriched from tap water and easily detected using HPLC-MS analysis.
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| 8. |
- Shen, Xiantao, et al.
(författare)
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Molecular recognition with colloidosomes enabled by imprinted polymer nanoparticles and fluorogenic boronic acid
- 2013
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Ingår i: Journal of Materials Chemistry. B. - : Royal Society of Chemistry (RSC). - 2050-7518 .- 2050-750X. ; 1:36, s. 4612-4618
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Tidskriftsartikel (refereegranskat)abstract
- Multifunctional colloidosomes are prepared from molecularly imprinted polymer nanoparticles and fluorogenic boronic acid using a Cu(I)-catalyzed click reaction. The molecular selectivity of the colloidosomes was investigated by radioligand binding analysis, which indicated that the inter-particle click reaction did not affect the molecular specificity of the MIP nanoparticles on the colloidosomes for the model template, propranolol. Besides specific molecular recognition of the MIP nanoparticles, the colloidosomes also displayed dose-dependent fluorescence response to fructose at physiological pH. Moreover, the immobilized boronic acid in the core could effectively bind isoproterenol, a template analogue containing a catecholamine moiety. The depletion of isoproterenol from solution allowed the MIP nanoparticles on the colloidosomes to bind propranolol more efficiently. The pre-designed molecular selectivity and fluorescence response of the colloidosomes are interesting for potential applications in controlled delivery, chemical sensing and bioseparation.
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| 9. |
- Shen, Xiantao, et al.
(författare)
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Molecularly Imprinted Polymers for Clean Water: Analysis and Purification
- 2013
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 52:39, s. 13890-13899
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Tidskriftsartikel (refereegranskat)abstract
- Because of their predetermined selectivity, molecularly imprinted polymers (MIPs) have been extensively investigated to offer efficient separation of organic pollutants for water analysis and purification. In this review, we first describe the current development of water compatible MIPs, and the physical encapsulation and chemical immobilization of MIP particles for practical applications related to water analysis and purification. We summarize the challenges in understanding the mechanisms in molecular imprinting, with a special emphasis on the use of nuclear magnetic resonance (NMR), dynamic light scattering (DLS), and synchronous fluorescence spectroscopy to gain theoretical insights into the molecular imprinting process. The highlighted synthetic methods and the mechanistic investigations discussed in this review should facilitate the identification of the most crucial factors affecting the applications of MIPs for clean water.
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| 10. |
- Shi, Liyang, et al.
(författare)
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Biocompatible Injectable Magnetic Hydrogel Formed by Dynamic Coordination Network
- 2019
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 11:49, s. 46233-46240
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic hydrogel that can respond to a magnetic stimulus is a promising biomaterial for tissue regeneration and cancer treatment. In this study, a novel magnetic hydrogel is formed by simply mixing bisphosphonate (BP)-modified hyaluronic acid (i.e., HA-BP) polymeric solution and iron oxide (Fe3O4) nanoparticle dispersion, in which the hydrogel networks are cross linked by BP groups and iron atoms on the surface of particle. The iron BP coordination chemistry affords a dynamic network, characterized by self-healing, shear-thinning, and smoothly injectable properties. Moreover, the HA-BP-Fe3O4 magnetic hydrogel demonstrates heat-generation characterization under an alternating magnetic field. The animal experiments confirm the biocompatibilities of HA BP center dot Fe3O4 hydrogel, which presents the hydrogels potential for tissue regeneration and anticancer treatment applications.
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| 11. |
- Wang, JunXin, et al.
(författare)
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A novel phase function describing light scattering of layers containing colloidal nanospheres
- 2019
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Ingår i: Nanoscale. - : ROYAL SOC CHEMISTRY. - 2040-3364 .- 2040-3372. ; 11:15, s. 7404-7413
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Tidskriftsartikel (refereegranskat)abstract
- Light scattering from small particles exhibit unique angular scattering distributions, which are strongly dependent on the radius to wavelength ratio as well as the refractive index contrast between the particles and the surrounding medium. As the concentration of the particles increases, multiple scattering becomes important. This complicates the description of the angular scattering patterns, and in many cases one has to resort to empirical phase functions. We have measured the angle dependence of light scattering from a polymer layer containing sub-micron metallic and dielectric particles. The samples exhibited strongly forward and backward peaked scattering patterns, which were fitted to a number of empirical approximative phase functions. We found that a novel two-term Reynolds-McCormick (TTRM) phase function gave the best fit to the experimental data in all cases. The feasibility of the TTRM approach was further validated by good agreement with numerical simulations of Mie single scattering phase functions at various wavelengths and sizes, ranging from the Rayleigh scattering regime to the geometrical optics regime. Hence, the widely adaptable TTRM approach is able to describe angular scattering distributions of different kinds of nanospheres and nanocomposites, both in the single scattering and multiple scattering regimes.
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| 12. |
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| 13. |
- Wang, JunXin, et al.
(författare)
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Extraction of Backscattering and Absorption Coefficients of Magnetite Nanosphere Composites from Light-Scattering Measurements : Implications for Optomagnetic Sensing
- 2020
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 3, s. 11172-11183
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Tidskriftsartikel (refereegranskat)abstract
- Interaction of light with magnetic nanoparticles, dispersed insolution or embedded in other materials, is of major interest in a range of applications, one example being optomagnetic sensors. In applied research, light absorption and scattering of nanoparticle composites are often quantified by the Kubelka−Munk two-flux radiative transfer model. In this paper, we synthesized magnetite (Fe3O4) nanospheres with different diameters and encapsulated them into a polymer matrix. Their spectral transmittance and reflectance were investigated by spectrophotometry, together with measurements of angle-resolved scattering in the forward and backward hemispheres. The measured angular distribution was applied to approximate the scattering-phase function inside the film, which could be well described by the revised Reynolds−McCormick model. The backscattering and absorption coefficients were derived by inversion of the Kubelka−Munk relations, using the interface reflectances obtained from angle-dependent measurements. We present detailed optical properties for samples with various particle concentrations and scattering layer thicknesses, consisting of the magnetite and polymer composites. The absorption and backscattering coefficients for particles of diameter 458 nm showed qualitative agreement with single-scattering Mie calculations. The optical properties of composites with smaller particles might beinfluenced by an oxidized Fe2O3-like surface layer. The present approach can be used to study different kinds of magnetic nanoparticle clusters, dispersed in a supporting medium, and thus provide optical parameters of relevance for interpreting results ofoptomagnetic sensing experiments.
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| 14. |
- Wang, JunXin, et al.
(författare)
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General Method for Determining Light Scattering and Absorption of Nanoparticle Composites
- 2019
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Ingår i: Advanced Optical Materials. - : Wiley-VCH Verlagsgesellschaft. - 2162-7568 .- 2195-1071. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Scattering and absorption from nanoparticles are of major importance in optical research as well as in a range of applications. The Kubelka–Munk two-flux radiative transfer model gives a simple description of light scattering in nanoparticle composite materials, but inversion of experimental transmittance and reflectance data to obtain backscattering and absorption coefficients remains challenging. Here, a general method for evaluating these parameters from transmittance and reflectance spectra, combined with spectral angle resolved light scattering measurements is developed. The angular dependence is approximatedby an extension of the empirical Reynolds–McCormick phase function, which is fitted to the experimental angle resolved light scattering data. This approach is verified by measurements on three typical nanoparticle/polymer composites containing plasmonic Au, ferromagnetic Fe3O4, and dielectric TiO2 particles. An approximation to the angular scattering pattern is further demonstrated, which can be applied to obtain the optical parameters using only reflectance and transmittance data, in cases where angle-resolved measurements are not available. These results can be extended to a wide range of isotropic, anisotropic, and multiple scattering systems, and will be highly useful in the fields of light scattering coatings/metamaterials, UV-shielding films, displays, absorption/scattering layers in solar cells and biological scatterers.
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| 15. |
- Xu, Changgang, et al.
(författare)
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Clickable molecularly imprinted nanoparticles.
- 2011
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 47, s. 6096-6098
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Tidskriftsartikel (refereegranskat)abstract
- Terminal alkynyl and azide groups are introduced on the surface of molecularly imprinted core-shell nanoparticles using precipitation polymerization. These clickable groups enable simple nanoparticle conjugation and surface modification under mild reaction conditions, opening new opportunities for nanoparticle-based assays and chemical sensing.
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| 16. |
- Xu, Changgang
(författare)
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Fabrication of Functional Molecularly Imprinted Materials using Nanoparticle Building Blocks
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Molecularly imprinted polymers (MIPs) have attracted great interest in many applications including bioseparation, chemical sensing, catalysis, drug delivery, etc. Recently, molecularly imprinted nanoparticles have become accessible due to a number of synthetic methods that have been developed. The high molecular binding selectivity, fast binding kinetics and colloidal stability make MIP nanoparticles ideal building blocks for fabrication of new multifunctional materials. As examples, magnetic susceptibility, fluorescence response, plasmonic enhancements have been integrated into MIP materials by different physical entrapments or chemical conjugation methods. In this thesis, the use of nanoparticle building blocks for preparation of functional MIP materials is studied. First, different chemical conjugation methods are investigated to allow MIP nanoparticles to be covalently linked to various materials extending from fluorescent molecules, magnetic nanoparticles, to hydrophilic cryogels. Click chemistry based on Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction and amine-glutaraldehyde crosslinking reaction are used to conjugate core-shell MIP nanoparticles with other functional components. To enable ordinary MIP nanoparticles to act as useful building blocks, a simple photo-conjugation method based on perfluorophenyl azide (PFPA) has been developed. The composite materials obtained by the different chemical conjugation methods display not only high molecular selectivity, but also additional attractive features, such as magnetic susceptibility, fluorescence response, as well as macroporous structure allowing purification of complex samples. In the second part, inorganic nanoparticles are used as surfactants to stabilize oil-in-water emulsion (Pickering emulsion) to synthesize water-compatible MIP microspheres. The new MIP material exhibits high molecular selectivity and allows direct separation of target analytes in water. The chemical conjugation methods developed in this thesis have a general applicability and should provide convenient means to developing other functional materials and devices. The use of nanoparticle surfactants in molecular imprinting has enabled direct molecular separation under pure aqueous condition. The new synthetic approach based on Pickering emulsion polymerization opens new possibilities for molecularly imprinted materials, particularly in the area of bioseparation and sensing.
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| 17. |
- Xu, Changgang, et al.
(författare)
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Feasibility of using DNA-immobilized nanocellulose-based immunoadsorbent for systemic lupus erythematosus plasmapheresis
- 2016
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 143, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- The goal of this project was to study the feasibility of using a DNA-immobilized nanocellulose-based immunoadsorbent for possible application in medical apheresis such as systemic lupus erythematosus (SLE) treatment. Calf thymus DNA was bound to high surface area nanocellulose membrane at varying concentrations using UV-irradiation. The DNA-immobilized samples were characterized with scanning electron microscopy, atomic force microscopy, and phosphorus elemental analysis. The anti-ds-DNA IgG binding was tested in vitro using ELISA. The produced sample showed high affinity in vitro to bind anti-ds-DNA-antibodies from mice, as much as 80% of added IgG was bound by the membrane. Furthermore, the binding efficiency was quantitatively dependent on the amount of immobilized DNA onto nanocellulose membrane. The described nanocellulose membranes are interesting immunoadsorbents for continued clinical studies.
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| 18. |
- Xu, Changgang, et al.
(författare)
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Molecularly imprinted magnetic materials prepared from modular and clickable nanoparticles
- 2012
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 1364-5501 .- 0959-9428. ; 22:15, s. 7427-7433
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Tidskriftsartikel (refereegranskat)abstract
- We report a new strategy toward construction of functional composite materials for fast molecular separation. Molecularly imprinted nanoparticles containing surface-exposed alkyne groups were synthesized by one-pot precipitation polymerization. Magnetic Fe3O4 nanoparticles were first coated with a silica shell, and then modified with terminal azide groups. The two types of clickable nanoparticles were conjugated through a Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to give composite magnetic particles, which displayed high molecular recognition selectivity and could be easily separated using a simple magnet.
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| 19. |
- Xu, Changgang, et al.
(författare)
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Photoconjugation of Molecularly Imprinted Polymer with Magnetic Nanoparticles.
- 2013
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 5:11, s. 5208-5213
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Tidskriftsartikel (refereegranskat)abstract
- Because of their synthetic accessibility, molecularly imprinted polymer (MIP) nanoparticles are ideal building blocks for preparing multifunctional composites. In this work, we developed a general photocoupling chemistry to enable simple conjugation of MIP nanoparticles with inorganic magnetic nanoparticles. We first synthesized MIP nanoparticles using propranolol as a model template and perfluorophenyl azide-modified silica-coated magnetic nanoparticles. Using a simple photoactivation followed by facile purification with a magnet, we obtained magnetic composite particles that showed selective uptake of propranolol. We characterized the nanoparticles and composite materials using FT-IR, TEM, fluorescence spectroscopy, and radioligand binding analysis. Through the high molecular selectivity of the magnetic composite, we demonstrated the nondestructive feature and the high efficiency of the photocoupling chemistry. The versatile photoconjugation method developed in this work should also be very useful for combining organic MIPs with other inorganic nanoparticles to enable new chemical sensors and high efficiency photocatalysts.
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| 20. |
- Zhang, Xudong, et al.
(författare)
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Binary superlattice ceramic membrane-coated soft carbon/hard carbon microspheres for high energy mixed-ion batteries
- 2019
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Ingår i: Journal of Power Sources. - : ELSEVIER. - 0378-7753 .- 1873-2755. ; 438
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Tidskriftsartikel (refereegranskat)abstract
- The assembly of two different materials into a composite with binary superlattices can provide a most efficient and inexpensive path to the synthesis of electrode materials with high energy density. Here, Li9Fe3P8O29/Na2HPO4 binary superlattice ceramic membrane-coated mesoporous soft carbon/hard carbon microspheres (BSLCM-MSC/HCMs) are synthesized via a hydrothermal carbonization method using acyl nucleoside triphosphate disodium salt (Na(2)ATP) as a multifunctional template. Here Na(2)ATP is not only a phosphorus source, a sodium source and a nucleating agent for the rapid synthesis of BSLCM, but also is a carbon source which is easily transformed into MSC/HCMs after being heat-treated in a N-2 atmosphere. This special structure design brings a remarkable synergic effect for both Li+/Na+ mixed-ion storage and transfer kinetics. As a new nanocomposite cathode for mixed-ion batteries (MIBs), the BSLCM-MSC/HCMs display a self-enhancement of discharge capacity via electrolyte penetration in the core-shell mesoporous microspheres. Importantly, the discharge specific energy of a MIB assembled with the BSLCM-MSC/HCMs-2 cathode is up to 400 W h kg(-1) at a high current rate of 10C, which outperforms all lithium-ion batteries and sodium-ion batteries reported so far. The findings in this study may benefit to the development of high energy mixed-ion batteries.
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