With the combined surface imprinting technique and immobilized template strategy, molecularly imprinted magnetic nanoparticles were successfully prepared and coupled with high‐performance liquid chromatography to selectively separate and determine gallic acid from the pomegranate rind. On the surface of carboxyl‐functionalized magnetic nanospheres, thin imprinting shells were formed using dopamine as monomer and crosslinker. The characteristics, polymerization conditions, and adsorption performances of the resultant nanomaterials were investigated in detail. In addition of good crystallinity, satisfactory magnetism, and uniform morphology of the obtained polymers, they had rapid binding kinetics, high adsorption capacity, and favorable reusability. In the mixed solution of four hydroxybenzoic acids, the prepared nanomaterials have an excellent selectivity to gallic acid with an imprinting factor of as high as 17.5. Therefore, the polymers have great potentials in specific extraction and enrichment of gallic acid from the complex natural resources. 相似文献
An efficient fabrication technique for large area periodic metallic split-ring arrays has been demonstrated by the combination of tilted nanoimprint lithography and nanotransfer imprinting. The feature size of the split-rings can be adjusted by varying the key geometry parameters of the original imprinting mold. Due to the flexible nature of PDMS molds, these arrays can be patterned on curved surfaces. The molds for nanoimprint lithography and nanotransfer imprinting can be used multiple times without a loss of fidelity. 相似文献
The fabrication of patterned microstructures in poly(dimethylsiloxane) (PDMS) is a prerequisite for soft lithography. Herein, curvilinear surface relief microstructures in PDMS are fabricated through a simple three‐stage approach combining microcontact printing (μCP), selective surface wetting/dewetting and replica molding (REM). First, using an original PDMS stamp (first‐generation stamp) with linear relief features, a chemical pattern on gold substrate is generated by μCP using hexadecanethiol (HDT) as an ink. Then, by a dip‐coating process, an ordered polyethylene glycol (PEG) polymer‐dot array forms on the HDT‐patterned gold substrate. Finally, based on a REM process, the PEG‐dot array on gold substrate is used to fabricate a second‐generation PDMS stamp with microcavity array, and the second‐generation PDMS stamp is used to generate third‐generation PDMS stamp with microbump array. These fabricated new‐generation stamps are utilized in μCP and in micromolding in capillaries (MIMIC), allowing the generation of surface micropatterns which cannot be obtained using the original PDMS stamp. The method will be useful in producing new‐generation PDMS stamps, especially for those who want to use soft lithography in their studies but have no access to the microfabrication facilities. 相似文献
Summary: A soft‐lithographic imprinting approach to fabricate super‐hydrophobic surfaces has been developed in this work. In this process, fresh lotus leaves were used as masters and PDMS stamps were prepared by replica molding against the lotus‐leaf surfaces. By using the stamps and an epoxy‐based azo polymer solution as “ink”, the mimicked lotus‐leaf surfaces made of the polymer were fabricated by pressing the featured faces of the stamps against “inked” substrates and drying under a proper condition after peeling off the stamps. The lotus‐leaf‐like surfaces show super‐hydrophobic characteristics with the water contact angle higher than 150° and contact angle hysteresis less than 3°.
SEM images of lotus‐leaf‐like papillary structures on the imprinted surface. 相似文献
This paper demonstrates a new method of implementing complex microchannels in PDMS, which is simply constructed using three-dimensional photoresist structures as a master mold for the PDMS replica process. The process utilizes UV-insensitive LOR resist as a sacrificial layer to levitate the structural photoresist. In addition, the thickness of photoresist structures can be controlled by multi-step UV exposure. By using these techniques, various three-dimensional photoresist structures were successfully implemented, including the recessed cantilevers, suspended bridges, and the complex plates with micro-pits or micro-villi. We demonstrate that the three-dimensional photoresist structures are applicable to implementing complex multiple microchannels in PDMS by using the PDMS replica method. 相似文献
A protein imprinting approach for the synthesis of core–shell structure nanoparticles with a magnetic core and molecularly imprinted polymer (MIP) shell was developed using a simple distillation–precipitation polymerization method. In this work, Fe3O4 magnetic nanoparticles were first synthesized through a solvothermal method and then were conveniently surface‐modified with 3‐(methacryloyloxy)propyltrimethoxylsilane as anchor molecules to donate vinyl groups. Next a high‐density MIP shell was coated onto the surface of the magnetic nanoparticles by the copolymerization of functional monomer acrylamide (AAm), cross‐linking agent N,N′‐methylenebisacrylamide (MBA), the initiator azodiisobutyronitrile (AIBN), and protein in acetonitrile heated at reflux. The morphology, adsorption, and recognition properties of the magnetic molecularly imprinted nanoparticles were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and rebinding experiments. The resulting MIP showed a high adsorption capacity (104.8 mg g?1) and specific recognition (imprinting factor=7.6) to lysozyme (Lyz). The as‐prepared Fe3O4@Lyz‐MIP nanoparticles with a mean diameter of 320 nm were coated with an MIP shell that was 20 nm thick, which enabled Fe3O4@Lyz‐MIP to easily reach adsorption equilibrium. The high magnetization saturation (40.35 emu g?1) endows the materials with the convenience of magnetic separation under an external magnetic field and allows them to be subsequently reused. Furthermore, Fe3O4@Lyz‐MIP could selectively extract a target protein from real egg‐white samples under an external magnetic field. 相似文献
The preparation of molecularly imprinted core–shell magnetic nanoparticles and their subsequent use in the solid‐phase extraction of thiabendazole from citrus sample extracts is described. Molecularly imprinted core–shell magnetic nanoparticles were prepared by the precipitation copolymerization of the imprinting polymerization mixture on the surface of vinyl‐modified silica magnetic nanoparticles and were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The obtained molecularly imprinted core–shell magnetic nanoparticles exhibited a high selectivity for thiabendazole and were easily collected and separated by an external magnetic field without additional centrifugation or filtration steps. Under optimum conditions, a magnetic molecularly imprinted solid‐phase extraction method was developed allowing the extraction of thiabendazole from citrus sample extracts and final determination by high‐performance liquid chromatography with fluorescence detection. The detection limit was 0.2 mg/kg, far lower than the maximum residue limit established within the European Union for thiabendazole in citrus samples. 相似文献
A UV-based imprint lithography method is used for the direct surface structuring of hydrogel-based biomaterials, which are prepared from a family of tailor-made star poly(ethylene glycol) formulations. Bulk star poly(ethylene glycol) (PEG) hydrogels are fabricated by cross-linking acrylate-functionalized star PEG macromolecules. Cross-linking is achieved by radical reactions initiated by UV irradiation. This UV-curable star PEG formulation allows templating of mold structures to yield a stable, stand-alone, elastomeric replica of the mold. In particular, when a secondary, soft mold is used that consists of a perfluorinated elastomer with inherent excellent release properties, nanometer-sized features (down to 100 nm) can be imprinted without specialized equipment. The applied UV-based imprint lithography is a fast and simple technique to employ for the direct topographic structuring of bulk PEG-based biomaterials. The UV-based imprinting into the star PEG prepolymer by means of a perfluorinated, soft mold can be carried out on the bench top, while nanoscale resolution is demonstrated. 相似文献
The current achievements in magnetic transmission soft X-ray microscopy will be reviewed. The magnetic contrast is given by X-ray magnetic circular dichroism (X-MCD), i.e., the dependence of the absorption coefficient of circularly polarized X rays on the projection of the magnetization in a ferromagnetic system onto the photon propagation direction. X-MCD contrast can reach, e.g., at L2,3 edges in transition metals, large values up to 50%. Combined with a soft X-ray microscope where Fresnel zone plates acting as optical elements provide a lateral resolution down at 25 nm, it allows for imaging magnetic microstructures. Specific features of this photon-based technique are the recording of images in varying external magnetic fields, an inherent chemical specificity, a high sensitivity to thin magnetic layers, due to the large contrast, and the possibility to distinguish between in-plane and out-of plane contributions. In this report, recent results obtained with the XM-1 microscope at the ALS (Berkeley/CA) demonstrate the broad applicability of this novel experimental technique to both fundamental and technological relevant issues in nanomagnetism. The future potential will be briefly outlined. 相似文献
Polystyrene (PS), a standard material for cell culture consumable labware, was molded into microstructures with high fidelity of replication by an elastomeric polydimethylsiloxane (PDMS) mold. The process was a simple, benchtop method based on soft lithography using readily available materials. The key to successful replica molding by this simple procedure relies on the use of a solvent, for example, gamma-butyrolactone, which dissolves PS without swelling the PDMS mold. PS solution was added to the PDMS mold, and evaporation of the solvent was accomplished by baking the mold on a hotplate. Microstructures with feature sizes as small as 3 μm and aspect ratios as large as 7 were readily molded. Prototypes of microfluidic chips made from PS were prepared by thermal bonding of a microchannel molded in PS with a flat PS substrate. The PS microfluidic chip displayed much lower adsorption and absorption of hydrophobic molecules (e.g. rhodamine B) compared to a comparable chip created from PDMS. The molded PS surface exhibited stable surface properties after plasma oxidation as assessed by contact angle measurement. The molded, oxidized PS surface remained an excellent surface for cell culture based on cell adhesion and proliferation. To demonstrate the application of this process for cell biology research, PS was micromolded into two different microarray formats, microwells and microposts, for segregation and tracking of non-adherent and adherent cells, respectively. The micromolded PS possessed properties that were ideal for biological and bioanalytical needs, thus making it an alternative material to PDMS and suitable for building lab-on-a-chip devices by soft lithography methods. 相似文献
Aligned polymer microstructures in the field of biomaterials, semiconductors, and ion‐conductive membranes expand steadily. Here, an alternative aligned polybenzimidazole (WM PBI) microstructures fabrication strategy based on the utilization of a weak magnetic field (0.3 T) via the solvent casting method is demonstrated. The anisotropic alignment is induced by the interaction of the π‐electron‐rich structure with the magnetic field. A ripple‐like structure was observed in the field‐emission scanning electron microscopy image for the WM PBI membrane, which depicted the successful alignment of the PBI structure toward magnetic field direction. Electrochemical studies revealed the bulk resistance of WM PBI with only 13.71 × 103 Ω compared to the unaligned PBI (WOM PBI) (63.01 × 103 Ω). WM PBI marked as the highest proton conductivity of 610.66 × 10?6 S cm?1, and it was proven that the external magnetic field does bring the impact toward the augmentation of the proton conductivity, which is useful in various future generation applications. 相似文献