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Assembly Technique (assembly + technique)
Selected AbstractsElectrochemical Biosensors Based on Layer-by-Layer AssembliesELECTROANALYSIS, Issue 18 2006Wei Zhao Abstract Layer-by-layer (LBL) assemblies, which have undergone great progress in the past decades, have been used widely in the construction of electrochemical biosensors. The LBL assemblies provide a strategy to rationally design the properties of immobilized films and enhance the performance of biosensors. The following review focuses on the application of LBL assembly technique on electrochemical enzyme biosensors, immunosensors and DNA sensors. [source] Construction of Polyethyleneimine-,-cyclodextrin/pDNA Multilayer Structure for Improved In Situ Gene Transfection,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Yan Hu This study reports in situ gene delivery from gene-functionalized poly(D,L -lactic acid) (PDLLA, Mw of around 2.0,×,105,g,mol,1) films, which were constructed via layer-by-layer (LbL) assembly technique with low molecular weight polyethylenimine-,-cyclodextrin (PEI-CD) conjugate and plasmid DNA (pDNA). PEI-CD was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR), respectively. The buildup of multilayered PEI-CD/pDNA pairs onto PDLLA films was monitored with contact angle measurements and UV,Vis spectrometer, respectively. A sustained release of pDNA from multilayered films was observed for 28,h. The mechanism of in situ gene delivery on PDLLA film was investigated in this study as well. Spherical PEI-CD/pDNA complexes were formed and released following the deconstruction of multilayered films, which was confirmed by transmission electron microscopy (TEM) and gel electrophoresis, respectively. Surface mediated in situ gene transfection was achieved when culturing hepatoma G2 (HepG2) and human embryonic kidney 293 (HEK293) onto PEI-CD/pDNA multilayered films. Furthermore, PEI-CD improved the gene transfection efficiency when compared with that of PEI. Such gene-functionalized biomaterial reported here has potential application in tissue engineering and implant technology. [source] Fabrication of Galactosylated Polyethylenimine and Plasmid DNA Multilayers on poly (D,L -lactic acid) Films for in situ Targeted Gene Transfection,ADVANCED ENGINEERING MATERIALS, Issue 5 2009Yan Hu This study presents surface-mediated targeted in situ gene delivery from gene-tagged poly(D,L -lactic acid) (PDLLA) films, which were fabricated via a layer-by-layer (LbL) assembly technique with galactosylated polyethylenimine (GP) and plasmid DNA (pDNA, pSV-,-galactosidase). A linear growth of GP/pDNA multilayered films was observed. The pDNA was continuously released from multilayered films for over 32,h. The multilayered structure degraded and simultaneously formed GP/pDNA complexes in situ when exposing to a physiological environment. The pDNA was well protected by GP against DNase I digestion within formed GP/pDNA complexes. Our results demonstrated that GP contributes to receptor-mediated targeting for cell uptake and in situ gene transfection. The results reported here are potentially important for gene therapy, surface engineering of biomaterials, tissue engineering and implant technology. [source] Cover Picture: Composite Silica Spheres with Magnetic and Luminescent Functionalities (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 4 2006Mater. Abstract Photographs of a colloidal dispersion of composite nanoparticles with magnetic and luminescent functionalities are shown (left, in column), which are schematically illustrated in the main image. As reported by Salgueirińo-Maceira and co-workers on p.,509, such functionalities are imparted by magnetic and semiconductor nanoparticles within a silica matrix. In the absence of a magnetic field the particles are uniformly dispersed, although they accumulate and can be dragged under the influence of a magnetic field. Their movement can be monitored by their photoluminescence. A new class of highly fluorescent, photostable, and magnetic core/shell nanoparticles in the submicrometer size range has been synthesized from a modified Stöber method combined with the layer-by-layer (LbL) assembly technique. Luminescent magnetic nanoparticles are prepared via two main steps. The first step involves controlled addition of tetraethoxysilane to a dispersion of Fe3O4/,-Fe2O3 nanoparticles, which are thereby homogeneously incorporated as cores into monodisperse silica spheres. The second step involves the LbL assembly of polyelectrolytes and luminescent CdTe quantum dots onto the surfaces of the silica-coated magnetite/maghemite particles, which are finally covered with an outer shell of silica. These spherical particles have a typical diameter of 220,±,10,nm and a saturation magnetization of 1.34,emu,g,1 at room temperature, and exhibit strong excitonic photoluminescence. Nanoparticles with such a core/shell architecture have the added benefit of providing a robust platform (the outer silica shell) for incorporating diverse functionalities into a single nanoparticle. [source] Layer-By-Layer Assembly of ,-Estradiol Loaded Mesoporous Silica Nanoparticles on Titanium Substrates and Its Implication for Bone HomeostasisADVANCED MATERIALS, Issue 37 2010Yan Hu Drug-loadingmesoporous silica nanoparticles that serve as a nanoreservoir-type drug-delivery system are successfully attached to titanium substrates via the layer-by-layer assembly technique (see scheme). The obtained structure demonstrates great potential for regulating the biological behaviors of osteoblasts/ steoclasts in order to maintain bone homeostasis. The approach we present here may have wide applications in implant technology, tissue engineering, and regenerative medicine. [source] Design of a Microfluidic System to Investigate the Mechanical Properties of Layer-by-Layer Fabricated CapsulesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 12 2003Michelle Prevot Abstract A microfluidic system was designed, fabricated and implemented to study the behavior of polyelectrolyte capsules flowing in microscale channels. The device contains microchannels that lead into constrictions intended to capture polyelectrolyte microcapsules which were fabricated with the well-known layer-by-layer (LbL) assembly technique. The behavior of hollow capsules at the constrictions was visualized and the properties of the capsules were investigated before and after introduction into the device. Time series of video frames showing capsules being compressed into a constriction. [source] Magneto-transport studies of single ferromagnetic nanowirePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2007Y. Rheem Abstract The magnetotransport properites of individual ferromagnetic nanowires (e.g. Ni, Co23Ni77, Ni85Fe15) with 200 nm diameters were investigated. The ferromagnetic nanowires were successfully electrodeposited within an anodized alumina by controlling solution composition, temperature, and current density. Using a magnetic assembly technique, single nanowire was successfully bridged across microfabricated gold elecrodes. The temperature coefficient of resistance for ferromagnetic nanowires was lower than the bulk because of a larger residual resistance from increased electrical scattering in one-dimensional structures. The ferromagnetic nanowires showed typical anisotropic magnetoresistance where the magnetoresistance ratio was lower than bulk values. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Quantum Dots Arrangement and Energy Transfer Control via Charge-Transfer Complex Achieved on Poly(Phenylene Ethynylene)/Schizophyllan NanowiresCHEMISTRY - AN ASIAN JOURNAL, Issue 9 2009Tomohiro Shiraki Abstract Assemblies of organic and inorganic compounds in the nanoscale region have contributed to the development of novel functional materials toward future applications, including sensors and opto-electronics. We succeed in fabricating hybrid nanowires composed of a conjugated polymer and semiconductor quantum dots (QDs) by a supramolecular assembly technique. The 1-D fashion of the nanowire structure is obtained by the polymer wrapping of cationic poly(phenylene ethynylene) (PPE) with helix-forming polysaccharide schizophyllan (SPG). The electrostatic interaction between cationic PPE and anionic QDs affords the nanowires decorated with QDs. Upon addition of an acceptor molecule, tetranitrofluorenone (TNF), the charge-transfer (CT) complex between PPE and TNF is formed, resulting in energy transfer from the QDs to PPE arising from the induced spectral overlap. Furthermore, the employment of the conjugated polymer allows highly sensitive quenching of the QD's emission by raising the transmission efficiency to the CT complexed electron deficient sites along the polymer backbone. [source] Template-synthesized Protein Nanotubes with Controlled Size Based on Layer-by-layer MethodCHINESE JOURNAL OF CHEMISTRY, Issue 2 2010Caihong Tao Abstract The protein nanotubes fabricated by a layer-by-layer deposition method using the porous alumina membrane as the template were described. The combination of the template method and the layer-by-layer assembly technique for the fabrication of protein nanotubes presented simplicity and versatility. The nanotubes composed of two kinds of proteins (bovine serum albumin and hemoglobin lyophilized bovine erythrocytes) with different sizes could be synthesized through this method. The outside diameter of the obtained nanotubes was determined by the diameter of the pores of the template. And the wall thickness of the protein nanotubes increased with the increase of the number of protein layers that made up of the walls of nanotubes. Such biodegradable nanotubes with good biocompatibility should be useful for in vivo applications. [source] | |||||||||||||