Photocatalytic multilayer nanocomposite films composed of anatase TiO2 nanoparticles and lignosulfonates (LS) were fabricated on quartz slides by the layer‐by‐layer (LBL) self‐assembly technique. X‐ray photoelectron spectroscopy (XPS), UV‐vis spectroscopy and atomic force microscopy (AFM) were used to characterize the TiO2/LS multilayer nanocomposite films. Moreover, the photocatalytic properties (decomposition of methyl orange and bacteria) of multilayer nanocomposite films were investigated. XPS results indicated that the intensities of titanium and sulfur peaks increased with the LBL deposition process. A linear increase in absorbance at 280 nm was found by UV‐Vis spectroscopy, suggesting that stepwise multilayer growth occurs on the substrate and this deposition process is highly reproducible. AFM images showed that quartz slide was completely covered by TiO2 nanoparticles when a 10‐bilayer multilayer film was formed. The decomposition efficiency of methyl orange by TiO2/LS multilayer films under the same UV irradiation time increased linearly with the number of TiO2 layers, and the results of decomposition of bacteria under UV irradiation showed that TiO2/LS multilayer nanocomposite films exhibited excellent decomposition activity of bacteria (Escherichia coil). 相似文献
Summary: The multilayers of polycation‐based non‐viral DNA nanoparticles and biodegradable poly(L ‐glutamic acid) (PGA) were constructed by a layer‐by‐layer (LbL) technique. Poly(ethyleneimine) (PEI) was used to condense DNA to develop non‐viral DNA nanoparticles. AFM, UV‐visible spectrometry, and TEM measurements revealed that the PEI‐DNA nanoparticles were successfully incorporated into the multilayers. The well‐structured, easily processed multilayers with the non‐viral DNA nanoparticles may provide a novel approach to precisely control the delivery of DNA, which may have great potential for gene therapy applications in tissue engineering, medical implants, etc.
A TEM image of the cross section of a (PGA/PEI‐DNA nanoparticle)20 multilayer. 相似文献
We investigated the effects of the multilayer polymer‐clay nanohybrid passivation films on the stability of pentacene organic thin‐film transistors (OTFTs) exposed to air and UV irradiation. Well‐ordered multilayer films were deposited by the spin‐assisted layer‐by‐layer assembly method using photocrosslinkable poly(vinyl alcohol) with the N‐methyl‐4(4′‐formylstyryl)pyridinium methosulfate acetal group (SbQ‐PVA) and Na+‐montmorillonite in a water‐based solution process. When photocrosslinked, these SbQ‐PVA/clay multilayers were found to serve as excellent barriers to O2 and UV‐light. Moreover, when used as passivation layers, they enhanced the stability of pentacene OTFT devices exposed to air and UV radiation. 相似文献
The fabrication of stable polyelectrolyte/Au nanoparticle multilayer films was achieved by the UV irradiation of layer‐by‐layer self‐assembled multilayers consisting of diazoresins and Au nanoparticles. The method promises to be a simple and efficient strategy to construct covalently attached organic/inorganic multilayer hybrids. 相似文献
Graphene/mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin multilayer films composed of graphene sheet (GS) and mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (NH2‐β‐CD) were fabricated easily by two steps. First, negatively charged graphene oxide (GO) and positively charged mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (NH2‐β‐CD) were layer‐by‐layer (LBL) self‐assembled on glassy carbon electrode (GCE) modified with a layer of poly(diallyldimethylammonium chloride) (PDDA). Then graphene/mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (GS/NH2‐β‐CD) multilayer films were built up by electrochemical reduction of graphene oxide/mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (GO/NH2‐β‐CD). Combining the high surface area of GS and the active recognition sites on β‐cyclodextrin (β‐CD), the GS/NH2‐β‐CD multilayer films show excellent electrochemical sensing performance for the detection of DA with an extraordinary broad linear range from 2.53 to 980.05 µmol·L?1. This study offers a simple route to the controllable formation of graphene‐based electrochemical sensor for the detection of DA. 相似文献
An electrochemical DNA sensing film was constructed based on the multilayers comprising of poly‐L ‐lysine (pLys) and Au‐carbon nanotube (Au‐CNT) hybrid. A precursor film of mercaptopropionic acid (MPA) was firstly self‐assembled on the Au electrode surface. pLys and Au‐CNT hybrid layer‐by‐layer assembly films were fabricated by alternately immersing the MPA‐modified electrode into the pLys solution and Au‐CNT hybrid solution. Cyclic voltammetry was used to monitor the consecutive growth of the multilayer films by utilizing [Fe(CN)6]3?/4? and [Co(phen)3]3+/2+ as the redox indicators. The outer layer of the multilayer film was the positively charged pLys, on which the DNA probe was easily linked due to the strong electrostatic affinity. The hybridization detection of DNA was accomplished by using methylene blue (MB) as the indicator, which possesses different affinities to dsDNA and ssDNA. Differential pulse voltammetry was employed to record the signal response of MB and determine the amount of the target DNA sequence. The established biosensor has high sensitivity, a relatively wide linear range from 1.0×10?10 mol/L to 1.0×10?6 mol/L and the ability to discriminate the fully complementary target DNA from single or double base‐mismatched DNA. The sequence‐specific DNA related to phosphinothricin acetyltransferase gene from the transgenically modified plants was successfully detected. 相似文献
Ultrathin multilayer films of a rare-earth-containing polyoxometalate Na9[Eu(W5O18)2](EW) and poly (allymamine hydrochloride)(PAH) have been prepared by layer-by-layer self-assembly from dilute aqueous solution.The fabrication process of the EW/PAH multilaryer films was followed by UV-vis spectroscopy and ellipsometry,which show that the deposition process is linear and highly reproducible from layer to layer.An average EW/PAH bilayer thickness of ca.2.1nm was determined by ellipsometry.In addition,the scanning electron microscopy(SEM) image of the EW/PAH film indicates that the film surface is relatively uniform and smooth.The photoluminescent properties of these films were also investigated by fluorescence spectroscopy. 相似文献
The thin films containing transition metal complex tris(1,10‐phenanthroline) ruthenium(II) Ru(phen)3Cl2 (abbr Ru(phen)3, phen=1,10‐phenanthroline), and 12‐molybdophosphoric acid [PMo12O40]3? (abbr PMo12) were fabricated on quartz, silicon and ITO substrates by layer‐by‐layer (LBL) method. The LBL films were characterized by the UV‐vis spectroscopy, X‐ray photoelectron spectroscopy, atomic force microscopy and cyclic voltammetry. The films can catalyze both the reduction of ClO , BrO , IO , and the oxidation of C2O due to the presence of bifunctional composite, and the redox potentials depend on pH as a result of protonation. The photoluminescence of films were also investigated. The films exhibited photoluminescence arising from π*–t2g ligand‐to‐metal transition of Ru(phen)3. 相似文献
The assembly of alternating DNA and positively charged poly‐(dimethyldiallylammonium chloride) (PDDA) multilayer films by electrostatic layer‐by‐layer adsorption has been studied. Real time surface plasmon resonance (BIAcore) technique was used to characterize and monitor the formation of multilayer films in solution in real time continuously. The results indicate that the uniform multilayer can be obtained on the poly‐(ethylenimine) (PEI) coated substrate surface. The kinetics of the adsorption of DNA on PDDA surface was also studied by real‐time BIAcore technique, and the observed rate constant was calculated using a Langmuir model (kobs = (1.28 ± 0.08) × 10?2s?1). 相似文献
Abstract Cationic nanocrystalline TiO2 particles have been synthesized for which the size and composition of the nanoparticles were analyzed by a transmission emission microscopy and energy dispersive x‐ray spectrometer (EDXS). Multilayered films have been fabricated by sequential adsorption of TiO2 nanoparticles and poly(3‐thiophene acetic acid) (PTAA). Each layer of the nanoparticles and PTAA in the thin film has also been characterized by x‐ray photoelectron spectroscopy, atomic force microscopy, and UV‐visible spectroscopy. These types of multilayered nanocomposite films may find applications in the fabrication of efficient light harvesting photovoltaic cells. 相似文献
Two Vanadium‐substituted Keggin‐type polyoxometalates, K3H2[α‐SiVW11O40]?6H2O (SiVW11) and K4H2[γ(1, 2)‐SiV2W10O40]?4H2O (SiV2W10) were first successfully immobilized on 4‐aminobenzoic acid modified glass carbon electrodes respectively by layer‐by‐layer assembly with poly (ethylenimine) (PEI) as counterions. The regular growth processes were monitored by cyclic voltammetry (CV), and it was proved that the multilayer films were uniform and stable. The cyclic voltammetry results indicated that the electrochemical behavior of two multilayer films was similar, and their redox couples are pH‐ and scan rate‐dependent. The multilayer films show favorable electrocatalytic active toward the reduction of NO2?, IO3? and H2O2. 相似文献
Biodegradable multi‐l ‐arginyl‐poly‐l ‐aspartate (MAPA), more commonly cyanophycin, prepared with recombinant Escherichia coli contains a polyaspartate backbone with lysine and arginine as side chains. Two assemblies of polyelectrolyte multilayers (PEMs) are fabricated at three different concentration ratios of insoluble MAPA (iMAPA) with hyaluronic acid (iMAPA/HA) and with γ‐polyglutamic acid (iMAPA/γ‐PGA), respectively, utilizing a layer‐by‐layer approach. Both films with iMAPA and its counterpart, HA or γ‐PGA, as the terminal layer are prepared to assess the effect on film roughness, cell growth, and cell migration. iMAPA incorporation is higher for a higher concentration of the anionic polymer due to better charge interaction. The iMAPA/HA films when compared to iMAPA/γ‐PGA multilayers show least roughness. The growth rates of L929 fibroblast cells on the PEMs are similar to those on glass substrate, with no supplementary effect of the terminal layer. However, the migration rates of L929 cells increase for all PEMs. γ‐PGA incorporated films impart 50% enhancement to the cell migration after 12 h of culture as compared to the untreated glass, and the smooth films containing HA display a maximum 82% improvement. The results present the use of iMAPA to construct a new layer‐by‐layer system of polyelectrolyte biopolymers with a potential application in wound dressing. 相似文献
The Pd, AuPd, and ZrO2 nanoparticle–decorated functionalised multiwalled carbon nanotubes (f‐MWCNTs) were reported as efficient catalysts of formic acid (FA) electro‐oxidation. Different preparation conditions influence their chemical and structural properties analysed by X‐ray photoelectron spectroscopy aided with the quantitative analysis of surfaces by electron spectroscopy. Different reduction procedures such as NaBH4, a polyol microwave‐assisted method (PMWA), and a high pressure microwave reactor (HPMWR) were applied for decorating ZrO2/f‐MWCNTs with Pd and AuPd nanoparticles. The ZrO2 nanoparticles are attached through oxygen groups to the surface of f‐MWCNTs. In NaBH4 and HPMWR procedures, Pd nanoparticles precipitate predominantly on ZrO2 of nearly nominal stoichiometry, whereas in PMWA procedure, Pd and AuPd nanoparticles precipitate predominantly on the surface of f‐MWCNTs, bridging with oxygen groups and ZrOx (x < 2) and leading to Pd‐O‐Zr phase formation. Strong reducing procedures (NaBH4 and FA) led to smaller Pd nanoparticle size, Pd oxide content, and PdOx overlayer thickness in contrary to weak reduction procedures (HPMWR and PMWA). The highest content of Pd‐O‐Zr phase appeared for Pd predominant precipitation on ZrO2 nanoparticles (HPMWR) in contrary to Pd and AuPd predominant precipitation on surface of f‐MWCNTs (NaBH4 ~ FA > PMWA). Larger content of Pd‐O‐Zr phase in AuPd‐decorated ZrO2/f‐MWCNTs in contrary to Pd‐decorated sample (PMWA) could be justified by different electronic properties of nanoparticles. The FA treatment of Pd and AuPd‐ZrO2/f‐MWCNTs samples provided decreasing Pd oxide content, overlayer thickness, nanoparticle size, increasing nanoparticle surface coverage and density, amount of Pd‐O‐Zr, what results from reduction of oxygen groups bridging with Pd and ZrOx nanoparticles, also through Pd‐O‐Zr phase. 相似文献