Enzymatic Synthesis and Surface Deposition of Tin Dioxide using Silicatein-α
Nanostructured tin dioxide was synthesized by making use of the catalytic activity of silicatein-α. TEM, HRTEM, and XRD revealed the formation of cassiterite SnO2. Surface bound silicatein retains its biocatalytic activity. This was demonstrated by immobilizing silicatein on glass surfaces using a histidine-tag chelating anchor. The subsequent deposition of SnO2 on glass was monitored by quartz crystal microbalance (QCM) measurements and scanning electron microscopy (SEM). This new aspect of silicatein activity toward the formation of metal oxides other than SiO2, TiO2, and BaTiO3 opens up new vistas in composite material synthesis.
Controlled synthesis of linear and branched Au@ZnO hybrid nanocrystals and their photocatalytic properties.
Colloidal Au@ZnO hybrid nanocrystals with linear and branched shape were synthesized. The number of ZnO domains on the Au seeds can be controlled by the solvent mixture. Imidazole-functionalized Au@ZnO hybrid nanocrystals were soluble in water and exhibited a greatly enhanced photocatalytic activity compared to ZnO nanocrystals. The pristine heterodimeric NPs were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-Vis spectroscopy.
Synthesis and immobilization of molecular switches onto titaniumdioxide nanowires
Abstract The precursor [Fe III (L)Cl (L = N , N ′-bis(2′-hydroxy-3′-methyl-benzyliden)-1,7-diamino-4-azaheptane) is combined with [Mo(CN) 8 ] 4− yields a star shaped nona-nuclear cluster, [Mo IV {(CN)Fe III (L)} 8 ]Cl 4 . This Fe 8 Mo molecule is a high-spin system at room temperature. On cooling to 20 K some of the iron(III) centres in the molybdenum(IV)-star switch to the low-spin state as proven by Mossbauer spectroscopy. This molecule was deposited on TiO 2 nanowires by electrostatic interactions between the cluster cations and the surface functionalized titanium oxide nanowire. The synthesis and surface binding of the multistable molecular switch was demonstrated using IR and UV–Vis s…
Molecular Camouflage: Making Use of Protecting Groups To Control the Self-Assembly of Inorganic Janus Particles onto Metal-Chalcogenide Nanotubes by Pearson Hardness
Hard and soft: Binding of inorganic Pt@Fe3O4 Janus particles to WS2 nanotubes through their Pt or Fe3O4 domains is governed by the difference in Pearson hardness: the soft Pt block has a higher sulfur affinity than the harder magnetite face; thus the binding proceeds preferentially through the Pt face. This binding preference can be reversed by masking the Pt face with an organic protecting group.
Solvothermal Synthesis of Molybdenum–Tungsten Oxides and Their Application for Photoelectrochemical Water Splitting
Molybdenum and tungsten oxides are of interest as semiconductors for the production of clean and sustainable energy. Here we show that synergistic effects arising from a combination of noncrystalli...
Facile hybridization of Ni@Fe2O3 superparticles with functionalized reduced graphene oxide and its application as anode material in lithium-ion batteries
Abstract In our present work we developed a novel graphene wrapping approach of Ni@Fe2O3 superparticles, which can be extended as a concept approach for other nanomaterials as well. It uses sulfonated reduced graphene oxide, but avoids thermal treatments and use of toxic agents like hydrazine for its reduction. The modification of graphene oxide is achieved by the introduction of sulfate groups accompanied with reduction and elimination reactions, due to the treatment with oleum. The successful wrapping of nanoparticles is proven by energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy and Raman spectroscopy. The developed composite material shows strongly i…
Formation of layered titania and zirconia catalysed by surface-bound silicatein
Silicatein immobilised on self-assembled polymer layers using a histidine-tag chelating anchor group retains its hydrolytical activity for the formation of biosilica, and catalyses the formation of layered arrangements of biotitania and biozirconia.
High-Performance TiO2 Nanoparticle/DOPA-Polymer Composites
Many natural materials are complex composites whose mechanical properties are often outstanding considering the weak constituents from which they are assembled. Nacre, made of inorganic (CaCO 3 ) and organic constituents, is a textbook example because of its strength and toughness, which are related to its hierarchical structure and its well-defi ned organic–inorganic interface. Emulating the construction principles of nacre using simple inorganic materials and polymers is essential for understanding how chemical composition and structure determine biomaterial functions. A hard multilayered nanocomposite is assembled based on alternating layers of TiO 2 nanoparticles and a 3-hydroxytyramine…
Biomolecular conjugation inside synthetic polymer nanopores via glycoprotein-lectin interactions
We demonstrate the supramolecular bioconjugation of concanavalin A (Con A) protein with glycoenzyme horseradish peroxidase (HRP) inside single nanopores, fabricated in heavy ion tracked polymer membranes. Firstly, the HRP-enzyme was covalently immobilized on the inner wall of the pores using carbodiimide coupling chemistry. The immobilized HRP-enzyme molecules bear sugar (mannose) groups available for the binding of Con A protein. Secondly, the bioconjugation of Con A on the pore wall was achieved through its biospecific interactions with the mannose residues of the HRP enzyme. The immobilization of biomolecules inside the nanopore leads to the reduction of the available area for ionic tran…
Functionalized magnetic nanoparticles for selective targeting of cells
AbstractInitiation of pathways that lead to proliferation and chemoresistance by Toll-like receptors (TLRs) is an important factor in cancer progression. Here, we show the response of human cancer cells to TLR signaling inevitably linked to tumor biology. The approach is based on tailored multifunctional magnetic nanoparticles equipped with pathogen-derived ligands (CpG) functioning as TLR agonists (molecular component) to investigate the impact of transcription factor immune activation on human cancer cells. Magnetic nanoparticles (MnO and bifunctional Au-MnO) particles were covalently coated with a multifunctional polymer, displaying no cytotoxicity, to being able to enter cells while car…
Functional Polymer-Opals from Core-Shell Colloids
Colloidal photonic crystals were prepared from monodisperse core-shell particles. The shell is hereby formed from a functional monomer, such as glycidylmethacrylate or different reactive ester monomers, which can perform chemical reactions and the core from a standard monomer, which yields highly monodisperse colloids. It was possible to crystallize the core-shell particles into artificial opals with excellent optical properties. Reactions on the functional surface of the colloids were carried out, which lead to a dramatic rise in the mechanical stability or to a functionalization of His-tagged silicatein, which acts as nanoreactor to synthesize and immobilize gold nanoparticles from auric …
Monitoring the formation of biosilica catalysed by histidine-tagged silicatein.
Surface bound silicatein retains its biocatalytic activity, which was demonstrated by monitoring the immobilisation of silicatein using a histidine-tag chelating anchor and the subsequent biosilicification of SiO(2) on surfaces by surface plasmon resonance spectroscopy, atomic force microscopy and scanning electron microscopy.
Reversible self-assembly of metal chalcogenide/metal oxide nanostructures based on Pearson hardness.
Nanotechnology has reached a stage of development where not individual nanoparticles but rather systems of greater complexity are the focus of concern. These complex structures incorporate two or more types of materials, an example of which is the formation of metal–semiconductor hybrids, which effectively combine the properties of both materials. The assembly of multicomponent nanoparticles from constituents with different optical, electrical, magnetic, and chemical properties can lead to novel functionalities that are independent of the individual components and may be tailored to fit a specific application. These applications include such far-reaching challenges as solar energy conversio…
Hydrogen peroxide sensors for cellular imaging based on horse radish peroxidase reconstituted on polymer-functionalized TiO2 nanorods
We describe the reconstitution of apo-horse radish peroxidase (apo-HRP) onto TiO2 nanorods functionalized with a multifunctional polymer. After functionalization, the horse radish peroxidase (HRP) functionalized TiO2 nanorods were well dispersible in aqueous solution, catalytically active and biocompatible, and they could be used to quantify and image H2O2 which is a harmful secondary product of cellular metabolism. The shape, size and structure of TiO2 nanorods (anatase) were analyzed by transmission electron microscopy (TEM), high resolution TEM (HRTEM), electron diffraction (ED) and X-ray diffraction (XRD). The surface functionalization, HRP reconstitution and catalytic activity were con…
Synthesis, characterization, and hierarchical organization of tungsten oxide nanorods: spreading driven by Marangoni flow.
Tungsten oxide nanorods were synthesized by a soft chemistry approach using tungsten alkoxide and trioctyl amine and oleic acid as the surfactants. The optical properties of the nanorods were studied. The nanorods were found to be soluble in a wide range of solvents like chloroform, cyclohexane, and so on. Upon solvent evaporation, the nanorods formed hierarchically organized solid state structures. Depending on the solvent used, the nanorods organized in different mesostructures. Moreover, the organization of the nanorods from mixtures of polar and nonpolar solvents was studied. Here, the Marangoni effect resulting from differences in the surface tensions of the two solvents was found to p…
Synthesis and functionalization of chalcogenide nanotubes
New synthetic approaches to MS 2 (M = Sn, Nb, Mo, W) chalcogenide nanostructures are highlighted. Most chalcogenide particles can be functionalized directly with inorganic nanoparticles such as Au, ZnO or MnO. Depending on the Pearson hardness of the metal involved, the functionalization may be reversible or irreversible. A covalent functionalization strategy is based on a steric shielding of the coordination sphere of transition metal atoms in such a way that only coordination sites are available for bonding to the chalcogenide surface. This allows the immobilization of fluorophors, redox active groups or proteins onto chalcogenide nanoparticle.
Precursor Polymers for the Carbon Coating of Au@ZnO Multipods for Application as Active Material in Lithium-Ion Batteries
The synthesis of statistical and block copolymers based on polyacrylonitrile, as a source for carbonaceous materials, and thiol-containing repeating units as inorganic nanoparticle anchoring groups is reported. These polymers are used to coat Au@ZnO multipod heteroparticles with polymer brushes. IR spectroscopy and transmission electron microscopy prove the successful binding of the polymer onto the inorganic nanostructures. Thermogravimetric analysis is applied to compare the binding ability of the block and statistical copolymers. Subsequently, the polymer coating is transformed into a carbonaceous (partially graphitic) coating by pyrolysis. The obtained carbon coating is characterized by…
Molybdenum Trioxide Nanoparticles with Intrinsic Sulfite Oxidase Activity
Sulfite oxidase is a mitochondria-located molybdenum-containing enzyme catalyzing the oxidation of sulfite to sulfate in the amino acid and lipid metabolism. Therefore, it plays a major role in detoxification processes, where defects in the enzyme cause a severe infant disease leading to early death with no efficient or cost-effective therapy in sight. Here we report that molybdenum trioxide (MoO3) nanoparticles display an intrinsic biomimetic sulfite oxidase activity under physiological conditions, and, functionalized with a customized bifunctional ligand containing dopamine as anchor group and triphenylphosphonium ion as targeting agent, they selectively target the mitochondria while bein…
A Step into the Future: Applications of Nanoparticle Enzyme Mimics.
We describe elementary concepts, up-to-date developments, and perspectives of the emerging field of nanoparticle enzyme mimics (so-called "nanozymes") at the interface of chemistry, biology, materials, and nanotechnology. The design and synthesis of functional enzyme mimics is a long-standing goal of biomimetic chemistry. Metal complexes, polymers and engineered biomolecules capturing the structure of natural enzymes or their active centers have been made to achieve high rates and enhanced selectivities. Still, the design of new "artificial enzymes" that are not related to proteins but with capacity of production and stability at industrial level, remains a goal. Inorganic nanoparticles bea…
Potential biological role of laccase from the sponge Suberites domuncula as an antibacterial defense component
Abstract Background Laccases are copper-containing enzymes that catalyze the oxidation of a wide variety of phenolic substrates. Methods We describe the first poriferan laccase from the marine demosponge Suberites domuncula. Results This enzyme comprises three characteristic multicopper oxidase homologous domains. Immunohistological studies revealed that the highest expression of the laccase is in the surface zone of the animals. The expression level of the laccase gene is strongly upregulated after exposure of the animals to the bacterial endotoxin lipopolysaccharide. To allow the binding of the recombinant enzyme to ferromagnetic nanoparticles, a recombinant laccase was prepared which con…
Orientation and Dynamics of ZnO Nanorod Liquid Crystals in Electric Fields.
ZnO nanorod polymer hybrids (i.e., ZnO nanorods coated with a block copolymer with a short anchor block (dopamine) and a longer solubilizing block of polystyrene (PS)) form liquid crystalline (LC) phases if they are dispersed at high concentration e.g., in a PS oligomer matrix. Due to the high mobility of the low T(g)-matrix the nanorod polymer hybrids show a switching behavior under an applied AC electric field. Hence, the orientation of the nanorod mesogens can be changed from planar (parallel to the substrate) to homeotropic (perpendicular) in full analogy to the switching of low molecular liquid crystals in an electric field. Dielectric measurements show that such a switching is mainly …
Functionalization of TiO2Nanoparticles with Semiconducting Polymers Containing a Photocleavable Anchor Group and Separation via Irradiation Afterward
The controlled radical polymerization (RAFT polymerization) of semiconducting polymers based on poly(4,4′-dimethyl-triphenylamine) is described. These polymers are afterward end-functionalized with a photocleavable group and an anchor unit (catechol) for oxidic nanoparticles (NPs). Serving as a reference, polystyrene oligomers with the same end groups are also synthesized. Using these polymers allows functionalization of the TiO2-NPs, leading to an improved solubility and miscibility in organic solvents or polymer matrices. Irradiation in the UV region is used to split the photocleavable group and remove the polymer chains from the NPs, which leads to their aggregation.
Influence of Binding-Site Density in Wet Bioadhesion
Biogenic synthesis of palladium nanoparticles using Pulicaria glutinosa extract and their catalytic activity towards the Suzuki coupling reaction.
Green synthesis of nanomaterials finds the edge over chemical methods due to its environmental compatibility. Herein, we report a facile and eco-friendly method for the synthesis of palladium (Pd) nanoparticles (NPs) using an aqueous solution of Pulicaria glutinosa, a plant widely found in a large region of Saudi Arabia, as a bioreductant. The as-prepared Pd NPs were characterized using ultraviolet-visible (UV-vis) spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform-infrared spectroscopy (FT-IR). The hydroxyl groups of the plant extract (PE) molecules were found mainly responsible for the red…
dsRNA-functionalized multifunctional gamma-Fe2O3 nanocrystals: a tool for targeting cell surface receptors.
Hierarchical Assembly of TiO2 Nanoparticles on WS2 Nanotubes Achieved Through Multifunctional Polymeric Ligands
Thefunctionalization of nanotubes is required in order to bene-fit from their outstanding properties, as any application inmaterials and devices is hindered by processing and manipu-lation difficulties. Only the attachment of appropriate chem-ical functionalities on the nanotube surface allows tailoringof the properties for the respective applications. As an ex-ample, the enhancement of the nanotube solubility is onemajor task since most pristine nanotubes are insoluble inboth water and organic solvents. Thus, the improvement ofthe solubility by chemical functionalization is an importantconcept for synthetic chemists and materials scientists. Tai-loring of the surface chemical bonds might a…
Synthesis, characterization and functionalization of nearly mono-disperse copper ferrite CuxFe3−xO4 nanoparticles
Magnetic nanocrystals are of great interest for a fundamental understanding of nanomagnetism and for their technological applications. CuxFe3−xO4 nanocrystals (x ≈ 0.32) with sizes ranging between 5 and 7 nm were synthesized starting from Cu(HCOO)2 and Fe(CO)5 using oleic acid and oleylamine as surfactants. The nanocrystals were characterized by high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), magnetization studies and Mossbauer spectroscopy. The CuxFe3−xO4 particles are superparamagnetic at room temperature 300 K with a saturation magnetization of 30.5 emu g−1. Below their blocking temperature of 60 K, they become ferrimagnetic, and at 5 K they show a co…
Ni@Fe2O3 heterodimers: controlled synthesis and magnetically recyclable catalytic application for dehalogenation reactions
Ni@Fe2O3 heterodimer nanoparticles (NPs) were synthesized by thermal decomposition of organometallic reactants. After functionalization, these Ni@Fe2O3 heterodimers became water soluble. The pristine heterodimeric NPs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Mossbauer spectroscopy and magnetic susceptibility measurements. A special advantage of the heterodimers lies in the fact that nanodomains of different composition can be used as catalysts for the removal of environmentally hazardous halogenated pollutants.
Multiple cross-linked hydroxypropylcellulose–succinate–salicylate: prodrug design, characterization, stimuli responsive swelling–deswelling and sustained drug release
A hydroxypropylcellulose–succinic anhydride (HPC–SAn) conjugate was synthesized homogeneously at 80 °C for 6 h under N2 in N,N-dimethylacetamide (DMA). The HPC–SAn conjugate was further covalently linked with salicylic acid (SA) drug using the versatile reagent ZrOCl2·8H2O at 80 °C for 6 h. Multiple crosslinking of the benign HPC–SAn–SA conjugate was achieved using oxalyl chloride. The resultant cross-linked prodrug (CL-HPC–SAn–SA conjugate) was characterized using different spectroscopic techniques. UV/Vis analysis of the HPC–SAn–SA conjugate has indicated that it contains 26 mg of SA per 100 mg. CL-HPC–SAn–SA showed reasonably good swelling properties in water and at different physiologic…
CpG-DNA loaded multifunctional MnO nanoshuttles for TLR9-specific cellular cargo delivery, selective immune-activation and MRI
Initiation of pathways that lead to a proliferation and chemoresistance by Toll-like receptors (TLRs) are an important factor in cancer progression. Multifunctional magnetic nanoparticles equipped with a pathogen-derived ligand (CpG) functioning as TLR agonists were used to show the impact of immune activation on human HNSCC (head and neck squamous cell carcinoma) cells. The response of human cancer cells to TLR signaling is linked to tumor biology. The magnetic MnO nanoparticles were coated with a multifunctional polymer, displaying no cytotoxicity and being able to enter cells while carrying foreign DNA (unmethylated CpG) to recognize intracellular TLR9. Both the particle and the nucleic …
Light induced charging of polymer functionalized nanorods.
ZnO nanorods were functionalized with new block copolymers containing a hole transporting moiety in one block and a dye and an anchor system in the second block. After functionalization, the ZnO nanorods are well dispersible in organic media and the fluorescence of the dye is quenched. Kelvin probe force microscopy was used to measure changes in electrical potential between the ZnO nanorod and the polymeric corona. Upon light irradiation, potential changes on the order of some tens of millivolts were observed on individual structures. This effect is attributed to light-induced charge separation between the ZnO nanorod and its hole transporting polymeric corona.
Enzyme-Mediated Deposition of a TiO2Coating onto Biofunctionalized WS2 Chalcogenide Nanotubes
A chemically specific and facile method for the biofunctionalization of WS2 nanotubes (NT-WS2) is reported. The covalent modification strategy is based on the affinity of the nitrilotriacetic acid (NTA) side chain, which serves as a ligand for the surface binding to NT-WS2 and simultaneously as an anchor group for the binding of His-tagged proteins to the polymer backbone. The polymer functionalized WS2 nanotubes can be solubilized either in water or organic solvents; they are stable for at least one week. The probes were characterized by FT-IR and UV-vis spectroscopy. The immobilization of silicatein, a hydrolytic protein encountered in marine sponges, was visualized by scanning force micr…
Plasmon-enhanced photocurrent in quasi-solid-state dye-sensitized solar cells by the inclusion of gold/silica core–shell nanoparticles in a TiO2 photoanode
Direct evidence of the effects of the localized surface plasmon resonance (LSPR) of gold nanoparticles (Au NPs) in TiO2 photoanodes on the performance enhancement in quasi-solid-state dye-sensitized solar cells (DSCs) is reported by comparing gold/silica core–shell nanoparticles (Au@SiO2 NPs) and hollow silica nanoparticles with the same shell size of the core–shell nanoparticles. The Au nanoparticles were shelled by a thin SiO2 layer to produce the core–shell structure, and the SiO2 hollow spheres were made by dissolving the Au cores of the gold/silica core–shell nanoparticles. Therefore, the size and morphology of the SiO2 hollow spheres were the same as the Au@SiO2 NPs. The energy conver…
Graphene based metal and metal oxide nanocomposites: synthesis, properties and their applications
Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials has increased exponentially. Particularly the development of easy preparation methods for graphene like materials, such as highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of vari…
Orientation of Polymer Functionalized Nanorods in Thin Films
A directed self assembly of anisotropic nanostructures offers a possibility to provide unique functional materials, which are e.g., important in optoelectronic devices. We use the liquid crystalline behavior of polymer functionalized TiO2 and ZnO nanorods to apply methods well known for low molecular liquid crystals to achieve oriented thin films. Convective forces in the meniscus on a structured substrate obtain thin layers of oriented nanoparticles with a ordering parameter of S = 0.7. As another method we present the orientation of polystyrene covered ZnO nanorods under an applied electric field. The method offers a perpendicular alignment of the rods to the surface.
Stabilizing nanostructured lithium insertion materials via organic hybridization: A step forward towards high-power batteries
Abstract Herein, we present the electrochemical characterization of carbon-coated TiO 2 nanorods, obtained by carbonizing RAFT (reversible addition fragmentation chain transfer) polymerization derived block copolymers anchored on anatase TiO 2 nanorods. These carbon-coated TiO 2 nanorods show an improved electrochemical performance in terms of first cycle reversibility, specific capacity, cycling stability, and high rate capability. More importantly, however, the structural disordering observed in the uncoated TiO 2 nanorods by means of galvanostatic and potentiodynamic cycling as well as ex situ XRD analysis, does not occur for the carbon-coated material. Preventing this structural disorde…
Overcoming the Insolubility of Molybdenum Disulfide Nanoparticles through a High Degree of Sidewall Functionalization Using Polymeric Chelating Ligands
Highly water-soluble magnetic iron oxide (Fe3O4) nanoparticles for drug delivery: enhanced in vitro therapeutic efficacy of doxorubicin and MION conjugates
We report a simple one step protocol for the preparation of fairly monodisperse and highly water-soluble magnetic iron oxide nanoparticles (MIONs) through a co-precipitation method using a novel multifunctional, biocompatible and water-soluble polymer ligand dodecanethiol–polymethacrylic acid (DDT–PMAA). DDT–PMAA owing to its several intrinsic properties, not only efficiently controls the size of the MIONs but also gives them excellent water solubility, long time stability against aggregation and oxidation, biocompatibility and multifunctional surface rich in thioether and carboxylic acid groups. The molecular weight and concentration of the polymer ligand were optimized to produce ultrasma…
Engineered Multifunctional Nanotools for Biological Applications
Smart multifunctional magnetic nanoparticles are popular candidates for several biological applications owing to their intrinsic magnetic property and diverse applications that range from rare protein separation and biomedical utilization to cancer therapy and diagnostics. A universal protocol, for the development of such nanocarriers, is highly desirable for scientists with different backgrounds so that custom-made multifunctional nanoparticles can be developed to address their needs, among which are the superparamagnetic iron oxide and manganese oxide nanoparticles that are synthesized through high temperature decomposition reactions. However, an interface is needed to present these inorg…
Hydroxypropylcellulose as a novel green reservoir for the synthesis, stabilization, and storage of silver nanoparticles
Muhammad Ajaz Hussain,1 Abdullah Shah,1 Ibrahim Jantan,2 Muhammad Raza Shah,3 Muhammad Nawaz Tahir,4 Riaz Ahmad,5 Syed Nasir Abbas Bukhari2 1Department of Chemistry, University of Sargodha, Sargodha, Pakistan; 2Drug and Herbal Research Centre, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia; 3International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan; 4Institute of Inorganic and Analytical Chemistry, Johannes Guttenberg University, Duesbergweg, Mainz, Germany; 5Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Pakistan Abstract: Polysaccharides are attracting the vigil eye of…
From Single Molecules to Nanoscopically Structured Functional Materials: Au Nanocrystal Growth on TiO2 Nanowires Controlled by Surface-Bound Silicatein
Succinate-bonded pullulan: An efficient and reusable super-sorbent for cadmium-uptake from spiked high-hardness groundwater.
Abstract Chemically modified pullulan was evaluated for its sorption efficiency and selectivity to remove cadmium (Cd) from spiked high-hardness groundwater (GW). Pullulan esterified with succinic anhydride using dimethylaminopyridine showed a fairly high degree of substitution value as confirmed by 1 H NMR spectroscopy. Pullulan succinate (Pull-Suc) was converted into the sodium salt (Pull-Suc-Na). The effect of contact time (5–200 min) and pH (2–8) on Cd-uptake by the sorbent (Pull-Suc-Na) was investigated. The sorbent showed more than 90% Cd-removal in first 15 min from distilled water (DW) and GW solution, respectively. Comparison of Pull-Suc-Na with other polysaccharidal sorbents sugge…
Bio-nano: Theranostic at Cellular Level
Functionalized nanoparticles are important platforms for targeted drug delivery and multimodal imaging. Materials scientists provide tailor-made tools for medical research, diagnosis and treatment. These tools are rationally designed to have defined functions. Still, the value of these tools can only be determined by the users in medical sciences that develop assays for applying these tools. Until now, little is known about the impact of multifunctional particles that display intrinsic chemical and physical asymmetry which poses new challenges for cells associated with the amphiphilicity, dipole moments and chemical diversity/patchiness of the functionalized nanoparticles. Why is it importa…
The 2′-5′-oligoadenylate synthetase in the lowest metazoa: isolation, cloning, expression and functional activity in the sponge Lubomirskia baicalensis
Aquatic animals, especially filter feeders such as sponges [phylum Porifera], are exposed to a higher viral load than terrestrial species. Until now, the antiviral defense system in the evolutionary oldest multicellular organisms, sponges, is not understood. One powerful protection of vertebrates against virus infection is mediated by the interferon (IFN)-inducible 2'-5'-oligoadenylate synthetase [(2-5)A synthetase] system. In the present study we cloned from the freshwater sponge Lubomirskia baicalensis a cDNA encoding a 314 aa long ORF with a calculated size of 35748Da, a putative (2-5)A synthetase, and raised antibodies against the recombinant protein. The native enzyme was identified in…
Iron Oxide Superparticles with Enhanced MRI Performance by Solution Phase Epitaxial Growth
Organized three-dimensional (3D) nanomaterial architectures are promising candidates for applications in optoelectronics, catalysis, or theranostics owing to their anisotropy and advanced structural features that allow tailoring their physical and chemical properties. The synthesis of such complex but well-organized nanomaterials is difficult because the interplay of interfacial strain and facet-specific reactivity must be considered. Especially the magnetic anisotropy with controlled size and morphology plays a decisive role for applications like magnetic resonance imaging (MRI) and advanced data storage. We present a solution phase seed mediated synthesis of colloidal, well dispersible ir…
Synthesis of Mesoporous Supraparticles on Superamphiphobic Surfaces
A method for mesoporous supraparticle synthesis on superamphiphobic surfaces is designed. Therefore, supraparticles assembled with nanoparticles are synthesized by the evaporation of nanoparticle dispersion drops on the superamphiphobic surface. For synthesis, no further purification is required and no organic solvents are wasted. Moreover, by changing the conditions such as drop size and concentration, supraparticles of different sizes, compositions, and architectures are fabricated.
Silicatein conjugation inside nanoconfined geometries through immobilized NTA–Ni(ii) chelates
The chemical modification and bioconjugation processes inside confined geometries by His-tagged silicatein promote sensitive changes in the polarity and surface charge density that mainly contribute to the ionic current rectification properties of the single conical nanopores.
Synthesis of Hierarchically Grown ZnO@NT-WS2 Nanocomposites
A chemically specific and facile method for growth of ZnO nanorods on WS2 nanotubes (NT-WS2) is reported. The modification strategy is based on the chalcophilic affinity of Zn, which serves as an anchor to immobilize ZnO colloids onto the WS2 nanotubes. The surface bound ZnO colloids have been used as a seed to grow ZnO nanorods on WS2 nanotubes. The immobilization of ZnO colloids was monitored by UV−vis spectroscopy and photoluminescence spectroscopy whereas the growth of ZnO nanorods was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
Solids Go Bio: Inorganic Nanoparticles as Enzyme Mimics
A longstanding goal of biomimetic chemistry is the design and synthesis of functional enzyme mimics. The past three decades have seen a wide variety of materials, including metal complexes, polymers and other biomolecules, that mimic the structures and functions of naturally occurring enzymes. Among these, inorganic nanoparticles offer huge potential, because they are more stable than their natural counterparts, while having large surface areas and sizes comparable to those of natural enzymes. Therefore, a considerable number of “artificial enzymes” derived from inorganic nanomaterials have been reported. This microreview highlights the recent progress in the field of enzymatically active i…
Hierachical Ni@Fe2O3superparticles through epitaxial growth of γ-Fe2O3nanorods on: In situ formed Ni nanoplates
One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Ni@γ-Fe2O3 superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3 (maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3 interface in combination with Mossbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 …
Bioorganic/inorganic hybrid composition of sponge spicules: matrix of the giant spicules and of the comitalia of the deep sea hexactinellid Monorhaphis.
The giant basal spicules of the siliceous sponges Monorhaphis chuni and Monorhaphis intermedia (Hexactinellida) represent the largest biosilica structures on earth (up to 3 m long). Here we describe the construction (lamellar organization) of these spicules and of the comitalia and highlight their organic matrix in order to understand their mechanical properties. The spicules display three distinct regions built of biosilica: (i) the outer lamellar zone (radius: >300 mu m), (ii) the bulky axial cylinder (radius: <75 mu m), and (iii) the central axial canal (diameter: <2 mu m) with its organic axial filament. The spicules are loosely covered with a collagen net which is regularly perforated …
Silica-coated Au@ZnO Janus particles and their stability in epithelial cells
Multicomponent particles have emerged in recent years as new compartmentalized colloids with two sides of different chemistry or polarity that have opened up a wide field of unique applications in medicine, biochemistry, optics, physics and chemistry. A drawback of particles containing a ZnO hemisphere is their low stability in biological environment due to the amphoteric properties of Zn2+. Therefore we have synthesized monodisperse Au@ZnO Janus particles by seed-mediated nucleation and growth whose ZnO domain was coated selectively with a thin SiO2 layer as a protection from the surrounding environment that imparts stability in aqueous media while the Au domain remained untouched. The thi…
Chemical Mimicry: Hierarchical 1D TiO2@ZrO2 Core−Shell Structures Reminiscent of Sponge Spicules by the Synergistic Effect of Silicatein-α and Silintaphin-1
In nature, mineralization of hard tissues occurs due to the synergistic effect of components present in the organic matrix of these tissues, with templating and catalytic effects. In Suberites domuncula, a well-studied example of the class of demosponges, silica formation is mediated and templated by an axial proteinaceous filament with silicatein-α, one of the main components. But so far, the effect of other organic constituents from the proteinaceous filament on the catalytic effect of silicatein-α has not been studied in detail. Here we describe the synthesis of core-shell TiO(2)@SiO(2) and TiO(2)@ZrO(2) nanofibers via grafting of silicatein-α onto a TiO(2) nanowire backbone followed by …
Structural and optical properties of Fe and Zn substituted CuInS2 nanoparticles synthesized by a one-pot facile method
We substitute indium present in the CuInS2 ternary compound by iron and zinc using a facile one-pot synthesis method. The quaternary compound of CuIn1−xMxS2 (M = Fe and Zn) was synthesized by dissolving CuCl, InCl3, FeCl3, Zn(ac)2 and SC(NH2)2 as precursors in 1-octadecene, oleylamine and oleic acid as non-coordinating, coordinating and capping agent solvents, respectively. Oleic acid, oleylamine and thiourea were used respectively as a hard Lewis base, borderline Lewis base (in comparison with oleic acid) and soft Lewis base to form appropriate complexes. The complex formation, structure, and optical properties of CuIn1−xMxS2 (M = Fe and Zn) nanoparticles were studied by Fourier transform …
Soluble IF-ReS2 nanoparticles by surface functionalization with terpyridine ligands.
A major drawback in the application of layered chalcogenide nanoparticles/tubes is their inertness to chemical and biological modification and functionalization. Their potential use in composite materials might be greatly enhanced by improving the chalcogenide/matrix interface bonding. A novel modification strategy for layered chalcogenide nanoparticles based on the chalcophilic affinity of metals and the chelating terpyridine is reported. The terpyridine anchor group can be conjugated to fluorescent tags or hydrophilic/hydrophobic groups that confer solubility in various solvents to the otherwise insoluble chalcogenide nanoparticles. The functionalized particles are characterized using TEM…
Phase separated Cu@Fe3O4 heterodimer nanoparticles from organometallic reactants
Cu@Fe3O4 heteroparticles with distinct morphologies were synthesized from organometallic reactants. The shape of the magnetic domains could be controlled by the solvent and reaction conditions. They display magnetic and optical properties that are useful for simultaneous magnetic and optical detection. After functionalization, the Cu@Fe3O4 heterodimers become water soluble. The morphology, structure, magnetic and optical properties of the as-synthesized heterodimer nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), mossbauer spectroscopy, superconducting quantum interference device (SQUID) magnetometry, and dark field imaging. A special a…
Growth Mechanism and Surface Functionalization of Metal Chalcogenides Nanostructures
Following the discovery of carbon fullerenes and nanotubes (NTs), nanostructured materials and their synthesis have attracted tremendous attention due to their superior mechanical properties, their unique electronic behavior, and their high potential in making technologically advanced nanodevices. Among different classes, layered metal chalcogenides nanostructures are of interest for a variety of applications ranging from nanoelectronics or as source materials for energy applications, nanotribology and in heterogeneous catalysis. These nanoparticles are metastable phases. Therefore, equilibrium methods are necessary to prevent the formation of the thermodynamically stable bulk phase. On the…
Metal ion affinity-based biomolecular recognition and conjugation inside synthetic polymer nanopores modified with iron-terpyridine complexes.
Here we demonstrate a novel biosensing platform for the detection of lactoferrin (LFN) via metal-organic frameworks, in which the metal ions have accessible free coordination sites for binding, inside the single conical nanopores fabricated in polymeric membrane. First, monolayer of amine-terminated terpyridine (metal-chelating ligand) is covalently immobilized on the inner walls of the nanopore via carbodiimide coupling chemistry. Second, iron-terpyridine (iron-terPy) complexes are obtained by treating the terpyridine modified-nanopores with ferrous sulfate solution. The immobilized iron-terPy complexes can be used as recognition elements to fabricate biosensing nanodevice. The working pri…
Au@MnO nanoflowers: hybrid nanocomposites for selective dual functionalization and imaging.
Recently, the development of hybrid nanostructures consisting of various materials has attracted considerable interest. The assembly of different nanomaterials with specific optical, magnetic, or electronic properties to multicomponent composites can change and even enhance the properties of the individual constituents. Specifically tuning the structure and interface interactions within the nanocomposites has resulted in novel platforms of materials that may lead the way to various future technologies, such as synchronous biolabeling, protein separation and detection, heterogeneous catalysis, and multimodal imaging in biomedicine. Of the various kinds of nanomaterials, gold nanorods show an…
Controlling phase formation in solids: rational synthesis of phase separated Co@Fe2O3 heteroparticles and CoFe2O4 nanoparticles
A wet chemical approach from organometallic reactants allowed the targeted synthesis of Co@Fe(2)O(3) heterodimer and CoFe(2)O(4) ferrite nanoparticles. They display magnetic properties that are useful for magnetic MRI detection.
Graphene-type sheets of Nb(1-x)W(x)S2: synthesis and in situ functionalization.
Enlightened by the discovery of graphenes, a variety of inorganic analogues have been synthesized and characterized in recent years. Solvated Nb1−xWxS2 analogues of graphene-type sheets were prepared by lithiation and exfoliation of multistacked Nb1−xWxS2 coin roll nanowires (CRNWs), followed by in situ functionalization with gold nanoparticles to synthesize gold-loaded Nb1−xWxS2/Au nanocomposites. The Nb1−xWxS2 nanosheets and the corresponding Nb1−xWxS2/Au nanocomposites were characterized by high resolution electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), scanning transmission electron microscopy (STEM), dynamic light scattering (DLS) and scanning force microscopy …
Genotoxic effects of zinc oxide nanoparticles
The potential toxicity of nanoparticles has currently provoked public and scientific discussions, and attempts to develop generally accepted handling procedures for nanoparticles are under way. The investigation of the impact of nanoparticles on human health is overdue and reliable test systems accounting for the special properties of nanomaterials must be developed. Nanoparticular zinc oxide (ZnO) may be internalised through ambient air or the topical application of cosmetics, only to name a few, with unpredictable health effects. Therefore, we analysed the determinants of ZnO nanoparticle (NP) genotoxicity. ZnO NPs (15-18 nm in diameter) were investigated at concentrations of 0.1, 10 and …
Structural analysis of Gossypium hirsutum fibers grown under greenhouse and hydroponic conditions
Cotton is the one of the world's most important crops. Like any other crop, cotton growth/development and fiber quality is highly dependent on environmental factors. Increasing global weather instability has been negatively impacting its economy. Cotton is a crop that exerts an intensive pressure over natural resources (land and water) and demands an overuse of pesticides. Thus, the search for alternative cotton culture methods that are pesticide-free (biocotton) and enable customized standard fiber quality should be encouraged. Here we describe a culture of Gossypium hirsutum ("Upland" Cotton) utilizing a greenhouse and hydroponics in which the fibers are morphological similar to conventio…
Rational assembly and dual functionalization of Au@MnO heteroparticles on TiO2 nanowires
Au–MnO heteroparticles were immobilized on the surface of TiO2 nanowires and tagged subsequently with a fluorescent ligand. The immobilization of the Au@MnO heteroparticles was achieved by functionalizing the TiO2 nanowire support with a polymer containing catechol anchor groups for binding to the metal oxide surface and amine groups for conjugation to the Au domains of the Au@MnO heteroparticles. The Au domain of the resulting TiO2@Au–MnO nanocomposite could be functionalized selectively with a thiol-tagged 24 mer oligomer containing Texas red (SH-ODN-TXS red), whereas a green dye (NBD–Cl) could be anchored selectively to the TiO2 “support” using the free amine groups of the polymeric liga…
Growth of fibrous aggregates of silica nanoparticles: Fibre growth by mimicking the biogenic silica patterning processes
We describe the self-assembly of discrete SiO2 nanofibers via grafting of silicatein side chains to a polymer backbone. The covalent binding of silicatein to the backbone of the polymer is based on the affinity of the nitrilotriacetic acid (NTA) side chain, which serves as a ligand for the immobilization of His-tagged silicatein. The surface charge and the bulkiness of the protein moieties prevent the entropically favoured coil formation of the polymer and force it to adopt an open chain structure after hydrolysis of the silica precursors. The probes were characterized by scanning force microscopy (SFM) and optical light microscopy. Surface complexation of the resulting silica nanoparticles…
Green synthesis of Pd@graphene nanocomposite: Catalyst for the selective oxidation of alcohols
Abstract Due to their excellent physicochemical properties and synergistic effect, graphene metallic NPs based nanocomposites have gained significant attention in various technological fields including catalysis. Here we demonstrate a single pot, facile and environmental friendly synthesis of catalytically active palladium(Pd)@graphene nanocomposites (SP-HRG-Pd) by the simultaneous reduction of graphene oxide (GRO) and PdCl 2 using Salvadora persica L. (miswak) root extract (RE) as bioreductant. The synthesis of SP-HRG-Pd was confirmed by various spectroscopic and microscopic techniques, including ultraviolet–visible (UV–vis), Fourier-transform infrared (FT-IR), Raman and X-ray photoelectro…
Fabrication of a Silica Coating on Magnetic γ-Fe2O3 Nanoparticles by an Immobilized Enzyme
Silicatein, a hydrolytic protein encountered in marine sponges, was immobilized on maghemite (γ-Fe2O3) nanoparticles that were surface functionalized with a reactive mulfunctional polymer. This polymer carries an anchor group based on dopamine which is capable of binding to the γ-Fe2O3 surface and a reactive functional group which allows binding of various biomolecules onto inorganic nanoparticles. This functional nitrilotriacetic acid (NTA) group allows immobilization of His-tagged silicatein on the surface of the γ-Fe2O3 nanoparticles. The surface-bound protein retains its native hydrolytic activity to catalyze formation of silica through copolymerization of alkoxysilanes Si(OR)4. Functio…
Pathogen-Mimicking MnO Nanoparticles for Selective Activation of the TLR9 Pathway and Imaging of Cancer Cells
Here, design of the first pathogen-mimicking metal oxide nanoparticles with the ability to enter cancer cells and to selectively target and activate the TLR9 pathway, and with optical and MR imaging capabilities, is reported. The immobilization of ssDNA (CpG ODN 2006) on MnO nanoparticles is performed via the phosphoramidite route using a multifunctional polymer. The multifunctional polymer used for the nanoparticle surface modification not only affords a protective organic biocompatible shell but also provides an efficient and convenient means for loading immunostimulatory oligonucleotides. Since fluorescent molecules are amenable to photodetection, a chromophore (Rhodamine) is introduced …
One pot light assisted green synthesis, storage and antimicrobial activity of dextran stabilized silver nanoparticles.
Background Green synthesis of nanomaterials finds the edge over chemical methods due to its environmental compatibility. Herein, we report green synthesis of silver nanoparticles (Ag NPs) mediated with dextran. Dextran was used as a stabilizer and capping agent to synthesize Ag NPs using silver nitrate (AgNO3) under diffused sunlight conditions. Results UV–vis spectra of as synthesized Ag nanoparticles showed characteristic surface plasmon band in the range from ~405-452 nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies showed spherical Ag NPs in the size regime of ~50-70 nm. Face centered cubic lattice of Ag NPs was confirmed by powder X-ray diffraction (PXRD…
From Single Molecules to Nanoscopically Structured Materials: Self-Assembly of Metal Chalcogenide/Metal Oxide Nanostructures Based on the Degree of Pearson Hardness
A chemically specific and facile method for the immobilization of metal oxide nanoparticles onto the surface of IF-MoS2 nested fullerenes is reported. The modification strategy is based on the chalcophilic affinity of transition metals such as Fe2+/Fe3+, Fe3+, or Zn2+ as described by the Pearson HSAB concept. The binding capabilities of the 3d metals are dictated by their Pearson hardness. Pearson hard cations such as Fe3+ (Fe2O3) do not bind to the chalcogenide surfaces; borderline metals such as Fe2+ (Fe3O4) or Zn2+ (ZnO) bind reversibly. Pearson-soft metals like Au bind irreversibly. The immobilization of metal oxide nanoparticle colloids was monitored by transmission electron microscopy…
Hydrogen peroxide sensing with horseradish peroxidase-modified polymer single conical nanochannels.
Inspired from the funtioning and responsiveness of biological ion channels, researchers attempt to develop biosensing systems based on polymer and solid-state nanochannels. The applicability of these nanochannels for detection/sensing of any foreign analyte in the surrounding environment depends critically on the surface characteristics of the inner walls. Attaching recognition sites to the channel walls leads to the preparation of sensors targeted at a specific molecule. There are many nanochannel platforms for the detection of DNA and proteins, but only a few are capable of detecting small molecules. Here, we describe a nanochannel platform for the detection of hydrogen peroxide, H(2)O(2)…
Design, characterization and evaluation of hydroxyethylcellulose based novel regenerable supersorbent for heavy metal ions uptake and competitive adsorption
Abstract Hydroxyethylcellulose succinate-Na (HEC-Suc-Na) was designed and evaluated for removal of some heavy metal ions from aqueous solution. Pristine sorbent HEC-Suc-Na was thoroughly characterized by FTIR and solid-state CP/MAS 13C NMR spectroscopy, SEM-EDS and zero point charge analyses. Langmuir isotherm, pseudo second order kinetic and ion exchange models provided best fit to the experimental data of sorption of metal ions. Maximum sorption capacities of supersorbent HEC-Suc-Na for sorption of heavy metal ions from aqueous solution as calculated by Langmuir isotherm model were found to be 1000, 909.09, 666.6, 588 and 500 mg g−1 for Pb(II), Cr(VI), Co(II), Cu(II) and Ni(II), respectiv…
Solid State Fluorination on the Minute Scale: Synthesis of WO 3− x F x with Photocatalytic Activity
Extraordinary Performance of Carbon‐Coated Anatase TiO 2 as Sodium‐Ion Anode
The synthesis of in situ polymer‐functionalized anatase TiO2 particles using an anchoring block copolymer with hydroxamate as coordinating species is reported, which yields nanoparticles (≈11 nm) in multigram scale. Thermal annealing converts the polymer brushes into a uniform and homogeneous carbon coating as proven by high resolution transmission electron microscopy and Raman spectroscopy. The strong impact of particle size as well as carbon coating on the electrochemical performance of anatase TiO2 is demonstrated. Downsizing the particles leads to higher reversible uptake/release of sodium cations per formula unit TiO2 (e.g., 0.72 eq. Na+ (11 nm) vs only 0.56 eq. Na+ (40 nm)) while the …
Synthesis and characterization of carbon coated sponge-like tin oxide (SnOx) films and their application as electrode materials in lithium-ion batteries
Nanoporous metal oxides are widely used for the development of various functional nanostructures. We report on the synthesis of sponge-like tin oxide films on copper foil by anodization of electrochemically deposited tin films. The thin films are functionalized using a surface-anchoring carbon precursor-polymer (poly(acrylonitrile-b-dopamine acrylamide)) followed by annealing at elevated temperature to convert the polymer coating into a carbonaceous coating. The as prepared and the carbon coated films are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectroscopy. Subsequently, both SnOx films are employed as a…
IF-ReS2 with Covalently Linked Porphyrin Antennae
The preparation of inorganic and organic hybrid materials, of metals or semiconductor systems which are functionalized with functional molecules to fabricate devices — nanotechnology — is currently an area of intense activity in both fundamental science and applied science on an international scale. Principally, nanotechnology aims at manipulating atoms, molecules, and nanosize particles in a precise and controlled manner in order to build materials with a fundamentally new organization and novel properties. The embryonic stage of nanotechnology is atomic assembly, whereas the mature form of nanotechnology will be molecular assembly to make nano-building blocks for the design of nanocomposi…
Liquid crystalline phases from polymer functionalised semiconducting nanorods
The orientation of semiconducting nanomaterials is a hot topic in optoelectronic applications. Liquid crystallinity offers the potential to orient inorganic anisotropic nanorods, if they can be solubilised sufficiently as realised by polymer functionalisation. In this work we functionalised TiO2, SnO2, ZnO and CdTe nanorods with PMMA, PS and PDEGMEMA (poly(diethylene glycol monomethyl ether) methacrylate) diblock copolymers containing anchor groupsvia grafting-to. The block copolymers were synthesised by RAFT polymerisation (PDI ≈ 1.2) via reactive ester diblock copolymers, which were functionalised later with anchor units polymer-analogously. The surface coverage of the nanorods (determine…
From Single Molecules to Nanoscopically Structured Functional Materials
AbstractThe synthesis of MS2 (M = Mo, W) onion-like nanoparticles by means of a high temperature MOCVD process starting from W(CO)6 and elemental sulfur is reported. The reaction can also be carried out in two steps where the intermediate amorphous WS2 nanoparticles formed through the high temperature reaction of tungsten and sulfur in the initial phase of the reaction are isolated and converted in a separate annealing step to onion-type WS2 nanoparticles. Based on a study of the temperature dependence of the reaction a set of conditions could be derived where onion-like structures were formed in a one-step reaction. Onion-like structures obtained in the single-step process were filled, whe…
Reactive Polymers: A Versatile Toolbox for the Immobilization of Functional Molecules on TiO2 Nanoparticles
Facile synthesis and characterization of monocrystalline cubic ZrO2 nanoparticles
Abstract Crystalline ZrO2 nanoparticles were prepared from zirconium isopropoxide by slow hydrolysis and subsequent hydrothermal treatment of solutions containing various amounts of sodium hydroxide at 180 °C. Whereas moderately basic solutions lead to the formation of nanoparticles of monoclinic ZrO2 with plate-like morphology, and nanoparticles of the cubic ZrO2 high-temperature polymorph with diameters of approx. 5 nm were obtained from strongly basic solutions. The morphology, structure and properties of as-synthesized nanoparticles were characterized using HRTEM, XRD, Raman spectroscopy, UV–vis, PL spectroscopy and BET measurements. The formation of both, the monoclinic and the cubic p…
Self-cleaning antimicrobial surfaces by bio-enabled growth of SnO2 coatings on glass.
Conventional vapor-deposition techniques for coatings require sophisticated equipment and/or high-temperature resistant substrates. Therefore bio-inspired techniques for the fabrication of inorganic coatings have been developed in recent years. Inspired by the biology behind the formation of the intricate skeletons of diatoms orchestrated by a class of cationic polyamines (silaffins) we have used surface-bound spermine, a naturally occurring polyamine, to promote the fast deposition of homogeneous, thin and transparent biomimetic SnO2 coatings on glass surfaces. The bio-enabled SnO2 film is highly photoactive, i.e. it generates superoxide radicals (O2˙(-)) upon sunlight exposure resulting i…
Surface Defects as a Tool to Solubilize and Functionalize WS 2 Nanotubes
Layered transition metal dichalcogenides contain a number of crystal defects which significantly change their properties may be beneficial or detrimental for a specific application. We have prepared defect-rich multiwalled WS2 nanotubes by reductive sulfidization of W18O49 nanowires that were obtained solvothermally from tungsten chloride in different alcohols. The synthesis of the W18O49 nanowires was monitored and their morphological characteristics (e. g. length, rigidity and aspect ratio) are described in detail. The effect of morphology of the nanowires on the synthesis of WS2 nanotubes was investigated in order to obtain WS2 nanotubes that are highly solvent dispersible. Dispersions o…
Pulicaria glutinosa plant extract: a green and eco-friendly reducing agent for the preparation of highly reduced graphene oxide
The environmentally friendly synthesis of nanomaterials using green chemistry has attracted tremendous attention in recent years due to its easy handling, low cost, and biocompatibility. Here we demonstrate a facile and efficient route for the synthesis of highly reduced graphene oxide (PE-HRG) by the green reduction of graphene oxide (GRO) using the Pulicaria glutinosa plant extract (PE). The phytomolecules present in the P. glutinosa extract are not only responsible for the reduction of GRO, but also for the functionalization of the surface of the PE-HRG nanosheets and stabilize them in various solvents, thereby limiting the use of any other external and harmful chemical reductants and su…