Versatile Template Research Articles

Synthesis of Multibranched Gold Nanoechinus Using a Gemini Cationic Surfactant and Its Application for Surface Enhanced Raman Scattering.

High-yield multibranched Au nanoechinus possessing lengthy and dense branched nanorods on the surface were synthesized using a seed-mediated surfactant-directed approach in the presence of gemini cationic surfactant N,N,N'N'-tetramethyl-N,N'-ditetradecylethane-1,2-diaminium bromide (C14C2C14Br2), HAuCl4, AgNO3, and ascorbic acid. C14C2C14Br2 surfactant provides a versatile template in designing the unique morphology of Au nanoechinus with the assistance of AgNO3. UV-vis spectroscopic analysis proves that Au nanoechinus possess a unique intense broad localized surface plasmon resonance (LSPR) peak, which extends from 400 to 1700 nm in the NIR region making a highly potential platform for biomedical applications. Systematic time-dependent TEM, UV-vis-NIR, and XRD analysis were performed to monitor the morphological evolution of multibranched Au nanoechinus. It was found that the surface of branched nanorods of Au NE preferentially grew along (111) crystal planes. Furthermore, as-synthesized Au nanoechinus shows excellent SERS enhancement ability for dopamine inside HeLa cells.

Atomic-Scale Mapping of Layer-by-Layer Hydrogen Etching and Passivation of SiC(0001) Substrates

Preparation of SiC(0001) substrates is of high relevance to graphene growth. Yet, if only a smooth surface could be achieved, heteroepitaxy of many other two-dimensional materials comes into reach. Here we report a novel approach to hydrogen etching of SiC, based on stepwise ultrapure H exposure with slow substrate cooling rates. For the first time, the atomic evolution of the surface structure is witnessed by scanning tunneling microscopy. A detailed picture of the gas phase chemistry emerges, such as a zipper-like material desorption at step edges. The Si–C sheets are removed in layer-by-layer fashion, leading to large terraces with straight rims. The process ultimately results in an atomically smooth surface with complete H-passivation, with no detectable defect states in photoemission. The degree of perfection achieved suggests the use of this substrate as a versatile nanostructure template.

Human Pyruvate Dehydrogenase Complex E2 and E3BP Core Subunits: New Models and Insights from Molecular Dynamics Simulations.

Targeted manipulation and exploitation of beneficial properties of multienzyme complexes, especially for the design of novel and efficiently structured enzymatic reaction cascades, require a solid model understanding of mechanistic principles governing the structure and functionality of the complexes. This type of system-level and quantitative knowledge has been very scarce thus far. We utilize the human pyruvate dehydrogenase complex (hPDC) as a versatile template to conduct corresponding studies. Here we present new homology models of the core subunits of the hPDC, namely E2 and E3BP, as the first time effort to elucidate the assembly of hPDC core based on molecular dynamic simulation. New models of E2 and E3BP were generated and validated at atomistic level for different properties of the proteins. The results of the wild type dimer simulations showed a strong hydrophobic interaction between the C-terminal and the hydrophobic pocket which is the main driving force in the intertrimer binding and the core self-assembly. On the contrary, the C-terminal truncated versions exhibited a drastic loss of hydrophobic interaction leading to a dimeric separation. This study represents a significant step toward a model-based understanding of structure and function of large multienzyme systems like PDC for developing highly efficient biocatalyst or bioreaction cascades.

Graphene Emerges as a Versatile Template for Materials Preparation.

Graphene and its derivatives are emerging as a class of novel but versatile templates for the controlled preparation and functionalization of materials. In this paper a conceptual review on graphene-based templates is given, highlighting their versatile roles in materials preparation. Graphene is capable of acting as a low-dimensional hard template, where its two-dimensional morphology directs the formation of novel nanostructures. Graphene oxide and other functionalized graphenes are amphiphilic and may be seen as soft templates for formatting the growth or inducing the controlled assembly of nanostructures. In addition, nanospaces in restacked graphene can be used for confining the growth of sheet-like nanostructures, and assemblies of interlinked graphenes can behave either as skeletons for the formation of composite materials or as sacrificial templates for novel materials with a controlled network structure. In summary, flexible graphene and its derivatives together with an increasing number of assembled structures show great potentials as templates for materials production. Many challenges remain, for example precise structural control of such novel templates and the removal of the non-functional remaining templates.

Programmably Shaped Carbon Nanostructure from Shape-Conserving Carbonization of DNA.

DNA nanostructures are versatile templates for low cost, high resolution nanofabrication. However, due to the limited chemical stability of pure DNA structures, their applications in nanofabrication have long been limited to low temperature processes or solution phase reactions. Here, we demonstrate the use of DNA nanostructure as a template for high temperature, solid-state chemistries. We show that programmably shaped carbon nanostructures can be obtained by a shape-conserving carbonization of DNA nanostructures. The DNA nanostructures were first coated with a thin film of Al2O3 by atomic layer deposition (ALD), after which the DNA nanostructure was carbonized in low pressure H2 atmosphere at 800-1000 °C. Raman spectroscopy and atomic force microscopy (AFM) data showed that carbon nanostructures were produced and the shape of the DNA nanostructure was preserved. Conductive AFM measurement shows that the carbon nanostructures are electrically conductive.

Versatile Photocrosslinked Protein Hydrogel Matrix for Magnetic-Nanoparticle-Doping and Biomineralization.

A versatile template biomaterial was facilely obtained by ultraviolet (UV) photocrosslinking approach using protein molecules as building blocks. As-formed photocrosslinked protein hydrogel matrix (PPHM) was proved to be composed of covalently bound and dense packing protein molecules. Therefore, the PPHM was endowed with highly smooth topograghy with an average roughness of approximately 5 nm, and was self-supporting and flexible. The PPHM could be easily functionalized by doping Fe3O4 magnetic nanoparticles inside the protein hydrogel. Further, PPHM was experimentally demonstrated to be used as a applicable template for biomineralization.

Controlled synthesis of hollow Si–Ni–Sn nanoarchitectured electrode for advanced lithium-ion batteries

The hollow Si–Ni–Sn nanospheres with porous and hollow microspheric structure were fabricated via a versatile template synthesis approach followed by an in situ chemical reaction, and directly used as an anode material for lithium-ion batteries.

Increasing the Morphological Stability of DNA-Templated Nanostructures with Surface Hydrophobicity.

DNA has been extensively used as a versatile template to assemble inorganic nanoparticles into complex architectures; thanks to its programmability, stability, and long persistence length. But the geometry of self-assembled nanostructures depends on a complex combination of attractive and repulsive forces that can override the shape of a molecular scaffold. In this report, an approach to increase the morphological stability of DNA-templated gold nanoparticle (AuNP) groupings against electrostatic interactions is demonstrated by introducing hydrophobicity on the particle surface. Using single nanostructure spectroscopy, the nanometer-scale distortions of 40 nm diameter AuNP dimers are compared with different hydrophilic, amphiphilic, neutral, and negatively charged surface chemistries, when modifying the local ionic strength. It is observed that, with most ligands, a majority of studied nanostructures deform freely from a stretched geometry to touching particles when increasing the salt concentration while hydrophobicity strongly limits the dimer distortions. Furthermore, an amphiphilic surface chemistry provides DNA-linked AuNP dimers with a high long-term stability against internal aggregation.

Five hybrid thiocyanate networks oriented by polyvalent cationic templates: Synthesis, structure and properties

The N-1-methylimidazole-substituted multication-templated self-assembly of CuSCN/AgSCN leads to five novel complex salts: {(tbi)[Cu3(SCN)6]}n (1), {(tbmi)[Cu2(SCN)5]}n (2), {(tebi)[Cu(SCN)2]4}n (3), {(tebi)[Cu(SCN)2]4}n (4) and {(tbmi)2[Ag5(SCN)11]}n (5) [tbi3+=1,3,5-tri[3′(1′-methyl)imidazoliummethyl]benzene, tbmi3+=1,3,5-tri[3′-(1′-methyl)imidazoliummethyl]-2,4,6-trimethylbenzene and tebi4+=1,2,4,5-tetra[3′-(1′-methyl)imidazoliummethyl]benzene]. Single-crystal X-ray diffraction shows that 2, 3 and 5 display a 2D sandwich structure, 4 presents a 2D polypseudorotaxane network, whereas, 1 exhibits a 3D polypseudorotaxane architecture. It is worth noting that SCN− can present five coordinating modes. All these results confirm the versatile template effect and correct choice of multications. In addition, elemental analysis, IR and UV–Vis spectra, powder X-ray diffraction patterns, thermogravimetric analyses of these complexes have been investigated.

Sulfate Anion as a pH‐Switchable Template: Three‐State Switchable Systems Based on Diamidocarbazoles

AbstractThe sulfate anion SO42– – one of the most powerful and versatile anionic templates – can be reversibly “switched off” in aprotic solvents by protonation to the very weakly binding anion HSO4–. This sharp ON/OFF behaviour opens new opportunities for switching and manipulation of anion templated supramolecular systems, such as reversible folding/unfolding, assembly/disassembly or induction of mechanical motions. As a proof of concept, two new acid/base switchable three‐state systems are presented here.

Supramolecular Assembly of Helical Porphyrin Nanostructures on Single Stranded DNA Via Directional Hydrogen Bonds

Chiral nanomaterials and metamaterials have great potential for applications in plasmonics, biological sensing, labelling, chiral memory, data storage, and optical communication. Porphyrins’ modular photophysical and structural properties, high stability, and accessible synthetic routes make them one of the most commonly utilized functional building blocks in molecular engineering. Single stranded DNA (ssDNA) represents a versatile supramolecular template, since its nucleotide sequence and structure can be easily copied into newly formed periodically arranged helical nanostructures. This lecture will present the synthesis of porphyrin-purine conjugates and their assembly into helical supramolecular porphyrin and metalloporphyrin nanostructures formed on a single stranded oligothymidine template via directional hydrogen bonding (see Figure).[1,2] We will describe how the helicity of ssDNA-templated porphyrin and metalloporphyrin nanoarrays can be controlled and switched using external stimuli to preferentially prepare left-handed and right-handed nanoassemblies. We will also present external stimuli induced, reversible switching of helical twist of ssDNA-templated porphyrin nanoassemblies. Time-dependent density functional theory (TD DFT) simulations of UV-vis and circular dichroism (CD) spectra for model porphyrin nanostacks have been used to confirm the origin of observed chiroptical properties and to assign the handedness of porphyrin nanoassemblies. We will also discuss successful use of dialysis to separate porphyrin nanoassemblies from porphyrin monomers. The chiral DNA-templated multiporphyrin nanostructures exhibited high thermal and acid/base stability: the helicity was fully preserved up to +85 °C and pH between 3 and 12. High resolution transition electron microscopy (HRTEM) has showed formation of metalloporphyrin nanoassemblies and their assembly into helical fibrils with micrometer lengths.[2] 1. G. Sargsyan, B. M. Leonard, J. Kubelka, M. Balaz, ‘Supramolecular ssDNA templated porphyrin and metalloporphyrin nanoassemblies with tunable helicity.’ Chem. Eur. J., 2014, 20, 1878-1892 (VIP) 2. G. Sargsyan, A. A. Schatz, J. Kubelka, M. Balaz, ‘Formation and helicity control of ssDNA templated porphyrin nanoassemblies.’ Chem. Commun. , 2013, 49, 1020-1022 Figure 1

Metal-organic framework templated synthesis of ultrathin, well-aligned metallic nanowires.

With well-defined porous structures and dimensions, metal-organic frameworks (MOFs) can function as versatile templates for the growth of metallic nanostructures with precisely controlled shapes and sizes. Using MOFs as templates, metallic nanostructures can be grown without the need of bulky surfactants and thus preserve their intrinsic surface. Additionally, the high surface area of MOFs can also ensure that the surface of the template metallic nanostructures is readily accessible, which is critical for the proper function of catalysts or sensors. The hybrid metal@MOF structures have been demonstrated to exhibit useful properties not found in either component separately. Here we report the growth of ultrafine metallic nanowires inside one-dimensional MOF pores with well-controlled shape and size. Our study shows that solvent selection plays an important role in controlling precursor loading and the reduction rate inside the MOF pores for the formation of the nanowires. The growth of the well-aligned, ultrathin nanowires was monitored and characterized by transmission electron microscopy, X-ray diffraction, UV-vis spectroscopy, fluorescence studies, and Brunauer-Emmet-Teller surface area analysis.

Poriferan Chitin as a Versatile Template for Extreme Biomimetics

In this mini-review, we shall first cover a short history of the discovery of chitin isolated from sponges; as well as its evolutionarily ancient roots. Next, we will delve into the unique structural, mechanical, and thermal properties of this naturally occurring polymer to illuminate how its physicochemical properties may find uses in diverse areas of the material sciences. We show how the unique properties and morphology of sponge chitin renders it quite useful for the new route of “Extreme Biomimetics”; where high temperatures and pressures allow a range of interesting bioinorganic composite materials to be made. These new biomaterials have electrical, chemical, and material properties that have applications in water filtration, medicine, catalysis, and biosensing.

Recycling nanowire templates for multiplex templating synthesis: a green and sustainable strategy.

Template-directed synthesis of nanostructures has been emerging as one of the most important synthetic methodologies. A pristine nanotemplate is usually chemically transformed into other compounds and sacrificed after templating or only acts as an inert physical template to support the new components. If a nanotemplate is costly or toxic as waste, to recycle such a nanotemplate becomes highly desirable. Recently, ultrathin tellurium nanowires (TeNWs) have been demonstrated as versatile chemical or physical templates for the synthesis of a diverse family of uniform 1D nanostructures. However, ultrathin TeNWs as template are usually costly and are discarded as toxic waste in ionic species after chemical reactions or erosion. To solve the above problem, we conceptually demonstrate that such a nanotemplate can be economically recycled from waste solutions and repeatedly used as template.

Analgesic and anti-inflammatory activities of certain 6-aryl-9-substituted-6,9-diazaspiro-[4,5]decane-8,10-diones in mice

Background and objective2,6-Diketopiperazines are promising bioactive chemical entities in drug discovery. They could be considered a versatile template for the synthesis of a variety of scaffolds because of the presence of the reactive endocyclic nucleophilic imide group. It is worth mentioning that the 2,6-diketopiperazine system is embedded in the chemical skeleton of 6,9-diazaspiro-[4,5]decane-8,10-diones. The aim of the present work was to study both peripheral and central analgesic activities as well as the anti-inflammatory activity of 6-aryl-9-substituted-6,9-diazaspiro-[4,5]decane-8,10-diones 1-9 in different in-vivo experimental models.Materials and methodsThe test compounds 1-9 were evaluated for their analgesic activity in adult male Swiss albino mice using the writhing (12.5 and 25 mg/kg) and hot-plate (25 mg/kg) tests. Moreover, the anti-inflammatory activity was assessed for compounds 1-9 at dose 25 mg/kg (0.066-0.079 mmol/kg) by intraperitoneal administration using carrageenan-induced hind-paw edema assay in mice at 1, 2, and 3 h after carrageenan challenge and compared with diclofenac sodium at dose 10 mg/kg (0.031 mmol/kg) as the reference drug.Results and conclusionAll compounds 1-9 showed significant inhibition of acetic acid induced writhing in the writhing test. Their percentage inhibition of abdominal writhing induced by acetic acid (peripheral effect) at doses of 12.5 mg/kg (0.033-0.039 mmol/kg) and 25 mg/kg (0.066-0.079 mmol/kg) ranged from 68.55 to 17.74% and from 88.71 to 53.23%, respectively. Compound 7 (R 1 = H, R 2 = CH 2 CH 2 Ph) demonstrated the highest writhing inhibition percentage at both dose levels (88.71 and 68.55%, respectively) and exhibited significantly lower number of writhes compared with diclofenac sodium as the reference standard. In the hot-plate test (central effect), compounds 2 (R 1 = CH 3 , R 2 = CH 2 COOH 3 ) and 3 (R 1 = 4-OCH 3 , R 2 = CH 2 COOCH 3 ) at doses of 0.076 and 0.072 mmol/kg, respectively (equivalent to 25 mg/kg), significantly raised the pain threshold and exhibited the best analgesic activity at 30 min. Both of them displayed nonsignificant difference from tramadol hydrochloride (0.095 mmol/kg, 25 mg/kg) at 30 min. In contrast, compounds 1 (R 1 = H, R 2 = CH 2 COOH 3 ) at dose 0.079 mmol/kg and 5 (R 1 = CH 3 , R 2 = CH 2 Ph) at dose 0.068 mmol/kg showed slight lower analgesic potency compared with 2 and 3 with significant difference from the reference drug. The most powerful anti-inflammatory effect in this series was demonstrated in 9-N-methyl acetate derivatives (1-3), where compound 1 (R 1 = H, R 2 = CH 2 COOH 3 ) at dose 0.079 mmol/kg exhibited 53.93% maximum protection (inhibition of edema size) at 3 h, compared with diclofenac sodium (0.0314 mmol/kg), which reached 60.40%. On the other hand, compounds 4-9 displayed 36.90-26.77% protection against carrageenan-induced edema.

Capillary assembly of cross-gradient particle arrays using a microfluidic chip

Arrays with well-defined particle registration are of high importance in device fabrication for biosensors, electronics and optics. Also, materials exhibiting gradient variations of properties (e.g. wettability) in one, two or three dimensions have proven their capability for high-throughput screening of various interactions (e.g. cell–surface interactions). Here, we present the fabrication of cross-gradient particle arrays (CGPA) featuring a gradual cross-over from one particle type to another, while keeping the overall particle density constant. CGPAs were prepared by means of a capillary assembly setup assisted by a microfluidic chip. This setup offers a high level of control over the capillary assembly process with respect to the composition and location of the assembled arrays. A CGPA can be a versatile template or precursor for fabricating surface-bound gradient materials, e.g. by selectively transferring one population of assembled particles or by functionalizing particles before or after assembly. The resulting two complementary gradients may be used in combinatorial studies of biological and chemical interactions. We demonstrate the application of a CGPA as a two-level security feature with unclonable finger-print-like patterns. Moreover, we show the possibility of obtaining a 2D CGPA by capitalizing on diffusive transport within the capillary bridge perpendicular to the assembly direction.

M13 Bacteriophage Displaying DOPA on Surfaces: Fabrication of Various Nanostructured Inorganic Materials without Time-Consuming Screening Processes

M13 bacteriophage (phage) was engineered for the use as a versatile template for preparing various nanostructured materials via genetic engineering coupled to enzymatic chemical conversions. First, we engineered the M13 phage to display TyrGluGluGlu (YEEE) on the pVIII coat protein and then enzymatically converted the Tyr residue to 3,4-dihydroxyl-l-phenylalanine (DOPA). The DOPA-displayed M13 phage could perform two functions: assembly and nucleation. The engineered phage assembles various noble metals, metal oxides, and semiconducting nanoparticles into one-dimensional arrays. Furthermore, the DOPA-displayed phage triggered the nucleation and growth of gold, silver, platinum, bimetallic cobalt-platinum, and bimetallic iron-platinum nanowires. This versatile phage template enables rapid preparation of phage-based prototype devices by eliminating the screening process, thus reducing effort and time.

Developing genetically engineered encapsulin protein cage nanoparticles as a targeted delivery nanoplatform.

Protein cage nanoparticles are excellent candidates for use as multifunctional delivery nanoplatforms because they are built from biomaterials and have a well-defined structure. A novel protein cage nanoparticle, encapsulin, isolated from thermophilic bacteria Thermotoga maritima, is prepared and developed as a versatile template for targeted delivery nanoplatforms through both chemical and genetic engineering. It is pivotal for multifunctional delivery nanoplatforms to have functional plasticity and versatility to acquire targeting ligands, diagnostic probes, and drugs simultaneously. Encapsulin is genetically engineered to have unusual heat stability and to acquire multiple functionalities in a precisely controlled manner. Hepatocellular carcinoma (HCC) cell binding peptide (SP94-peptide, SFSIIHTPILPL) is chosen as a targeting ligand and displayed on the surface of engineered encapsulin (Encap_loophis42C123) through either chemical conjugation or genetic insertion. The effective and selective targeted delivery of SP94-peptide displaying encapsulin (SP94-Encap_loophis42C123) to HepG2 cells is confirmed by fluorescent microscopy imaging. Aldoxorubicin (AlDox), an anticancer prodrug, is chemically loaded to SP94-Encap_loophis42C123 via thiol-maleimide Michael-type addition, and the efficacy of the delivered drugs is evaluated with a cell viability assay. SP94-Encap_loophis42C123-AlDox shows comparable killing efficacy with that of free drugs without the platform's own cytotoxicity. Functional plasticity and versatility of the engineered encapsulin allow us to introduce targeting ligands, diagnostic probes, and therapeutic reagents simultaneously, providing opportunities to develop multifunctional delivery nanoplatforms.

A Simple Method for the Production of AAO Templates for DC Electrodeposition of Nanostructures

Low-cost template based nano-fabrication approaches are extensively studied for obtaining functional arrays of nanostructures. Among them anodic aluminum oxide (AAO) templates obtained via two-step anodization stands still today as an elegant and straightforward approach for electrochemistry based nanofabrication. However using AAO for direct electrochemical growth of metallic compounds is still a challenging task due to the presence of an insulating barrier oxide layer situated at the pore bottoms. Several intriguing strategies have been developed for the removal of the barrier layer 1–11 but none of them allows the use of AAO readily as produced without undertaking meticulous procedures or requiring expensive laboratory equipment. In this work we present an easy route to overcome this handicap of otherwise very versatile AAO templates by drawing renewed attention to a process long known by the aluminum industry as zincating. 12 Zincated AAO films are robust and easy to manipulate since they are still bound to the base aluminum metal. Furthermore they are suitable for DC electrodeposition of metallic nanostructures without any additional treatment.

Fabrication of Metal Nanowires Containing Highly Controllable Nanospaces

Hollow nanostructures are of scientific and technological interest in the broad applications due to their ability to interact with other materials not only at their surfaces, to modulate refractive index, to improve the catalytic activity and to lower the density of nanostructures [1]. To prepare hollow structures, various methods such as versatile template methods based on the removal of sacrificial template [2] and simple templateless method [3] have been developed and enable to incorporate the void space or nanospaces into various nanostructures such as the nanosphene, nanocubes, nanorods and nanowires. Among these nanostructures, porous nanowires have much attention in the many field because they acquire the above advantages of hollow structures as well as the advantage of 1 D structures [4]. On the other hand, the precise control of pore size, volume and density in arbitrary structures is important because the size, volume and density directly determine the new ability depending on the nanospaces to provide the desired functions. Herein, we report the facile, high-throughput and novel route to fabricate the metal nanowires containing highly controllable nanospaces. The metal nanowires containing highly controllable nanospaces were fabricated by the template method based on the removal of sacrificial template. We choose Nickel (Ni) as the metal and Silver (Ag) as the sacrificial template. We confirmed the Ni nanowires containing highly controllable Ag segment were fabricated by the pulsed electrodeposition in Anodic Aluminum oxide template. After etching the Ag segment, we clearly observed the Ni nanowires containing highly controllable nanospaces. By taking the advantage of the well controllability of the electroplating conditions such as the time of the deposition and the concentration of the plating solution, we found the size and the pitch of the hollowed segments were successfully controlled. [1] Y. Zhao et al., Advanced Materials 2009, 21, 3621.[2] F. Carusoet al., Science 1998, 282, 1111.[3] Y. Yin et al., Science 2004, 304, 711.[4] H. Jiang et al., Chemical Communications 2012, 48, 4465.