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- ItemAnalysis of fatty acids and triacylglycerides by Pd nanoparticle-assisted laser desorption/ionization mass spectrometry(Cambridge : Royal Society of Chemistry, 2015) Silina, Yuliya E.; Fink-Straube, Claudia; Hayen, Heiko; Volmer, Dietrich A.In this study, we propose a simple and rapid technique for characterization of free fatty acids and triacylglycerides (TAG) based on palladium nanoparticular (Pd-NP) surface-assisted laser desorption/ionization (SALDI) mass spectrometry (MS). The implemented Pd-NP material allowed detection of free fatty acids and TAGs exclusively as [M + K]+ ions in positive ion mode. Under negative ionization conditions, unusual trimetric structures were generated for free fatty acids, while TAGs underwent irreproducible degradation reactions. Importantly, the mass spectra obtained from Pd-NP targets in positive ion mode were very clean without interferences from matrix-derived ions in the low m/z range and readily enabled the detection of intact TAGs in vegetable oils without major fragmentation reactions as compared to conventional MALDI-MS, requiring only a minimal amount of sample preparation.
- ItemSurface-assisted laser desorption/ionization mass spectrometry using ordered silicon nanopillar arrays(Cambridge : Royal Society of Chemistry, 2014) Alhmoud, Hashim Z.; Guinan, Taryn M.; Elnathan, Roey; Kobus, Hilton; Voelcker, Nicolas H.Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is ideally suited for the high-throughput analysis of small molecules in bodily fluids (e.g. saliva, urine, and blood plasma). A key application for this technique is the testing of drug consumption in the context of workplace, roadside, athlete sports and anti-addictive drug compliance. Here, we show that vertically-aligned ordered silicon nanopillar (SiNP) arrays fabricated using nanosphere lithography followed by metal-assisted chemical etching (MACE) are suitable substrates for the SALDI-MS detection of methadone and small peptides. Porosity, length and diameter are fabrication parameters that we have explored here in order to optimize analytical performance. We demonstrate the quantitative analysis of methadone in MilliQ water down to 32 ng mL-1. Finally, the capability of SiNP arrays to facilitate the detection of methadone in clinical samples is also demonstrated.
- ItemA novel precursor system and its application to produce tin doped indium oxide(Cambridge : Royal Society of Chemistry, 2011) Veith, Michael; Bubel, Carsten; Zimmer, MichaelA new type of precursor has been developed by molecular design and synthesised to produce tin doped indium oxide (ITO). The precursor consists of a newly developed bimetallic indium tin alkoxide, Me2In(OtBu)3Sn (Me = CH3, OtBu = OC(CH3)3), which is in equilibrium with an excess of Me2In(OtBu). This quasi single-source precursor is applied in a sol–gel process to produce powders and coatings of ITO using a one-step heat treatment process under an inert atmosphere. The main advantage of this system is the simple heat treatment that leads to the disproportionation of the bivalent Sn(II) precursor into Sn(IV) and metallic tin, resulting in an overall reduced state of the metal in the final tin doped indium oxide (ITO) material, hence avoiding the usually necessary reduction step. Solid state 119Sn-NMR measurements of powder samples confirm the appearance of Sn(II) in an amorphous gel state and of metallic tin after annealing under nitrogen. The corresponding preparation of ITO coatings by spin coating on glass leads to transparent conductive layers with a high transmittance of visible light and a low electrical resistivity without the necessity of a reduction step.
- ItemNovel single-source precursors for the fabrication of PbTiO3, PbZrO3 and Pb(Zr1-x Tix)O3 thin-films by chemical vapor deposition(Cambridge : Royal Society of Chemistry, 2011) Veith, Michael; Bender, Michael; Lehnert, Tobias; Zimmer, Michael; Jakob, AnetteLead titanate, lead zirconate, and lead zirconate titanate (PZT) films in the sub-μm-range were produced at temperatures around 400 °C using novel single-source precursors in a classical thermal CVD process. The design of two bimetallic alkoxide compounds, a lead titanate and a lead zirconate source with almost identical physical properties and complement miscibility, resulted in a new quasi-single-source PZT precursor, an azeotropic mixture that evaporates at 30 °C and at a pressure of 4 × 10−1 mbar. After thermal treatment at 650 °C, transparent (100)-oriented PZT films with remnant polarization of 20 μC cm−2 and a coercive field strength of 20 V μm−1 were achieved. An additional lead source is not required.
- ItemComment on "Synthesis, characterization and growth mechanism of flower-like vanadium carbide hierarchical nanocrystals"(Cambridge : Royal Society of Chemistry, 2012) Presser, Volker; Vakifahmetoglu, CekdarThis Letter is in response to a recent paper by Ma et al. (CrystEngComm, 2010, 12, 750-754) which arguably studied vanadium carbide nanostructures whereas all available evidence indicates the study of vanadium oxide. We feel that it is important to communicate to the community several inconsistencies so that the interesting material reported can be seen in the right light, especially with several groups nowadays having reported similar structures from vanadium oxide synthesis.
- ItemSwitching adhesion and friction by light using photosensitive guest - host interactions(Cambridge : Royal Society of Chemistry, 2015) Blass, Johanna; Bozna, Bianca; Albrecht, Marcel; Krings, Jennifer A.; Ravoo, Bart Jan; Wenz, Gerhard; Bennewitz, RolandFriction and adhesion between two β-cyclodextrin functionalized surfaces can be switched reversibly by external light stimuli. The interaction between the cyclodextrin molecules attached to the tip of an atomic force microscope and a silicon wafer surface is mediated by complexation of ditopic azobenzene guest molecules. At the single molecule level, the rupture force of an individual complex is 61 ± 10 pN.
- ItemGold nanorods with conjugated polymer ligands: sintering-free conductive inks for printed electronics(Cambridge : Royal Society of Chemistry, 2016) Reiser, B.; González-GarcÃa, L.; Kanelidis, I.; Maurer, J.H.M.; Kraus, T.Metal-based nanoparticle inks for printed electronics usually require sintering to improve the poor electron transport at particle-particle interfaces. The ligands required for colloidal stability act as insulating barriers and must be removed in a post-deposition sintering step. This complicates the fabrication process and makes it incompatible with many flexible substrates. Here, we bind a conjugated, electrically conductive polymer on gold nanorods (AuNRs) as a ligand. The polymer, poly[2-(3-thienyl)-ethyloxy-4-butylsulfonate] (PTEBS), provides colloidal stability and good electron transport properties to stable, sintering-free inks. We confirm that the polymer binds strongly through a multidentate binding motif and provides superior colloidal stability in polar solvents over months by IR and Raman spectrometry and zeta potential measurements. We demonstrate that the developed ligand exchange protocol is directly applicable to other polythiophenes such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). Films of AuNRs coated with above polymers reached conductivities directly after deposition comparable to conventional metal inks after ligand removal and retained their conductivity for at least one year when stored under ambient conditions.
- ItemFacile, fast, and inexpensive synthesis of monodisperse amorphous Nickel-Phosphide nanoparticles of predefined size(Cambridge : Royal Society of Chemistry, 2011) Arzt, Eduard; Moh, Karsten; Cavelius, Christian; Mandel, Karl; Dillon, Frank; Koos, Antal A.; Aslam, Zabeada; Jurkschat, Kerstin; Cullen, Frank; Crossley, Alison; Bishop, Hugh; Grobert, NicoleMonodisperse, size-controlled Ni–P nanoparticles were synthesised in a single step process using triphenyl-phosphane (TPP), oleylamine (OA), and Ni(II)acetyl-acetonate. The nanoparticles were amorphous, contained 30 at% P and their size was controlled between 7–21 nm simply by varying the amount of TPP. They are catalytically active for tailored carbon nanotube growth.
- ItemBi-phasic nanostructures for functional applications(Cambridge : Royal Society of Chemistry, 2012) Veith, Michael; Lee, Juseok; Miro, Marina Martinez; Akkan, C. Kaan; Dufloux, Cecile; Aktas, O. CenkBiphasic solid state composites of the type metal/metal oxide or element/element oxide can be synthesized in one pot chemical reactions using so called molecular "single source precursors". Due to their singular genesis these composites show peculiar hetero-structures based on core-shell hierarchies such as superlattices and composite nanospheres or nanowires. They exhibit superior or new functional properties compared to their individual constituent compounds. In the current work, we review in particular the synthetical and mechanistical approach of bi-phasic (Al/Al2O3) nanostructures such as nanospheres, nanowires and nanoloops using a single source precursor. Other bi-phasic materials of the general formula M/MOx (for example M = Ge, Sn, Pb) are addressed for comparison. The impact of different synthetical conditions as well as of modification of surfaces by laser techniques and their technological relevance are presented briefly. Additionally, functional applications of the prepared surfaces are explained with some outstanding case studies. These case studies are primarily concerned with their use as biomaterials and their application in medicine as well as with their use as thin films for optics and functional surfaces.
- ItemThe springtail cuticle as a blueprint for omniphobic surfaces(Cambridge : Royal Society of Chemistry, 2015) Hensel, René; Neinhuis, Christoph; Werner, CarstenOmniphobic surfaces found in nature have great potential for enabling novel and emerging products and technologies to facilitate the daily life of human societies. One example is the water and even oil-repellent cuticle of springtails (Collembola). The wingless arthropods evolved a highly textured, hierarchically arranged surface pattern that affords mechanical robustness and wetting resistance even at elevated hydrostatic pressures. Springtail cuticle-derived surfaces therefore promise to overcome limitations of lotus-inspired surfaces (low durability, insufficient repellence of low surface tension liquids). In this review, we report on the liquid-repellent natural surfaces of arthropods living in aqueous or temporarily flooded habitats including water-walking insects or water spiders. In particular, we focus on springtails presenting an overview on the cuticular morphology and chemistry and their biological relevance. Based on the obtained liquid repellence of a variety of liquids with remarkable efficiency, the review provides general design criteria for robust omniphobic surfaces. In particular, the resistance against complete wetting and the mechanical stability strongly both depend on the topographical features of the nano- and micropatterned surface. The current understanding of the underlying principles and approaches to their technological implementation are summarized and discussed.