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Papers by Wolfgang Tremel

Research paper thumbnail of Solvothermal Synthesis of VO2 Nanoparticles with Locally Patched V2O5 Surface Layer and their Morpohology-Dependent Catalytic Properties for the Oxidation of Alcohol

Dalton Transactions, Dec 31, 2023

Research paper thumbnail of Cellulose ether derivatives: a new platform for prodrug formation of fluoroquinolone antibiotics

Research paper thumbnail of Well-defined carbohydrate-based polymers in calcium carbonate crystallization: Influence of stereochemistry in the polymer side chain on polymorphism and morphology

European Polymer Journal, 2015

Research paper thumbnail of Precursor Polymers for the Carbon Coating of Au@ZnO Multipods for Application as Active Material in Lithium-Ion Batteries

Macromolecular rapid communications, Jan 19, 2015

The synthesis of statistical and block copolymers based on polyacrylonitrile, as a source for car... more 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 Raman spectroscopy and energy-dispersive X-ray (EDX) spectroscopy. The benefit of the conformal carbon coating of the Au@ZnO multipods regarding its application as lithium-ion anode material is revealed by performing galvanostatic cycling, showing a highly enhanced and stabilized electrochemical ...

Research paper thumbnail of Growth Mechanism and Surface Functionalization of Metal Chalcogenides Nanostructures

Research paper thumbnail of Magnetic transitions in double perovskiteSr2FeRe1−xSbxO6(0⩽x⩽0.9)

Research paper thumbnail of Self-cleaning antimicrobial surfaces by bio-enabled growth of SnO2 coatings on glass

Nanoscale, 2013

Conventional vapor-deposition techniques for coatings require sophisticated equipment and/or high... more 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 in a strong degradation of organic contaminants and a strong antimicrobial activity. Upon illumination the biomimetic SnO2 coating exhibits a switchable amphiphilic behavior, which - in combination with its photoactivity - creates a self-cleaning surface. The intrinsic self-cleaning properties could lead to the development of new protective, antifouling coatings on various substrates.

Research paper thumbnail of Polyacrylonitrile Block Copolymers for the Preparation of a Thin Carbon Coating Around TiO2 Nanorods for Advanced Lithium-Ion Batteries

Macromolecular Rapid Communications, 2013

Research paper thumbnail of A Facile Approach for Transferring Hydrophobic Magnetic Nanoparticles into Water-Soluble Particles

Macromolecular Chemistry and Physics, 2008

A novel, easy and high-efficient method is described for transferring hydrophobic magnetic Fe 3 O... more A novel, easy and high-efficient method is described for transferring hydrophobic magnetic Fe 3 O 4 nanoparticles from organic to aqueous solution by wrapping a thermo-responsive and photocrosslinkable poly (N-isopropylacrylamide)(PNIPAm) terpolymer around the ...

Research paper thumbnail of Soluble IF-ReS2 Nanoparticles by Surface Functionalization with Terpyridine Ligands

Research paper thumbnail of Chemical Mimicry: Hierarchical 1D TiO2@ZrO2 Core−Shell Structures Reminiscent of Sponge Spicules by the Synergistic Effect of Silicatein-α and Silintaphin-1

Research paper thumbnail of CpG-DNA loaded multifunctional MnO nanoshuttles for TLR9-specific cellular cargo delivery, selective immune-activation and MRI

Journal of Materials Chemistry, 2012

ABSTRACT Initiation of pathways that lead to a proliferation and chemoresistance by Toll-like rec... more ABSTRACT 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 acid were tagged with fluorescent markers for simultaneous visualization inside the cell. Cell and animal studies show that the multimodal nanoparticles used as a TLR carrier system allow monitoring simultaneously nanoparticle cellular trafficking and transport by optical and MRI imaging.

Research paper thumbnail of Translational and rotational diffusion of gold nanorods near a wall

The Journal of Chemical Physics, 2013

We measured the rotational and translational diffusivity of dilute gold nanorods in aqueous suspe... more We measured the rotational and translational diffusivity of dilute gold nanorods in aqueous suspension close to a hard planar wall. Therefore, resonance enhanced dynamic light scattering, an evanescent technique, was applied, making use of the strong scattering intensity near the longitudinal surface plasmon resonance frequency of the particle. We observed a slowing down beyond the known hydrodynamic models.

Research paper thumbnail of Orientation and Dynamics of ZnO Nanorod Liquid Crystals in Electric Fields

Macromolecular rapid communications, Jan 16, 2010

ZnO nanorod polymer hybrids (i.e., ZnO nanorods coated with a block copolymer with a short anchor... more 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 due to the cooperative LC behavior, because the rods themselves exhibit only a very small effective dipole moment. The process can be investigated by polarizing microscopy. SEM images show the orientations of the individual nanorods, which correspond to the Fredericks transition well known for li...

Research paper thumbnail of Synthesis of Hierarchically Grown ZnO@NT-WS2 Nanocomposites

Chemistry of Materials, 2009

Research paper thumbnail of Large Scale MOCVD Synthesis of Hollow ReS2 Nanoparticles with Nested Fullerene-Like Structure

Chemistry of Materials, 2008

Research paper thumbnail of Graphitically encapsulated cobalt nanocrystal assemblies

Chemical Communications, 2010

Research paper thumbnail of Hydroxypropylcellulose-aceclofenac conjugates: high covalent loading design, structure characterization, nano-assemblies and thermal kinetics

Cellulose, 2013

ABSTRACT This article presents synthesis of novel macromolecular prodrugs of aceclofenac (an anti... more ABSTRACT This article presents synthesis of novel macromolecular prodrugs of aceclofenac (an anti-inflammatory drug) onto hydroxypropylcellulose (HPC). The HPC-aceclofenac conjugates were prepared using an acylating agent 1,1′-carbonyldiimidazole (CDI) under homogenous reaction conditions. Aceclofenac was first activated by using CDI to form its N-acylimidazole. The N-acylimidazole of aceclofenac was then reacted with HPC polymer at 80 °C for 24 h. Highly pure prodrugs of aceclofenac were synthesized with a wide range of moderate to high degree of substitution (DS 0.41–2.12) as calculated by 1H NMR spectroscopy. The UV spectroscopic analysis has also revealed that the active drug aceclofenac was found in different conjugates from 28 to 67 mg/100 mg of HPC-aceclofenac conjugates which are in good agreement with DS calculated by 1H NMR spectroscopy. The gel permeation chromatography showed unimodal absorption that indicates no significant degradation in polymer chains during the reaction. The macromolecular prodrugs of aceclofenac were characterized using different spectroscopic and chromatographic techniques. The thermal analysis has revealed that HPC-aceclofenac conjugates (prodrugs) are 92 and 96 °C more stable than pure aceclofenac regarding their initial (Tdi) and maximum degradation temperatures (Tdm), respectively. The activation energy (Ea) and frequency factor (Z) of the degradation reactions were evaluated using Friedman, Broido and Chang methods. Degradation followed first order (n) kinetics. Transmission electron microscopy has revealed the formation of sponge like nano aggregates with population size distribution of around 80–150 nm.

Research paper thumbnail of Au@MnO Nanoflowers: Hybrid Nanocomposites for Selective Dual Functionalization and Imaging

Angewandte Chemie International Edition, 2010

Page 1. Functional Nanomaterials DOI: 10.1002/anie.200906689 Au@MnO Nanoflowers: Hybrid Nanocompo... more Page 1. Functional Nanomaterials DOI: 10.1002/anie.200906689 Au@MnO Nanoflowers: Hybrid Nanocomposites for Selective Dual Functionalization and Imaging** Thomas D. Schladt, Mohammed Ibrahim Shukoor, Kerstin ...

Research paper thumbnail of Reversible Self-Assembly of Metal Chalcogenide/Metal Oxide Nanostructures Based on Pearson Hardness

Angewandte Chemie International Edition, 2010

Research paper thumbnail of Solvothermal Synthesis of VO2 Nanoparticles with Locally Patched V2O5 Surface Layer and their Morpohology-Dependent Catalytic Properties for the Oxidation of Alcohol

Dalton Transactions, Dec 31, 2023

Research paper thumbnail of Cellulose ether derivatives: a new platform for prodrug formation of fluoroquinolone antibiotics

Research paper thumbnail of Well-defined carbohydrate-based polymers in calcium carbonate crystallization: Influence of stereochemistry in the polymer side chain on polymorphism and morphology

European Polymer Journal, 2015

Research paper thumbnail of Precursor Polymers for the Carbon Coating of Au@ZnO Multipods for Application as Active Material in Lithium-Ion Batteries

Macromolecular rapid communications, Jan 19, 2015

The synthesis of statistical and block copolymers based on polyacrylonitrile, as a source for car... more 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 Raman spectroscopy and energy-dispersive X-ray (EDX) spectroscopy. The benefit of the conformal carbon coating of the Au@ZnO multipods regarding its application as lithium-ion anode material is revealed by performing galvanostatic cycling, showing a highly enhanced and stabilized electrochemical ...

Research paper thumbnail of Growth Mechanism and Surface Functionalization of Metal Chalcogenides Nanostructures

Research paper thumbnail of Magnetic transitions in double perovskiteSr2FeRe1−xSbxO6(0⩽x⩽0.9)

Research paper thumbnail of Self-cleaning antimicrobial surfaces by bio-enabled growth of SnO2 coatings on glass

Nanoscale, 2013

Conventional vapor-deposition techniques for coatings require sophisticated equipment and/or high... more 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 in a strong degradation of organic contaminants and a strong antimicrobial activity. Upon illumination the biomimetic SnO2 coating exhibits a switchable amphiphilic behavior, which - in combination with its photoactivity - creates a self-cleaning surface. The intrinsic self-cleaning properties could lead to the development of new protective, antifouling coatings on various substrates.

Research paper thumbnail of Polyacrylonitrile Block Copolymers for the Preparation of a Thin Carbon Coating Around TiO2 Nanorods for Advanced Lithium-Ion Batteries

Macromolecular Rapid Communications, 2013

Research paper thumbnail of A Facile Approach for Transferring Hydrophobic Magnetic Nanoparticles into Water-Soluble Particles

Macromolecular Chemistry and Physics, 2008

A novel, easy and high-efficient method is described for transferring hydrophobic magnetic Fe 3 O... more A novel, easy and high-efficient method is described for transferring hydrophobic magnetic Fe 3 O 4 nanoparticles from organic to aqueous solution by wrapping a thermo-responsive and photocrosslinkable poly (N-isopropylacrylamide)(PNIPAm) terpolymer around the ...

Research paper thumbnail of Soluble IF-ReS2 Nanoparticles by Surface Functionalization with Terpyridine Ligands

Research paper thumbnail of Chemical Mimicry: Hierarchical 1D TiO2@ZrO2 Core−Shell Structures Reminiscent of Sponge Spicules by the Synergistic Effect of Silicatein-α and Silintaphin-1

Research paper thumbnail of CpG-DNA loaded multifunctional MnO nanoshuttles for TLR9-specific cellular cargo delivery, selective immune-activation and MRI

Journal of Materials Chemistry, 2012

ABSTRACT Initiation of pathways that lead to a proliferation and chemoresistance by Toll-like rec... more ABSTRACT 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 acid were tagged with fluorescent markers for simultaneous visualization inside the cell. Cell and animal studies show that the multimodal nanoparticles used as a TLR carrier system allow monitoring simultaneously nanoparticle cellular trafficking and transport by optical and MRI imaging.

Research paper thumbnail of Translational and rotational diffusion of gold nanorods near a wall

The Journal of Chemical Physics, 2013

We measured the rotational and translational diffusivity of dilute gold nanorods in aqueous suspe... more We measured the rotational and translational diffusivity of dilute gold nanorods in aqueous suspension close to a hard planar wall. Therefore, resonance enhanced dynamic light scattering, an evanescent technique, was applied, making use of the strong scattering intensity near the longitudinal surface plasmon resonance frequency of the particle. We observed a slowing down beyond the known hydrodynamic models.

Research paper thumbnail of Orientation and Dynamics of ZnO Nanorod Liquid Crystals in Electric Fields

Macromolecular rapid communications, Jan 16, 2010

ZnO nanorod polymer hybrids (i.e., ZnO nanorods coated with a block copolymer with a short anchor... more 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 due to the cooperative LC behavior, because the rods themselves exhibit only a very small effective dipole moment. The process can be investigated by polarizing microscopy. SEM images show the orientations of the individual nanorods, which correspond to the Fredericks transition well known for li...

Research paper thumbnail of Synthesis of Hierarchically Grown ZnO@NT-WS2 Nanocomposites

Chemistry of Materials, 2009

Research paper thumbnail of Large Scale MOCVD Synthesis of Hollow ReS2 Nanoparticles with Nested Fullerene-Like Structure

Chemistry of Materials, 2008

Research paper thumbnail of Graphitically encapsulated cobalt nanocrystal assemblies

Chemical Communications, 2010

Research paper thumbnail of Hydroxypropylcellulose-aceclofenac conjugates: high covalent loading design, structure characterization, nano-assemblies and thermal kinetics

Cellulose, 2013

ABSTRACT This article presents synthesis of novel macromolecular prodrugs of aceclofenac (an anti... more ABSTRACT This article presents synthesis of novel macromolecular prodrugs of aceclofenac (an anti-inflammatory drug) onto hydroxypropylcellulose (HPC). The HPC-aceclofenac conjugates were prepared using an acylating agent 1,1′-carbonyldiimidazole (CDI) under homogenous reaction conditions. Aceclofenac was first activated by using CDI to form its N-acylimidazole. The N-acylimidazole of aceclofenac was then reacted with HPC polymer at 80 °C for 24 h. Highly pure prodrugs of aceclofenac were synthesized with a wide range of moderate to high degree of substitution (DS 0.41–2.12) as calculated by 1H NMR spectroscopy. The UV spectroscopic analysis has also revealed that the active drug aceclofenac was found in different conjugates from 28 to 67 mg/100 mg of HPC-aceclofenac conjugates which are in good agreement with DS calculated by 1H NMR spectroscopy. The gel permeation chromatography showed unimodal absorption that indicates no significant degradation in polymer chains during the reaction. The macromolecular prodrugs of aceclofenac were characterized using different spectroscopic and chromatographic techniques. The thermal analysis has revealed that HPC-aceclofenac conjugates (prodrugs) are 92 and 96 °C more stable than pure aceclofenac regarding their initial (Tdi) and maximum degradation temperatures (Tdm), respectively. The activation energy (Ea) and frequency factor (Z) of the degradation reactions were evaluated using Friedman, Broido and Chang methods. Degradation followed first order (n) kinetics. Transmission electron microscopy has revealed the formation of sponge like nano aggregates with population size distribution of around 80–150 nm.

Research paper thumbnail of Au@MnO Nanoflowers: Hybrid Nanocomposites for Selective Dual Functionalization and Imaging

Angewandte Chemie International Edition, 2010

Page 1. Functional Nanomaterials DOI: 10.1002/anie.200906689 Au@MnO Nanoflowers: Hybrid Nanocompo... more Page 1. Functional Nanomaterials DOI: 10.1002/anie.200906689 Au@MnO Nanoflowers: Hybrid Nanocomposites for Selective Dual Functionalization and Imaging** Thomas D. Schladt, Mohammed Ibrahim Shukoor, Kerstin ...

Research paper thumbnail of Reversible Self-Assembly of Metal Chalcogenide/Metal Oxide Nanostructures Based on Pearson Hardness

Angewandte Chemie International Edition, 2010