0000000000024881
AUTHOR
Martin Kluenker
showing 11 related works from this author
Zinc overload mediated by zinc oxide nanoparticles as innovative anti-tumor agent
2017
The predicted global cancer burden is expected to surpass 20 million new cancer cases by 2025. Despite recent advancement in tumor therapy, a successful cancer treatment remains challenging. The emerging field of nanotechnology offers great opportunities for diagnosis, imaging, as well as treatment of cancer. Zinc oxide nanoparticles (ZnO NP) were shown to exert selective cytotoxicity against tumor cells via a yet unknown mechanism, most likely involving the generation of reactive oxygen species (ROS). These nanoparticles are a promising therapeutic opportunity as zinc is a nontoxic trace element and its application in medically-related products is considered to be safe. We could show that …
Intrinsic superoxide dismutase activity of MnO nanoparticles enhances the magnetic resonance imaging contrast
2020
Superoxide radicals are associated with the development of many severe diseases, such as cancer. Under nonpathogenic conditions, the natural enzyme superoxide dismutase (SOD) regulates the intracellular superoxide concentrations, but nearly all tumor tissues show reduced SOD levels. Selective imaging in early progression stages remains a key requirement for efficient cancer diagnosis and treatment. Magnetic resonance imaging (MRI) as a noninvasive tool with high spatial resolution may offer advantages here, but MRI contrast agents exhibiting a redox-triggered change in the image contrast towards superoxide radicals have not been reported so far. Here we show that manganese oxide (MnO) nanop…
Monitoring Thiol–Ligand Exchange on Au Nanoparticle Surfaces
2018
Surface functionalization of nanoparticles (NPs) plays a crucial role in particle solubility and reactivity. It is vital for particle nucleation and growth as well as for catalysis. This raises the quest for functionalization efficiency and new approaches to probe the degree of surface coverage. We present an (in situ) proton nuclear magnetic resonance (1H NMR) study on the ligand exchange of oleylamine by 1-octadecanethiol as a function of the particle size and repeated functionalization on Au NPs. Ligand exchange is an equilibrium reaction associated with Nernst distribution, which often leads to incomplete surface functionalization following “standard” literature protocols. Here, we show…
Bio-nano: Theranostic at Cellular Level
2018
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…
Iron Oxide Superparticles with Enhanced MRI Performance by Solution Phase Epitaxial Growth
2018
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…
From Single Molecules to Nanostructured Functional Materials: Formation of a Magnetic Foam Catalyzed by Pd@FexO Heterodimers
2017
Multicomponent nanostructures containing purely organic or inorganic as well as hybrid organic–inorganic components connected through a solid interface are, unlike conventional spherical particles, able to combine different or even incompatible properties within a single entity. They are multifunctional and resemble molecular amphiphiles, like surfactants or block copolymers, which makes them attractive for the self-assembly of complex structures, drug delivery, bioimaging, or catalysis. We have synthesized Pd@FexO heterodimer nanoparticles (NPs) to fabricate a macroporous, hydrophobic, magnetically active, three-dimensional (3D), and template-free hybrid foam capable of repeatedly separati…
Determination of the LD50 with the chick embryo chorioallantoic membrane (CAM) assay as a promising alternative in nanotoxicological evaluation
2021
Toxicity tests in rodents are still considered a controversial topic concerning their ethical justifiability. The chick embryo chorioallantoic membrane (CAM) assay may offer a simple and inexpensive alternative. The CAM assay is easy to perform and has low bureaucratic hurdles. At the same time, the CAM assay allows the application of a broad variety of analytical methods in the field of nanotoxicological research. We evaluated the CAM assay as a methodology for the determination of nanotoxicity. Therefore we calculated the median lethal dose (LD50), performed in vivo microscopy and immunohistochemistry to identify organ-specific accumulation profiles, potential organ damage, and the kineti…
Glycine-functionalized copper(ii) hydroxide nanoparticles with high intrinsic superoxide dismutase activity
2017
Superoxide dismutases (SOD) are a group of enzymes that catalyze the dismutation of superoxide (O2−) radicals into molecular oxygen (O2) and H2O2 as a first line of defense against oxidative stress. Here, we show that glycine-functionalized copper(II) hydroxide nanoparticles (Gly-Cu(OH)2 NPs) are functional SOD mimics, whereas bulk Cu(OH)2 is insoluble in water and catalytically inactive. In contrast, Gly-Cu(OH)2 NPs form water-dispersible mesocrystals with a SOD-like activity that is larger than that of their natural CuZn enzyme counterpart. Based on this finding, we devised an application where Gly-Cu(OH)2 NPs were incorporated into cigarette filters. Cigarette smoke contains high concent…
Controlling the Morphology of Au–Pd Heterodimer Nanoparticles by Surface Ligands
2018
Controlling the morphology of noble-metal nanoparticles is mandatory to tune specific properties such as catalytic and optical behavior. Heterodimers consisting of two noble metals have been synthesized, so far mostly in aqueous media using selective surfactants or chemical etching strategies. We report a facile synthesis for Au@Pd and Pd@Au heterodimer nanoparticles (NPs) with morphologies ranging from segregated domains (heteroparticles) to core-shell structures by applying a seed-mediated growth process with Au and Pd seed nanoparticles in 1-octadecene (ODE), which is a high-boiling organic solvent. The as-synthesized oleylamine (OAm) functionalized Au NPs led to the formation of OAm-Au@…
Pd@Fe2O3 Superparticles with Enhanced Peroxidase Activity by Solution Phase Epitaxial Growth
2017
Compared to conventional deposition techniques for the epitaxial growth of metal oxide structures on a bulk metal substrate, wet-chemical synthesis based on a dispersible template offers advantages such as low cost, high throughput, and the capability to prepare metal/metal oxide nanostructures with controllable size and morphology. However, the synthesis of such organized multicomponent architectures is difficult because the size and morphology of the components are dictated by the interplay of interfacial strain and facet-specific reactivity. Here we show that solution-processable two-dimensional Pd nanotetrahedra and nanoplates can be used to direct the epitaxial growth of γ-Fe2O3 nanoro…
Abstract 857: Metal oxide nanoparticles as adjuvant for radiation therapy
2018
Abstract Background: Radiation therapy comprises a fundamental component of modern tumor treatment. Unfortunately, its success is limited by the development of radiation resistances. The emerging field of nanotechnology offers great opportunities for diagnosing, imaging, as well as treating cancer. Metal oxide nanoparticles in particular zinc oxide nanoparticles (ZnO-NP) have been shown to display a selective cytotoxic effect on tumor cells via a yet unknown mechanism. Most likely the generation of reactive oxygen species (ROS), breakdown of mitochondria and DNA damage are involved. The success of radiation therapy equally relies on the generation of ROS, which develop their cytotoxic poten…