Holger Schönherr

Universität Siegen · Department of Chemistry and Biology & Research Center of Micro and Nanochemistry and (Bio)Technology (Cμ)

Cell sheet harvesting offers a great potential for the development of new therapies for regenerative medicine. For cells to adhere onto surfaces, proliferate, and to be released on demand, thermoresponsive polymeric coatings are generally considered to be required. Herein, an alternative approach for the cell sheet harvesting and rapid release on d...

The fabrication, characterization and application of a nanoporous Silicon Rugate Filter (pSiRF) loaded with an enzymatically degradable polymer is reported as a bare eye detection optical sensor for enzymes of pathogenic bacteria, which is devoid of any dyes. The nanopores of pSiRF were filled with poly(lactic acid) (PLA), which, upon enzymatic deg...

A high-speed imaging methodology to study the two-phase flow occurring during enhanced subcritical dense phase carbon dioxide pasteurization

Antimicrobial photodynamic therapy (aPDT) depends on a variety of parameters notably related to the photosensitizers used, the pathogens to target and the environment to operate. In a previous study using a series of Ruthenium(II) polypyridyl ([Ru(II)]) complexes, we reported the importance of the chemical structure on both their photo-physical/phy...

The rapid and selective detection of bacterial contaminations and bacterial infections in a non-laboratory setting using advanced sensing materials holds the promise to enable robust point-of-care tests and rapid diagnostics for applications in the medical field as well as food safety. Among the various possible analytes, bacterial enzymes have bee...

The aim of this study was to determine the effects of silver nanoparticles (AgNPs; speciation: NM-300 K) in the lab on the behavior of larvae in European Whitefish (Coregonus lavaretus), a relevant model species for temperate aquatic environments during alternating light and darkness phases. The behavioral parameters measured included activity, tur...

High oil sorption, dynamic oil/water selectivity and oil retention are essential for advanced materials to remediate offshore oil spills. In this context, superoleophilic-hydrophobic kapok bundles, synthesized via a simple, one-step and energy efficient carbonization (300°C), were investigated as effective oil sorbents. It was shown that the surfac...

Poly-anionic Xanthan gum-based hydrogels were synthesized and used as potent adsorbents for the removal of dye pollutants from waste water effluents. The adsorbents were synthesized by esterification of Xanthan gum with maleic anhydride, followed by thiol-ene cross-linking chemistry with 2,2′-(ethylenedioxy)diethanethiol. Methylene blue was used as...

Pyrene is known for the quenched emission of excimers, especially in aqueous solution. Here, we report strong emission of pyrene excimers realized in amphiphile assemblies by controlling the face-to-face distance between the pyrene planes. We find that both the self-assembly behavior and emission properties of a cationic pyrene-containing amphiphil...

We investigate a model bioassay in a liquid environment using a z-scanning planar Yagi-Uda antenna, focusing on the fluorescence collection enhancement of ATTO-647N dye conjugated to DNA (deoxyribonucleic acid) molecules. The antenna changes the excitation and the decay rates and, more importantly, the emission pattern of ATTO-647N, resulting in a...

We report on the fabrication and characterization of color-encoded chitosan hydrogels for the rapid, sensitive and specific detection of bacterial enzymes as well as the selective detection of a set of tested bacteria through characteristic enzyme reactions. These patterned sensor hydrogels are functionalized with three different colorimetric enzym...

The design and synthesis of novel active materials as the capacitor electrodes is of great significance to fabricate high-performance supercapacitors, namely those with large and stable capacitances as well as high power- and energy-densities. In this work, binder-free and hierarchical carbon nanofibers@nickel phosphide nanoparticles are grown in a...

Antimicrobial photodynamic therapy (aPDT) has become a fundamental tool in modern therapeutics, notably due to the expanding versatility of photosensitizers (PSs) and the numerous possibilities to combine aPDT with other antimicrobial treatments to combat localized infections. After revisiting the basic principles of aPDT, this review first highlig...

Toxicological studies were performed to examine silver nanoparticle (AgNP, size: 14.4 ± 2.5 nm) transformation within three different test media and consequent effects on embryos of whitefish (Coregonus lavaretus) and roach (Rutilus rutilus). The test media, namely ASTM very hard water, ISO standard dilution medium, and natural lake water differed...

We provide some text that was inadvertently omitted from our article [ J. Opt. Soc. Am. B 38 , 2528 ( 2021 ) JOBPDE 0740-3224 10.1364/JOSAB.434980 ].

The 3‐(4‐(N,N ‐dimethylamino)phenyl)naphtho[1,2‐b ]quinolizinium was synthesized with a Suzuki‐Miyaura reaction in good yield, and its binding properties with duplex DNA, quadruplex DNA (G4‐DNA), RNA, and BSA were investigated by photometric, fluorimetric and polarimetric titrations and DNA denaturation analysis. The compound intercalates into DNA...

Current treatment of chronic wounds has been critically limited by various factors, including bacterial infection, biofilm formation, impaired angiogenesis, and prolonged inflammation. Addressing these challenges, we developed a multifunctional wound dressing-based three-pronged approach for accelerating wound healing. The multifunctional wound dre...

An effective approach to improve the detection efficiency of nanoscale light sources relies on a planar antenna configuration, which beams the emitted light into a narrow cone. Planar antennas operate like optical Yagi-Uda antennas, where reflector and director elements are made of metal films. Here we introduce and investigate, both theoretically...

POLY-CHAR 2020 [Venice] is an International Polymer Characterization Conference, under the auspices of the Scientific Committee of POLY-CHAR and International Union of Pure and Applied Chemistry (IUPAC). This event, which was originally scheduled in May 2020, but was postponed due to the pandemic, was held, for the first time in virtual format, fro...

An effective approach to improve the detection efficiency of nanoscale light sources relies on a planar antenna configuration, which beams the emitted light into a narrow cone. Planar antennas operate like optical Yagi-Uda antennas, where reflector and director elements are made of metal films. Here we introduce and investigate, both theoretically...

Xanthan gum-based hydrogels were synthesized and investigated in an attempt to develop efficient adsorbents for removal of dye pollutants from wastewaters. The hydrogels were obtained by first esterifying Xanthan gum with maleic anhydride and subsequent cross-linking of the pendant vinyl groups via thiol-ene click chemistry with oligoethyleneglycol...

Despite decades of biomedical advances, the colonization of implant devices with bacterial biofilms is still a leading cause of implant failure. Clearly, new strategies and materials that suppress both initial and later stage bacterial colonization are required in this context. Ideal would be the implementation of a bactericidal functionality in th...

The development of efficient and sustainable microbial inactivation approaches is an important objective. Dense-Phase-Carbon-Dioxide and related approaches, which utilize high pressure CO2, were reported to be feasible methods. However, a major challenge is the enhancement of sustainability and economic viability by reducing the necessary temperatu...

The fabrication of covalently cross-linked high-surface-area biopolymeric nanogel fibers by nanopore extrusion is reported for the first time. The biopolymer pullulan was functionalized with tert-butyl acetoacetate via a transesterification reaction to synthesize the water-soluble ketone-rich precursor pullulan acetoacetate (PUAA). PUAA and carboni...

This poster reflects some of our recent and outstanding research work on the use of copious green seaweeds from the Mauritian beaches to extract their potential source of cellulose polysaccharide together with health beneficial ulvans oligosaccharides. This powdered form of the green seaweed-derived extract is transformed into 2D nanofibrous mats f...

Polymer brush synthesis is a powerful approach to fabricate functional bio-interfaces. To enhance the control over brush synthesis and end groups, we have synthesized poly(glycidyl methacrylate) PGMA brushes with carboxylic acid end functional groups by interface-mediated dissociative electron transfer reversible addition-fragmentation chain transf...

Traditional froth flotation is the primary method for the separation and upgrading of fine mineral particles. However, it is still difficult for micro-fine and low-quality minerals to effectively separate. It is generally believed that bubble miniaturization is of great significance to improve flotation efficiency. Due to their unique physical and...

Boron doped diamond (BDD) has been widely used in various electrochemical fields, due to its unique physical and chemical properties. However, the investigation of the electrochemistry of bi-element incorporated diamond, especially the variation of surface components after nitrogen incorporation into BDD and the corresponding electron transfer of i...

There is a growing demand for rapid and sensitive detection approaches for pathogenic bacteria that can be applied by non-specialists in non-laboratory field settings. Here, the detection of the typical E. coli enzyme β-glucuronidase using a chitosan-based sensing hydrogel-coated paper sensor and the detailed analysis of the reaction kinetics, as d...

The non-fluorescent 9-nitrobenzo[b]quinolizinium is readily reduced by nitroreductase to a fluorescent reaction product. The resulting light-up effect enables the selective detection of nitro-reductase activity in vitro and in Escherichia coli...

Decoration of inorganic substrates with surface-grafted and perpendicularly oriented conjugated polymers has gained substantial attention spurred by the development of new facile synthetic methodologies. We have recently shown that conjugated polymer brushes with interesting optoelectrical properties and presupposed ladder-like architecture could b...

Cellulose has been extracted from a wide range of land resources, whereas it has been scarcely exploited from marine resources. Cellulose from green seaweeds can be extracted together with smaller molecules called ulvans. We have successfully extracted and characterized cellulose from Ulva sp. Solid state 13 C NMR indicated the presence of ulvans i...

In article number 2002202, Nianjun Yang, Xin Jiang and co‐workers employ diamond fibers with a fibrous core/shell structure to assemble zinc‐ion supercapacitors, which exhibit high gravimetric and volumetric energy and power densities, along with long‐term stability and high flexibility. These diamond zinc‐ion supercapacitors have promise as energy...

The enhancement of standard dense phase carbon dioxide (DPCD) pasteurization by additional mechanical effects was assessed in this work. These effects were induced during pasteurization by the sudden depressurization in a narrow minitube. The high flow velocities, moderate pressures (40–80 bar) and low temperatures (25–45 °C) lead to intense degasi...

The increasing use of manufactured nanomaterials (MNMs) and their inevitable release into the environment, especially via wastewater treatment plants (WWTPs), poses a potential threat for aquatic organisms. The characterization of MNMs with analytical tools in order to comprehend their fate and effect on the ecosystem is hence of great importance f...

Herein, we demonstrate a combined fluorescent probe/shape encoded hydrogel strategy for the fast, sensitive and selective detection of bacterial species via their characteristic enzymes. A polyvinyl alcohol (PVA) hydrogel loaded with the fluorescent probe N,N'-(3-oxo-3H-spiro[isobenzofuran-1,9'-xanthene]-3',6'-diyl)bis(2,2,3,3,3-pentafluoropropanam...

Here, we report a new pentafluoropropanamido rhodamine fluorescent probe (ACS-HNE) that allows for the selective detection of neutrophil elastase (NE). ACS-HNE displayed high sensitivity, with a low limit of detection (<5.3 nM), and excellent selectivity toward elastase over other relevant biological analytes and enzymes. The comparatively poor sol...

Low energy densities of traditional supercapacitors have strongly restricted their applications. The utilization of novel capacitor electrodes to enhance the energy densities of supercapacitors is thus of great significance. Herein, a binder-free Ni12P5/Ni/TiC nanocomposite film is synthesized and further employed as the capacitor electrode. This n...

Heterojunctions are especially attractive for photo‐electrocatalytic applications if both high‐performance photo and electrocatalysts are employed for their construction. Herein, a p–n heterojunction is synthesized using uniform patterns of p‐type boron doped diamond (BDD) and an n‐type anatase TiO2 film. The exposure ratios of the BDD patterns are...

Here, the formation of giant enzyme‐degradable polymersomes using the electroformation method is reported. Poly(ethylene glycol)‐block‐poly(ε‐caprolactone) polymersomes have been shown previously to be attractive candidates for the detection of bacterial proteases and protease mediated release of encapsulated reporter dyes and antimicrobials. To ma...

We report on the polymerization kinetics of thermoresponsive poly(diethylene glycol methylether methacrylate) (PDEGMA) brushes, which are used in novel cell release coating, on curved spherical silica nanoparticles (NPs, with radii of 23 ± 5 nm, 70 ± 13 nm and 148 ± 16 nm) and aligned cylindrical silicon nanowires (SiNWs, with radii of 155 ± 10 and...

The effect of systematically varied mechanical properties and nano- and microscale surface topography on the adhesion and proliferation of human pancreatic cancer cells on fibronectin-functionalized poly(vinyl alcohol) (PVA) hydrogels was studied in order to understand the impact of these properties of the cell microenvironment on cell attachment a...

We report on the synthesis and characterization of poly(diethylene glycol methylether methacrylate) (PDEGMA) brushes by surface-initiated atom transfer radical polymerization (SI-ATRP) inside ordered cylindrical nanopores of anodic aluminum oxide (AAO) with different pore radii between 20 and 185 nm. In particular, the dependence of polymerization...

To tailor cell-surface interactions, precise and controlled attachment of cell-adhesive motifs is required, while any background non-specific cell and protein adhesion has to be blocked effectively. Herein, a versatile and highly reproducible antifouling surface modification based on "clickable" groups and hierarchically structured diblock copolyme...

The modification of cylindrical anodic aluminum oxide (AAO) nanopores by alternating layer by layer (LBL) deposition of poly(sodium-4-styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) was studied in situ by Reflectometric Interference Spectroscopy (RIfS). In particular, the kinetics of polyelectrolyte deposition inside the 37 ± 3 nm...

Due to their widespread use, silver (Ag) and titanium dioxide (TiO2) nanoparticles (NPs) are commonly discharged into aquatic environments via wastewater treatment plants. The study was aimed to assess the effects of wastewater-borne AgNPs (NM-300 K; 15.5 ± 2.4 nm; 25−125 μg L⁻¹) and TiO2NPs (NM-105; 23.1 ± 6.2 nm; 12.5−100 μg L⁻¹), from a laborato...

The permittivity of polymers and its spatial distribution play a crucial role in the behavior of thin films, such as those used, e.g., as sensor coatings. In an attempt to develop a conclusive approach to determine these quantities, the polarity of the model polymer poly(methyl methacrylate) (PMMA) in 600 nm thin films on a glass support was probed...

The influence of chirality on cell behavior is closely related with relevant biological events, however, many recent studies only focus on the apparent chiral influence of supramolecular nanofibers and ignore the respective effects of molecular chirality and supramolecular chirality in biological processes. Herein, the inherent molecular and supram...

The combination of styryl dye properties with the acidity and strong photoacidity of the 2,2ʹ‐[(1''‐hydroxy‐4''‐methyl‐(E)‐2'',6''‐phenylene)]‐bisquinolizinium enables the detection of DNA by distinct absorption and emission color changes and the fluorimetric detection of DNA in cells with epifluorescence and confocal fluorescence microscopy.

Over two years we assessed silver-containing nanoparticles (SCN) and total silver in the in- and effluent of a wastewater treatment plant (WWTP) discharging purified wastewater into a lake. Additionally, total silver was measured in sludge of the WWTP and in water, sediment, and fish of the receiving lake at several points with varying distance to...

The selective detachment of undifferentiated human induced pluripotent stem (iPS) cells from a thermal release coating, fabricated from a tailored poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA) homopolymer layer on gold, is reported. By exploiting the mild, thermally triggered release of iPS cell colonies in the absence of any releasi...

The selective detachment of undifferentiated human induced pluripotent stem (iPS) cells from a thermal release coating, fabricated from a tailored poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA) homopolymer layer on gold, is reported. By exploiting the mild, thermally triggered release of iPS cell colonies in the absence of any releasi...

A combination of in-situ electrical and Grazing-Incidence X-ray Diffraction (GIXD) is a powerful tool for studies of correlations between the microstructure and charge transport in thin organic films. The information provided by such experimental approach can help optimizing the performance of the films as active layers of organic electronic device...

Color centers in diamond represent a promising platform for developing solid-state single-photon sources and spin-photon interfaces as building blocks for photonics-based quantum technologies. However, although they exhibit a combination of features that make them so attractive, they also suffer from limited control in their emission properties, su...

Ultra-thin thermoresponsive poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA) homopolymer layers are reported as a novel platform for label-free temperature-stimulated cell separation from a co-culture of eukaryotic cell lines. Pancreatic tumor cells (PaTu 8988t) and fibroblasts (NIH 3T3) were shown to attach and proliferate on PDEGMA la...

The fabrication and characterization of advanced 3D cell culture microenvironments that enable systematic structure - property relationship studies are reported. The asymmetric multifunctional 3D cell microenvironments were obtained by capillary force-assisted assembly of microscale cubes at the water/air interface. The identical wettability of dis...

The dependence of the orientation of microscale PS cubes, which are surface functionalized on only 5 faces, at the water/air interface and the ordered aggregates formed by capillary force assembly are reported. Depending on the wettability of the faces, the cubes were shown to adopt a preferred orientation that changes with decreasing wettability f...

Gas-filled surface nanobubbles are conclusively identified and rapidly differentiated from siloxane-based oil nanodroplets by co-localizationexperiments with atomic force microscopy and time resolved fluorescence microscopy. This approach exploits the marked dependenceof the fluorescence lifetime of the tracer dye Rhodamine 6G on its local environm...

The knowledge of fundamental aspects in cell biology has rapidly increased in the last decades also aided by the fabrication of artificial cell microenvironments in both 2-D and 3-D. To overcome the current lack of spatial control of parameters affecting cellular fate in structure-property relationship studies, including topographic nanostructures...

The rising production volume of engineered nanoparticles (NPs) leads to an increasing risk of environmental pollution. After passing sewage treatment plants (STPs), a significant concentration of NPs may end up in the aquatic environment where NPs can accumulate in the aquatic food chain and may cause harmful effects on aquatic organisms. However,...