The properties of paper sheets can be tuned by adjusting the surface or bulk chemistry using func... more The properties of paper sheets can be tuned by adjusting the surface or bulk chemistry using functional polymers that are applied during (online) or after (offline) papermaking processes. In particular, polymers are widely used to enhance the mechanical strength of the wet state of paper sheets. However, the mechanical strength depends not only on the chemical nature of the polymeric additives but also on the distribution of the polymer on and in the lignocellulosic paper. Here, we analyze the photochemical attachment and distribution of hydrophilic polydimethylacrylamide-co-methacrylate-benzophenone P(DMAA-co-MABP) copolymers with defined amounts of photoreactive benzophenone moieties in model paper sheets. Raman microscopy was used for the unambiguous identification of P(DMAA-co-MABP) and cellulose specific bands and thus the copolymer distribution within the cellulose matrix. Two-dimensional Raman spectral maps at the intersections of overlapping cellulose fibers document that th...
Nanomachining of thin polymer resist films with an atomic force microscope (AFM) is a promising r... more Nanomachining of thin polymer resist films with an atomic force microscope (AFM) is a promising route for the fabrication of nanoscale devices. In order to enhance the controllability of the nanomachining process an in-plane acoustic wave is coupled to the sample support. This enhances the intermittent force exerted by the AFM tip. The lateral resolution reached by this method is only limited by the physical size of the AFM tip to dimensions far below the light diffraction limit. The main process parameters are the frequency and magnitude of the acoustic wave, and the preloading force. In this work, the feasibility of acoustical force lithography and the influence of the relevant parameters are investigated.
For the fabrication of microfluidic devices based on SU-8, the wetting properties of the polymer ... more For the fabrication of microfluidic devices based on SU-8, the wetting properties of the polymer surface need to be adjusted. We investigated the effects of wet chemical and plasma processes with respect to wetting properties, surface roughness, and surface chemistry.
The dynamics of the microcantilever in atomic force microscopy ͑AFM͒ is represented by a multiple... more The dynamics of the microcantilever in atomic force microscopy ͑AFM͒ is represented by a multipledegrees-of-freedom state-space model and is discussed within the framework of system theory. The cantilever dynamics is modeled as a linear time-invariant system with a nonlinear output feedback due to the tip-sample interaction. This allows one to use the same model to analyze different aspects of atomic force microscopy such as the dynamics of contact-mode or the dynamics of tapping-mode AFM. The state-space approach to the dynamic response of the AFM cantilever allows for numerically efficient simulations. We show that not only the eigenfrequency but also the modal damping of a cantilever interacting with a surface strongly depends on the contact stiffness. This is important for a quantitative characterization of elastic sample properties. Additionally, our model shows the presence of higher harmonics in tapping-mode AFM. The excitation of higher eigenmodes can strongly distort the system response. The results illustrate that higher eigenmodes have to be considered in the analysis of dynamic AFM.
Toll-like receptors (TLRs) belong to the Toll-like receptor/interleukin-1 receptor (TLR/IL-1R) su... more Toll-like receptors (TLRs) belong to the Toll-like receptor/interleukin-1 receptor (TLR/IL-1R) superfamily which is defined by a common cytoplasmic Toll/interleukin-1 receptor (TIR) domain. TLRs recognize pathogen-associated molecular patterns and initiate an intracellular kinase cascade to trigger an immediate defensive response. SIGIRR (single immunoglobulin interleukin-1 receptor-related molecule), another member of the TLR/IL-1R superfamily, acts as a negative regulator of MyD88-dependent TLR signaling. It attenuates the recruitment of MyD88 adaptors to the receptors with its intracellular TIR domain. Thus, SIGIRR is a highly important molecule for the therapy of autoimmune diseases caused by TLRs. So far, the structural mechanism of interactions between SIGIRR, TLRs and adaptor molecules is unclear. To develop a working hypothesis for this interaction, we constructed three-dimensional models for the TIR domains of TLR4, TLR7, MyD88 and SIGIRR based on computational modeling. Through protein-protein docking analysis, we developed models of essential complexes involved in the TLR4 and 7 signaling and the SIGIRR inhibiting processes. We suggest that SIGIRR may exert its inhibitory effect through blocking the molecular interface of TLR4, TLR7 and the MyD88 adaptor mainly via its BB-loop region.
Page 1. Nanomanipulation by Atomic Force Microscopy** By F. Javier Rubio-Sierra, Wolfgang M. Heck... more Page 1. Nanomanipulation by Atomic Force Microscopy** By F. Javier Rubio-Sierra, Wolfgang M. Heckl, Robert W. Stark* 1. Introduction Technologies to control and manipulate objects on the nanometer scale are thought to ...
Multiple genetic factors contribute to the clinical variability of spontaneous systemic lupus ery... more Multiple genetic factors contribute to the clinical variability of spontaneous systemic lupus erythematosus (SLE) but their role in drug-induced SLE remain largely unknown. Hydrocarbon oil-induced SLE depends on mesothelial cell apoptosis and Toll-like receptor (TLR)-7-mediated induction of type I interferons. Hence, we hypothesized that TIR8/SIGIRR, an endogenous TLR inhibitor, prevents oil-induced SLE. Sigirr-deficient dendritic cells expressed higher TLR7 mRNA levels and TLR7 activation resulted in increased IL-12 production in vitro. In vivo, lack of SIGIRR increased surface CD40 expression on spleen CD11c + dendritic cells and MX-1, TNF, IL-12, BAFF and BCL-2 mRNA expression 6 months after pristane injection. Spleen cell counts of CD4 − /CD8 − 'autoreactive' T cells and B220 + B cells were also increased in Sigirr −/− mice. Serum autoantibody analysis revealed that Sigirr deficiency specifically enhanced the production of rheumatoid factor (from 4 months of age) and anti-snRNP IgG (from 5 months of age), while anti-Smith IgG or anti-dsDNA IgG were independent of the Sigirr genotype. This effect was sufficient to significantly aggravate lupus nephritis in Sigirr-deficient mice. Structure model prediction identified the BB loop of SIGIRR's intracellular TIR domain to interact with TLR7 and MyD88. BB loop deletion was sufficient to completely abrogate SIGIRR's inhibitory effect on TLR7 signalling. Thus, TIR8/SIGIRR protects from hydrocarbon oil-induced lupus by suppressing the TLR7-mediated activation of dendritic cells, via its intracellular BB loop.
The properties of paper sheets can be tuned by adjusting the surface or bulk chemistry using func... more The properties of paper sheets can be tuned by adjusting the surface or bulk chemistry using functional polymers that are applied during (online) or after (offline) papermaking processes. In particular, polymers are widely used to enhance the mechanical strength of the wet state of paper sheets. However, the mechanical strength depends not only on the chemical nature of the polymeric additives but also on the distribution of the polymer on and in the lignocellulosic paper. Here, we analyze the photochemical attachment and distribution of hydrophilic polydimethylacrylamide-co-methacrylate-benzophenone P(DMAA-co-MABP) copolymers with defined amounts of photoreactive benzophenone moieties in model paper sheets. Raman microscopy was used for the unambiguous identification of P(DMAA-co-MABP) and cellulose specific bands and thus the copolymer distribution within the cellulose matrix. Two-dimensional Raman spectral maps at the intersections of overlapping cellulose fibers document that th...
Nanomachining of thin polymer resist films with an atomic force microscope (AFM) is a promising r... more Nanomachining of thin polymer resist films with an atomic force microscope (AFM) is a promising route for the fabrication of nanoscale devices. In order to enhance the controllability of the nanomachining process an in-plane acoustic wave is coupled to the sample support. This enhances the intermittent force exerted by the AFM tip. The lateral resolution reached by this method is only limited by the physical size of the AFM tip to dimensions far below the light diffraction limit. The main process parameters are the frequency and magnitude of the acoustic wave, and the preloading force. In this work, the feasibility of acoustical force lithography and the influence of the relevant parameters are investigated.
For the fabrication of microfluidic devices based on SU-8, the wetting properties of the polymer ... more For the fabrication of microfluidic devices based on SU-8, the wetting properties of the polymer surface need to be adjusted. We investigated the effects of wet chemical and plasma processes with respect to wetting properties, surface roughness, and surface chemistry.
The dynamics of the microcantilever in atomic force microscopy ͑AFM͒ is represented by a multiple... more The dynamics of the microcantilever in atomic force microscopy ͑AFM͒ is represented by a multipledegrees-of-freedom state-space model and is discussed within the framework of system theory. The cantilever dynamics is modeled as a linear time-invariant system with a nonlinear output feedback due to the tip-sample interaction. This allows one to use the same model to analyze different aspects of atomic force microscopy such as the dynamics of contact-mode or the dynamics of tapping-mode AFM. The state-space approach to the dynamic response of the AFM cantilever allows for numerically efficient simulations. We show that not only the eigenfrequency but also the modal damping of a cantilever interacting with a surface strongly depends on the contact stiffness. This is important for a quantitative characterization of elastic sample properties. Additionally, our model shows the presence of higher harmonics in tapping-mode AFM. The excitation of higher eigenmodes can strongly distort the system response. The results illustrate that higher eigenmodes have to be considered in the analysis of dynamic AFM.
Toll-like receptors (TLRs) belong to the Toll-like receptor/interleukin-1 receptor (TLR/IL-1R) su... more Toll-like receptors (TLRs) belong to the Toll-like receptor/interleukin-1 receptor (TLR/IL-1R) superfamily which is defined by a common cytoplasmic Toll/interleukin-1 receptor (TIR) domain. TLRs recognize pathogen-associated molecular patterns and initiate an intracellular kinase cascade to trigger an immediate defensive response. SIGIRR (single immunoglobulin interleukin-1 receptor-related molecule), another member of the TLR/IL-1R superfamily, acts as a negative regulator of MyD88-dependent TLR signaling. It attenuates the recruitment of MyD88 adaptors to the receptors with its intracellular TIR domain. Thus, SIGIRR is a highly important molecule for the therapy of autoimmune diseases caused by TLRs. So far, the structural mechanism of interactions between SIGIRR, TLRs and adaptor molecules is unclear. To develop a working hypothesis for this interaction, we constructed three-dimensional models for the TIR domains of TLR4, TLR7, MyD88 and SIGIRR based on computational modeling. Through protein-protein docking analysis, we developed models of essential complexes involved in the TLR4 and 7 signaling and the SIGIRR inhibiting processes. We suggest that SIGIRR may exert its inhibitory effect through blocking the molecular interface of TLR4, TLR7 and the MyD88 adaptor mainly via its BB-loop region.
Page 1. Nanomanipulation by Atomic Force Microscopy** By F. Javier Rubio-Sierra, Wolfgang M. Heck... more Page 1. Nanomanipulation by Atomic Force Microscopy** By F. Javier Rubio-Sierra, Wolfgang M. Heckl, Robert W. Stark* 1. Introduction Technologies to control and manipulate objects on the nanometer scale are thought to ...
Multiple genetic factors contribute to the clinical variability of spontaneous systemic lupus ery... more Multiple genetic factors contribute to the clinical variability of spontaneous systemic lupus erythematosus (SLE) but their role in drug-induced SLE remain largely unknown. Hydrocarbon oil-induced SLE depends on mesothelial cell apoptosis and Toll-like receptor (TLR)-7-mediated induction of type I interferons. Hence, we hypothesized that TIR8/SIGIRR, an endogenous TLR inhibitor, prevents oil-induced SLE. Sigirr-deficient dendritic cells expressed higher TLR7 mRNA levels and TLR7 activation resulted in increased IL-12 production in vitro. In vivo, lack of SIGIRR increased surface CD40 expression on spleen CD11c + dendritic cells and MX-1, TNF, IL-12, BAFF and BCL-2 mRNA expression 6 months after pristane injection. Spleen cell counts of CD4 − /CD8 − 'autoreactive' T cells and B220 + B cells were also increased in Sigirr −/− mice. Serum autoantibody analysis revealed that Sigirr deficiency specifically enhanced the production of rheumatoid factor (from 4 months of age) and anti-snRNP IgG (from 5 months of age), while anti-Smith IgG or anti-dsDNA IgG were independent of the Sigirr genotype. This effect was sufficient to significantly aggravate lupus nephritis in Sigirr-deficient mice. Structure model prediction identified the BB loop of SIGIRR's intracellular TIR domain to interact with TLR7 and MyD88. BB loop deletion was sufficient to completely abrogate SIGIRR's inhibitory effect on TLR7 signalling. Thus, TIR8/SIGIRR protects from hydrocarbon oil-induced lupus by suppressing the TLR7-mediated activation of dendritic cells, via its intracellular BB loop.
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