20 research outputs found
Optimality in superselective surface binding by multivalent DNA nanostars
Weak multivalent interactions govern a large variety of biological processes
like cell-cell adhesion and virus-host interactions. These systems distinguish
sharply between surfaces based on receptor density, known as superselectivity.
Earlier experimental and theoretical work provided insights into the control of
selectivity: Weak interactions and a high number of ligands facilitate
superselectivity. Present experimental studies typically involve tens or
hundreds of interactions, resulting in a high entropic contribution leading to
high selectivities. However, if, and if so how, systems with few ligands, such
as multi-domain proteins and virus binding to a membrane, show superselective
behavior is an open question. Here, we address this question with a multivalent
experimental model system based on star shaped branched DNA nanostructures (DNA
nanostars) with each branch featuring a single stranded overhang that binds to
complementary receptors on a target surface. Each DNA nanostar possesses a
fluorophore, to directly visualize DNA nanostar surface adsorption by total
internal reflection fluorescence microscopy (TIRFM). We observe that DNA
nanostars can bind superselectively to surfaces and bind optimally at a valency
of three. We quantitatively explain this optimum by extending the current
theory with interactions between DNA nanostar binding sites (ligands). Our
results add to the understanding of multivalent interactions, by identifying
microscopic mechanisms that lead to optimal selectivity, and providing
quantitative values for the relevant parameters. These findings inspire
additional design rules which improve future work on selective targeting in
directed drug delivery.Comment: 14 pages, 4 figure
Elastocapillary Levelling of Thin Viscous Films on Soft Substrates
A thin liquid film with non-zero curvature at its free surface spontaneously
flows to reach a flat configuration, a process driven by Laplace pressure
gradients and resisted by the liquid's viscosity. Inspired by recent progresses
on the dynamics of liquid droplets on soft substrates, we here study the
relaxation of a viscous film supported by an elastic foundation. Experiments
involve thin polymer films on elastomeric substrates, where the dynamics of the
liquid-air interface is monitored using atomic force microscopy. A theoretical
model that describes the coupled evolution of the solid-liquid and the
liquid-air interfaces is also provided. In this soft-levelling configuration,
Laplace pressure gradients not only drive the flow, but they also induce
elastic deformations on the substrate that affect the flow and the shape of the
liquid-air interface itself. This process represents an original example of
elastocapillarity that is not mediated by the presence of a contact line. We
discuss the impact of the elastic contribution on the levelling dynamics and
show the departure from the classical self-similarities and power laws observed
for capillary levelling on rigid substrates
Immunological fingerprint in coronavirus disease-19 convalescents with and without post-COVID syndrome
BackgroundSymptoms lasting longer than 12â weeks after severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection are called post-coronavirus disease (COVID) syndrome (PCS). The identification of new biomarkers that predict the occurrence or course of PCS in terms of a post-viral syndrome is vital. T-cell dysfunction, cytokine imbalance, and impaired autoimmunity have been reported in PCS. Nevertheless, there is still a lack of conclusive information on the underlying mechanisms due to, among other things, a lack of controlled study designs.MethodsHere, we conducted a prospective, controlled study to characterize the humoral and cellular immune response in unvaccinated patients with and without PCS following SARS-CoV-2 infection over 7âŻmonths and unexposed donors.ResultsPatients with PCS showed as early as 6âŻweeks and 7âŻmonths after symptom onset significantly increased frequencies of SARS-CoV-2-specific CD4+ and CD8+ T-cells secreting IFNÎł, TNF, and expressing CD40L, as well as plasmacytoid dendritic cells (pDC) with an activated phenotype. Remarkably, the immunosuppressive counterparts type 1 regulatory T-cells (TR1: CD49b/LAG-3+) and IL-4 were more abundant in PCS+.ConclusionThis work describes immunological alterations between inflammation and immunosuppression in COVID-19 convalescents with and without PCS, which may provide potential directions for future epidemiological investigations and targeted treatments
The coming decade of digital brain research: a vision for neuroscience at the intersection of technology and computing
In recent years, brain research has indisputably entered a new epoch, driven by substantial methodological advances and digitally enabled data integration and modelling at multiple scalesâ from molecules to the whole brain. Major advances are emerging at the intersection of neuroscience with technology and computing. This new science of the brain combines high-quality research, data integration across multiple scales, a new culture of multidisciplinary large-scale collaboration and translation into applications. As pioneered in Europeâs Human Brain Project (HBP), a systematic approach will be essential for meeting the coming decadeâs pressing medical and technological challenges. The aims of this paper are to: develop a concept for the coming decade of digital brain research, discuss this new concept with the research community at large, to identify points of convergence, and derive therefrom scientific common goals; provide a scientific framework for the current and future development of EBRAINS, a research infrastructure resulting from the HBPâs work; inform and engage stakeholders, funding organisations and research institutions regarding future digital brain research; identify and address the transformational potential of comprehensive brain models for artificial intelligence, including machine learning and deep learning; outline a collaborative approach that integrates reflection, dialogues and societal engagement on ethical and societal opportunities and challenges as part of future neuroscience research
Red Light District - Prostitution eller forlystelsespark?: Red Light District - Prostitution or amusementpark
TU-Spektrum 3/2007, Magazin der Technischen UniversitÀt Chemnitz
dreimal im Jahr erscheinende Zeitschrift ĂŒber aktuelle Themen der TU Chemnit
TU-Spektrum 1/2008, Magazin der Technischen UniversitÀt Chemnitz
dreimal im Jahr erscheinende Zeitschrift ĂŒber aktuelle Themen der TU Chemnit
TU-Spektrum 3/2008, Magazin der Technischen UniversitÀt Chemnitz
dreimal im Jahr erscheinende Zeitschrift ĂŒber aktuelle Themen der TU Chemnit
Elastocapillary levelling of thin viscous films on soft substrates
A thin liquid film with non-zero curvature at its free surface spontaneously flows to reach a flat configuration, a process driven by Laplace pressure gradients and resisted by the liquid's viscosity. Inspired by recent progresses on the dynamics of liquid droplets on soft substrates, we here study the relaxation of a viscous film supported by an elastic foundation. Experiments involve thin polymer films on elastomeric substrates, where the dynamics of the liquid-air interface is monitored using atomic force microscopy. A theoretical model that describes the coupled evolution of the solid-liquid and the liquid-air interfaces is also provided. In this soft-levelling configuration, Laplace pressure gradients not only drive the flow, but they also induce elastic deformations on the substrate that affect the flow and the shape of the liquid-air interface itself. This process represents an original example of elastocapillarity that is not mediated by the presence of a contact line. We discuss the impact of the elastic contribution on the levelling dynamics and show the departure from the classical self-similarities and power laws observed for capillary levelling on rigid substrates
TU-Spektrum 2/2008, Magazin der Technischen UniversitÀt Chemnitz
dreimal im Jahr erscheinende Zeitschrift ĂŒber aktuelle Themen der TU Chemnit