Of “raisins” and “yeast”: mobilisation and framing in the East German revolution of 1989

There is no shortage of literature on the social movements that arose in East Germany in 1989. Numerous studies have shed light upon the nature, scale and dynamics of the uprising of that year. But on certain issues questions remain. No consensus exists, for example, on the relationship between the “civic groups” (New Forum, Democratic Awakening, etc.) and the street protests of the autumn of 1989. Were these simply two facets of a single movement? Or are they better characterised as two distinct streams within the same movement delta? Did the street protests push the civic movement activists into the limelight? Or is it more accurate to say, with Reinfried Musch, that “the civic movement brought the people onto the streets”?1 This paper considers two contrasting interpretations of these issues, and finds both wanting. An alternative interpretation is offered, one that draws upon Marc Steinberg's “dialogical” development of frame theory

Polyglycerol-based amphiphilic dendrons as potential siRNA carriers for in vivo applications

The development of nonviral synthetic vectors for clinical application of gene therapy using siRNA transfection technology is of particular importance for treatment of human diseases, which is yet an unsolved challenge. By employing a rational design approach, we have synthesized a set of well-defined, low- molecular-weight dendritic polyglycerol-based amphiphiles, which are decorated peripherally with the DAPMA (N,N-di-(3-aminopropyl)-N-(methyl)amine) moiety. The main differences that were introduced in the structural motif relate to dendron generation and the type of linker between the hydrophilic and hydrophobic segment. The synthesized amphiphiles were then characterized for their aggregation behaviour and further evaluated with respect to their siRNA transfection potential by comparing their physico-chemical and biological features. Our findings demonstrated that all four synthesized amphiphiles yielded high gene binding affinities. Furthermore, the ester-linked compounds (G1-Ester-DAPMA, G2-Ester-DAPMA) revealed noticeable gene silencing in vitro without affecting the cell viability in the tumor cell line 786-O. Remarkably, neither G1-Ester-DAPMA nor G2-Ester-DAPMA induced inflammatory side effects after systemic administration in vivo, which is noteworthy because such highly positively charged compounds are typically associated with toxicity concerns which in turn supports their prospective application for in vivo purposes. Therefore, we believe that these structures may serve as new promising alternatives for nonviral siRNA delivery systems and have great potential for further synthetic modifications

A targeted fluorescent nanosensor for ratiometric pH sensing at the cell surface

The correlation between altered extracellular pH and various pathological conditions, including cancer, inflammation and metabolic disorders, is well known. Bulk pH measurements cannot report the extracellular pH value at the cell surface. However, there is a limited number of suitable tools for measuring the extracellular pH of cells with high spatial resolution, and none of them are commonly used in laboratories around the world. In this study, a versatile ratiometric nanosensor for the measurement of extracellular pH was developed. The nanosensor consists of biocompatible polystyrene nanoparticles loaded with the pH-inert reference dye Nile red and is surface functionalized with a pH-responsive fluorescein dye. Equipped with a targeting moiety, the nanosensor can adhere to cell membranes, allowing direct measurement of extracellular pH at the cell surface. The nanosensor exhibits a sensitive ratiometric pH response within the range of 5.5–9.0, with a calculated pKa of 7.47. This range optimally covers the extracellular pH (pHe) of most healthy cells and cells in which the pHe is abnormal, such as cancer cells. In combination with the nanosensors ability to target cell membranes, its high robustness, reversibility and its biocompatibility, the pHe nanosensor proves to be well suited for in-situ measurement of extracellular pH, even over extended time periods. This pH nanosensor has the potential to advance biomedical research by improving our understanding of cellular microenvironments, where extracellular pH plays an important role

Self-Assembled Multivalent (SAMul) Polyanion Binding – Impact of Hydrophobic Modifications in the Micellar Core on DNA and Heparin Binding at the Peripheral Cationic Ligands

This paper reports a small family of cationic surfactants designed to bind polyanions such as DNA and heparin. Each molecule has the same hydrophilic cationic ligand, and a hydrophobic aliphatic group with eighteen carbon atoms with either one, two or three alkene groups within the hydrophobic chain (C18-1, C18-2 and C18-3). Dynamic light scattering indicates that more alkenes lead to geometric distortion, giving rise to larger self-assembled multivalent (SAMul) nanostructures. Mallard Blue and Ethidium Bromide dye displacement assays demonstrate that heparin and DNA have markedly different binding preferences, with heparin binding most effectively to C18-1, and DNA to C18-3, even though the molecular structural differences of these SAMul systems are buried in the hydrophobic core. Multiscale modelling suggests that adaptive heparin maximises enthalpically-favourable interactions with C18-1, while shape-persistent DNA forms a similar number of interactions with each ligand display, but with slightly less entropic cost for binding to C18-3 – fundamental thermodynamic differences in SAMul binding of heparin or DNA. This study therefore provides unique insight into electrostatic molecular recognition between highly charged nanoscale surfaces in biologically-relevant systems

ROS generating BODIPY loaded nanoparticles for photodynamic eradication of biofilms

Bacterial biofilms can pose a serious health risk to humans and are less susceptible to antibiotics and disinfection than planktonic bacteria. Here, a novel method for biofilm eradication based on antimicrobial photodynamic therapy utilizing a nanoparticle in conjunction with a BODIPY derivative as photosensitizer was developed. Reactive oxygen species are generated upon illumination with visible light and lead to a strong, controllable and persistent eradication of both planktonic bacteria and biofilms. One of the biggest challenges in biofilm eradication is the penetration of the antimicrobial agent into the biofilm and its matrix. A biocompatible hydrophilic nanoparticle was utilized as a delivery system for the hydrophobic BODIPY dye and enabled its accumulation within the biofilm. This key feature of delivering the antimicrobial agent to the site of action where it is activated resulted in effective eradication of all tested biofilms. Here, 3 bacterial species that commonly form clinically relevant pathogenic biofilms were selected: Escherichia coli, Staphylococcus aureus and Streptococcus mutans. The development of this antimicrobial photodynamic therapy tool for biofilm eradication takes a promising step towards new methods for the much needed treatment of pathogenic biofilms

Environmental considerations and current status of grouping and regulation of engineered nanomaterials

This article reviews the current status of nanotechnology with emphasis on application and related environmental considerations as well as legislation. Application and analysis of nanomaterials in infrastructure (construction, building coatings, and water treatment) is discussed, and in particular nanomaterial release during the lifecycle of these applications. Moreover, possible grouping approaches with regard to ecotoxicological and toxicological properties, and the fate of nanomaterials in the environment are evaluated. In terms of potential exposure, the opportunities that arise from leveraging advances in several key areas, such as water treatment and construction are addressed. Additionally, this review describes challenges with regard to the European Commission’s definition of ‘nanomaterial’. The revised REACH information requirements, intended to enable a comprehensive risk assessment of nanomaterials, are outlined

Analytical and toxicological aspects of nanomaterials in different product groups: Challenges and opportunities

The widespread integration of engineered nanomaterials into consumer and industrial products creates new challenges and requires innovative approaches in terms of design, testing, reliability, and safety of nanotechnology. The aim of this review article is to give an overview of different product groups in which nanomaterials are present and outline their safety aspects for consumers. Here, release of nanomaterials and related analytical challenges and solutions as well as toxicological considerations, such as dose-metrics, are discussed. Additionally, the utilization of engineered nanomaterials as pharmaceuticals or nutraceuticals to deliver and release cargo molecules is covered. Furthermore, critical pathways for human exposure to nanomaterials, namely inhalation and ingestion, are discussed in the context of risk assessment. Analysis of NMs in food, innovative medicine or food contact materials is discussed. Specific focus is on the presence and release of nanomaterials, including whether nanomaterials can migrate from polymer nanocomposites used in food contact materials. With regard to the toxicology and toxicokinetics of nanomaterials, aspects of dose metrics of inhalation toxicity as well as ingestion toxicology and comparison between in vitro and in vivo conclusions are considered. The definition of dose descriptors to be applied in toxicological testing is emphasized. In relation to potential exposure from different products, opportunities arising from the use of advanced analytical techniques in more unique scenarios such as release of nanomaterials from medical devices such as orthopedic implants are addressed. Alongside higher product performance and complexity, further challenges regarding material characterization and safety, as well as acceptance by the general public are expected