Microwave assisted patterning of vertically aligned carbon nanotubes onto polymer substrates

© 2006 American Vacuum Society. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Vacuum Society. The electronic version of this article is the complete one and can be found at: http://dx.doi.org/10.1116/1.2221320This paper presents a low pressure hot embossing method for transferring patterns of vertically aligned carbon nanotubes into thermoplastic substrates. The procedure utilizes the synthesis of carbon nanotubes in discrete patterns on silicon substrates through the vapor liquid solid growth mechanism. The nanotube pattern and silicon stamp is placed on top of a polycarbonate film and locally heated above the glass transition temperature using microwave processing. The weight of the silicon substrate presses the nanotubes into the polycarbonate, resulting in the complete transfer of vertically aligned patterns. The technique is a rapid processing method, which could be used to integrate aligned nanomaterials with MEMS and flexible electronics that are fabricated on a wide range of thermoplastic polymer materials

Nanomaterial transfer using hot embossing for flexible electronic devices

We demonstrate hot embossing to pattern carbon nanotubes (CNTs) on flexible substrates. Patterns of CNTs grown on both microtextured and flat silicon templates were transferred into polymer substrates, with good replication of both the CNT patterns and surface relief features. The transferred CNTs formed a highly entangled network with electrical resistance of 1 kΩ–9 MΩ, depending on growth and embossing conditions. The electrical properties showed a strong sensitivity to both light and temperature. This dry transfer process shows promise for high throughput manufacturing of nanomaterial-based flexible electronic devices

Direct Injection of Functional Single-Domain Antibodies from E. coli into Human Cells

Intracellular proteins have a great potential as targets for therapeutic antibodies (Abs) but the plasma membrane prevents access to these antigens. Ab fragments and IgGs are selected and engineered in E. coli and this microorganism may be also an ideal vector for their intracellular delivery. In this work we demonstrate that single-domain Ab (sdAbs) can be engineered to be injected into human cells by E. coli bacteria carrying molecular syringes assembled by a type III protein secretion system (T3SS). The injected sdAbs accumulate in the cytoplasm of HeLa cells at levels ca. 105–106 molecules per cell and their functionality is shown by the isolation of sdAb-antigen complexes. Injection of sdAbs does not require bacterial invasion or the transfer of genetic material. These results are proof-of-principle for the capacity of E. coli bacteria to directly deliver intracellular sdAbs (intrabodies) into human cells for analytical and therapeutic purposes

The Human Polyoma JC Virus Agnoprotein Acts as a Viroporin

Virus infections can result in a range of cellular injuries and commonly this involves both the plasma and intracellular membranes, resulting in enhanced permeability. Viroporins are a group of proteins that interact with plasma membranes modifying permeability and can promote the release of viral particles. While these proteins are not essential for virus replication, their activity certainly promotes virus growth. Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease resulting from lytic infection of oligodendrocytes by the polyomavirus JC virus (JCV). The genome of JCV encodes six major proteins including a small auxiliary protein known as agnoprotein. Studies on other polyomavirus agnoproteins have suggested that the protein may contribute to viral propagation at various stages in the replication cycle, including transcription, translation, processing of late viral proteins, assembly of virions, and viral propagation. Previous studies from our and other laboratories have indicated that JCV agnoprotein plays an important, although as yet incompletely understood role in the propagation of JCV. Here, we demonstrate that agnoprotein possesses properties commonly associated with viroporins. Our findings demonstrate that: (i) A deletion mutant of agnoprotein is defective in virion release and viral propagation; (ii) Agnoprotein localizes to the ER early in infection, but is also found at the plasma membrane late in infection; (iii) Agnoprotein is an integral membrane protein and forms homo-oligomers; (iv) Agnoprotein enhances permeability of cells to the translation inhibitor hygromycin B; (v) Agnoprotein induces the influx of extracellular Ca2+; (vi) The basic residues at amino acid positions 8 and 9 of agnoprotein key are determinants of the viroporin activity. The viroporin-like properties of agnoprotein result in increased membrane permeability and alterations in intracellular Ca2+ homeostasis leading to membrane dysfunction and enhancement of virus release

Stepwise Release of Biologically Active HMGB1 during HSV-2 Infection

BACKGROUND: High mobility group box 1 protein (HMGB1) is a major endogenous danger signal that triggers inflammation and immunity during septic and aseptic stresses. HMGB1 recently emerged as a key soluble factor in the pathogenesis of various infectious diseases, but nothing is known of its behaviour during herpesvirus infection. We therefore investigated the dynamics and biological effects of HMGB1 during HSV-2 infection of epithelial HEC-1 cells. METHODOLOGY/PRINCIPAL FINDINGS: Despite a transcriptional shutdown of HMGB1 gene expression during infection, the intracellular pool of HMGB1 protein remained unaffected, indicating its remarkable stability. However, the dynamics of HMGB1 was deeply modified in infected cells. Whereas viral multiplication was concomitant with apoptosis and HMGB1 retention on chromatin, a subsequent release of HMGB1 was observed in response to HSV-2 mediated necrosis. Importantly, extracellular HMGB1 was biologically active. Indeed, HMGB1-containing supernatants from HSV-2 infected cells induced the migration of fibroblasts from murine or human origin, and reactivated HIV-1 from latently infected T lymphocytes. These effects were specifically linked to HMGB1 since they were blocked by glycyrrhizin or by a neutralizing anti-HMGB1 antibody, and were mediated through TLR2 and the receptor for Advanced Glycation End-products (RAGE). Finally, we show that genital HSV-2 active infections also promote HMGB1 release in vivo, strengthening the clinical relevance of our experimental data. CONCLUSIONS: These observations target HMGB1 as an important actor during HSV-2 genital infection, notably in the setting of HSV-HIV co-infection

Genetic Control of the Variable Innate Immune Response to Asymptomatic Bacteriuria

The severity of urinary tract infection (UTI) reflects the quality and magnitude of the host response. While strong local and systemic innate immune activation occurs in patients with acute pyelonephritis, the response to asymptomatic bacteriuria (ABU) is low. The immune response repertoire in ABU has not been characterized, due to the inherent problem to distinguish bacterial differences from host-determined variation. In this study, we investigated the host response to ABU and genetic variants affecting innate immune signaling and UTI susceptibility. Patients were subjected to therapeutic urinary tract inoculation with E. coli 83972 to ensure that they were exposed to the same E. coli strain. The innate immune response repertoire was characterized in urine samples, collected from each patient before and after inoculation with bacteria or PBS, if during the placebo arm of the study. Long-term E. coli 83972 ABU was established in 23 participants, who were followed for up to twelve months and the innate immune response was quantified in 233 urine samples. Neutrophil numbers increased in all but two patients and in an extended urine cytokine/chemokine analysis (31 proteins), the chemoattractants IL-8 and GRO-α, RANTES, Eotaxin-1 and MCP-1, the T cell chemoattractant and antibacterial peptide IP-10, inflammatory regulators IL-1-α and sIL-1RA and the T lymphocyte/dendritic cell product sIL-2Rα were detected and variably increased, compared to sterile samples. IL-6, which is associated with symptomatic UTI, remained low and numerous specific immune mediators were not detected. The patients were also genotyped for UTI-associated IRF3 and TLR4 promoter polymorphisms. Patients with ABU associated TLR4 polymorphisms had low neutrophil numbers, IL-6, IP-10, MCP-1 and sIL-2Rα concentrations. Patients with the ABU-associated IRF3 genotype had lower neutrophils, IL-6 and MCP-1 responses than the remaining group. The results suggest that the host-specific, low immune response to ABU mainly includes innate immune mediators and that host genetics directly influence the magnitude of this response

Overview of homocysteine and folate metabolism. With special references to cardiovascular disease and neural tube defects

This overview addresses homocysteine and folate metabolism. Its functions and complexity are described, leading to explanations why disturbed homocysteine and folate metabolism is implicated in many different diseases, including congenital birth defects like congenital heart disease, cleft lip and palate, late pregnancy complications, different kinds of neurodegenerative and psychiatric diseases, osteoporosis and cancer. In addition, the inborn errors leading to hyperhomocysteinemia and homocystinuria are described. These extreme human hyperhomocysteinemia models provide knowledge about which part of the homocysteine and folate pathways are linked to which disease. For example, the very high risk for arterial and venous occlusive disease in patients with severe hyperhomocysteinemia irrespective of the location of the defect in remethylation or transsulphuration indicates that homocysteine itself or one of its “direct” derivatives is considered toxic for the cardiovascular system. Finally, common diseases associated with elevated homocysteine are discussed with the focus on cardiovascular disease and neural tube defects