Tandem Solar Cell Concept Using Black Silicon for Enhanced Infrared Absorption

AbstractIn this work we present a novel tandem solar cell concept that is based on enhanced below band gap infrared absorption. The solar cell structure is based on silicon and infrared activated Black Silicon. Infrared active Black Silicon is produced by exposing silicon to fs-laser pulses. It features an enhanced IR absorption, when processed under a sulfur-containing atmosphere. Then sulfur is incorporated into the silicon lattice during laser processing providing energy states in the band gap. This silicon based tandem cell thus absorbs light with wavelengths beyond 1.1μm. This can potentially increase the overall efficiency. In this paper we present the first experimental realization of this concept. We use a standard aluminium-back-surface-field (Al-BSF) silicon solar cell and implement a Black Silicon solar cell on its rear side for enhanced IR absorption. Current and voltage measurements show the feasibility of our concept

Tailoring the Absorption Properties of Black Silicon

AbstractSamples of crystalline silicon for use as solar cell material are structured and hyperdoped with sulfur by irradiation with femtosecond laser pulses under a sulfur hexafluoride atmosphere. The sulfur creates energy levels in the silicon band gap, allowing light absorption in the infrared wavelength regime, which offers the potential of a significant efficiency increase. This Black Silicon is a potential candidate for impurity or intermediate band photovoltaics. In this paper we determine the laser processed sulfur energy levels by deep-level transient spectroscopy (DLTS). We present how the number of laser pulses per sample spot influence the sulfur energy levels and hence the DLTS spectra. Further we show that changing the laser pulse by splitting it with a Michelson interferometer setup results in altered absorption which is most likely due to altered sulfur energy levels. This contribution focuses on the possibility of controlling the sulfur in Black Silicon through manipulating the laser pulse shape. As a first step samples of microstructured silicon are fabricated with doubled laser pulses at two different laser pulse distances and the absorption spectra by integrating sphere measurements are compared

Targeting the tumor microenvironment with fluorescence-activatable bispecific endoglin/fibroblast activation protein targeting liposomes

Liposomes are biocompatible nanocarriers with promising features for targeted delivery of contrast agents and drugs into the tumor microenvironment, for imaging and therapy purposes. Liposome-based simultaneous targeting of tumor associated fibroblast and the vasculature is promising, but the heterogeneity of tumors entails a thorough validation of suitable markers for targeted delivery. Thus, we elucidated the potential of bispecific liposomes targeting the fibroblast activation protein (FAP) on tumor stromal fibroblasts, together with endoglin which is overexpressed on tumor neovascular cells and some neoplastic cells. Fluorescence-quenched liposomes were prepared by hydrating a lipid film with a high concentration of the self-quenching near-infrared fluorescent dye, DY-676-COOH, to enable fluorescence detection exclusively upon liposomal degradation and subsequent activation. A non-quenched green fluorescent phospholipid was embedded in the liposomal surface to fluorescence-track intact liposomes. FAP- and murine endoglin-specific single chain antibody fragments were coupled to the liposomal surface, and the liposomal potentials validated in tumor cells and mice models. The bispecific liposomes revealed strong fluorescence quenching, activatability, and selectivity for target cells and delivered the encapsulated dye selectively into tumor vessels and tumor associated fibroblasts in xenografted mice models and enabled their fluorescence imaging. Furthermore, detection of swollen lymph nodes during intra-operative simulations was possible. Thus, the bispecific liposomes have potentials for targeted delivery into the tumor microenvironment and for image-guided surgery.Deutsche Forschungsgemeinschaf

Rapid target binding and cargo release of activatable liposomes bearing HER2 and FAP single-chain antibody fragments reveal potentials for image-guided delivery to tumors

Liposomes represent suitable tools for the diagnosis and treatment of a variety of diseases, including cancers. To study the role of the human epidermal growth factor receptor 2 (HER2) as target in cancer imaging and image-guided deliveries, liposomes were encapsulated with an intrinsically quenched concentration of a near-infrared fluorescent dye in their aqueous interior. This resulted in quenched liposomes (termed LipQ), that were fluorescent exclusively upon degradation, dye release, and activation. The liposomes carried an always-on green fluorescent phospholipid in the lipid layer to enable tracking of intact liposomes. Additionally, they were functionalized with single-chain antibody fragments directed to fibroblast activation protein (FAP), a marker of stromal fibroblasts of most epithelial cancers, and to HER2, whose overexpression in 20-30% of all breast cancers and many other cancer types is associated with a poor treatment outcome and relapse. We show that both monospecific (HER2-IL) and bispecific (Bi-FAP/HER2-IL) formulations are quenched and undergo HER2-dependent rapid uptake and cargo release in cultured target cells and tumor models in mice. Thereby, tumor fluorescence was retained in whole-body NIRF imaging for 32-48 h post-injection. Opposed to cell culture studies, Bi-FAP/HER2-IL-based live confocal microscopy of a high HER2-expressing tumor revealed nuclear delivery of the encapsulated dye. Thus, the liposomes have potentials for image-guided nuclear delivery of therapeutics, and also for intraoperative delineation of tumors, metastasis, and tumor margins

Cytogerontology since 1881: A reappraisal of August Weismann and a review of modern progress

Cytogerontology, the science of cellular ageing, originated in 1881 with the prediction by August Weismann that the somatic cells of higher animals have limited division potential. Weismann's prediction was derived by considering the role of natural selection in regulating the duration of an organism's life. For various reasons, Weismann's ideas on ageing fell into neglect following his death in 1914, and cytogerontology has only reappeared as a major research area following the demonstration by Hayflick and Moorhead in the early 1960s that diploid human fibroblasts are restricted to a finite number of divisions in vitro. In this review we give a detailed account of Weismann's theory, and we reveal that his ideas were both more extensive in their scope and more pertinent to current research than is generally recognised. We also appraise the progress which has been made over the past hundred years in investigating the causes of ageing, with particular emphasis being given to (i) the evolution of ageing, and (ii) ageing at the cellular level. We critically assess the current state of knowledge in these areas and recommend a series of points as primary targets for future research

Antibody Engineering Using Phage Display with a Coiled-Coil Heterodimeric Fv Antibody Fragment

A Fab-like antibody binding unit, ccFv, in which a pair of heterodimeric coiled-coil domains was fused to VH and VL for Fv stabilization, was constructed for an anti-VEGF antibody. The anti-VEGF ccFv showed the same binding affinity as scFv but significantly improved stability and phage display level. Furthermore, phage display libraries in the ccFv format were constructed for humanization and affinity maturation of the anti-VEGF antibody. A panel of VH frameworks and VH-CDR3 variants, with a significant improvement in affinity and expressibility in both E. coli and yeast systems, was isolated from the ccFv phage libraries. These results demonstrate the potential application of the ccFv antibody format in antibody engineering

The TNFR1 antagonist Atrosimab is therapeutic in mouse models of acute and chronic inflammation

Therapeutics that block tumor necrosis factor (TNF), and thus activation of TNF receptor 1 (TNFR1) and TNFR2, are clinically used to treat inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease and psoriasis. However, TNFR1 and TNFR2 work antithetically to balance immune responses involved in inflammatory diseases. In particular, TNFR1 promotes inflammation and tissue degeneration, whereas TNFR2 contributes to immune modulation and tissue regeneration. We, therefore, have developed the monovalent antagonistic anti-TNFR1 antibody derivative Atrosimab to selectively block TNFR1 signaling, while leaving TNFR2 signaling unaffected. Here, we describe that Atrosimab is highly stable at different storage temperatures and demonstrate its therapeutic efficacy in mouse models of acute and chronic inflammation, including experimental arthritis, non-alcoholic steatohepatitis (NASH) and experimental autoimmune encephalomyelitis (EAE). Our data support the hypothesis that it is sufficient to block TNFR1 signaling, while leaving immune modulatory and regenerative responses via TNFR2 intact, to induce therapeutic effects. Collectively, we demonstrate the therapeutic potential of the human TNFR1 antagonist Atrosimab for treatment of chronic inflammatory diseases

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