Influence of Different Phase-Forming Parameters on the Phase Diagram of Several PEG–Salt Aqueous Two-Phase Systems

Different poly­(ethylene glycol) (PEG) + potassium phosphate or sodium citrate aqueous two-phase systems (ATPS) were investigated at 23 °C, containing different PEG types (molecular weights 2000 g·mol^–1 to 8000 g·mol^–1) and pH values (5 to 9). Furthermore, the effect of the added salt NaCl (0 wt % to 8 wt %) on the PEG + potassium phosphate/sodium citrate ATPS was studied at 23 °C. The experimental binodal data were successfully correlated with the empirical nonlinear equation proposed by Hu. The effects of increasing molecular weight of PEG, pH, NaCl, and salt type on the obtained binodal curves were determined, resulting in a binodal curve shift toward the origin. Thus, an expansion of the two-phase region occurred by increasing molecular weight of the PEG, pH, and NaCl and due to the Gibbs free energy of hydration of ions of phosphate. Furthermore, the phase equilibrium compositions, tie-line lengths, slopes of tie-lines, critical points, and effective excluded volumes were obtained for all studied systems. Finally, the experimental tie-line compositions were successfully correlated by using the Othmer–Tobias and Bancroft equations, and linear dependency was confirmed

Label-Free Optical Biosensors Based on Aptamer-Functionalized Porous Silicon Scaffolds

A proof-of-concept for a label-free and reagentless optical biosensing platform based on nanostructured porous silicon (PSi) and aptamers is presented in this work. Aptamers are oligonucleotides (single-stranded DNA or RNA) that can bind their targets with high affinity and specificity, making them excellent recognition elements for biosensor design. Here we describe the fabrication and characterization of aptamer-conjugated PSi biosensors, where a previously characterized his-tag binding aptamer (6H7) is used as model system. Exposure of the aptamer-functionalized PSi to the target proteins as well as to complex fluids (i.e., bacteria lysates containing target proteins) results in robust and well-defined changes in the PSi optical interference spectrum, ascribed to specific aptamer-protein binding events occurring within the nanoscale pores, monitored in real time. The biosensors show exceptional stability and can be easily regenerated by a short rinsing step for multiple biosensing analyses. This proof-of-concept study demonstrates the possibility of designing highly stable and specific label-free optical PSi biosensors, employing aptamers as capture probes, holding immense potential for application in detection of a broad range of targets, in a simple yet reliable manner

Supplemental_Material_Austerjostetal.pdf – Supplemental material for Introducing a Virtual Assistant to the Lab: A Voice User Interface for the Intuitive Control of Laboratory Instruments

<p>Supplemental material, Supplemental_Material_Austerjostetal.pdf for Introducing a Virtual Assistant to the Lab: A Voice User Interface for the Intuitive Control of Laboratory Instruments by Jonas Austerjost, Marc Porr, Noah Riedel, Dominik Geier, Thomas Becker, Thomas Scheper, Daniel Marquard, Patrick Lindner and Sascha Beutel in SLAS Technology</p

Aqueous Synthesis of PEGylated Quantum Dots with Increased Colloidal Stability and Reduced Cytotoxicity

Ligands used on the surface of colloidal nanoparticles (NPs) have a significant impact on physiochemical properties of NPs and their interaction in biological environments. In this study, we report a one-pot aqueous synthesis of 3-mercaptopropionic acid (MPA)-functionalized CdTe/CdS/ZnS quantum dots (Qdots) in the presence of thiol-terminated methoxy polyethylene glycol (mPEG) molecules as a surface coordinating ligand. The resulting mPEG–Qdots were characterized by using ζ potential, FTIR, thermogravimetric (TG) analysis, and microscale thermophoresis (MST) studies. We investigated the effect of mPEG molecules and their grafting density on the Qdots photophysical properties, colloidal stability, protein binding affinity, and in vitro cellular toxicity. Moreover, cellular binding features of the resulting Qdots were examined by using three-dimensional (3D) tumor-like spheroids, and the results were discussed in detail. Promisingly, mPEG ligands were found to increase colloidal stability of Qdots, reduce adsorption of proteins to the Qdot surface, and mitigate Qdot-induced side effects to a great extent. Flow cytometry and confocal microscopy studies revealed that PEGylated Qdots exhibited distinctive cellular interactions with respect to their mPEG grafting density. As a result, mPEG molecules demonstrated a minimal effect on the ZnS shell deposition and the Qdot fluorescence efficiency at a low mPEG density, whereas they showed pronounced effect on Qdot colloidal stability, protein binding affinity, cytotoxicity, and nonspecific binding at a higher mPEG grafting amount

Nanostructured Amphiphilic Star-Hyperbranched Block Copolymers for Drug Delivery

A robust drug delivery system based on nanosized amphiphilic star-hyperbranched block copolymer, namely, poly­(methyl methacrylate-<i>block</i>-poly­(hydroxylethyl methacrylate) (PMMA-<i>b</i>-PHEMA) is described. PMMA-<i>b</i>-PHEMA was prepared by sequential visible light induced self-condensing vinyl polymerization (SCVP) and conventional vinyl polymerization. All of the synthesis and characterization details of the conjugates are reported. To accomplish tumor cell targeting property, initially cell-targeting (arginylglycylaspactic acid; RGD) and penetrating peptides (Cys-TAT) were binding to each other via the well-known EDC/NHS chemistry. Then, the resulting peptide was further incorporated to the surface of the amphiphilic hyperbranched copolymer via a coupling reaction between the thiol (−SH) group of the peptide and the hydroxyl group of copolymer by using <i>N</i>-(<i>p</i>-maleinimidophenyl) isocyanate as a heterolinker. The drug release property and targeting effect of the anticancer drug (doxorobucin; DOX) loaded nanostructures to two different cell lines were evaluated in vitro. U87 and MCF-7 were chosen as integrin α_vβ₃ receptor positive and negative cells for the comparison of the targeting efficiency, respectively. The data showed that drug-loaded copolymers exhibited enhanced cell inhibition toward U87 cells in compared to MCF-7 cells because targeting increased the cytotoxicity of drug-loaded copolymers against integrin α_vβ₃ receptor expressing tumor cells

Disease-related autoantibody profile in patients with systemic sclerosis

<p><b>Background:</b> Autoantibodies (autoAbs) help in diagnosis and predicting clinical phenotypes in systemic sclerosis (SSc).</p> <p><b>Aim of the study:</b> To determine the clinical utility of 13 SSc-related autoAbs in SSc patients.</p> <p><b>Material and methods:</b> A total of 131 consecutive patients with SSc (111 female, mean age 58.1 ± 14 years; 49 with diffused cutaneous SSc [dcSSc] and 82 with limited cutaneous SSc [lcSSc]) were analysed by a multiplex line immunoassay (Euroimmun) for autoantibodies (autoAbs) against 13 SSc-related antigens. A total of 22 patients with primary Raynaud phenomenon (RP), and 22 healthy controls were also analysed.</p> <p><b>Results:</b> ANA by indirect immunofluorescence was present in 128 (97.7%) patients with SSc. Excluding anti-Ro52, 113 (89.3%) SSc patients were positive for at least one autoAb: anti-Topoisomerase I (anti-Topo) I abs in 54 (41.2%), anti-centromere proteins (anti-CENP) in 37 (28.2%, all reactive with centromere protein-A (CENPA) and centromere protein B (CENPB)), anti-RNA polymerase III(RP11) in 19 (14.5%), anti-RNA polymerase III(RP155) in 13 (9.9%), anti-fibrillarin in 4 (3.1%), anti-Ku in 6 (4.6%), anti-nucleolus-organizing region (anti-NOR90) in 8 (6.1%), anti-PM-Scl100 in 2 (1.5%), and anti-PM-Scl75 in 4 (3.1%). There was no immunoreactivity for Th/To or platelet-derived growth factor receptor (PDGFR). Overall, 102 (77.9%) SSc patients had autoAbs against Topo I, CENPA or CENPB, RP11 or RP155. Anti-Topo I abs were strongly associated with dcSSc, interstitial lung disease (ILD) (<i>p</i> < .001), pulmonary hypertension (PH) (<i>p</i> = .019) and ILD-PH (<i>p</i> = .003). Anti-CENPB abs were associated with lcSSc, and negatively associated with ILD. Anti-RP11 and anti-NOR90 abs were associated with male gender, and anti-NOR90 associated with ILD.</p> <p><b>Conclusions:</b> Anti-Topo I, anti-CENP, and anti-RNA pol III are the most prevalent autoAbs in SSc. Anti-Topo I and anti-NOR90 abs are associated with ILD and/or PAH.</p

Identification of the Target Binding Site of Ethanolamine-Binding Aptamers and Its Exploitation for Ethanolamine Detection

Aptamers are promising recognition elements for sensitive and specific detection of small molecules. We have previously selected ssDNA aptamers for ethanolamine, one of the smallest aptamer targets so far. The work presented here focuses on the determination of the binding region within the aptamer structure and its exploitation for the development of an aptamer-based assay for detection of ethanolamine. Sequence analysis of the aptamers resulted in the identification of a G-rich consensus sequence, which was able to fold in a typical two- or three-layered G-quartet structure. Experiments with stepwise truncated variants of the aptamers revealed that the consensus sequence is responsible and sufficient for binding to the target. On the basis of the knowledge of the aptamers binding site, we developed an aptamer-based microarray assay relying on competition between ethanolamine and an oligonucleotide complementary to the consensus sequence. Competitive binding of ethanolamine and fluorescently labeled complementary oligonucleotides resulted in fluorescence intensities dependent on ethanolamine concentration with a limit of detection of 10 pM. This method enables detection of small molecules without any labeling of analytes. The competitive assay could potentially be transferred to other aptamers and thus provides a promising system for aptamer-based detection of diverse small molecules

From Invisible Structures of SWCNTs toward Fluorescent and Targeting Architectures for Cell Imaging

Single-walled carbon nanotubes (SWNTs) are unique nanostructures used as cargo systems for variety of diagnostic and therapeutic agents. For taking advantage of these structures in biological processes, they should be visible. Therefore, fluorescence labeling of SWCNTs with various probes is a significant issue. Herein, we demonstrate a simple approach for cell specific imaging and diagnosis by combining SWCNTs with a copolymer poly­(<i>para</i>-phenylene) (PPP) containing polystyrene (PSt) and poly­(ε-caprolactone) (PCL) side chains (PPP-<i>g</i>-PSt-PCL). In this approach PPP-<i>g-</i>PSt-PCL is noncovalently attached on carboxyl functional SWCNTs. The obtained fluorescent probe is bound to folic acid (FA) for targeted imaging of folate receptor (FR) positive HeLa cells. In vitro studies demonstrate that this conjugate can specifically bind to HeLa cells and indicate great potential for targeting and imaging studies

Supplemental material for Comparison of different three dimensional-printed resorbable materials: <i>In vitro</i> biocompatibility, <i>In vitro</i> degradation rate, and cell differentiation support

<p>Supplemental material for Comparison of different three dimensional-printed resorbable materials: <i>In vitro</i> biocompatibility, <i>In vitro</i> degradation rate, and cell differentiation support by Lukas Raddatz, Marline Kirsch, Dominik Geier, Jörn Schaeske, Kevin Acreman, Rafael Gentsch, Scott Jones, Andreas Karau, Tommy Washington, Meike Stiesch, Thomas Becker, Sascha Beutel, Thomas Scheper and Antonina Lavrentieva in Journal of Biomaterials Applications</p