Aqueous Self-Assembly of a Protein-Mimetic Ampholytic Block Copolypeptide

This report describes the aggregation behavior of an ABC-type ampholytic block copolypeptide, poly(ethylene oxide)-block-poly(l-lysine)-block-poly(l-glutamate), in aqueous media in dependence of pH. Polypeptide secondary structures and self-assemblies are investigated by circular dichroism (CD), Fourier transform infrared (FT-IR) and NMR spectroscopy, zeta potential measurements, analytical ultracentrifugation (AUC), dynamic/static light scattering (DLS/SLS), and cryogenic transmission electron microscopy (cryo-TEM). The polymer chains tend to form vesicles when the hydrophobic polypeptide helix is located at the chain end (acidic pH) and are existing as single chains when it is located in the center and flanked by the two hydrophilic segments (basic pH). Precipitation occurs in the intermediate pH range due to polyion complexation of the charged polypeptide segments

Generation of an NCS1 gene knockout human induced pluripotent stem cell line using CRISPR/Cas9

NCS1 (Neuronal calcium sensor protein 1) encodes a highly conserved calcium binding protein abundantly expressed in neurons. It modulates intracellular calcium homeostasis, calcium-dependent signaling pathways as well as neuronal transmission and plasticity. Here, we generated a NCS1 knockout human induced pluripotent stem cell (hiPSC) line using CRISPR-Cas9 genome editing. It shows regular expression of pluripotent markers, normal iPSC morphology and karyotype as well as no detectable off-target effects on top 6 potentially affected genes. This newly generated cell line constitutes a valuable tool for studying the role of NCS1 in the pathophysiology of various neuropsychiatric disorders and non-neurological disease

Generation of 20 human induced pluripotent stem cell lines from patients with focal segmental glomerulosclerosis (FSGS)

Focal segmental glomerulosclerosis (FSGS) is a major cause of familial nephrotic syndrome. We generated 20 induced pluripotent stem cell lines from patients diagnosed with FSGS. The iPSC lines include 8 female and 12 male lines and cover a donor age range from 31 to 78. The lines were generated from peripheral blood mononuclear cells by integration-free reprogramming using Sendai virus vectors. Cell lines were fully characterized regarding their pluripotency and differentiation potential, and quality controlled for karyotypic integrity, identity and clearance of reprogramming vectors. The generated cell lines represent a valuable tool for disease modelling and drug development for FSGS

Critical behavior of nanoparticle-containing binary liquid mixtures

Simultaneous measurements of small-angle neutron scattering and dynamic light scattering have been performed on a binary mixture of partially miscible liquids, 2,6-dimethylpyridine and water. At critical composition the temperature dependence of the correlation length of fluctuations in composition is strongly affected by the addition of nanoparticles of a triblock copolymer polyethylene oxide-polypropylene oxide- polyethylene oxide. A crossover between Ising-type critical behavior and mean-field critical behavior is observed when the correlation length is equal to the size of the nanoparticles

Performance Assessment of the Fecal Leukocyte Test for Inpatients

Traditionally, fecal leukocyte testing detects large bowel inflammation or disruption, conditions that allow leukocytes into the stool. However, test usefulness with inpatients is unclear. Two hundred five inpatients who had undergone one to three tests were identified, and their FLT results were compared to their gastrointestinal disease diagnoses at time of discharge. A specificity of 92% for detecting intact colonic mucosae in inpatients was found

Single-step electrospinning to bioactive polymer nanofibers

A single-step process to polymer nanofiber meshes that possess biofunctional peptide segments on their surfaces is described here, which requires a standard electrospinning setup only. Spinning a homogeneous mixture composed of a valuable polymer-peptide conjugate (poly(lactic acid)-block-CGGRGDS) and a biocompatible commodity poly(lactic-co-glycolic acid) (PLGA) leads to nonwovens where the bioactive peptide part is enriched up to 11 times on their fiber surface. This is determined by X-ray photoelectron spectroscopy (XPS). The surface accessibility of the peptide is proved on the macroscale by contact angle measurements comparing pure PLGA fibers with GRGDS-functionalized fiber meshes as well as on the nanoscale by probing electrostatic interaction between CGGRGDS surface functionalities and a colloidal silica probe via atomic force microscopy (AFM). Ultimately, bioavailability and bioactivity of the peptides on the fiber surfaces are demonstrated, showing that the me shes promote adhesion and migration of fibroblasts in comparison topure PLGA meshes. The one-step production of hydrophilic PLGA-based fibers could be exploited to electrospin into living cell culture without indication of toxic adverse effects on cell proliferation. This might be useful for directly production of cell-loaded scaffolds or biohybrid materials

Bidirectional nanoparticle crossing of oil-water interfaces induced by different stimuli : insight into phase transfer

International audienceSwap transactions: Bidirectional spontaneous transfer of gold nanoparticles coated with stimuli-responsive polymer brushes across oil-water interfaces has been implemented. The water-to-oil transfer of the gold nanoparticles is dictated by the ionic strength in water, while the nanoparticle oil-to-water transfer occurs only when the environmental temperature is reduced below 5 °C