Facile synthesis of high-molecular-weight acid-labile polypeptides using urethane derivatives

Polypeptides have received noticeable attention in the biomedical field due to their structural versatility and biomimetic properties. Particularly, polypeptides that are responsive to biological stimuli, such as mildly acidic extracellular and intracellular conditions, have great potential as delivery carriers for therapeutics. However, synthesis of high-molecular-weight acid-labile peptides is often daunting due to highly restrictive polymerization conditions and limitations in preserving acid-degradable functional groups. For instance, the popular N-carboxyanhydride (NCA) ring-opening polymerization (ROP) is efficient, but acid-labile NCA monomers are difficult to synthesize and store. In this study, acid-labile polypeptides with high molecular weights were synthesized under mild, permissive conditions using carboxylated urethane derivative monomers which are stable for ease of handling. The polymerization was successful in various organic solvents at room temperature, and did not require additional energy or initiation to drive the formation of NCA intermediates. The polymerization was also rapid enough to be independent of inert atmosphere. The strategy explored here to synthesize high-molecular-weight acid-labile polypeptides offers significant advantages including facile synthesis of acid-labile urethane derivative monomers that are stable, even in contact with moisture, and fast polymerization under easily achievable conditions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 280–286     

Advances towards Cell-Specific Gene Transfection: A Small-Molecule Approach Allows Order-of-Magnitude Selectivity

A transfection vector that can home in on tumors is reported. Whereas previous vectors that allow moderately cell selective gene transfection used larger systems, this small-molecule approach paved the way for precise structure-activity relationship optimization. For this, biotin, which mediates cell selectivity, was combined with the potent DNA-binding motif tetralysine-guanidinocarbonypyrrol via a hydrophilic linker, thus enabling SAR-based optimization. The new vector mediated biotin receptor (BR)-selective transfection of cell lines with different BR expression levels. Computer-based analyses of microscopy images revealed a preference of one order of magnitude for the BR-positive cell lines over the BR-negative controls.     

Structural and electronic properties of amorphous bismuth calcium borate from first-principle calculations

Structural Chemistry - We investigatethe electronic and structural properties of two new amorphous materials, Bi6Ca2O28B12 and Bi6Ca2 O28B11:Tm, using density functional theory with a short-range...     

Umbelliferone Decorated Water-soluble Zinc(II) Phthalocyanines – In Vitro Phototoxic Antimicrobial Anti-cancer Agents

In this contribution we report on the synthesis, characterization and application of water-soluble zinc(II) phthalocyanines, which are decorated with four or eight umbelliferone moieties for photodynamic therapy (PDT). These compounds are linked peripherally to zinc(II) phthalocyanine by a triethylene glycol linker attached to pyridines, leading to cationic pyridinium units, able to increase the water solubility of the system. Beside their photophysical properties they were analyzed concerning their cellular distribution in human hepatocyte carcinoma (HepG2) cells as well as their phototoxicity towards HepG2 cells, Gram-positive (S. aureus strain 3150/12 and B. subtilis strain DB104) and Gram-negative bacteria (E. coli strain UTI89 and E. coli strain Nissle 1917). At low light doses and concentrations, they exhibit superb antimicrobial activity against Gram-positive bacteria as well as anti-tumor activity against HepG2. They are even capable to inactivate Gram-negative bacteria, whereas the dark toxicity remains low. These unique water-soluble compounds can be regarded as all-in-one type photosensitizers with broad applications ranges in the future.     

Competitive and noncompetitive phage immunoassays for the determination of benzothiostrobin

Twenty-three phage-displayed peptides that specifically bind to an anti-benzothiostrobin monoclonal antibody (mAb) in the absence or presence of benzothiostrobin were isolated from a cyclic 8-residue peptide phage library. Competitive and noncompetitive phage enzyme linked immunosorbent assays (ELISAs) for benzothiostrobin were developed by using a clone C3-3 specific to the benzothiostrobin-free mAb and a clone N6-18 specific to the benzothiostrobin immunocomplex, respectively. Under the optimal conditions, the half maximal inhibition concentration (IC₅₀) of the competitive phage ELISA and the concentration of analyte producing 50% saturation of the signal (SC₅₀) of the noncompetitive phage ELISA for benzothiostrobin were 0.94 and 2.27 ng mL⁻¹, respectively. The noncompetitive phage ELISA showed higher selectivity compared to the competitive. Recoveries of the competitive and the noncompetitive phage ELISAs for benzothiostrobin in cucumber, tomato, pear and rice samples were 67.6–119.6% and 70.4–125.0%, respectively. The amounts of benzothiostrobin in the containing incurred residues samples detected by the two types of phage ELISAs were significantly correlated with that detected by high-performance liquid chromatography (HPLC).     

Electron Spectroscopy - A Potentially Useful Tool for Environmental Studies

The technique of electron spectroscopy (ESCA) is reviewed. Those aspects are discussed which seem to be of greatest potential interest to workers in environmental studies. Basic theory of the photoelectron ejection process is considered along with the Auger effect. Factors affecting the calculation of electron binding energies are discussed. Instrumentation utilizing both magnetic and electrostatic monochromators is discussed in some detail.

The nature of ESCA data is considered, along with an extensive tabulation of chemical shifts observed for 15 elements. Application of ESCA to surface studies is reviewed, using examples like effect of layers of material on electron intensities, investigations of zeolites and some elementary catalysis studies. A review of the quantitative aspects of ESCA considers the determination of arsenic in soils and the measurement of mixed oxide ratios.     

Lactose as a “Trojan Horse” for Quantum Dot Cell Transport

A series of glycan‐coated quantum dots were prepared to probe the effect of glycan presentation in intracellular localization in HeLa and SV40 epithelial cells. We show that glycan density mostly impacts on cell toxicity, whereas glycan type affects the cell uptake and intracellular localization. Moreover, we show that lactose can act as a “Trojan horse” on bi‐functionalized QDs to help intracellular delivery of other non‐internalizable glycan moieties and largely avoid the endosomal/lysosomal degradative pathway.