Bifunctional Submicron Colloidosomes Coassembled from Fluorescent and Superparamagnetic Nanoparticles

Colloidosomes are microcapsules consisting of nanoparticle shells. These microcarriers can be self‐assembled from a wide range of colloidal particles with selective chemical, physical, and morphological properties and show promise for application in the field of theranostic nanomedicine. Previous studies have mainly focused on fairly large colloidosomes (>1 μm) based on a single kind of particle; however, the intrinsic building‐block nature of this microcarrier has not been exploited so far for the introduction of tailored functionality at the nanoscale. We report a synthetic route based on interfacial shear rheology studies that allows the simultaneous incorporation of different nanoparticles with distinct physical properties, that is, superparamagnetic iron oxide and fluorescent silica nanoparticles, in a single submicron colloidosome. These tailor‐made microcapsules can potentially be used in various biomedical applications, including magnetic hyperthermia, magnetic particle imaging, drug targeting, and bioimaging.     

Porcine gastric mucin (PGM) at the water/poly(dimethylsiloxane) (PDMS) interface: influence of pH and ionic strength on its conformation, adsorption, and aqueous lubrication properties

We have investigated the influence of pH and ionic strength on the conformation of porcine gastric mucin (PGM) in bulk aqueous solution, its adsorption behavior onto poly(dimethylsiloxane) (PDMS) surfaces, and its lubricating behavior upon the self-mated sliding contact of a PDMS tribopair by means of circular dichroism (CD) spectroscopy, optical waveguide lightmode spectroscopy (OWLS), and pin-on-disk tribometry, respectively. In a low-concentration regime (1 mg/mL), where the formation of a mucus-gel is generally excluded, PGM is still observed to exhibit effective aqueous lubricating properties under specific conditions of acidic pH and low ionic strength. This behavior was closely correlated with specific conformations in the bulk solution as well as specific adsorption behavior at the water/PDMS interface. The lubrication mechanism of the self-mated sliding contact of PDMS by means of surface modification with PGM is discussed in terms of isoviscous-elastic/soft-elastohydrodynamic lubrication (soft-EHL).     

Change of zeta potential of biocompatible colloidal oxide particles upon adsorption of bovine serum albumin and lysozyme

The amounts of negatively charged bovine serum albumin and positively charged lysozyme adsorbed on alumina, silica, titania, and zirconia particles (diameters 73 to 271 nm) in aqueous suspensions are measured. The adsorbed proteins change the zeta potentials and the isoelectric points (IEP) of the oxide particles. The added to adsorbed protein ratios at pH 7.5 are compared with the protein treated particle zeta potentials. It is found that the amounts of adsorbed proteins on the alumina, silica, and titania (but not on the zirconia) particle surfaces are highly correlated with the zeta potential. For the slightly less hydrophilic zirconia particles high amounts of protein adsorption are observed even under repulsive electrostatic conditions. One reason could be that the hydrophobic effect plays a more important role for zirconia than electrostatic interaction.     

Syntheses of [F]5-fluoro-3-nitro-l-tyrosine

The detection of 3-nitro-l-tyrosine has been used as a biomarker of “reactive nitrogen species” in biological matrices and has been an ongoing challenge in analytical chemistry. In this work, fluorine-18 labelled 5-fluoro-3-nitro-l-tyrosine (FNT) was synthesized as a potential radiotracer to probe the biological fate of 3-nitro-l-tyrosine. The synthesis of []FNT was carried out by reaction of []3-fluoro-l-tyrosine with NaNO₃ in TFA solvent for 5 min at 4 °C. The radiochemical yield (RCY) of []FNT was 96±2% and []3-fluoro-l-tyrosine, was 29±1%, relative to []3-fluoro-l-tyrosine and []F₂, respectively. The syntheses of []FNT were also accomplished by direct fluorination of 3-nitro-l-tyrosine with []F₂ and by nitration of l-tyrosine with NaNO₃, followed by fluorination, in TFA (4 °C) or anhydrous HF (−65 °C) solvent. The latter two synthetic routes produced []FNT in 13.5±1.5% RCY, within 1 h. Products were characterized by use of , and NMR spectroscopy and mass spectrometry.     

Highly efficient silica gel-supported 1,2-diaminocyclohexane-Pd catalyst for Suzuki-Miyaura and Sonogashira coupling reactions

A palladium (Pd) catalyst was prepared by immobilization of a 1,2-diaminocyclohexane based Pd-complex onto amorphous silica gel and its applications as a heterogeneous catalyst for Suzuki-Miyaura and Sonogashira coupling reactions are described. The catalyst was highly efficient, reusable and air-stable. An erratum to this article is available at .     

Adsorption and reduction of glutathione disulfide on α-Al2O3 nanoparticles: experiments and modeling

Glutathione disulfide (GSSG; γ-GluCysGly disulfide) was used as a physiologically relevant model molecule to investigate the fundamental adsorption mechanisms of polypeptides onto α-alumina nanoparticles. Its adsorption/desorption behavior was studied by enzymatic quantification of the bound GSSG combined with zeta potential measurements of the particles. The adsorption of GSSG to alumina nanoparticles was rapid, was prevented by alkaline pH, was reversed by increasing ionic strength, and followed a nearly ideal Langmuir isotherm with a standard Gibbs adsorption energy of -34.7 kJ/mol. Molecular dynamics simulations suggest that only one of the two glutathionyl moieties contained in GSSG binds stably to the nanoparticle surface. This was confirmed experimentally by the release of GSH from the bound GSSG upon reducing its disulfide bond with dithiothreitol. Our data indicate that electrostatic interactions via the carboxylate groups of one of the two glutathionyl moieties of GSSG are predominantly responsible for the binding of GSSG to the alumina surface. The results and conclusions presented here can provide a base for further experimental and modeling studies on the interactions of biomolecules with ceramic materials.     

Gamma Radiation-Induced Graft Copolymerization of Styrene Onto Polyethyleneterephthalate Films: Application in Fuel Cell Technology as a Proton Exchange Membrane

Polyethyleneterephthalate (PET) based proton exchange membrane for using in fuel cells was successfully prepared by gamma radiation-induced graft copolymerization of styrene monomer onto PET film and the consequent selective sulfonation of the grafting chain in the film state using chlorosulfonic acid (ClSO₃H). The effects of grafting conditions (e.g., monomer concentration, irradiation dose) on the degree of grafting and sulfonation condition (e.g., optimum concentration of ClSO₃H) on the degree of sulfonation were studied. The degree of grafting, the degree of sulfonation and the physico-chemical properties (such as, water uptake, mechanical strength, thermal durability, hydrolytic stability, oxidative stability) of the gamma radiation-induced grafted membrane were found to be better when compared to those of the UV-radiation grafted membrane. The membrane shows higher ion exchange capacity (0.9 mmol g^?1) and higher proton conductivity (0.075 S cm^?1), similar to those of Nafion membrane.     

The role of ligands on protein retention in adsorption chromatography: A surface energetics approach

Protein adsorption onto hydrophobic chromatographic supports has been investigated using a colloid theory surface energetics approach. The surface properties of commercially available chromatographic beads, Toyopearl Phenyl 650‐C, and Toyopearl Butyl 650‐C, have been experimentally determined by contact angle and zeta potential measurements. The adsorption characteristics of these beads, which bear the same backbone matrix but harbor different ligands, have been studied toward selected model proteins, in the hydrated as well as dehydrated state. There were two prominent groups of proteins observed with respect to the chromatographic supports presented in this work: loosely retained proteins, which were expected to have lower average interaction energies, and the strongly retained proteins, which were expected to have higher average interaction energies. Results were also compared and contrasted with calculations derived from adsorbent surface energies determined by inverse liquid chromatography. These results showed a good qualitative agreement, and the interaction energy minima obtained from these extended Derjaguin, Landau, Verwey and Overbeek calculations were shown to correlate well with the experimentally determined adsorption behavior of each protein.