Preparation and medical application of magnetic beads conjugated with bioactive molecules

Ferrite nanobeads were synthesized from an aqueous solution utilizing Fe²⁺ to Fe³⁺ oxidation for use as magnetic carriers in bioscreening, bio-molecular recognition and anti-cancer diagnosis and therapy. The beads had a crystal structure that was intermediate between Fe₃O₄ and γ-Fe₂O₃. Functional biomolecules were strongly conjugated onto the surfaces of the ferrite beads via COOH and SH groups. The addition of ferrite seed crystals (3-8 nm in size) together with a disaccharide enabled the synthesis of monodisperse, spherical ferrite beads with average diameters (d¯) between 50 and 150 nm and relative deviation Δd/d¯=9-16%. Hollow ferrite nano-spheres (d¯=150-450 nm, Δd/d¯≈10%) were prepared using silica spheres as templates, which were dissolved in NaOH solution. Ferrite beads 40 nm in size were encapsulated in polymer spheres of styrene and polymerized glycidyl methacrylate (poly-GMA), 184±9 nm in diameter. They were used for high throughput bioscreening system for affinity purification of target proteins which make specific bindings to anti-cancer drugs, porphyrins, environment hormones, etc.     

Bifunctional Heterogeneous Catalysis of Silica–Alumina‐Supported Tertiary Amines with Controlled Acid–Base Interactions for Efficient 1,4‐Addition Reactions

We report the first tunable bifunctional surface of silica–alumina‐supported tertiary amines (SA–NEt₂) active for catalytic 1,4‐addition reactions of nitroalkanes and thiols to electron‐deficient alkenes. The 1,4‐addition reaction of nitroalkanes to electron‐deficient alkenes is one of the most useful carbon–carbon bond‐forming reactions and applicable toward a wide range of organic syntheses. The reaction between nitroethane and methyl vinyl ketone scarcely proceeded with either SA or homogeneous amines, and a mixture of SA and amines showed very low catalytic activity. In addition, undesirable side reactions occurred in the case of a strong base like sodium ethoxide employed as a catalytic reagent. Only the present SA‐supported amine (SA–NEt₂) catalyst enabled selective formation of a double‐alkylated product without promotions of side reactions such as an intramolecular cyclization reaction. The heterogeneous SA–NEt₂ catalyst was easily recovered from the reaction mixture by simple filtration and reusable with retention of its catalytic activity and selectivity. Furthermore, the SA–NEt₂ catalyst system was applicable to the addition reaction of other nitroalkanes and thiols to various electron‐deficient alkenes. The solid‐state magic‐angle spinning (MAS) NMR spectroscopic analyses, including variable‐contact‐time ¹³C cross‐polarization (CP)/MAS NMR spectroscopy, revealed that acid–base interactions between surface acid sites and immobilized amines can be controlled by pretreatment of SA at different temperatures. The catalytic activities for these addition reactions were strongly affected by the surface acid–base interactions.     

Catalyst-transfer polycondensation for the synthesis of poly(p-phenylene) with controlled molecular weight and low polydispersity

To examine whether catalyst-transfer polycondensation, which affords well-defined polythiophenes, has generality for other conjugated polymers, the synthesis of poly(p-phenylene) (PPP) with various Ni catalysts was investigated. Monomer 1, 1-bromo-4-chloromagnesio-2,5-dihexyloxybenzene, was polymerized with Ni(dppe)Cl2 in the presence of equimolar LiCl to give PPP with a narrow polydispersity. The number-average molecular weight (Mn) of PPP thus obtained increased in proportion to the conversion of 1, indicating that this polymerization also proceeded in a chain-growth polymerization manner. Furthermore, the molecular weight of PPP was controlled by the feed ratio of 1 to the Ni catalyst up to at least Mn = 30000.     

Cytotoxicity and physico-chemical evaluation of acetylated and pegylated cellulose nanocrystals

The high hydrophilicity of cellulose nanocrystals (CNC) may result in poor dispersion in some matrices and solvents. So in this work, two different methodologies were used to reduce the hydrophilicity of CNC. In the first methodology, CNC were acetylated (CNC-Ac) in a mixture of acetic and hydrochloric acid, and in the second methodology, polyethylene glycol (PEG) was adsorbed onto CNC surface (CNC-PEG) under stirring in aqueous solution. CNC obtained by both methods were characterized by transmission electron microscopy (TEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential, and thermogravimetric analysis (TGA). Images of TEM showed that the intrinsic morphology of cellulose was preserved after both treatments. FTIR confirmed acetylation reaction by the presence of a new band at 1732 cm^?1 (acetate groups) and the consumption of OH groups. XRD showed a reduction in the crystallinity index for both applied methodologies. DLS showed reduced stability in water for CNC-Ac and CNC-PEG. Values of zeta potential changed after acetylation, from ??45 mV (CNC) to ??1 mV (CNC-Ac), and after adsorption of PEG, to ??26.7 mV (CNC-PEG). TGA showed a reduction in the thermal stability after both treatments and a change in the main degradation behavior for CNC-PEG. MTT assays showed that both proposed functionalizations induce cell proliferation, being even more evident for acetylation because, in addition to viability increase with time, it increased with the sample concentration.     

The Active Phase of Nickel/Ordered Ce(2) Zr(2) O(x) Catalysts with a Discontinuity (x=7-8) in Methane Steam Reforming

Breaking news: A unique discontinuous property and an active phase of Ni/ordered Ce(2) Zr(2) O(x) (x=7-8) solid-solution catalysts were observed during methane steam reforming. The catalytic performance of Ni/Ce(2) Zr(2) O(x) strongly depended on the phase and oxygen content of the Ce(2) Zr(2) O(x) support.     

Interfacial modification of organic photovoltaic devices by molecular self-organization

This feature article focuses on the relationship between the interfacial structures constructed by molecular self-organization and the properties of organic photovoltaic devices. The use of self-assembled monolayers (SAMs) is reviewed for metal and metal oxide/organic interfaces, while surface-segregated monolayers (SSMs) are introduced as a new method for the modification of organic/organic interfaces. Research up to now has clearly demonstrated the effectiveness of the control of energy levels and other properties at the interfaces to enhance photovoltaic performance. The possibility of more precise control of the interfacial structures is also discussed.     

Size-exclusion SPR sensor chip: application to detection of aggregation and disaggregation of biological particles

We propose a novel surface plasmon resonance (SPR) sensor chip with a microfabricated slit array. The microslit excludes micrometre-size objects larger than its slit size from the SPR sensing area, so that it functions as an in situ filter. We demonstrated the sensing of microparticles of different diameters using the chip, and the results show a successful size-exclusion effect. As a demonstration of the biological application, we performed the detection of aggregation and disaggregation of biological particles using sugar-chain-immobilized gold nanoparticles as a test sample.