Polyphenol composition and antioxidant capacity from different extracts of Aster scaber.

Phenolic contents and antioxidant capacities from different solvent extracts (petroleum ether, ethyl acetate, methanol, butanol and water) of Aster scaber leaf were investigated. Antioxidant activity was evaluated by three different methods, namely DPPH radical scavenging activity, reducing power assay and phosphomolybdenum activity. A total of twenty-three polyphenolic compounds were identified and quantified from A. scaber leaf extracts, including hydroxybenzoic acids, hydroxycinnamic acids, flavonols and other groups of phenolic compounds. Ultra high performance liquid chromatography (UHPLC) analysis of the leaf extract revealed that myricetin (4850.45 µg/g) was the most dominant flavonols, compared to quercetin and kaempferol. Caffeic acid was the dominant phenolic compound in A. scaber leaf extracts, it constituted about 104.20 µg/g, followed by gentisic acid (84.50 µg/g), gallic acid (61.05 µg/g) and homogentisic acid (55.65 µg/g). The total phenolic and flavonoid content was the highest in ethyl acetate extract (322.43 and 6.51 mg/g). The decreasing order of antioxidant activity among the A. scaber leaf extracts assayed through all the three methods was found to be ethyl acetate > butanol > methanol > petroleum ether > water extract.

Series of new ß-cyclodextrin-cored starlike carriers for gene delivery.

The development of safe and effective ß-cyclodextrin (ß-CD)-cored cationic star gene carriers has attracted considerable attention. In this work, a series of star-shaped hemocompatible CD-PGPP, CD-PGAEPP, and CD-PGAPP vectors composed of ß-CD cores and piperazine (PP)-, N-(aminoethyl)piperazine (AEPP)-, or N-(3-aminopropyl)-2-pyrrolidinone (APP)-functionalized poly(glycidyl methacrylate) arms were successfully proposed and compared for highly efficient gene delivery. Such star carriers possess plentiful secondary amine, tertiary amine, and nonionic hydroxyl groups. CD-PGPP, CD-PGAEPP, and CD-PGAPP were effective in condensing plasmid DNA into nanoparticles, whose sizes were 100-200 nm and positive ζ potentials were 25-40 mV at nitrogen/phosphate (N/P) ratios of 10 and above. CD-PGPP, CD-PGAEPP, and CD-PGAPP showed significantly lower cytotoxicity than control poly(ethylenimine) (PEI; ∼25 kDa). At most N/P ratios, CD-PGAPP exhibited better gene transfection performance than CD-PGPP and CD-PGAEPP particularly in HepG2 cells. More importantly, in comparison with PEI, all of the CD-PGPP, CD-PGAEPP, and CD-PGAPP vectors did not cause undesirable hemolysis.

Bioreducible comb-shaped conjugates composed of secondary amine and hydroxyl group-containing backbones and disulfide-linked side chains with tertiary amine groups for facilitating gene delivery.

Comb-shaped polymeric vectors (SS-PGEADMs) consisting of ethanolamine/cystamine-functionalized poly(glycidyl methacrylate) (SS-PGEA-NH2) backbones and bioreducible poly((2-dimethyl amino)ethyl methacrylate) (PDMEAMA) side chains were prepared by a combination of the ring-opening reaction and atom transfer radical polymerization (ATRP). The SS-PGEA-NH2 backbones, which were prepared via the ring-opening reaction of the pendant epoxide groups of poly(glycidyl methacrylate) with the amine moieties of ethanolamine/cystamine, possess plentiful flanking secondary amine and hydroxyl groups and some flanking disulfide bond-containing cystamine derivatives. The primary amine groups of the cystamine derivatives were activated to produce bromoisobutylryl-terminated SS-PGEA (SS-PGEA-Br) as multifunctional initiators for subsequent ATRP of DMAEMA. The resultant disulfide-linked short PDMEAMA side chains possess pendant tertiary amine groups and are biocleavable. Such SS-PGEADMs can effectively condense pDNA. The cytotoxicity of SS-PGEADMs could be controlled by adjusting the grafting amount of PDMEAMA side chains. In comparison with the pristine SS-PGEA-NH2, the moderate introduction of PDMEAMA side chains can further enhance the gene transfection efficiency in different cell lines. The present approach to well-defined comb-shaped vectors with multifunctional groups could provide a versatile means for tailoring the functional structures of advanced gene/drug vectors.

High-power millimeter-wave rotary joint.

The rotary joint is a useful microwave component that connects a fixed part to a rotatable part. This study systematically analyzes the effect of the discontinuity on the interface of a rotary joint for several waveguide modes. Simulation results indicate that the transmission of the TE(01) mode is independent of the geometry of the joint, and thus is ideal for such application. A rotary joint consisting of two identical TE(01) mode converters, clasped each other by a bearing, is designed, fabricated, and tested. Back-to-back transmission measurements exhibit an excellent agreement to the results of computer simulations. The measured optimum transmission is 97% with a 3 dB bandwidth of 8.5 GHz, centered at 35.0 GHz. The cold measurement shows that the results are independent of the angle of rotation. In addition, a high-power experiment is conducted. The just developed rotary joint can operate up to a peak input power of 210 W with a duty of 18%. The working principle, although demonstrated in the millimeter-wave region, can be applied up to the terahertz region where the joint gap is generally critical except for the operating TE(01) mode.