A point-of-care testing platform for on-site identification of genetically modified crops.

Genetically modified (GM) food is still highly controversial nowadays. Due to the disparate policies and attitudes worldwide, demands for a rapid, cost-effective and user-friendly GM crop identification method are increasingly significant for import administration, market supervision, etc. However, as the most-recognized methods, nucleic acid-based identification approaches require bulky instruments, long turn-around times and trained personnel, which are only suitable in laboratories. To fulfil the urgent needs of on-site testing, we develop a point-of-care testing platform that is able to identify 12 types of GM crops in less than 40 minutes without using laboratory settings. Our system integrates sample pre-treatment modules in a microfluidic chip, performs DNA amplification via a battery-powered portable kit, and presents results via eye-recognized colorimetric change. A paraffin-based reflow method and a slip plate-based fluid switch are developed to encapsulate and release amplification primers in individual microwells on demand, thus enabling identification of varied targets simultaneously. Our system offers an efficient, affordable and convenient tool for GM crop identification, thus it will not only benefit customs and market administration bureaus, but also satisfy demands of numerous consumers.

Research on the application of Thelephora ganbajun exopolysaccharides in antioxidant, anti-inflammatory and spot-fading cosmetics.

Thelephora ganbajun exopolysaccharides (TGEP) with a "coral-like" branched chain structure (main chain diameter âˆ¼ 80 nm) were prepared by liquid fermentation and fractionated by ion-exchange chromatography. The main fraction (TGEP-2) with the highest in vitro antioxidant capacity was composed of Glc, Man, Gal, GalA, GlcA, Ara, Rha, GlcN, Fuc and Rib in a molar ratio of 465.43:420.43:219.14:188.43:37:35.14:31.43:19.43:11.14:1, with a molecular weight of 1.879 × 104 Da. The sequence of monosaccharide residue release revealed that Gal, Glc and Ara residues were more distributed in the side-branch chains and at their ends, whereas Man and GalA residues were more distributed in the main chains. TGEP-2 contained linear residues (mainly →4)-Glcp-(1 â†’ and →4)-Manp-(1→), branch residues (→3,6)-Glcp-(1→, →4,6)-Glcp-(1 â†’ and →3,6)-Galp-(1→) and terminal residues (Galp-(1→, Manp-(1 â†’ and Glcp-(1→). TGEP-2 consisted of α- and ß-glycosidically linked pyranosides, with a triple helical conformation and many long branches. Zebrafish oxidative stress and inflammation models found that TGEP-2 had antioxidant and anti-inflammatory activities. The zebrafish skin black spot assay showed that TGEP-2 inhibited melanin formation. Therefore, extracellular polysaccharides of T. ganbajun have strong application potential in anti-oxidant, anti-inflammatory and skin spot-fading functions cosmetics.

Preparation and structure-activity relationship of highly active black garlic polysaccharides.

The aim of this study was to establish a method to improve the biological activity of polysaccharides. Three acid-treated polysaccharides (BGPS-2, BGPS-3 and BGPS-4) were obtained by treating black garlic polysaccharides (BGPS-1) with sulfuric acid at different intensities. The structure was characterized using the sulfuric acid-carbazole assay, IC, HPSEC-MALLS and FT-IR. The biological functions were evaluated using antioxidant and melanin biosynthesis inhibition assays. Compared with BGPS-1, the molecular weight of acid-treated polysaccharides significantly decreased, and the uronic acid content significantly increased. Antioxidant capacity negatively correlated with molecular weight, whereas melanin inhibition activity positively correlated with uronic acid content. BGPS-4 had the highest antioxidant capacity and the lowest molecular weight (1.25 × 103 Da), 79.41 % lower than that of BGPS-1. BGPS-3 was the strongest inhibitor of melanin formation and had the highest uronic acid content (50.73 %), 238.2 % higher than that of BGPS-1. Molecular weight and uronic acid content were the main structural characteristics that affected the antioxidant and melanin biosynthesis inhibition activities, respectively. BGPS-1, BGPS-2, BGPS-3, and BGPS-4 all had ß-linked pyranose, multi-branched, and non-triple helical spiral structures. Therefore, the acid hydrolysis method markedly modified the structural characteristics of black garlic polysaccharides, and increased their antioxidant capacity and melanin biosynthesis inhibition activity.