Study on metabolic variation in whole grains of four proso millet varieties reveals metabolites important for antioxidant properties and quality traits.

Proso millet (Panicum miliaceum L.) is a minor cereal crop that has been considered as health-promoting food. Little information is available however, about the metabolic basis of nutritional values of proso millet. In this study, using a UHPLC-QqQ-MS/MS-based metabolomics approach, we compared the metabolomes of whole grains from four proso millet varieties with different bran color, namely White, Black, Gray and Red. In total, 672 metabolites were identified, among which 121, 116 and 148 metabolites showed differential accumulation in the three comparison groups (White vs. Black/Gray/Red). The results demonstrated the main pathways that were differentially activated included: tryptophan metabolism, flavonoid, isoflavonoid, flavone, and flavonol biosynthesis. Considerable difference between varieties was observed in accumulation of phenolic acids and flavonoids, which might lead to difference in antioxidant activities. The results of this study provide useful information for further investigation of proso millet food chemistry and for sufficient utilization of this special crop.

Ultralong Room-Temperature Phosphorescence from Supramolecular Behavior via Intermolecular Electronic Coupling in Pure Organic Crystals.

Ultralong room-temperature phosphorescence (RTP) of organic materials is extremely attractive for its tremendous potential use. However, the design of organic materials with ultralong and efficient RTP is very challenging due to the lack of general design principles. A new design principle for organic materials with ultralong room-temperature phosphorescence based on π-π-dominated supramolecular aggregates in crystal is proposed, and strong intermolecular electronic coupling with specific molecular alignment is identified to be responsible for supramolecular behavior in persistent emission. Small substituents in molecular structure favor the formation of supramolecular aggregates in the crystal, thus facilitating the generation of ultralong RTP under ambient conditions. Our results also reveal that the introduction of heavy atoms into supramolecular aggregates as a general rule can be used to achieve efficient persistent phosphorescence.

Fabrication of Stable and Luminescent Copper Nanocluster-Based AIE Particles and Their Application in ß-Galactosidase Activity Assay.

Thiolated copper nanoclusters (CuNCs) with aggregation-induced emission characteristic are becoming a novel luminescent material, but it is still a challenging task to retain its bright luminescence in a neutral solution. In this work, we report a new copper nanocluster with aggregation-induced emission (AIE) enhancement property using a hydrophobic molecule as the protecting ligand, and brightly luminescent AIE particles of copper nanocluster were prepared via hydrophobic interaction. These CuNCs AIE particles possess uniform rod-like shapes, with sizes in hundreds of nanometer, and an intense luminescence; more importantly, its luminescence remains stable in neutral and alkaline solutions. It is found that 4-nitrophenol is able to effectively quench the luminescence of CuNC AIE particles through strong hydrophobic interaction and electron transfer between them. This strong quenching effect was adopted to develop a luminescent assay for ß-galactosidase at physiological condition. This work presents a demonstration of preparing CuNC AIE particles with bright luminescence at neutral condition and gives an example of the use of AIE particles in monitoring the enzyme activity.