A novel near-infrared antibacterial material, Er3+-Yb3+-Fe3+ tridoped TiO2 nanopowder, was synthesized and applied to kill Aeromonas hydrophia with a maximal bactericidal rate of 65% in 90 min under 980 nm laser irradiation. However, Fe3+-TiO2 or Er3+-Yb3+-TiO2 nanopowders obtained under the same conditions barely could kill Aeromonas hydrophia. The initial energy applied in the photocatalysis antibacterial process is supplied by the upconversion emission of Er3+ and Yb3+ and the codoping of Fe3+, which has intensified the light absorption intensity and enlarged the absorption range. The analyses of phase structure and the optical properties including XRD, UV−vis diffuse reflectance spectra, and upconversion photoluminescence spectra of Er3+-Yb3+-Fe3+ tridoped TiO2 nanopowder have been performed in detail to reveal the complex energy transfer and change mechanism. According to our experimental results, the mechanism has been demonstrated involving the upconversion emission, multistep excitation by means of intermediate energy level, capture and transfer electrons of Fe3+, and so on. The photocatalystic antibacterial function of Er3+-Yb3+-Fe3+-TiO2 under near-infrared instead of ultraviolet light is also reported. Because of the strong penetrability of near-infrared, this kind of material may be used in photodynamic therapy (PDT) to kill bacteria or tumors directly.

In this paper, it has been found that a small biomolecule adenine can greatly affect the photoluminescence properties and stability of water-soluble CdTe quantum dots. The interaction between CdTe QDs and adenine is characterized by TEM, fluorescence microscope, and photoluminescence (PL), IR, and UV−vis spectra. The influences of reflux time, pH value, ionic strength, storage time, the ratio of CdTe QDs to adenine on the PL intensity, and the stability of CdTe−adenine conjugates are investigated in detail. The PL intensity and stability of CdTe−adenine conjugate are largely enhanced compared to that of pure CdTe QDs. At the same time the fluorescence quantum yield of the CdTe−adenine conjugate reaches 23.04% in comparison with 20.27% of the parent CdTe QDs. The existence of coordinated bond and hydrogen bond between CdTe QDs and adenine is illuminated by IR analysis. These bonds together with the passivation of adenine on the surface of CdTe are possibly the main reasons for the stability of the conjugate. As a new stabilization agent, adenine has no effects on the properties of the biological system but can increase the stability and PL intensity of CdTe QDs, which will enlarge the application of QDs in biomedicine and other fields.

The flavonoids of grapefruit peel were obtained by microwave‐assisted extraction. Five constituents have been identified by liquid chromatography/mass spectrometry analysis such as hesperitin‐7‐O‐glucoside, isonaringin, naringin, 2′,5′‐dihydroxy‐3,4′,5,6,7‐pentamethoxyflavone and neoeriocitrin. The last two compounds are reported first in grapefruit peel. The effects of solvent, time, ratio of solvent to material (liquid/solid) and output power on the extraction were investigated. The results show that the better extraction conditions are: 80% (v/v) ethanol as extraction solvent; 3 min of extraction time, 25:1 (mL/g) as the ratio of liquid to solid; and 560 W of microwave output power. Microwave‐assisted extraction is more efficient for getting flavonoids from grapefruit peel than reflux and ultrasonic extraction methods. The yield of optimized microwave‐assisted extraction reached 5.81%. PRACTICAL APPLICATIONS Grapefruit is one of the delicious fruits with abundant nutrition, such as vitamin C, carbohydrate and a small quantity of some special compounds. It may have some beneficial effects on human health, with anti‐oxidant, anti‐inflammatory and anti‐cancer properties, or may act as agents of other mechanisms contributing to cardio‐protective action. The main use of grapefruit in food industries is to make fresh juice or citrus‐based drinks. The peels are often used to feed animals or are thrown away directly. Very large amounts of wastes are formed every year, because almost half of the grapefruit is composed of peels. It is reported that grapefruit peels contain a high concentrationof phenolic compounds. It is significant to find a feasible way to obtain these useful compounds from peel wastes to increase their value. In our work, microwave‐assisted extraction of flavonoids from grapefruit peel is established and discussed. The extraction yield is higher than that of using traditional extraction methods. So, the results of this paper are very helpful in utilizing and making great use of natural resources.