Activities of polysaccharide fractions from corn silk: Hemostatic, immune, and anti-lung cancer potentials.

Corn silk is the stigma and style of corn and is rich in polysaccharides. Despite the extensive research on its polysaccharides, the hemostatic characteristics of effective parts and the related activities remain insufficiently explored. Corn silk polysaccharide (CSP) was extracted with hot water and purified using a diethylaminoethyl cellulose membrane. Then, it was separated with sephadex G-150 to obtain five fractions. These fractions were investigated for their potential in hemostasis, antioxidant, immune response, and anti-lung cancer activities. CSP-2, CSP-3, and CSP-4 significantly affected the coagulation indicators activated partial thromboplastin time (APTT) and thrombin time (TT) at 125-500 µg/mL. Corn silk flavonoids and saponins at 32.25 µg/mL significantly prolonged APTT, TT, and prothrombin time (PT). CSP-2, with potent antioxidant ability, approaches Vitamin C. At 25 µg/mL, CSPs nearly reached the phagocytosis of neutral red of lipopolysaccharides. The five fractions promoted the proliferation of RAW264.7 cells at 25-800 µg/mL and stimulated NO secretion at 25-100 µg/mL. CSP-2 also showed an 86 % inhibition rate effect on A549 at 200 µg/mL. These results indicate that CSP not only has hemostatic effects but also has immune and anti-lung cancer activities. Thus, it is a potential candidate compound with immune activity for managing bleeding in cancer.

Controlled growth of single-crystalline erbium chloride silicate with long-lived fluorescence.

Single-crystalline erbium chloride silicates have attracted extensive attention due to their high gain compatibility and silicon compatible properties. Long-lived near-infrared fluorescence is critical for reducing a pump density threshold when erbium containing materials are used as active devices. Here we developed a single-source chemical vapor deposition (CVD) method to grow high-quality single-crystalline erbium chloride silicate nanostructures. The growth mechanism is found composing of two steps, where silicon source comes from the minor evaporation of silicon substrate. The prepared single-crystalline erbium chloride silicate nanowires own diameter of about 200 nm with few lattice defects, and the fluorescence lifetime reaches up to 7.4 ms. A nanoscale thermometer based on their visible band fluorescence is realized.

Erbium chloride silicate-based vertical cavity surface-emitting laser at the near-infrared communication band.

Silicon-based integrated optoelectronics has become a hotspot in the field of computers and information processing systems. An integrated coherent light source on-chip with a small footprint and high efficiency is one of the most important unresolved devices. Here, we realize a silicon-based vertical cavity surface-emitting laser in the near-infrared communication band by making efforts in both controlled preparation of high-gain erbium silicate materials and novel design of high optical feedback microcavity. Single-crystal erbium/ytterbium silicate microplates with erbium concentration as high as 5 × 1021 cm-3 are controlled prepared by a chemical vapor deposition method. They can produce strong luminescence with quite a long lifetime (2.3 ms) at the wavelength of 1.5 µm. By embedding the erbium silicate microplates between two dielectric Bragg reflectors, we construct a vertical cavity surface-emitting laser at 1.5 µm, with a lasing threshold as low as 20 µJ/cm2 and Q factor of nearly 2000. Our study provides a new pathway to achieve a sub-micrometer coherent light source for optical communication.

Cell membranes targeted unimolecular prodrug for programmatic photodynamic-chemo therapy.

Photodynamic therapy (PDT) has emerged as one of the most up-and-coming non-invasive therapeutic modalities for cancer therapy in rencent years. However, its therapeutic effect was still hampered by the short life span, limited diffusion distance and ineluctable depletion of singlet oxygen (1O2), as well as the hypoxic microenvironment in the tumor tissue. Such problems have limited the application of PDT and appropriate solutions are highly demand. Methods: Herein, a programmatic treatment strategy is proposed for the development of a smart molecular prodrug (D-bpy), which comprise a two-photon photosensitizer and a hypoxia-activated chemotherapeutic prodrug. A rhodamine dye was designed to connect them and track the drug release by the fluorescent signal generated through azo bond cleavage. Results: The prodrug (D-bpy) can stay on the cell membrane and enrich at the tumor site. Upon light irradiation, the therapeutic effect was enhanced by a stepwise treatment: (i) direct generation of 1O2 on the cell membrane induced membrane destruction and promoted the D-bpy uptake; (ii) deep tumor hypoxia caused by two-photon PDT process further triggered the activation of the chemotherapy prodrug. Both in vitro and in vivo experiments, D-bpy have exhabited excellent tumor treatment effect. Conclusion: The innovative programmatic treatment strategy provides new strategy for the design of follow-up anticancer drugs.

Near-Unity Polarization of Valley-Dependent Second-Harmonic Generation in Stacked TMDC Layers and Heterostructures at Room Temperature.

With unique valley-dependent optical and optoelectronic properties, 2D transition metal dichalcogenides (2D TMDCs) are promising materials for valleytronics. Second-harmonic generation (SHG) in 2D TMDCs monolayers has shown valley-dependent optical selection rules. However, SHG in monolayer TMDCs is generally weak; it is important to obtain materials with both strong SHG signals and a large degree of polarization. In the work, a variety of inversion-symmetry-breaking (3R-like phase) TMDCs (WSe2 , WS2 , MoS2 ) atomic layers, spiral structures, and heterostructures are prepared, and their SHG polarization is studied. Through circular-polarization-resolved SHG experiments, it is demonstrated that the SHG intensity is enhanced in thicker samples by breaking inversion symmetry while maintaining the degree of polarization close to unity at room temperature. By studying TMDCs with different twist angles and the spiral structures, it is found that there is no significant effect of multilayer interlayer interaction on valley-dependent SHG. The realization of strong SHG with high degree of polarization may pave the way toward a new platform for nonlinear optical valleytronics devices based on 2D semiconductors.

Wavelength-Tunable Interlayer Exciton Emission at the Near-Infrared Region in van der Waals Semiconductor Heterostructures.

The wavelength-tunable interlayer exciton (IE) from layered semiconductor materials has not been achieved. van der Waals heterobilayers constructed using single-layer transition metal dichalcogenides can produce continuously changed interlayer band gaps, which is a feasible approach to achieve tunable IEs. In this work, we design a series of van der Waals heterostructures composed of a WSe2 layer with a fixed band gap and another WS2(1-x)Se2x alloy layer with continuously changed band gaps. The existence of IEs and tunable interlayer band gaps in these heterobilayers is verified by steady-state photoluminescence experiments. By tuning the composition of the WS2(1-x)Se2x alloy layers, we realized a very wide tunable band gap range of 1.97-1.40 eV with a wavelength-tunable IE emission range of 1.52-1.40 eV from the heterobilayers. The time-resolved photoluminescence experiments show the IE emission lifetimes over nanoseconds.

Large-Scale Growth of Ultrathin Low-Dimensional Perovskite Nanosheets for High-Detectivity Photodetectors.

Low-dimensional organic-inorganic hybrid perovskites have demonstrated to be promising semiconductor materials due to their unique optoelectronic properties, however, the controllable growth of high-quality ultrathin 2D perovskites with large lateral dimension still faces great challenges. Herein, we report the controllable growth of large-scale ultrathin 2D (C6H5(CH2)3NH3)3Pb2I7 ((PPA)3Pb2I7) perovskite nanosheets (NSs) using a facile antisolvent-assisted crystallization approach under mild condition. As a result, the well-defined regular-shaped (PPA)3Pb2I7 NSs, with the largest lateral size over 100 µm, have been successfully synthesized, which is more than several ten times larger than that of other 2D perovskite NSs previously reported. Moreover, the thickness of the achieved 2D perovskite NSs can be well-tuned by altering the concentration of the precursor solution, with the smallest thickness down to ∼4.7 nm. More importantly, the photodetectors based on the high-quality (PPA)3Pb2I7 perovskites exhibit fascinating performance, including an extremely low dark current (∼1.5 pA), fast response/recovery rate (∼850/780 µs), and high detectivity (∼1.2 × 1010 Jones). This work provides a simple and promising strategy to controllably grow large-scale and ultrathin 2D perovskite NSs for low-cost and high-performance optoelectronic devices.

Microwave-assisted extraction releases the antioxidant polysaccharides from seabuckthorn (Hippophae rhamnoides L.) berries.

Seabuckthorn berries are rich in various bioactive components and used as a traditional medicine for a long time. Until now, little information is available for the extraction of polysaccharides from seabuckthorn berries (PSB) by linking antioxidant activity and microwave power. In this study, microwave-assisted extraction, characterization, in vitro and in vivo antioxidant activities of PSB were explored. The maximum PSB extraction yield of 0.264±0.005% was obtained under the optimal conditions as follows: microwave power 600W, extraction time 6min, liquid to material ratio 10: 1mL/g, and extraction temperature 85°C. Meanwhile, effects of microwave power on antioxidant activity of PSB was investigated and found that microwave at power of 600W can facilitate the release of antioxidant PSB in a high yield. The main monosaccharides of PSB were Rha, Man, Glu, and Gal at a molar ratio of 1.00: 6.89: 1.62: 13.52, UV and FT-IR analysis coupled with molecular weight determination further indicated that PSB is a polydisperse polysaccharide. Moreover, PSB obtained under the optimal conditions equally exerted in vivo antioxidant activity through decreasing malonaldehyde and protein carbonyls and increasing superoxide dismutase and glutathione.

Acute toxicity and anti-fatigue activity of polysaccharide-rich extract from corn silk.

The aim of this study was to evaluate the safety and potential of PCS as the anti-fatigue functional food. PCS was prepared by water extracting-alcohol precipitating method, and its chemical compositions of monosaccharide were analyzed. Then, acute toxicity and anti-fatigue activity of PCS were evaluated. PCS is composed of Rha, Arab, Xyl, Man, Glu, and Gal, its molar ratio is 0.17: 0.30: 0.26: 0.35: 1.00: 0.57. No mortality and general symptoms of toxicity were observed in the PCS treated mice (7.5, 15, and 20g/kg body weight), the body weight and food consumption were not significantly changed compared with the normal control group. The relative weights of main organ, and biochemical indicators also did not markedly change. PCS can significantly prolong the duration of the swimming time to exhaustion in mice, decrease BUN, LA levels, increase LDH activities, and the contents of HG in the PCS treated mice. The dose of 400mg/kg body weight is the optimal dose for anti-fatigue activity both in male and female mice. In conclusion, PCS is a promising traditional natural-based therapeutic remedy for relieving fatigue with high safety.

Toxicological evaluation of Oviductus ranae: Acute, sub-acute and genotoxicity studies in mice and rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Oviductus ranae (OR) is a traditional animal-based Chinese medicine, which has been listed in the Chinese Pharmacopoeia since 1985 edition. Although its medicinal application has been widely acknowledged, there is little available information on its potential toxicity. AIM OF THE STUDY: The aim of this study was to investigate the acute, sub-acute, and genetic toxicities of OR. MATERIALS AND METHODS: In acute toxicity evaluation, OR was administered orally to mice at doses of 2.5, 5.0, 10.0, and 20.0g/kg BW for one time. Mortality, clinical signs, and body weight were observed for 14 days after treatment. In sub-acute toxicity evaluation, OR was administered orally to rats once a day for 28 consecutive days at doses of 1.75, 3.50, and 7.00g/kg BW. Animals were observed for general behaviors, mortality, food intake, and body weight changes. At the end of treatment, relative organ weight, pathology, hematological and biochemical parameters were monitored. In genotoxicity evaluation, bacterial reverse mutation assay (Ames test) was performed by treating OR with four different Salmonella typhimurium strains at doses of 8, 40, 200, 1000, and 5000µg/plate without or with S-9 mix, respectively. The genotoxicity of OR was also evaluated by micronucleus and sperm malformation assays in mice at doses of 2.5, 5.0, and 10.0g/kg BW, respectively. RESULTS: The results of acute toxicity study showed that the LD50 value of OR is higher than 20.0g/kg BW in mice. Death and abnormal clinical symptoms were not found during the period of experiment. In sub-acute toxicity, we found that the no-observed-adverse-effect levels (NOAEL) of OR in rats is up to 7.00g/kg BW. No statistically significant or toxicologically relevant defferences in body weight, food intake, relative organ weight, pathology, hematological and biochemical parameters were observed, when compared with control group. Results of Ames test, micronucleus and sperm malformation assays indicated that OR has no mutagenicity in vitro at a limited dose of 5000µg/plate, and dose not induce micronuclei and sperm malformation in mice at the dose of up to 10.0g/kg BW in mice. CONCLUSIONS: In conclusion, OR is a tranditional Chinese medicine with high safety.