Over 50 W all-fiber mid-infrared supercontinuum laser.

Broadband supercontinuum laser sources in the mid-infrared region have attracted enormous interest and found significant applications in spectroscopy, imaging, sensing, defense, and security. Despite recent advances in mid-infrared supercontinuum laser sources using infrared fibers, the average power of those laser sources is limited to 10-watt-level, and further power scaling to over 50 W (or hundred-watt-level) remains a significant technological challenge. Here, we report an over 50 W all-fiber mid-infrared supercontinuum laser source with a spectral range from 1220 to 3740 nm, by using low loss (<0.1 dB/m) fluorotellurite fibers we developed as the nonlinear medium and a tilted fusion splicing method for reducing the reflection from the fluorotellurite-silica fiber joint. Furthermore, the scalability of all-fiber mid-infrared supercontinuum laser sources using fluorotellurite fibers is analyzed by considering thermal effects and optical damage, which verifies its potential of power scaling to hundred-watt-level. Our results pave the way for realizing all-fiber hundred-watt-level mid-infrared lasers for real applications.

Third-order cascaded Raman shift in all-solid fluorotellurite fiber pumped at 1550†nm.

In this Letter, we demonstrate a third-order cascaded Raman shift in an all-solid fluorotellurite fiber pumped by a 1550 nm nanosecond laser. The fluorotellurite glass with a composition of TeO2-BaF2-Y2O3 (TBY) has a usable Raman shift of ∼785 cm-1 and a Raman gain coefficient of ∼1.65 × 10-12 m/W at 1550 nm, which is approximately 25.4 times larger than that of silica glass. By using a 5.38 m fluorotellurite fiber as the Raman gain medium and a 1550 nm nanosecond laser as the pump light, a third-order cascaded Raman shift is obtained via spontaneous cascaded Raman amplification in the fluorotellurite fiber, causing the generation of the first-, second-, and third-order Stokes emissions that peak at 1765, 2049, and 2438 nm, respectively. For an average pump power of ∼491.5 mW, the output power of the generated first-, second-, and third-order Stokes light is approximately 14.1, 67.4, and 31.6 mW, respectively. The corresponding conversion efficiency is approximately 2.87%, 13.70%, and 6.43%, respectively. Our results show that fluorotellurite fibers are promising Raman gain media for constructing cascaded Raman fiber lasers with a wide range of wavelengths.

Antitumor effect and molecular mechanism of antioxidant polysaccharides from Salvia miltiorrhiza Bunge in human colorectal carcinoma LoVo cells.

Salvia miltiorrhiza Bunge polysaccharides (SMP) was comprehensively investigated in this study. The polysaccharides were extracted by the method of water boiling and ethanol precipitation with high purity. The monosaccharide composition of SMP was characterized using the established HPLC-UV protocol with PMP precolumn derivatization, and the results indicate that the polysaccharides are mainly composed of d-galactose (Gal), d-glucose (Glc) and d-galacturonic acid (GalUA), and their mole percentages are 64.5%, 31.1% and 4.4%, respectively. In addition, the antioxidant potential of SMP was evaluated in terms of reducing power, scavenging ability against DPPH, superoxide and hydroxyl free radicals. The results indicate that polysaccharides from S. miltiorrhiza Bunge possess versatile antioxidant activities in a dose-dependent manner. Furthermore, SMP is observed with high inhibition ratio against LoVo cells (typical tumor cells) in both dose- and time-dependent manners. FCM analysis demonstrates that SMP is able to induce apoptosis of LoVo cells, arrest the cell cycle at S phase, as well as elevate the intracellular reactive oxygen pressure. These findings for the first time reveal the potential anti-tumor mechanism of SMP, suggesting that SMP may serve a natural anticancer agent with lower cost and cytotoxicity, as well as a bioactive factor for functional food development.

Antioxidant and antitumor effects of polysaccharides from the fungus Pleurotus abalonus.

Dietary supplement of edible Pleurotus abalonus (P. abalonus) rich in fungal polysaccharides is associated with anticancer health benefit. We here isolated the polysaccharides (PAP) from the fruiting bodies of P. abalonus, and evaluated the antiproliferative activity of the polysaccharides in human colorectal carcinoma LoVo cells. HPLC analysis showed that PAP consisted of D-mannose, D-ribose, l-rhamnose, D-glucuronic acid, D-glucose and D-galactose, and their corresponding mole percentages were 3.4%, 1.1%, 1.9%, 1.4%, 87.9% and 4.4%, respectively. PAP was shown to exert a high antioxidant activity in vitro and a dose-dependent antiproliferative effect against LoVo cancer cells. Flow cytometry analysis demonstrated that PAP exhibited a stimulatory effect on apoptosis of LoVo cells, and induced the cell-cycle arrest at the S phase. We also found that PAP could increase the generation of intracellular ROS which was a critical mediator in PAP-induced cell growth inhibition. These findings suggest that PAP may serve as a potential novel dietary agent for human colon cancer chemoprevention.

Compositional characterisation of soluble apple polysaccharides, and their antioxidant and hepatoprotective effects on acute CCl4-caused liver damage in mice.

Water-soluble apple peel polysaccharides (APP) and apple flesh polysaccharides (AFP) were isolated from Pink Lady fruits, and their in vitro antioxidant capacities were characterised by DPPH(), HO(), and O(2)(-) systems, and ferric-reducing antioxidant power assay. Oral administration of APP at 250 and 500 mg/kg bw in mice was shown to be as effective as AFP in lowering the CCl(4)-caused increases of serum alanine aminotransferase, aspartate aminotransferase and lactic dehydrogenase activities, and hepatic malondialdehyde level, and antagonising the decreases in antioxidant superoxide dismutase and glutathione peroxidase activities caused by CCl(4) (p<0.05). Histopathological examinations further confirmed that both APP and AFP could protect the liver from CCl(4)-induced histological alteration. HPLC analysis also showed similar profiles of monosaccharide composition for APP and AFP with arabinose, galactose and galacturonic acid being main component monosaccharides. All of these findings demonstrate that the extracts of both APP and AFP possess antioxidant and hepatoprotective potential.

ROS-dependent mitochondria molecular mechanisms underlying antitumor activity of Pleurotus abalonus acidic polysaccharides in human breast cancer MCF-7 cells.

BACKGROUND: A greater reduction in cancer risk associated with mushroom diet rich in fungus polysaccharides is generally accepted. Meanwhile, edible Pleurotus abalonus as a member of Abalone mushroom family is a popular nutritional supplement that purportedly prevents cancer occurrence. However, these anecdotal claims are supported by limited studies describing tumor-inhibitory responses to the promising polysaccharides, and the molecular mechanisms underlying these properties have not yet been elucidated. METHODOLOGY/PRINCIPAL FINDINGS: We here fractionated the crude polysaccharide preparation from the fruiting bodies of P. abalonus into three fractions, namely PAP-1, PAP-2 and PAP-3, and tested these fractions for antiproliferative activity in human breast cancer MCF-7 cells. The largest PAP-3, an acidic polysaccharide fraction with a molecular mass of 3.68×10(5) Da, was the most active in inhibiting MCF-7 cancer cells with an IC50 of 193 µg/mL. The changes in cell normal morphology were observed by DAPI staining and the PAP-3-induced apoptosis was confirmed by annexin V/propidium iodide staining. The apoptosis was involved in mitochondria-mediated pathway including the loss of mitochondrial membrane potential (Δψm), the increase of Bax/Bcl-2 ratio, caspase-9/3 activation, and poly(ADP-ribose) polymerase (PARP) degradation, as well as intracellular ROS production. PAP-3 also induced up-regulation of p53, and cell cycle arrest at the S phase. The incubation of MCF-7 cells with antioxidant superoxide dismutase (SOD) and N-acetylcysteine (NAC) significantly attenuated the ROS generation and apoptosis caused by PAP-3, indicating that intracellular ROS plays a pivotal role in cell death. CONCLUSIONS/SIGNIFICANCE: These findings suggest that the polysaccharides, especially acidic PAP-3, are very important nutritional ingredients responsible for, at least in part, the anticancer health benefits of P. abalonus via ROS-mediated mitochondrial apoptotic pathway. It is a major breakthrough bringing new insight of the potential use of the polysaccharides as health-care food or medicine to provide significant natural defense against human cancer.