pH-Responsive Smart Wettability Surface with Dual Bactericidal and Releasing Properties.

Biomaterial-associated infections caused by pathogenic bacteria have important implications on human health. This study presents the design and preparation of a smart surface with pH-responsive wettability. The smart surface exhibited synergistic antibacterial function, with high liquid repellency against bacterial adhesion and highly effective bactericidal activity. The wettability of the surface can switch reversibly between superhydrophobicity and hydrophobicity in response to pH; this controls bacterial adhesion and release. Besides, the deposited silver nanoparticles of the surface were also responsible for bacterial inhibition. Benefiting from the excellent liquid repellency, the surface could highly resist bacterial adhesion after immersing in a bacterial suspension for 10 s (85%) and 1 h (71%). Adhered bacteria can be easily eliminated using deposited silver nanoparticles during the subsequent treatment of alkaline bacterial suspension, and the ratio of deactivated bacteria was above 75%. After the pH returned to neutral, the deactivated bacteria can be easily released from the surface. This antibacterial surface showed an improved bacterial removal efficiency of about 99%. The results shed light on future antibacterial applications of the smart surface combining both bactericidal and adhesion-resistant functionalities.

Effects of Laser Shock Processing on Morphologies and Mechanical Properties of ANSI 304 Stainless Steel Weldments Subjected to Cavitation Erosion.

Effects of laser shock processing (LSP) on the cavitation erosion resistance of laser weldments were investigated by optical microscope (OM), scanning electron microscope (SEM) observations, roughness tester, micro hardness tester, and X-ray diffraction (XRD) technology. The morphological microstructures were characterized. Cumulative mass loss, incubation period, erosion rate, and damaged surface areas were monitored during cavitation erosion. Surface roughness, micro-hardness, and residual stress were measured in different zones. Results showed that LSP could improve the damage of morphological microstructures and mechanical properties after cavitation erosion. The compressive residual stresses were generated during the process of LSP, which was an effective guarantee for the improvement of the above mentioned properties.

Stability and activity of immobilized trypsin on carboxymethyl chitosan-functionalized magnetic nanoparticles cross-linked with carbodiimide and glutaraldehyde.

Enzyme cross-linkers, such as 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and glutaraldehyde (GA), have been used to improve the stability of immobilized enzymes. We have developed a relatively stable and high-activity immobilized trypsin through EDC and GA cross-linking. Carboxymethyl chitosan (CM-CTS)-functionalized magnetic nanoparticles (Fe3O4@CM-CTS) were prepared, and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy. The CM-CTS loading of Fe3O4 @CM-CTS was 8.701%, and the CM-CTS coating did not cause any significant changes in the crystal structure of Fe3O4. The Fe3O4@CM-CTS nanoparticles exhibited superparamagnetic properties. Trypsin was successfully immobilized on Fe3O4@CM-CTS via EDC and GA cross-linking (Fe3O4@CM-CTS-EDC-TRY and Fe3O4@CM-CTS-GA-TRY, respectively). Trypsin immobilization was verified by FTIR and enzyme assays. Changes in the secondary structures of the immobilized trypsin were present in both Fe3O4@CM-CTS-EDC-TRY and Fe3O4@CM-CTS-GA-TRY. However, kinetic studies demonstrated that the immobilized trypsin retained efficient biocatalytic activity. Fe3O4@CM-CTS-EDC-TRY and Fe3O4@CM-CTS-GA-TRY both showed maximum catalytic activity at pH 8.4 and 45°C, and retained 71% and 88.5%, respectively, of their initial activities after 6 usage cycles, and 80% and 88% of their initial activities after being stored for 14 d at 4°C. The Fe3O4@CM-CTS-GA-TRY showed higher activity and conformational stability than Fe3O4@CM-CTS-EDC-TRY, which indicates that GA is effective for the immobilization of trypsin on Fe3O4@CM-CTS.

Advances in antitumor polysaccharides from phellinus sensu lato: Production, isolation, structure, antitumor activity, and mechanisms.

Edible and medicinal fungi (mushrooms) are widely applied to functional foods and nutraceutical products because of their proven nutritive and medicinal properties. Phellinus sensu lato is a well-known medicinal mushroom that has long been used in preventing ailments, including gastroenteric dysfunction, diarrhea, hemorrhage, and cancers, in oriental countries, particularly in China, Japan, and Korea. Polysaccharides represent a major class of bioactive molecules in Phellinus s. l., which have notable antitumor, immunomodulatory, and medicinal properties. Polysaccharides that were isolated from fruiting bodies, cultured mycelia, and filtrates of Phellinus s. l. have not only activated different immune responses of the host organism but have also directly suppressed tumor growth and metastasis. Studies suggest that polysaccharides from Phellinus s. l. are promising alternative anticancer agents or synergizers for existing antitumor drugs. This review summarizes the recent development of polysaccharides from Phellinus s. l., including polysaccharide production, extraction and isolation methods, chemical structure, antitumor activities, and mechanisms of action.

The Antioxidant Inhibition of Clove Effective Fraction on Lipid, Protein and Spectra Variation of LDL.

Oxidation of low density lipoprotein (LDL) has been considered as the critical factor which led to atherosclerosis (AS). Lipid and protein in LDL were oxidized to cause change of spectra during oxidation. Clove has been demonstrated to possess the strongest antioxidant capacity among 87 both medical and edible plants proclaimed by China. However, whether LDL oxidation is inhibited by clove? If so, whether it inhibits the oxidation of lipid and protein in LDL, and how does spectral characteristic of LDL change during oxidation when clove was added into LDL. Currently, these questions are still unclear. Therefore, the inhibition efficiency of the effective fraction from clove (EFC) on oxidation of LDL was studied by UV-Visible spectra and fluorescence spectra. The results indicated that EFC might effectively delay propagation of conjugated diene (CD) during LDL oxidation and postpone reaching maximum of its content. Likewise, it might inhibit cholesterol degradation, tryptophan (Trp) fluorescence quenching, lysine (Lys) residues from being modified, and lipofuscins from being generated in peroxidatic reaction among lipid and protein. Besides, EFC also might affect variation of UV-Visible spectra of LDL during oxidation. This study provides reference for future research and development of clove functional food inhibiting AS.

Structure and antioxidative property of a polysaccharide from an ammonium oxalate extract of Phellinus linteus.

In this paper, the novel polysaccharide PL-A11 was purified from an ammonium oxalate extract of Phellinus linteus mycelia. Its physicochemical properties, structural characteristics, and antioxidant activities were investigated. Results showed that PL-A11 had a weight-average molecular weight (Mw) of 13.8kDa and was mainly composed of arabinose, xylose, mannose, and glucose in a molar ratio of 1.1:1.3:1.0:6.6. The backbone of PL-A11 was composed of (1→4)-α-d-glucopyranosyl, (1→2)-α-d-xylopyranosyl, and (1→3)-α-d-arabinofuranosyl residues, whereas the (1→6)-α-d-mannopyranosyl residues formed branches at the O-2 position with 1-linked-α-d-glucopyranosyl terminal residues. From the antioxidative activity tests in vivo, the administration of PL-A11 obviously enhanced the activity of antioxidant enzymes and significantly reduced the level of malondiadehyde (MDA) in the serum and liver of d-galactose-treated aging mice in a dose-dependent manner, as well as effectively stimulated the immune system of aging mice. These findings implied that PL-A11 could be developed as a potential antioxidant for applications in the functional food, pharmaceutical, cosmetic or nutraceutical industries.

Ultrasonic effects on the degradation kinetics, preliminary characterization and antioxidant activities of polysaccharides from Phellinus linteus mycelia.

In this study, a high-molecular-weight polysaccharide PL-N isolated from the alkaline extract of Phellinus linteus mycelia was degraded by ultrasound. Results showed that ultrasound treatment at different ultrasonic intensities decreased the intrinsic viscosity and molecular weight of PL-N, as well as narrowed the molecular weight distribution. A larger reduction in intrinsic viscosity and molecular weight was caused by a higher ultrasonic intensity. The degradation kinetics model was fitted to (1/Mt-1/M0)=k·t, and the reaction rate constant (k) increased with increasing ultrasonic intensity. Ultrasound degradation did not change the primary structure of PL-N, and scanning electron microscopy analysis indicated that the morphology of the original PL-N was different from that of degraded PL-N fractions. Antioxidant activity assays in vitro indicated that the degraded PL-N fraction with low molecular weight had stronger hydroxyl radical scavenging capacity and higher TEAC and FRAP values.

A novel chemo-enzymatic synthesis of hydrophilic phytosterol derivatives.

In this study, a novel method was developed for chemo-enzymatic synthesis of hydrophilic phytosterol derivatives, phytosteryl polyethylene glycol succinate (PPGS), through an intermediate phytosteryl hemisuccinate (PSHS), which was first chemically prepared and subsequently coupled with polyethylene glycol (PEG) through lipase-catalyzed esterification. The chemical structure of intermediate and goal product were finally confirmed to be PSHS and PPGS by FT-IR, MS and NMR, suggesting that hydrophilic phytosterol derivatives were successfully synthesized. The effects of various parameters on the conversion of PSHS to PPGS were investigated and the highest conversion (>78%) was obtained under the selected conditions: 75 mmol/L PSHS, 1:2M ratio of PSHS to PEG, 50 g/L Novozym 435, 120 g/L 3 Å molecular sieves in tert-butanol, 55 °C, 96 h and 200 rpm. The solubility of phytosterols in water was significantly improved by coupling with PEG, facilitating the incorporation into a variety of foods containing water.

Purification, characterization and antitumor activity of polysaccharides extracted from Phellinus igniarius mycelia.

Water-soluble intracellular polysaccharides (IPS) were extracted from cultured mycelia of Phellinus igniarius. The IPS were purified by ethanol fractional precipitation, ion-exchange and size exclusion chromatography in that order. Homogeneous polysaccharide IPSW-1, IPSW-2, IPSW-3, and IPSW-4 were obtained, which molecular characteristics were examined using multiangle laser-light scattering and refractive index detector system. The average molecular weights of them were 34.1, 17.7, 15.1, 21.7kDa, respectively. GC analysis indicated that IPSW-1, IPSW-2 and IPSW-3 all only contained glucose, while IPSW-4 was composed of rhamnose, xylose, mannose, glucose and galactose in a molar ratio of 1.29:1.21:1:43.86:1.86. UV and IR analysis suggested they belonged to α-type of the pyran group and didn't contain protein. These homogeneous polysaccharides could inhibit the growth of SW480 and HepG2 cells to a certain extent in a dose-dependent manner. So they could be beneficial for the further development of a natural carcinoma preventive agent and functional food.

Effects of ultrasound on molecular properties, structure, chain conformation and degradation kinetics of carboxylic curdlan.

In this study, high-intensity ultrasound (20 kHz), a simple, effective and without any additive method, was used to the degradation of carboxylic curdlan (Cc) produced by 4-acetamido-TEMPO-mediated oxidation. The effects of ultrasound on molecular properties, structure and chain conformations of Cc were investigated by viscometry, size-exclusion chromatography with multiangle laser-light scattering (SEC-MALLS) analysis, as well as FTIR and NMR spectroscopies. The results indicated that the intrinsic viscosity [η] and the weight-average molecular weight (Mw) of Cc decreased obviously after ultrasound, and a uniform and narrow distribution of degradation product was obtained. The z-average radius of gyrations (Rg) firstly increased and then decreased as the sonication time prolonged. Ultrasound destroyed the hydrogen bonds resulting in the transition from compact random coil conformation to more flexible and even shorter extended chains. Ultrasonic treatment could not alter the primary chemical structure of Cc molecules according to the structural analysis by FTIR and NMR spectroscopies. Degradation kinetics based on Schmid model was applied to estimate the degradation rate constant k. It was found that the k value of Cc decreased with increasing the polymer concentration from 0.05 to 0.2% (w/v).

Structural features and antitumor activity of a novel polysaccharide from alkaline extract of Phellinus linteus mycelia.

A novel high molecular weight polysaccharide (PL-N1) was isolated from alkaline extract of the cultured Phellinus linteus mycelia. The weight average molecular weight (Mw) of PL-N1 was estimated at 343,000kDa. PL-N1 comprised arabinose, xylose, glucose, and galactose in the molar ratio of 4.0:6.7:1.3:1.0. The chemical structure of PL-N1 was investigated by FTIR and NMR spectroscopies and methylation analysis. The results showed that the backbone of PL-N1 comprised (1→4)-linked ß-D-xylopyranosyl residues, (1→2)-linked α-D-xylopyranosyl residues, (1→4)-linked α-D-glucopyranosyl residues, (1→5)-linked ß-D-arabinofuranosyl residues, (1→4)-linked ß-D-xylopyranosyl residues which branched at O-2, and (1→4)-linked ß-D-galactopyranosyl residues which branched at O-6. The branches consisted of (1→)-linked α-D-arabinofuranosyl residues. Antitumor activity assay in vitro showed that PL-N1 could inhibit the growth of HepG2 cells to a certain extent in a dose-dependent manner. Thus, PL-N1 may be developed as a potential, natural antitumor agent and functional food.

Self-aggregated nanoparticles of carboxylic curdlan-deoxycholic acid conjugates as a carrier of doxorubicin.

In this study, a new non-toxic, biodegradable, biocompatible and water-soluble carboxylic curdlan bearing the dissociable COOH group in 100% purity, which was prepared by 4-acetamido-TEMPO-mediated oxidation, was hydrophobically modified by deoxycholic acid (DOCA) to attain novel amphiphilic curdlan derivatives (CCDs) for the preparation of nano-carriers for antitumor drug doxorubicin (DOX). Under the effect of ultrasonication, the carboxylic curdlan derivatives in water were self-aggregated into spherical nanoparticles with diameters ranging from 214 nm to 380 nm. The critical aggregation concentrations decreased from 0.047 mg/mL to 0.016 mg/mL with increasing DS of DOCA. DOX-loaded CCD nanoparticles were prepared in an aqueous medium with dialysis method. The DOX-CCD nanoparticles exhibited pH- and dose-dependent drug release profiles during in vitro release experiments. Moreover, the drug transport mechanism was Fickian diffusion according to the Ritger-Peppas model. The CCD nanoparticles might be explored as potential carriers for hydrophobic drugs with controlled release and delivery functions.

Highly selective and sensitive nucleic acid detection based on polysaccharide-functionalized silver nanoparticles.

Polysaccharide-functionalized silver nanoparticles (Oc-AgNPs) with a mean diameter of 15 nm were utilized as a novel and effective fluorescence-sensing platform for nucleic acid detection. Tests on the oligonucleotide sequences associated with the human immunodeficiency virus as a model system showed that the Oc-AgNPs effectively absorbed and quenched dye-labeled single-stranded DNA through strong hydrogen bonding interactions and slight electrostatic attractive interactions. The proposed system efficiently differentiated between complementary and mismatched nucleic acid sequences with high selectivity and good reproducibility at room temperature.

Efficient synthesis and characterization of ergosterol laurate in a solvent-free system.

Ergosterol and its derivatives have attracted much attention for a variety of health benefits, such as anti-inflammatory and antioxidant activities. However, ergosterol esters are advantageous because this compound has better solubility than the free ergosterol. In this work, ergosterol laurate was efficiently synthesized for the first time by direct esterification in a solvent-free system. The desired product was purified, characterized by Fourier transform infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance, and finally confirmed to be ergosterol laurate. Meanwhile, the effect of various catalysts, catalyst dose, reaction temperature, substrate molar ratio, and reaction time were studied. Both the conversion of ergosterol and the selectivity of the desired product can reach above 89% under the selected conditions: sodium dodecyl sulfate + hydrochloric acid as the catalyst, 2:1 molar ratio of lauric acid/ergosterol, catalyst dose of 4% (w/w), 120 °C, and 2 h. The oil solubility of ergosterol and its laurate was also compared. The results showed that the solubility of ergosterol in oil was significantly improved by direct esterification with lauric acid, thus greatly facilitating the incorporation into a variety of oil-based systems.

Thermal stability of ginkgolic acids from Ginkgo biloba and the effects of ginkgol C17:1 on the apoptosis and migration of SMMC7721 cells.

Ginkgolic acids are alkylsalicylic acid derivatives with a thermolabile carboxylic group from Ginkgo biloba L., and they exhibit anticancer activity. Their anticancer effects are closely associated with their thermal stability. In this study, the thermal decomposition of ginkgolic acids was analyzed at temperatures of 30, 50, 70 and 250°C. The results clearly showed that an obvious slow decarboxylation of the ginkgolic acids was detected at 70°C. When the temperature increased to 250°C, the decarboxylation reaction was rapidly completed. The ginkgolic acids were decarboxylated to yield ginkgols. The ginkgols C13:0, C15:1 and C17:1 were separated and definitively identified by IR, NMR and GC-MS. The cytotoxic effects of ginkgols C13:0, C15:1 and C17:1 were tested and compared with those of the corresponding ginkgolic acids. An MTT assay showed that ginkgol C17:1 (48-h IC50=8.5 µg·ml(-1)) has the strongest inhibition on SMMC-7721 cells in a dose- and time-dependent manner. The anticancer action may occur via the induction of apoptosis by the activation of caspases-3, the upregulation of Bax expression, and the inhibition migration of SMMC7721 cells. The results indicated that ginkgol C17:1 might be useful for the further development of a hepatocellular carcinoma preventive agent.

Effect of extraction media on preliminary characterizations and antioxidant activities of Phellinus linteus polysaccharides.

Three partially purified polysaccharides were extracted from Phellinus linteus mycelia using hot water, 1% (NH4)2C2O4, and 1.25M NaOH/0.05% NaBH4, and the extracts were named PL-W, PL-A, and, PL-N respectively. PL-N mainly comprised xylose and arabinose with a high molecular weight (Mw) and the highest carbohydrate and uronic acid contents. PL-W and PL-A were mainly composed of glucose with high and low Mw fractions in various ratios. All three polysaccharides existed as compact coils in aqueous solutions and exhibited strong scavenging capacity and antioxidant activities in a concentration-dependent manner. The polysaccharides also had high uronic acid and carbohydrate contents and strong antioxidant activities. The Mws, monosaccharide compositions, and chemical structures of the polysaccharides also affected their antioxidant activities. PL-A and PL-N had better antioxidant activities and could thus be developed as potential natural antioxidant agents for applications in food additives and biomedical industries.

Structural characteristics and antioxidant activities of different families of 4-acetamido-TEMPO-oxidised curdlan.

Regioselective oxidation was applied to commercial curdlan for the preparation of its water-soluble derivatives with improved antioxidant activities, using a 4-acetamido-2,2, 6,6-tetramethylpiperidine-1-oxyl radical/NaClO/NaClO2 system at pH 4.8 and 40°C. The structural features, molecular properties, and chain conformations of the oxidised curdlans were determined using Fourier transform (FT) infrared and FT Raman spectroscopy, carbon nuclear magnetic resonance, X-ray diffraction, and size-exclusion chromatography with multi-angle laser-light scattering analyses. The C6 primary hydroxyls of curdlan were successfully oxidised into carboxylate groups with less depolymerization, and no aldehyde groups were formed during oxidation. The crystalline region of curdlan was destroyed after oxidation. The oxidised curdlans formed random coils in aqueous solution, and the chain became more flexible and expanded with increasing carboxylate contents from 2.07mmol/g to 4.87mmol/g. The high polyglucuronic acid derivative (Cur-24) showed the best antioxidant activity in TEAC and FRAP assays, thus it could be explored as novel potential antioxidants for dietary and therapeutic applications.

Green synthesis of silver nanoparticles using 4-acetamido-TEMPO-oxidized curdlan.

A facile, simple, and eco-friendly method using 4-acetamido-2,2,6,6-tetramethypiperidine-1-oxyl radical-oxidized curdlan (Oc) as both reducing and stabilizing agents was developed for the fabrication of silver nanoparticles (AgNPs) from silver nitrate (AgNO3). The structure, morphology, and particle size of the as-prepared AgNPs were investigated by ultraviolet-visible spectroscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and dynamic laser light scattering. The well-dispersed AgNPs were sphere like with a mean diameter of 15 nm. Their formation was dependent on reaction duration, reaction temperature, Oc concentration, and AgNO3 concentration. Fourier transform-infrared and Raman spectra demonstrated that the as-prepared AgNPs can readily bind covalently with the carboxylate groups of Oc through the strong monodentate interaction in the reaction medium.

Sulfation and enhanced antioxidant capacity of an exopolysaccharide produced by the medicinal fungus Cordyceps sinensis.

EPS-1 was an exopolysaccharide produced by the medicinal fungus Cordyceps sinensis (Cs-HK1). In the present study, EPS-1 was sulfated with chlorosulfonic acid (CSA)-pyridine (Pyr) at different volume ratios, yielding four sulfated derivatives, SEPS-1A, B, C and D, with different degrees of substitution (DS: 0.25-1.38) and molecular weights (17.1-4.1 kDa). The sulfation of EPS-1 occurred most frequently at the C-6 hydroxyl groups due to their higher reactivity. In aqueous solution, the native EPS-1 formed random coils or aggregated networks, but the sulfated derivatives formed single helices. The antioxidant activities of the sulfated EPS-1 derivatives for scavenging hydroxyl radicals (•OH) and 2,2-azinobis-3-ehtylbenzothiazolin-6-sulfonic acid radicals (ABTS•+) were significantly increased with increasing DS and decreasing molecular weight (MW). Sulfation has thus been shown to be an effective and favorable strategy for improving the physico-chemical properties and bioactivities of fungal polysaccharides.

[Study on Ca2+ transmembrane behaviors of magnetic-treated S. aureus with Fura-2/AM fluorescence probe and LCSM].

The purpose of the present paper is to study Ca2+ transmembrane behaviors of the S. aureus treated with high intensity pulsed magnetic field. For this purpose, the method of Fura-2/AM fluorescence probe was investigated to determine the change in intracellular Ca2+ concentration in S. aureus, fluorescence intensities of S. aureus cells treated by pulsed magnetic field under different pulse number were determined, and the change in intracellular Ca2+ concentration was observed by laser confocal scanning microscope (LCSM). Research results showed that Fura-2/AM can load in S. aureus successfuuly, and can be used to determine the change in intracellular free Ca2+ concentration. After being treated with high intensity pulsed magnetic field, intra cellular free Ca2+ concentration of S. aureus went up significantly, and the regulation of Ca2+ increase was close consistent with the decrease in living bacterium number, and relatedness reached to -0.989 15; the number and fluorescence intensity of intracellular lightspot increased significantly, meaning that large amount of exocellular calcium ions across cell membrane enter into inside of cells. So, it was judged that the change in microbial membrane permeability and increase in intracellular free Ca2+ concentration are important reasones why high intensity pulsed magnetic field has sterilization effect.