Research progress on the biological modifications of implant materials in 3D printed intervertebral fusion cages.

Anterior spine decompression and reconstruction with bone grafts and fusion is a routine spinal surgery. The intervertebral fusion cage can maintain intervertebral height and provide a bone graft window. Titanium fusion cages are the most widely used metal material in spinal clinical applications. However, there is a certain incidence of complications in clinical follow-ups, such as pseudoarticulation formation and implant displacement due to nonfusion of bone grafts in the cage. With the deepening research on metal materials, the properties of these materials have been developed from being biologically inert to having biological activity and biological functionalization, promoting adhesion, cell differentiation, and bone fusion. In addition, 3D printing, thin-film, active biological material, and 4D bioprinting technology are also being used in the biofunctionalization and intelligent advanced manufacturing processes of implant devices in the spine. This review focuses on the biofunctionalization of implant materials in 3D printed intervertebral fusion cages. The surface modifications of implant materials in metal endoscopy, material biocompatibility, and bioactive functionalizationare summarized. Furthermore, the prospects and challenges of the biofunctionalization of implant materials in spinal surgery are discussed. Fig.a.b.c.d.e.f.g As a pre-selected image for the cover, I really look forward to being selected. Special thanks to you for your comments.

Effects of chelator lipids, paramagnetic metal ions and trehalose on liposomes by solid-state NMR.

The effects of various lipid bound paramagnetic metal ions on liposomes prepared in the presence of trehalose and chelator lipids are evaluated to observe site-specific signal changes on liposome samples with optimal resolution in solid-state NMR spectroscopy. We found that Mn2+, Gd3+ and Dy3+ have different influences on the lipid 13C sites depending on their penetration depths into the bilayer, which can be extracted as distance information. The trehalose-liposome mixture is efficiently packed into solid-state NMR rotors and provides optimal resolution at reasonable instrument temperatures (10-50 °C). The effectiveness and convenience of the trehalose preparation for studying a membrane protein in liposomes are demonstrated by a membrane sample with a model membrane peptide to show that trehalose is useful to prepare consistent and stable membrane protein liposome samples for solid-state NMR.

α, ω-Cholesterol-functionalized low molecular weight polyethylene glycol as a novel modifier of cationic liposomes for gene delivery.

Here, three novel cholesterol (Ch)/low molecular weight polyethylene glycol (PEG) conjugates, termed α, ω-cholesterol-functionalized PEG (Ch2-PEGn), were successfully synthesized using three kinds of PEG with different average molecular weight (PEG600, PEG1000 and PEG2000). The purpose of the study was to investigate the potential application of novel cationic liposomes (Ch2-PEGn-CLs) containing Ch2-PEGn in gene delivery. The introduction of Ch2-PEGn affected both the particle size and zeta potential of cationic liposomes. Ch2-PEG2000 effectively compressed liposomal particles and Ch2-PEG2000-CLs were of the smallest size. Ch2-PEG1000 and Ch2-PEG2000 significantly decreased zeta potentials of Ch2-PEGn-CLs, while Ch2-PEG600 did not alter the zeta potential due to the short PEG chain. Moreover, the in vitro gene transfection efficiencies mediated by different Ch2-PEGn-CLs also differed, in which Ch2-PEG600-CLs achieved the strongest GFP expression than Ch2-PEG1000-CLs and Ch2-PEG2000-CLs in SKOV-3 cells. The gene delivery efficacy of Ch2-PEGn-CLs was further examined by addition of a targeting moiety (folate ligand) in both folate-receptor (FR) overexpressing SKOV-3 cells and A549 cells with low expression of FR. For Ch2-PEG1000-CLs and Ch2-PEG2000-CLs, higher molar ratios of folate ligand resulted in enhanced transfection efficacies, but Ch2-PEG600-CLs had no similar in contrast. Additionally, MTT assay proved the reduced cytotoxicities of cationic liposomes after modification by Ch2-PEGn. These findings provide important insights into the effects of Ch2-PEGn on cationic liposomes for delivering genes, which would be beneficial for the development of Ch2-PEGn-CLs-based gene delivery system.

Stability of Newton black films under mechanical stretch--a molecular dynamics study.

The stability of Newton black films (NBFs) under lateral mechanical stretch was investigated by nonequilibrium molecular dynamics (NEMD) simulations using force field parameters validated by accurate prediction of surface tensions. The applied strains accelerated film ruptures, enabling efficient measurements of the critical thicknesses of the films. Two representative surfactants, sodium dodecyl sulfate (SDS) for ionic surfactant and pentaethylene glycol monododecyl ether (C12EO5H) for nonionic surfactant, were investigated and compared. The predicted critical thickness of C12EO5H-coated film is smaller than that of the SDS-coated film, which is consistent with previously reported experimental observations. Our simulation results show that while the two surfactant-coated films exhibit similar dynamic properties attributed to the Marangoni-Gibbs effect, their surface structural characteristics are quite different. Consequently the two films demonstrate distinct rupture mechanisms in which rupture starts at uncovered water domains in the SDS-coated film, but at lateral surfactant/water interfaces in the C12EO5H-coated film. Our findings provide new insights into the stabilization mechanisms of NBFs and will facilitate the design and development of new films with improved properties.

Health care seeking among detained undocumented migrants: a cross-sectional study.

BACKGROUND: As in many European countries, access to care is decreased for undocumented migrants in the Netherlands due to legislation. Studies on the health of undocumented migrants in Europe are scarce and focus on care-seeking migrants. Not much is known on those who do not seek care. METHODS: This cross-sectional study includes both respondents who did and did not seek care, namely undocumented migrants who have been incarcerated in a detention centre while awaiting expulsion to their country of origin. A consecutive sample of all new arrivals was studied. Data were collected through structured interviews and reviews of medical records. RESULTS: Among the 224 male migrants who arrived at the detention centre between May and July 2008, 173 persons were interviewed. 122 respondents met inclusion criteria. Only half of the undocumented migrants in this study knew how to get access to medical care in the Netherlands if in need. Forty-six percent of respondents reported to have sought medical help during their stay in the Netherlands while having no health insurance (n = 57). Care was sought most frequently for injuries and dental problems. About 25% of these care seekers reported to have been denied care by a health care provider. Asian migrants were significantly less likely to seek care when compared to other ethnic groups, independent from age, chronic health problems and length of stay in the Netherlands. CONCLUSION: The study underlines the need for a better education of undocumented patients and providers concerning the opportunities for health care in the Netherlands. Moreover, there is a need to further clarify the reasons for the denial of care to undocumented patients, as well as the barriers to health care as perceived by undocumented migrants.

Diversity of polyester-degrading bacteria in compost and molecular analysis of a thermoactive esterase from Thermobifida alba AHK119.

More than 100 bacterial strains were isolated from composted polyester films and categorized into two groups, Actinomycetes (four genera) and Bacillus (three genera). Of these isolates, Thermobifida alba strain AHK119 (AB298783) was shown to possess the ability to significantly degrade aliphatic-aromatic copolyester film as well as decreasing the polymer particle sizes when grown at 50 degrees C on LB medium supplemented with polymer particles, yielding terephthalic acid. The esterase gene (est119, 903 bp, encoding a signal peptide and a mature protein of 34 and 266 amino acids, respectively) was cloned from AHK119. The Est119 sequence contains a conserved lipase box (-G-X-S-X-G-) and a catalytic triad (Ser129, His207, and Asp175). Furthermore, Tyr59 and Met130 likely form an oxyanion hole. The recombinant enzyme was purified from cell-free extracts of Escherichia coli Rosetta-gami B (DE3) harboring pQE80L-est119. The enzyme is a monomeric protein of ca. 30 kDa, which is active from 20 degrees C to 75 degrees C (with an optimal range of 45 to 55 degrees C) and in a pH range of 5.5 to 7.0 (with an optimal pH of 6.0). Its preferred substrate among the p-nitrophenyl acyl esters (C2 to C8) is p-nitrophenyl hexanoate (C6), indicating that the enzyme is an esterase rather than a lipase.

Anti-PD-L1-modified and ATRA-loaded nanoparticles for immuno-treatment of oral dysplasia and oral squamous cell carcinoma.

Aim: To develop nanomedicines for immuno-therapy of oral dysplasia and oral squamous cell carcinoma. Materials & methods: All-trans retinoic acid (ATRA)-poly(lactide-co-glycolide acid) (PLGA)-poly(ethylene glycol) (PEG)-programmed death-ligand 1 (PD-L1) nanomedicines were fabricated by loading ATRA into PLGA-PEG nanocarriers and modification using an anti-PD-L1 antibody. Results: ATRA-PLGA-PEG-PD-L1 nanoparticles showed fast cellular uptake, significantly inhibited proliferation and induced apoptosis in DOK and CAL27 cells. Moreover, in C3H tumor-bearing mice, ATRA-PLGA-PEG-PD-L1 nanoparticles more specifically targeted tumor cells, enhanced anticancer activity and reduced side effects when compared with free ATRA. Furthermore, CD8+ T cells were activated around PD-L1 positive cells in the tumor microenvironment after treatment. Conclusion: ATRA-PLGA-PEG-PD-L1 nanoparticles had low toxicity, high biocompatibility and specifically targeted oral dysplasia and squamous carcinoma cells both in vitro and in vivo.

Liposomal honokiol inhibits VEGF-D-induced lymphangiogenesis and metastasis in xenograft tumor model.

Lymph nodes metastasis of tumor could be a crucial early step in the metastatic process. Induction of tumor lymphangiogenesis by vascular endothelial growth factor-D may play an important role in promoting tumor metastasis to regional lymph nodes and these processes can be inhibited by inactivation of the VEGFR-3 signaling pathway. Honokiol has been reported to possess potent antiangiogenesis and antitumor properties in several cell lines and xenograft tumor models. However, its role in tumor-associated lymphangiogenesis and lymphatic metastasis remains unclear. Here, we established lymph node metastasis models by injecting overexpressing VEGF-D Lewis lung carcinoma cells into C57BL/6 mice to explore the effect of honokiol on tumor-associated lymphangiogenesis and related lymph node metastasis. The underlying mechanisms were systematically investigated in vitro and in vivo. In in vivo study, liposomal honokiol significantly inhibited the tumor-associated lymphangiogenesis and metastasis in Lewis lung carcinoma model. A remarkable delay of tumor growth and prolonged life span were also observed. In in vitro study, honokiol inhibited VEGF-D-induced survival, proliferation and tube-formation of both human umbilical vein endothelial cells (HUVECs) and lymphatic vascular endothelial cells (HLECs). Western blotting analysis showed that liposomal honokiol-inhibited Akt and MAPK phosphorylation in 2 endothelial cells, and downregulated expressions of VEGFR-2 of human vascular endothelial cells and VEGFR-3 of lymphatic endothelial cells. Thus, we identified for the first time that honokiol provided therapeutic benefit not only by direct effects on tumor cells and antiangiogenesis but also by inhibiting lymphangiogenesis and metastasis via the VEGFR-3 pathway. The present findings may be of importance to investigate the molecular mechanisms underlying the spread of cancer via the lymphatics and explore the therapeutical strategy of honokiol on antilymphangiogenesis and antimetastasis.

Thin film structure of tetraceno[2,3-b]thiophene characterized by grazing incidence X-ray scattering and near-edge X-ray absorption fine structure analysis.

Understanding the structure-property relationship for organic semiconductors is crucial in rational molecular design and organic thin film process control. Charge carrier transport in organic field-effect transistors predominantly occurs in a few semiconductor layers close to the interface in contact with the dielectric layer, and the transport properties depend sensitively on the precise molecular packing. Therefore, a better understanding of the impact of molecular packing and thin film morphology in the first few monolayers above the dielectric layer on charge transport is needed to improve the transistor performance. In this Article, we show that the detailed molecular packing in thin organic semiconductor films can be solved through a combination of grazing incidence X-ray diffraction (GIXD), near-edge X-ray absorption spectra fine structure (NEXAFS) spectroscopy, energy minimization packing calculations, and structure refinement of the diffraction data. We solve the thin film structure for 2 and 20 nm thick films of tetraceno[2,3-b]thiophene and detect only a single phase for these thicknesses. The GIXD yields accurate unit cell dimensions, while the precise molecular arrangement in the unit cell was found from the energy minimization and structure refinement; the NEXAFS yields a consistent molecular tilt. For the 20 nm film, the unit cell is triclinic with a = 5.96 A, b = 7.71 A, c = 15.16 A, alpha = 97.30 degrees, beta = 95.63 degrees, gamma = 90 degrees; there are two molecules per unit cell with herringbone packing (49-59 degree angle) and tilted about 7 degrees from the substrate normal. The thin film structure is significantly different from the bulk single-crystal structure, indicating the importance of characterizing thin film to correlate with thin film device performance. The results are compared to the corresponding data for the chemically similar and widely used pentacene. Possible effects of the observed thin film structure and morphology on charge carrier mobility are discussed.

Liposomal honokiol, a potent anti-angiogenesis agent, in combination with radiotherapy produces a synergistic antitumor efficacy without increasing toxicity.

Honokiol is an active compound purified from magnolia that has been shown to induce cell differentiation, apoptosis, and anti-angiogenesis effects, as well as an enhancement in tumor growth delay in combination with chemotherapeutic agents in several mouse xenograft models. Our goal was to investigate the radiosensitization effect of honokiol on lung carcinoma. The radiosensitization effect of liposomal honokiol in Lewis lung carcinoma cells (LL/2) was analyzed using an in vitro clonogenic survival assay. For an in vivo study, Lewis lung carcinoma-bearing C57BL/6 mice were treated with either liposomal honokiol at 25 mg/kg or 5 Gy of single tumor radiation, or a combination of both over 12 days of treatment. The tumor growth delay and the survival time were evaluated. In addition, histological analysis of tumor sections was performed to examine changes by detecting the microvessel density and apoptosis in tumor tissues. In the clonogenic survival assay, LL/2 cells treated with IC(50) Lipo-HNK for 24 h showed a radiation enhancement ratio of 1.9. After 12 days of combination treatment, the tumor volume decreased 78% and produced an anti-tumor activity 1.3-fold greater than a predicted additive effect of honokiol and radiation alone. This combination treatment also caused an 8.7 day delay in tumor growth. The cell cycle distribution and histological analysis demonstrated that liposomal honokiol has an anti-tumor effect via inducing apoptosis and inhibiting angiogenesis. Liposomal honokiol can enhance tumor cell radiosensitivity in vitro and in vivo, indicating that radiotherapy combined with liposomal honokiol can lead to greater anti-tumor efficacy.

How many species of Apodemus and Rattus occur in China? A survey based on mitochondrial cyt b and morphological analyses.

Apodemus (mice) and Rattus (rats) are the top rodent reservoirs for zoonoses in China, yet little is known about their diversity. We reexamined the alpha diversity of these two genera based on a new collection of specimens from China and their cyt b sequences in GenBank. We also tested whether species could be identified using external and craniodental measurements exclusively. Measurements from 147 specimens of Apodemus and 236 specimens of Rattus were used for morphological comparisons. We analysed 74 cyt b sequences of Apodemus and 100 cyt b sequences of Rattus to facilitate phylogenetic estimations. Results demonstrated that nine species of Apodemus and seven species of Rattus, plus a new subspecies of Rattus nitidus, are distributed in China. Principal component analysis using external and craniodental measurements revealed that measurements alone could not separate the recognized species. The occurrence of Rattus pyctoris in China remains uncertain.

Liposomal quercetin efficiently suppresses growth of solid tumors in murine models.

PURPOSE: Quercetin is a potent chemotherapeutic drug. Clinical trials exploring different schedules of administration of quercetin have been hampered by its extreme water insolubility. To overcome this limitation, this study is aimed to develop liposomal quercetin and investigate its distribution in vivo and antitumor efficacy in vivo and in vitro. EXPERIMENTAL DESIGN: Quercetin was encapsulated in polyethylene glycol 4000 liposomes. Biodistribution of liposomal quercetin i.v. at 50 mg/kg in tumor-bearing mice was detected by high-performance liquid chromatography. Induction of apoptosis by liposomal quercetin in vitro was tested. The antitumor activity of liposomal quercetin was evaluated in the immunocompetent C57BL/6N mice bearing LL/2 Lewis lung cancer and in BALB/c mice bearing CT26 colon adenocarcinoma and H22 hepatoma. Tumor volume and survival time were observed. The mechanisms underlying the antitumor effect of quercetin in vivo was investigated by detecting the microvessel density, apoptosis, and heat shock protein 70 expression in tumor tissues. RESULTS: Liposomal quercetin could be dissolved in i.v. injection and effectively accumulate in tumor tissues. The half-time of liposomal quercetin was 2 hours in plasma. The liposomal quercetin induced apoptosis in vitro and significantly inhibited tumor growth in vivo in a dose-dependent manner. The optimal dose of liposomal quercetin resulted in a 40-day survival rate of 40%. Quantitative real-time PCR showed that liposomal quercetin down-regulated the expression of heat shock protein 70 in tumor tissues. Immunohistochemistry analysis showed that liposomal quercetin inhibited tumor angiogenesis as assessed by CD31 and induced tumor cell apoptosis. CONCLUSIONS: Our data indicated that pegylated liposomal quercetin can significantly improve the solubility and bioavailability of quercetin and can be a potential application in the treatment of tumor.

Platinum covalent shell cross-linked micelles designed to deliver doxorubicin for synergistic combination cancer therapy.

The preparation of polymer therapeutics capable of controlled release of multiple chemotherapeutic drugs has remained a tough problem in synergistic combination cancer therapy. Herein, a novel dual-drug co-delivery system carrying doxorubicin (DOX) and platinum(IV) (Pt[IV]) was developed. An amphiphilic diblock copolymer, PCL-b-P(OEGMA-co-AzPMA), was synthesized and used as a nanoscale drug carrier in which DOX and Pt(IV) could be packaged together. The copolymers were shell cross-linked by Pt(IV) prodrug via a click reaction. Studies on the in vitro drug release and cellular uptake of the dual-drug co-delivery system showed that the micelles were effectively taken up by the cells and simultaneously released drugs in the cells. Futhermore, the co-delivery polymer nanoparticles caused much higher cell death in HeLa and A357 tumor cells than either the free drugs or single-drug-loaded micelles at the same dosage, exhibiting a synergistic combination of DOX and Pt(IV). The results obtained with the shell cross-linked micelles based on an anticancer drug used as a cross-linking linkage suggested a promising application of the micelles for multidrug delivery in combination cancer therapy.

The incidence of dentinal cracks during root canal preparations with reciprocating single-file and rotary-file systems: A meta-analysis.

As a dangerous factor in vertical root fracture, dentinal crack formation is often associated with root canal instruments. We conducted this meta-analysis to compare the influence of two types of nickel titanium (NiTi) instruments that have different movements (reciprocating single-file versus full-sequence rotary file systems) on dentinal cracks formation during root canal preparation. Searches were conducted in PubMed, ISI Web of Knowledge, Embase and Cochrane Library using a combination of keywords. Titles and abstracts of all articles were independently assessed by two reviewers in accordance with the predefined inclusion criteria. Relevant studies were acquired in full-text form. Data in these articles were independently extracted. A meta-analysis was conducted using Review Manager 5.3. The results showed that the WaveOne and Reciproc files with a reciprocating motion produced significantly fewer dentinal cracks than the conventional rotational ProTaper technique.

[Contents and Health Risks of Organic Phosphorus Esters in Plastic Runway Products].

Using ultrasonic assisted extraction, column chromatograph purification and gas chromatograph-mass spectrometer(GC-MS) analysis method to quantify the contents of seven kinds of organic phosphorus ester(OPEs) in plastic tracks in Chengdu City. The recovery rates of this method ranged from 71.41% to 110.58% and the correlation coefficient (r) of the standard curve was higher than 0.99, which demonstrates satisfying quality control. Plastic track samples were collected from twelve schools in Chengdu. The results show that OPEs are detected in two-thirds of plastic track samples. TnBP[Tri-n-butyl phosphate] and TEHP[tris(2-ethylhexyl) phosphate] were detected with high frequency, while TCEP[tri(2-chloroethyl) phosphate], TDCPP[tridichloropropyl phosphate] and TPhP[triphenyl phosphate] were not detected in any samples. Contents of the total OPEs (Σ7OPEs) in the plastic track ranged from ND to 534.89 ng·g-1. TnBP was identified at the highest content levels (ND-462.18 ng·g-1). TCPP[Trichloropropyl phosphate], a chlorinated phosphate with higher toxicity, was detected in one sample with a contents of 205.94 ng·g-1. The average exposure dose for adults was 0.14 ng·(kg·d)-1, lower than that for children of 0.64 ng·(kg·d)-1. Risk quotients of OPEs for adults and children were only 10-7 -10-5 and could be ignored. These results indicate that the government should limit the consumption, as well as the type of OPEs which are added to plastic tracks, to protect population health.

[The capacity and biological characteristic of the p75 neurotrophin receptor-positive ectomesenchymal stem cell in vitro].

OBJECTIVE: To investigate the biological characteristic of ectomesenchymal stem cells (EMSC) and the differentiation of p75(+)EMSC and influencing factors. METHODS: The immunohistochemical staining method was used to observe the migration of EMSC from 12.5 d SD rat embryonic facial process. Then EMSC was labeled by p75 neurotrophin receptor, and the cell cycle and stem cell surface antigens of the p75(+) EMSC was examined. RESULTS: Immunohistochemical staining showed that stem cells from the cranial neural crest migrated to embryonic rat facial process at 12.5 days. The sorting rate of the p75(+)EMSC was 6.1%. The proportion of the p75(+)EMSCs' S/G2/M phase was stable during subculture. The special substances CD29, CD146 and Stro-1 were marked for p75(+)EMSC, and the expressions of the markers were all higher (> 90%) in p75(+) EMSC. CONCLUSIONS: The embryonic tooth did not start to grow on the conception 12.5 days of SD rats. The p75(+) EMSC after sorting had stable proliferation ability and had stem cell characteristics during subculture and didn't start differentiation.

[Study on preparation of lanthanum-doped TiO2 nanometer thin film materials and its photocatalytic activity].

In this paper, lanthanum-doped TiO2 nanometer film materials coated on glass were prepared in Ti(OBu)4 precursor solutions by sol-gel processing. Transmittance and photocatalytic activity were respectively investigated and tested for these nanometer thin films prepared with different amount of lanthanum (La), different amount of polyethylene glycol (PEG), and different coating layer times. Some reactive mechanisms were also discussed. For one layer La-addition had little effect on the film transmissivity; but the photocatalytic activity was significantly improved due to La-addition. With increasing PEG, the transmittance of the film decreased for one layer film; but its photocatalytic activity did not rise. Increasing layer number did not affect the transmissivity of multilayer film. After coating two times, increasing layer number did not significantly improve the photocatalytic activity. The highest photocatalytic activity and best transmissivity were obtained for two layer TiO2 film when the dosage of lanthanum was 0.5 g and the dosage of polyethylene was 0.2 g in the precursor solutions. These materials will probably be used in the protection of environment, waste water treatment, and air purification.

Migration speed and directionality switch of normal epithelial cells after TGF-ß1-induced EMT (tEMT) on micro-structured polydimethylsiloxane (PDMS) substrates with variations in stiffness and topographic patterning.

The epithelial to mesenchymal transition (EMT) involves several physiological and pathological phenomena and endows cells with invasive and migratory properties. However, the effects of substrate stiffness and topography on the migration of cells before or after transforming growth factor-ß1 (TGF-ß1)-induced EMT (tEMT) are unknown. Herein, we seed control or tEMT NMuMG cells on the 2D patterns consisted of 1 µm or 5 µm line-widths and groove or cone patterns on either 2 MPa (1.96 ± 0.48 MPa) or 4 MPa (3.70 ± 0.74 MPa) polydimethylsiloxane (PDMS) substrates. After tEMT, the increased expression of α-SMA with vinculin in focal adhesion (FA) sites led to an acceleration of tEMT cell motility. On the 2 MPa substrate, the most influenced substrate was the 1 µm, cone-patterned substrate, where the tEMT cells' motility decelerated by 0.13 µm/min (36% slower than the cells on groove pattern). However, on the 5 µm, groove-patterned substrate, where the tEMT cells demonstrated the most rapid motility relative to the control cells, with an increment of 0.18 µm/min (100%). Among the different physical cues from substrate, the cone pattern could impede the migration speed of tEMT cells. Furthermore, we recommend the groove-patterned with a 5 µm line-width substrate as a useful tool to differentiate control and tEMT cells by migration speed.

Xylans inhibit enzymatic hydrolysis of lignocellulosic materials by cellulases.

Hemicelluloses have been found to be physical barriers in the hydrolysis of cellulose, and prevent the access of enzymes to cellulose surface. In addition, soluble hemicelluloses may strongly inhibit the cellulase activity. In this work, birchwood xylan clearly inhibited the enzymatic hydrolysis of wheat straw, Avicel and nanocellulose by cellulases. Hydrolysis efficiencies of cellobiohydrolase I (CBHI, from Thermoascus aurantiacus), cellobiohydrolase II (CBHII, from Trichoderma reesei) and endoglucanase II (from T. aurantiacus) were clearly inhibited by birchwood xylan, respectively. The strongest inhibitory effect of birchwood xylan was observed on the hydrolysis of Avicel by CBHI and CBHII, as a dramatically decreased formation of the main product, cellobiose. After additions of soluble and insoluble oat spelt xylan, cleaved cellobiose units by CBHI from cellulose chain decreased from 8 to 4 and 6, respectively. The results in this work demonstrated that xylans clearly inhibited the hydrolysis efficiencies of both endoglucanase and cellobiohydrolase.

Immobilization of silver nanoparticles onto sulfonated polyethersulfone membranes as antibacterial materials.

By using the interaction between the sulfonated groups and silver ions, silver nanoparticles were successfully introduced onto the surface of sulfonated polyethersulfone (SPES) membranes by using vitamin C as reducing agent. The presence of silver nanoparticles on the surface of the PES/SPES hybrid membranes was characterized by UV spectrophotometer, scanning electron microscopy and transmission electron microscopy. Detailed studies on the antibacterial activity of the (PES/SPES)-Ag composites were carried out for Staphylococcus aureus, Staphylococcus albus, and Escherichia coli, for which, the composites exhibited significantly inhibition capacity. Cytocompatibility of the (PES/SPES)-Ag composites were also investigated by cell cytotoxicity and cell adhesion tests. The results indicated that after immobilizing with silver nanoparticles, the (PES/SPES)-Ag was still within the safe use range. To our knowledge, this is the first time that PES membranes have been prepared with antibacterial capacity. We anticipate that this novel and green method might lead to an expanded usage of PES with antibacterial properties in medical instruments and food processing industries in the future, and might also make a potential contribution to the fields of antibacterial chemistry.