All-in-one theranostic nano-platform based on polymer nanoparticles for BRET/FRET-initiated bioluminescence imaging and synergistically anti-inflammatory therapy for ulcerative colitis.

BACKGROUND: Ulcerative colitis (UC), a subtype of inflammatory bowel disease (IBD), has evolved into a global burden given its high incidence. There is a clinical need to create better diagnostic and therapeutic approaches to UC. RESULTS: We fabricated P-selectin binding peptide-decorated poly lactic-co-glycolic acid (PBP-PLGA-NP) doped with two lipophilic dyes, DiL and DiD. Meanwhile, two low-toxic anti-inflammatory natural products (betulinic acid [BA] and resveratrol [Res]) were co-loaded in the PBP-PLGA-NP system. The BA/Res-loaded NPs had an average size of around 164.18 nm with a negative zeta potential (- 25.46 mV). Entrapment efficiencies of BA and Res were 74.54% and 52.33%, respectively, and presented a sustained drug release profile. Further, the resulting PBP-PLGA-NP could be internalized by RAW 264.7 cells and Colon-26 cells efficiently in vitro and preferentially localized to the inflamed colon. When intravenously injected with luminol, MPO-dependent bioluminescence imaging to visualize tissue inflammation was activated by the bioluminescence and fluorescence resonance energy transfer (BRET-FRET) effect. Importantly, injected NPs could remarkably alleviate UC symptoms yet maintain intestinal microbiota homeostasis without inducing organ injuries in the mice models of colitis. CONCLUSIONS: This theranostic nano-platform not only serves as a therapeutic system for UC but also as a non-invasive and highly-sensitive approach for accurately visualizing inflammation.

Rapid screening and quantitative detection of Salmonella using a quantum dot nanobead-based biosensor.

The continuing hurdle of developing foodborne pathogen detection techniques is that compromises must be made among simplicity, portability, speed, sensitivity, and quantitation. Herein, we fabricated quantum dot nanobeads (QDNS) by a layer-by-layer assembly of quantum dots on the surface of polymer nanospheres. QDNS exhibited higher fluorescence intensity than the quantum dots at the same particle number. Based on the quantum dot nanobeads as the signal reporter, a quantitative lateral flow immunoassay was demonstrated for Salmonella typhimurium detection with improved sensitivity, specificity and accuracy. A visual detection limit of 5 × 103 CFU mL-1Salmonella typhimurium within 10 min has been proved and demonstrated. Additionally, higher concentrations of non-Salmonella typhimurium bacteria have negligible effects on the detection of Salmonella typhimurium. The results of 50 single blind tests by 10 testers suggested that the assay exhibited 100% accuracy. The results illustrate that the assay provides a balance among simplicity, speed, sensitivity and accuracy, and it can be a favorable alternative for Salmonella typhimurium screening in various samples.

Mutations in C1orf194, encoding a calcium regulator, cause dominant Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth disease is a hereditary motor and sensory neuropathy exhibiting great clinical and genetic heterogeneity. Here, the identification of two heterozygous missense mutations in the C1orf194 gene at 1p21.2-p13.2 with Charcot-Marie-Tooth disease are reported. Specifically, the p.I122N mutation was the cause of an intermediate form of Charcot-Marie-Tooth disease, and the p.K28I missense mutation predominately led to the demyelinating form. Functional studies demonstrated that the p.K28I variant significantly reduced expression of the protein, but the p.I122N variant increased. In addition, the p.I122N mutant protein exhibited the aggregation in neuroblastoma cell lines and the patient's peroneal nerve. Either gain-of-function or partial loss-of-function mutations to C1ORF194 can specify different causal mechanisms responsible for Charcot-Marie-Tooth disease with a wide range of clinical severity. Moreover, a knock-in mouse model confirmed that the C1orf194 missense mutation p.I121N led to impairments in motor and neuromuscular functions, and aberrant myelination and axonal phenotypes. The loss of normal C1ORF194 protein altered intracellular Ca2+ homeostasis and upregulated Ca2+ handling regulatory proteins. These findings describe a novel protein with vital functions in peripheral nervous systems and broaden the causes of Charcot-Marie-Tooth disease, which open new avenues for the diagnosis and treatment of related neuropathies.

Graphite oxide-dispersed CdTe quantum dots nanocomposite for flexible display luminescent membranes.

A quantum dot (QD) dispersant material was prepared using graphite oxide (GO). Luminescent films were prepared using polyvinyl alcohol as the polymer matrix. First, water-soluble CdTe QDs were prepared by wet chemistry and GO was synthesized using a modified Hummers method. X-Ray diffraction tests showed that the GO reflection peak [001] was 11.9°, which indicates that the d-spacing is 0.7431 nm; atomic force microscopy showed a GO thickness of 200 nm. Fourier transform infrared spectra showed vibrations at 1624 cm-1 for the carbonyl groups, and 3260 cm-1 for the GO samples; the -C-O vibration was at 1320 cm-1 and -COOH, -OH vibrations were at 950 cm-1 . Fluorescent tests showed that pH had an impact on the QD colloidal stability. GO was neutralized before use as the host media for the GO/QDs nanocomposite. The results proved that the resultant nanocomposite is promising for use in brightness enhancement films in flexible displays.

Preparation of carbon quantum dots based high photostability luminescent membranes.

Urethane acrylate (UA) was used to prepare carbon quantum dots (C-dots) luminescent membranes and the resultants were examined with FT-IR, mechanical strength, scanning electron microscope (SEM) and quantum yields (QYs). FT-IR results showed the polyurethane acrylate (PUA) prepolymer -C = C-vibration at 1101 cm-1 disappeared but there was strong vibration at1687cm-1 which was contributed from the-C = O groups in cross-linking PUA. Mechanical strength results showed that the different quantity of C-dots loadings and UV-curing time affect the strength. SEM observations on the cross-sections of the membranes are uniform and have no structural defects, which prove that the C-dots are compatible with the water-soluble PUA resin. The C-dot loading was increased from 0 to 1 g, the maximum tensile stress was nearly 2.67 MPa, but the tensile strain was decreased from 23.4% to 15.1% and 7.2% respectively. QYs results showed that the C-dots in the membrane were stable after 120 h continuous irradiation. Therefore, the C-dots photoluminescent film is the promising material for the flexible devices in the future applications.

Real-Time Discrimination and Versatile Profiling of Spontaneous Reactive Oxygen Species in Living Organisms with a Single Fluorescent Probe.

Fluorescent probes are powerful tools for the investigations of reactive oxygen species (ROS) in living organisms by visualization and imaging. However, the multiparallel assays of several ROS with multiple probes are often limited by the available number of spectrally nonoverlapping chromophores together with large invasive effects and discrepant biological locations. Meanwhile, the spontaneous ROS profilings in various living organs/tissues are also limited by the penetration capability of probes across different biological barriers and the stability in reactive in vivo environments. Here, we report a single fluorescent probe to achieve the effective discrimination and profiling of hydroxyl radicals (•OH) and hypochlorous acid (HClO) in living organisms. The probe is constructed by chemically grafting an additional five-membered heterocyclic ring and a lateral triethylene glycol chain to a fluorescein mother, which does not only turn off the fluorescence of fluorescein, but also create the dual reactive sites to ROS and the penetration capability in passing through various biological barriers. The reactions of probe with •OH and HClO simultaneously result in cyan and green emissions, respectively, providing the real-time discrimination and quantitative analysis of the two ROS in cellular mitochondria. Surprisingly, the accumulation of probes in the intestine and liver of a normal-state zebrafish and the transfer pathway from intestine-to-blood-to-organ/tissue-to-kidney-to-excretion clearly present the profiling of spontaneous •OH and HClO in these metabolic organs. In particular, the stress generation of •OH at the fresh wound of zebrafish is successfully visualized for the first time, in spite of its extremely short lifetime.

Do the cations in clay and the polymer matrix affect quantum dot fluorescent properties?

This paper studied the effects of cations and polymer matrix on the fluorescent properties of quantum dots (QDs). The results indicated that temperature has a greater impact on fluorescence intensity than clay cations (mainly K(+) and Na(+) ). Combined fluorescence lifetime and steady-state spectrometer tests showed that QD lifetimes all decreased when the cation concentration was increased, but the quantum yields were steady at various cation concentrations of 0, 0.05, 0.5 and 1 M. Poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA) and diepoxy resin were used to study the effects of polymers on QD lifetime and quantum yield. The results showed that the lifetime for QDs 550 nm in PEO and PVA was 17.33 and 17.12 ns, respectively; for the epoxy resin, the lifetime was 0.74 ns, a sharp decrease from 24.47 ns. The quantum yield for QDs 550 nm changed from 34.22% to 7.45% and 7.81% in PEO and PVA, respectively; for the epoxy resin the quantum yield was 2.25%. QDs 580 nm and 620 nm showed the same results as QDs 550 nm. This study provides useful information on the design, synthesis and application of QDs-polymer luminescent materials. Copyright © 2015 John Wiley & Sons, Ltd.

Ion Exchange and Antibiofouling Properties of Poly(ether sulfone) Membranes Prepared by the Surface Immobilization of Brønsted Acidic Ionic Liquids via Double-Click Reactions.

Brønsted acidic ionic liquids (BAILs) are unique ionic liquids that display chemical structures similar to zwitterions, and they were typically used as solvents and catalysts. In this work, an imidazole-based BAIL monolayer was fabricated onto poly(ether sulfone) (PES) membranes via surface clicking reactions, and the multifunctionality, including ion exchange and biofouling resistance to proteins and bacteria, was demonstrated, which was believed to be one of few works in which BAIL had been considered to be a novel fouling resistance layer for porous membranes. The successful immobilization of the BAILs onto a membrane surface was confirmed by X-ray photoelectron spectroscopy analysis, contact angle measurement, and ζ potential determination. The results from Raman spectroscopy showed that, as a decisive step prior to zwitterion, the BAIL was deprotonated in aqueous solution, and biofouling resistance to proteins and bacteria was found. However, BAIL displayed ion exchange ability at lower pH, and surface hydrophilicity/hydrophobicity of membranes could be tuned on purpose. Our results have demonstrated that the BAIL grafted onto membranes will not only act as an antibiofouling barrier like zwitterions but also provide a platform for surface chemical tailoring by ion exchange, the property of which will become especially important in acidic solutions where the fouling resistance performances of zwitterions are greatly weakened.

[An investigation analysis of prophylactic application of antibiotics in ten types of oral and maxillofacial surgery].

OBJECTIVE: To evaluate the prophylactic application of antibiotics in oral and maxillofacial surgery and to provide a scientific basis for its reasonable use. METHODS: The use of prophylactic antibiotics in the oral and maxillofacial surgery was conducted in our hospital from January 2011 to August 2013 based on a retrospective survey, and the conditions and affecting factors were analyzed. RESULTS: The utilization rates of prophylactic antibiotics were respectively 98.9%, 61.8%, and 24.6%, showing a downward trend. But the infection rate of surgical site did not significantly increase, and by Fisher's exact test, the difference was not significant (P>0.05). Surgical site infections (SSI) rates did not rise between using and not using prophylactic antibiotics (P>0.05). CONCLUSION: The use of prophylactic antibiotics is greatly influenced by the policy, and along with the decline in antibiotic usage, SSI have not increased significantly.

Effects of folate-chicory acid liposome on macrophage polarization and TLR4/NF-κB signaling pathway in ulcerative colitis mouse.

BACKGROUND: Chichoric acid (CA) is a major active ingredient found in chicory and Echinacea. As a derivative of caffeic acid, it has various pharmacological effects. PURPOSE: Due to the unclear etiology and disease mechanisms, effective treatment methods for ulcerative colitis (UC) are currently lacking. The study investigated the therapeutic effects of the folate-chicory acid liposome on both LPS-induced macrophage inflammation models and dextran sulfate sodium (DSS)-induced mouse UC models. METHODS: Folate-chicory acid liposome was prepared using the double emulsion ultrasonic method with the aim of targeting folate receptors specifically expressed on macrophages. The study investigated the therapeutic effects of the folate-chicory acid liposome on both LPS-induced macrophage inflammation models and DSS -induced mouse UC models. Furthermore, the effects of the liposomes on macrophage polarization and their underlying mechanisms in UC were explored. RESULTS: The average particle size of folate-chicory acid liposome was 120.4 ± 0.46 nm, with an encapsulation efficiency of 77.32 ± 3.19 %. The folate-chicory acid liposome could alleviate macrophage apoptosis induced by LPS, decrease the expression of inflammatory factors in macrophages, enhance the expression of anti-inflammatory factors, inhibit macrophage polarization towards the M1 phenotype, and mitigate cellular inflammation in vetro. In vivo test, folate-chicory acid liposome could attenuate clinical symptoms, increased colon length, reduced DAI scores, CMDI scores, and alleviated the severity of colonic histopathological damage in UC mice. Furthermore, it inhibited the polarization of macrophages towards the M1 phenotype in the colon and downregulated the TLR4/NF-κB signaling pathway, thereby ameliorating UC in mice. CONCLUSION: Folate-chicory acid liposome exhibited a uniform particle size distribution and high encapsulation efficiency. It effectively treated UC mice by inhibiting the polarization of macrophages towards the M1 phenotype in the colon and downregulating the TLR4/NF-κB signaling pathway.

Pulp waste extracted reinforced powder incorporated biodegradable chitosan composite film for enhancing red grape shelf-life.

Chitosan (CS) is widely used as a natural biopolymer due to its semi-crystalline structure, good film-forming properties, and easy availability. CS-based composite films are widely used in industry, particularly in the food sector as active food packaging. Despite all of these advantages, their wide range of applications are constrained by poor mechanical properties. Therefore, this work introduced refined bamboo cellulose powder (RBCP), a reinforcing material that is extracted from waste bamboo pulp and applied to CS composite films to enhance their mechanical and physicochemical properties. The chemical composition and crystallinity properties of CS composite films with RBCP addition were observed by ATR-FTIR and XRD. The homogeneous and heterogeneous surfaces of the RBCP incorporated films before biodegradation and after biodegradation (20 days) were observed by scanning electron microscopy (SEM). The increase in reinforcing RBCP materials from 0.00 to 5.00 % resulted in an increase in tensile strength for CS/RBCP films from 2.9 to 8.3 MPa. The application of the CS/RBCP/5 composite film as red grapefruit storage was also investigated, which performed much better than commercial plastic and control CS films with 92.8 and 88.6 % viability of S. aureus and E. coli bacteria. Overall achieved properties demonstrated strong potential for usage as active packaging materials to preserve and lengthen the shelf life of red grapefruits.

Photothermal and Concus Finn capillary assisted superhydrophobic fibrous network enabling instant viscous oil transport for crude oil cleanup.

Rapid and effective removal of highly viscous oil spills from the sea remains a great challenge globally. Superhydrophobic materials are attractive candidates for handling oil spills, but they are restrained to recover oils with low viscosity exclusively. Herein, we report a novel polypyrrole wrapped superhydrophobic fibrous network using cross-shaped polyester fibers as starting blocks. The polypyrrole coating enables the absorbent to convert light to heat, ensuring that the viscosity of heavy oils in the proximity can be easily controlled. In the meanwhile, the special structure of the starting fibers initiates Concus Finn (CFin) capillary allowing instant oil transport in the network. When the absorbent is exposed to light oils (0-500 mPa.s), the oils can be transported instantly via CFin capillary. Interestingly, under synergistic effect of light-to-heat conversion and CFin capillary, a drawing-sticking crude oil strip (105 mPa.s) is sucked instantly against gravity by the absorbent. The absorbent is successfully applied to efficiently separate both oil/water mixtures and oil/water emulsions (efficiency > 99%). Such absorbent can absorb 62.99-74.23 g/g light oils on average and up to 123.3 g/g crude oil under 0-2 sun illumination, holding a huge potential in managing oil spills.

Soluplus-Mediated Diosgenin Amorphous Solid Dispersion with High Solubility and High Stability: Development, Characterization and Oral Bioavailability.

BACKGROUND AND PURPOSE: The traditional Chinese medicine, diosgenin (Dio), has attracted increasing attention because it possesses various therapeutic effects, including anti-tumor, anti-infective and anti-allergic properties. However, the commercial application of Dio is limited by its extremely low aqueous solubility and inferior bioavailability in vivo. Soluplus, a novel excipient, has great solubilization and capacity of crystallization inhibition. The purpose of this study was to prepare Soluplus-mediated Dio amorphous solid dispersions (ASDs) to improve its solubility, bioavailability and stability. METHODS: The crystallization inhibition studies were firstly carried out to select excipients using a solvent shift method. According to solubility and dissolution results, the preparation methods and the ratios of drug to excipient were further optimized. The interaction between Dio and Soluplus was characterized by differential scanning calorimetry (DSC), fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and molecular docking. The pharmacokinetic study was conducted to explore the potential of Dio ASDs for oral administration. Furthermore, the long-term stability of Dio ASDs was also investigated. RESULTS: Soluplus was preliminarily selected from various excipients because of its potential to improve solubility and stability. The optimized ASDs significantly improved the aqueous solubility of Dio due to its amorphization and the molecular interactions between Dio and Soluplus, as evidenced by dissolution test in vitro, DSC, FT-IR spectroscopy, SEM, PXRD and molecular docking technique. Furthermore, pharmacokinetic studies in rats revealed that the bioavailability of Dio from ASDs was improved about 5 times. In addition, Dio ASDs were stable when stored at 40°C and 75% humidity for 6 months. CONCLUSION: These results indicated that Dio ASDs, with its high solubility, high bioavailability and high stability, would open a promising way in pharmaceutical applications.

[Healing of the periimplant mucosal tissue injury after placing retraction cord subgingivally in beagle dogs].

OBJECTIVE: This work aims to observe the healing of periimplant mucosal tissue injury in beagle dogs after subgingival retraction cord placement by examining the gingival index (GI), quantity of gingival crevicular fluid (GCF), and the proinflammatory cytokine in the GCF. METHODS: In eight beagle dogs, the fourth mandibular premolars on the left side were extracted (n=8); after two months of healing, bone-level implants were installed. A plaque control regimen was performed throughout the duration of the experiment. After three months, retraction cords were placed subgingivally for 5 min before the cement-retained implant-supported crowns were cemented. GI, GCF quantity, and levels of tumor necrosis factor-alpha (TNF-α) in GCF were assessed before application and on days 1, 3, 7, 14, 28, and 56 after application. RESULTS: GI, quantity of GCF, and TNF-α were significantly increased on days 1, 3, and 7 compared with those at the baseline and on days 14, 28, and 56 (P<0.05), and no statistically significant differences were observed among those on days 14, 28, and 56 and the baseline (P>0.05). CONCLUSIONS: Under the circumstances of good oral hygiene, acute injury caused by placing retraction cord subgingivally in periimplant mucosal tissue of bone-level implant is reversible. GI, the quantity of GCF, and TNF-α on day 14 return to the baseline levels.

A new water-soluble polythiophene derivative as a probe for real-time monitoring adenosine 5'-triphosphatase activity in lysosome of living cells.

Detection of the adenosine 5'-triphosphatase (ATPase) activity in lysosome of living cells is of great importance for clinical diagnosis of many related diseases, including cancer. In this work, a new water-soluble polythiophene derivative named ZnPT bearing both quaternary ammonium salt groups and dipicolylamine-Zn2+ (DPA-Zn2+) complexes in its side chain, was designed and synthesized for this propose. The probe mainly localized to lysosome with good biocompatibility and membrane penetration. The real-time, continuous, direct, and label-free assays were achieved through a fluorescence "turn-on" mode by taking advantages of the reaction specificity of ATPase with ATP and the high binding selectivity of ZnPT toward ATP substrate over its hydrolysis product (ADP). This well designed strategy should provide a facile and effective way for investigating ATPase-relevant biological processes.

Novel Inorganic-Based N-Halamine Nanofibrous Membranes As Highly Effective Antibacterial Agent for Water Disinfection.

Novel superhydrophilic inorganic-based N-halamine nanofibrous membranes with high active chlorine contents, outstanding rechargeability, favorable water swelling resistance, and superior mechanical performance were prepared through the combination of electrospinning and sol-gel processing, which could be applied to the dynamic disinfection of bacteria-contaminated water with high disinfection efficiency, large processing flux, and long-term durability. The successful preparation of such silica nanofiber membranous N-halamine antimicrobial with intriguing properties would provide the reference for developing novel antimicrobial nanofibers for multifunctional applications.

Soluble microbial products in membrane bioreactor operation: Behaviors, characteristics, and fouling potential.

This paper presents an experimental study on soluble microbial products (SMP) in membrane bioreactor (MBR) operation at different sludge retention times (SRTs). A laboratory-scale MBR was operated at SRT of 10, 20, and 40 days for treatment of readily biodegradable synthetic wastewater. The accumulation, composition, characteristics, and fouling potential of SMP at each SRT were examined. It was found that accumulation of SMP in the MBR became more pronounced at short SRTs. Carbohydrates and proteins appeared to be the components of SMP prone to accumulate in the MBR compared with aromatic compounds. The proportions of SMP with large molecular weight in supernatants and in effluents were almost identical, implying that membrane sieving did not work for most SMP. In addition, the majority of SMP was found to be composed of hydrophobic components, whose proportion in total SMP gradually increased as SRT lengthened. However, fouling potentials of SMP were relatively low at long SRTs. The hydrophilic neutrals (e.g., carbohydrates) were most likely the main foulants responsible for high fouling potentials of SMP observed at short SRTs.

Preliminary research on DNA methylation changes during murine palatogenesis induced by TCDD.

2,3,7,8-Tetrachlrodibenzo-p-dioxin (TCDD) has been shown to induce cleft palate through growth factor and receptor expression changes during palatogenesis. DNA methylation is an important epigenetic modification that can regulate gene expressions and may be involved in TCDD-induced cleft palate. In this study, we investigated the effects of TCDD on the global and CpG DNA methylation status and the expression levels of DNA methyltransferases (Dnmts) in palate tissue of fetal mice. Pregnant C57BL/6J mice were administered with corn oil or TCDD 28 µg/kg at gestation day 10.5(GD10.5), and sacrificed at GD13.5, 14.5, 15.5. Fetal palates were collected for molecular analysis. Global DNA methylation status was detected by Methylamp™ Global DNA Methylation Quantification Ultra Kit. The expression of DNA methyltransferases were examined by quantitative real-time PCR(q-PCR). Methylation Specific PCR (MSP) was performed to analyze CpG methylation status of Dnmts. We found that the global DNA methylation level and the expression of Dnmt3a were higher at GD13.5 in the TCDD group. The methylation level of CpG site 2 in the promoter region of Dnmt3a in the control group was higher than that of the TCDD group at GD13.5. The low CpG methylation level of Dnmt3a at GD13.5 which causes the up-expression of Dnmt3a may induce global hypermethylation in fetal palate tissue. The aberrant global methylation status at GD13.5 may be the cause of palate malformation in fetal mice induced by TCDD.

Hyaluronic acid-coated niosomes facilitate tacrolimus ocular delivery: Mucoadhesion, precorneal retention, aqueous humor pharmacokinetics, and transcorneal permeability.

Tacrolimus (FK506) was used to prevent corneal allograft rejection in patients who were resistant to steroids and cyclosporine. However, the formulation for FK506 ocular delivery remained a challenge due to the drug's high hydrophobicity, high molecular weight, and eye's physiological and anatomical constraints. The aim of this project is to develop an ocular delivery system for FK506 based on a combined strategy of niosomes and mucoadhesive hyaluronic acid (HA), i.e., FK506HA-coated niosomes, which exploits virtues of both niosomes and HA to synergistically improve ophthalmic bioavailability. The FK506HA-coated niosomes were characterized with particle size, zeta potential, and rheology behavior. Mucoadhesion of FK506HA-coated niosomes to mucin was investigated through surface plasmon resonance in comparison with non-coated niosomes and HA solution. The results showed that niosomes possessed adhesion to mucin, and HA coating enhanced the adhesion. The in vivo precorneal retention was evaluated in rabbit, and the results showed that HA-coated niosomes prolonged the residence of FK506 significantly in comparison with non-coated niosomes or suspension. Aqueous humor pharmacokinetics test showed that area under curve of HA-coated niosomes was 2.3-fold and 1.2-fold as that of suspension and non-coated niosomes, respectively. Moreover, the synergetic corneal permeability enhancement of the hybrid delivery system on FK506 was visualized and confirmed by confocal laser scanning microscope. Overall, the results indicated that the hybrid system facilitated FK506 ocular delivery on mucoadhesion, precorneal retention, aqueous humor pharmacokinetics and transcorneal permeability. Therefore, HA-coated niosomes may be a promising approach for ocular targeting delivery of FK506.

Effect of zero-valent iron on the start-up performance of anaerobic ammonium oxidation (anammox) process.

The long start-up time of anaerobic ammonium oxidation (anammox) process hinders the widespread application of anammox technology in practical wastewater treatment when anammox seed sludge is not available. Meanwhile, the production of nitrate cannot meet the increasingly more strict discharge standards. To combine the chemical nitrate reduction to ammonium with biological nitrogen removal, two anammox upflow anaerobic sludge blanket reactors packed with different types of zero-valent iron (ZVI), microscale ZVI (mZVI) and nanoscale ZVI (nZVI), were developed to accelerate the start-up of anammox process. The results revealed that anammox start-up time shortened from 126 to 105 and 84 days with the addition of mZVI and nZVI. The nitrogen removal performance was also improved remarkably by adding ZVI, especially in the start-up stage. The value of dissolved oxygen showed that ZVI could be regarded as a useful deoxidant to create anaerobic condition for the proliferation of anammox bacteria. ZVI was favorable for the secretion of EPS, which would represent the activity of anammox bacteria. The result of real-time quantitative PCR (qPCR) further confirmed that the proliferation of anammox bacteria was enhanced by ZVI.