Ion Exchange Resin Column Research Articles

Ion-exchange resins improve the analysis of metal nanoparticles in wastewater using single-particle inductively coupled plasma-mass spectrometry.

Improved measurement and analysis technologies are needed for investigating nanoparticle generation characteristics in sewage treatment plants. Single-particle inductively coupled plasma-mass spectrometry (spICP-MS) can be used to analyze metal nanoparticle characteristics. However, during spICP-MS analysis of environmental samples, high concentrations of ionic materials obscure the signals of particulate materials by increasing background signals. This can increase the threshold value for separating background and particle signals and increase the background-equivalent diameter (BED). In this study, particle size distributions in influent and effluent collected from sewage treatment plants were investigated using an improved spICP-MS method combining spICP-MS with ion-exchange resin (IER) column pretreatment. The ion removal effect of the IER column was first examined using a synthetic mixture of Ag nanoparticles (AgNPs) and ions. The method was then applied to wastewater from six different sewage treatment plants using an optimal IER packing of 5g. The ion removal efficiency for samples containing a proper mixture of AgNPs and Ag ions was 99.98%, and the BED significantly decreased from 73.0 ± 1.0 to 6.1 ± 0.3nm. Particle size distributions measured in the treatment plant influent and effluent ranged from 28.5nm (Co) to 220.3nm (Mg) and from 26.8nm (Co) to 291.8nm (Mg), respectively. spICP-MS/IER enabled the detection of smaller particles by removing ions from the sample and significantly decreasing the size detection limit. The results of this study offer a reference for developing predictive models for removing metal nanoparticles during sewage/wastewater treatment.

Impact of Wastewater from Outfall of River on Bitter Gourd: Morphological and Biochemical Studies, Peptide Synthesis and Antioxidant Activity

River pollution poses a significant concern for the people of India who heavily rely on river water for daily needs. This study focuses on assessing the status of river pollution in West Bengal, India, with a particular emphasis on a major canal (N22° 39'08.75'' E88° 21'27.60'') near Dakhineswar New Jetty, known for its Kali Temple and frequent ritual activities. The region's dependence on river water is evident in daily life. Analysis of three consecutive years (2016-2018) reveals alarming levels of Total Coliform, reaching up to 8.18 x 106 MPN/100ml during the premonsoon season. Disturbingly high concentrations of Lead (0.069 mg/L) and Mercury (0.008 mg/L) are recorded. Average Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD) are 2.3 mg/L and 7.9 mg/L, respectively, during the premonsoon. The impact of wastewater on Bitter Gourd (Momordica charantia L.) manifests in detrimental changes to both morphological and biochemical parameters, including total chlorophyll and protein content. Low molecular weight peptide(s) (3.0-0.5 kDa) are extracted, purified, and analyzed through ion exchange resin column, ultra-filtration, and HPLC. HPLC analysis distinguishes the presence of peptides compared to the control, revealing adverse effects of wastewater. The antioxidant activity of low molecular weight peptide(s) is demonstrated through DPPH scavenging. Bioassays, such as the germination percentage of wastewater-treated Bitter Gourd seeds, indicate inhibition. The intensified impact of wastewater during the premonsoon season underscores the urgency of addressing river pollution in this region.

Preliminary progress report on 10Be and 26Al sample preparation at the IHEG, CAGS AMS laboratory

Based on previous experimental methods, this study explored the separation of quartz from other minerals and an extraction protocol for 10Be and 26Al. The results showed that paramagnetic minerals are removed with current multistage physical and chemical purification process. A dowex 50 W × 8 (H+) ion-exchange resin column was used for 10Be and 26Al chromatography. The optimal elution fractions for separating Be using 1.1 M HCl were 40–140 ml with a recovery rate of 83 % and those for separating Al using 6 M HCl were 170–230 ml with a recovery rate of only 33 %. The blank values of 10Be/9Be and 26Al/27Al ratios were 4.59E−15 and 2.49E−14, respectively. Two granite pebbles samples were analyzed using the experimental procedure established in this study, and the 10Be/9Be and 26Al/27Al ratios were (4.72 ± 0.23)E−13, (2.99 ± 0.22)E−13, and (7.28 ± 0.40)E−13, (2.83 ± 0.29)E−13, respectively.

The Gut Microbiota Regulates the Metabolic Benefits Mediated by Red Raspberry Polyphenols

ObjectivesRed raspberry (RR) polyphenols, including ellagic acid and their gut-derived metabolites, the urolithins, reduce inflammation and improve insulin sensitivity. However, it is unknown whether the gut microbiota is responsible for these health benefits and why certain individuals do not transform ellagic acid into urolithins. Here, we determined the causative role for the microbiome in mediating the health benefits from RR polyphenols using germ-free and conventionalized mouse models of diet-induced obesity. We also tested whether Gordonibacter urolithinfaciens (G. uro), a gut microbe previously shown to metabolize ellagic acid into urolithins, could enhance metabolic benefits when administered as a synbiotic with RR polyphenols. MethodsRR polyphenols were extracted using a macroporous ion-exchange resin column to remove sugars and fibers. C3H/HeN mice with (CVZ) or without a microbiota (GF) were fed either a low fat (LF), high fat (HF), or HF diet with RR polyphenols (HF + RR) for 12 weeks. For synbiotic studies, GF C57BL/6 mice were given a G. uro deficient-microbiome and then fed either a HF or HF + RR diet plus 20% fructose water with or without G. uro for 7 weeks. ResultsFeeding a HF diet increased body weight and fat mass for both GF and CVZ mice compared to feeding a LF diet (P < 0.05). Feeding a HF diet with RR polyphenols significantly decreased visceral adipose tissue and liver triglycerides (P < 0.05) compared to a HF control diet in CVZ but not GF mice. G. uro administration to mice receiving a HF diet and fructose water significantly reduced body weight, body fat percentage, fasting blood glucose, and subcutaneous adipose tissue mass as well as increased ileal tight junction protein gene expression (P < 0.05) compared to controls. Notably, mice supplemented with both G. uro and RR polyphenols experienced no metabolic improvements compared to controls (P < 0.05). ConclusionsOur results demonstrate that the microbiome is required for mediating RR polyphenol metabolic benefits. Supplementation of G. uro improved metabolic health; however, those beneficial effects were abrogated in the presence of RR polyphenols. Together, these results highlight the importance of considering specific diet-microbiota interactions when developing foods for preventing and treating obesity-related diseases. Funding SourcesUSDA NIFA.

Neutral polysaccharide from Panaxnotoginseng enhanced cyclophosphamide antitumor efficacy in hepatoma H22-bearing mice

BackgroundOur previous studies demonstrated that the administration of crude Polysaccharide from Panax notoginseng (CPPN) can effectively prolong the lifespan of tumor-bearing mice via boosting the host immune system as well as weak cytotoxicity against hepatocellular carcinoma (HCC). In the present study, Neutral Polysaccharide (NPPN) were further purified from crude polysaccharide isolated from panax notoginseng. The effects of NPPN on the immune function and hematopoietic function of mice with low immunity and myelosuppression induced by cyclophosphamide (CTX) were investigated. The effect of NPPN combined with CTX on the tumor inhibition rate of the H22 tumor-bearing mice and the impact of NPPN on the proliferation of H22 liver cancer cells in vitro were investigated.MethodsCPPN was obtained by water extraction and alcohol precipitation method, and further purified by DEAE Sepharose Fast Flow ion exchange resin column. NPPN was added to the immunosuppressed with myelosuppression mice induced by CTX. Thymus index, spleen index, lymphocyte proliferation stimulation index by adding of concanavalin A, determination of serum hemolysin, NK cell activity assay, mice carbon clearance experiment, blood count tests were detected. The tumor inhibition rate of the H22 tumor-bearing mice treated with NPPN combined with CTX was recorded.ResultsNPPN and 4 kinds of acid polysaccharide from Panax notoginseng (APPN) were successfully isolated from the CPPN by DEAE Sepharose Fast Flow ion exchange resin column. NPPN inhibited the growth of H22 cells and significantly increase the tumor inhibition rate of the H22 tumor-bearing mice combined with CTX. The elevation of the cellular and humoral immunity levels as well as a variety of blood count tests indicators of immunosuppressive with myelosuppression mice may contribute to the antitumor activity of NPPN.ConclusionNPPN has a potential antitumor activity for the treatment of liver cancer combined with cyclophosphamide.

Sulphate Removal from Flotation Process Water Using Ion-Exchange Resin Column System

Water chemistry is one of the most important parameters affecting flotation performance. Various types of ions can dissolve and accumulate in process water depending on ore mineralogy, reagent scheme, grinding medium and chemistry of mine site water. Sulfur-based ions (sulfate, thiosulfate, polythionate) are generally observed in flotation of sulfide ores. High concentrations of these ions may reduce efficiency of the flotation process, causing scale problems. Removal of these ions from process water often requires complex water treatment plants with high capital and operating costs. In this study, partial cleaning of water was investigated as an alternative approach for decreasing high sulphate concentrations of 3000–3800 mg/L down to 1000–1500 mg/L, an acceptable concentration for most sulfide ore flotation plants, by using an ion-exchange resin. For this purpose, detailed adsorption tests were performed using a laboratory-scale column system to determine the most suitable type of resin for adsorption of sulfate and thiosalts, kinetics of adsorption and regeneration of the resins. A strong base anion ion exchange resin (Selion SBA2000) was used in the experiments. The findings from the laboratory scale studies were validated in a Cu-Pb-Zn Flotation Plant in an Iberian mine using a larger scale of column set-up. The results showed that 60–70% of sulphates could be successfully removed from process water. Adsorption capacity of the resin was determined as 80.3 mg SO4/g resin. Concentrations of thiosalts and polythionates were also reduced to nearly zero value from 500 mg/L and 1000 mg/L, respectively. Flowrate of water had a significant effect on adsorption performance. The resin could be regenerated successfully using 2% (w/v) NaOH solution and used multiple times for water treatment.

Synthesis and characterization of a novel soluble neohesperidin-copper(II) complex using Ion-exchange resin column

The complexation of a flavonoid with metal ions can help increase its bioactivity or bioavailability. A novel method was designed and developed to synthesize a new neohesperidin-Cu(II) complex using an ion-exchange resin column. The integration of the separation or desorption process of neohesperidin (NH) from the resin and the complexation reaction between neohesperidin and Copper (II) was achieved in the column. The possible synthetic mechanism was analyzed using UV–Vis, FT-IR, XRD, TGA, and Hard and Soft Acid and Base theory. Additionally, the inhibition of the complex on tyrosinase activity was studied. The experimental results showed that the macro-porous strong basic anion-exchange resin D296 can effectively enrich neohesperidin, with a saturated adsorption capacity was 2.38 mg/mL of wet resin. During the integrated method, the CuCl2 concentration was set as 0.2 mol/L. The proposed mechanism for the integration is based on three factors. The first one is the exchange between NH anions and Cl−; the second one is the fact that neohesperidin is a soft base and can form a stable complex with Cu2+ in the stoichiometric ratio of 2:1(neohesperidin: Cu2+), and the third factor is that the “embedding effect” of neohesperidin on Cu2+ and the “concentrate” effect of Cu2+ on neohesperidin increase the solubility of neohesperidin in the complexation process. The neohesperidin-copper(II) complex can inhibit tyrosinase activity, and the findings of this study can offer a reference to the value-added development of effective ingredients like neohesperidin in plants.

Recovery of Ni(II) from real electroplating wastewater using fixed-bed resin adsorption and subsequent electrodeposition

Effective recovery of high-value heavy metals from electroplating wastewater is of great significance, but recovering nickel ions from real electroplating wastewater as nickel sheet has not been reported. In this study, the pilot-scale fixed-bed resin adsorption was conducted to recover Ni(II) ions from real nickel plating wastewater, and then the concentrated Ni(II) ions in the regenerated solution were reduced to nickel sheet via electrodeposition. A commercial cation-exchange resin was selected and the optimal resin adsorption and regeneration conditions were investigated. The resin exhibited an adsorption capacity of 63 mg/g for Ni(II) ions, and the average amount of treated water was 84.6 bed volumes (BV) in the pilot-scale experiments. After the adsorption by two ion-exchange resin columns in series and one chelating resin column, the concentrations of Ni(II) in the treated wastewater were below 0.1 mg/L. After the regeneration of the spent resin using 3 BVof 4% (w/w) HCl solution, 1.5 BV of concentrated neutral nickel solution (>30 g/L) was obtained and used in the subsequent electrodeposition process. Using the aeration method, alkali and water required in resin activation process were greatly reduced to 2 BV and 3 BV, respectively. Under the optimal electrodeposition conditions, 95.6% of Ni(II) in desorption eluent could be recovered as the elemental nickel on the cathode. The total treatment cost for the resin adsorption and regeneration as well as the electrodeposition was calculated.

Repeatability and reproducibility of measurements of low dissolved radiocesium concentrations in freshwater using different pre-concentration methods

We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (Prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the 137Cs results were within ± 2, indicating that the methods were a good degree of precision. The relative standard deviations (RSDs) indicating the reproducibility among different laboratories were larger than the RSDs indicating the repeatability in each separate laboratory.

Synthesis, X-ray Crystal Structure, and Photochromism of a Sandwich-Type Mono-Aluminum Complex Composed of Two Tri-Lacunary α-Dawson-Type Polyoxotungstates.

The synthesis and molecular structure of a dimeric, mono-aluminum complex composed of two tri-lacunary α-Dawson polyoxometalates, [H14Al(B-α-P2W15O56)2]7− (1), is described herein. The tetra-n-butylammonium salt of 1, [(n-C4H9)4N]7[H14Al(B-α-P2W15O56)2] (TBA-1) was prepared by passing an aqueous solution of K6[B-α-H3P2W15O59{Al(OH2)}3]⋅14H2O through an ion-exchange resin column (H+-form), followed by addition of tetra-n-butylammonium bromide. Analytically pure and colorless crystals of TBA-1 were obtained via vapor diffusion from acetonitrile/methanol at ~25 °C. Single-crystal X-ray structure analysis revealed that a six-coordinate aluminum ion was sandwiched between two tri-lacunary α-Dawson-type units, resulting in an overall C2h symmetry. The characterization of TBA-1 was accomplished by elemental analyses, thermogravimetric/differential thermal analyses, Fourier-transform infrared spectroscopy, and solution 31P nuclear magnetic resonance spectroscopy. The photochromic properties of TBA-1 were also characterized in methanol under light irradiation (λ = 365 nm and ≥400 nm).

Critical point analysis and biocide treatment in a microbiologically contaminated water purification system of a power plant

Many industries use ultrapure water (UPW) for their operation. In spite of purification efforts, microbial contaminations are the major cause of manufacturing problems in these systems. In our experiments, the water purification system of a power plant was investigated: the microbiologically critical points of the ultrapure water purification system were located by checking the number and diversity of bacteria to determine the optimum operational unit for chemical intervention: the most contaminated site was the mixed-bed ion-exchange resin containing unit. Biocides were tested against bacteria previously isolated from the same system; effect of biocides was checked also in laboratory model systems, and based on the results, a biocide treatment was carried out in the mixed-bed ion-exchange resin columns of the working power plant. Kathon WT was the most effective from the studied chemicals, being effective already in low concentration against most studied microorganisms. In case of the handling of the mixed-bed ion-exchange resin, 8-h treatment with 25 ppm biocide concentration was effective. Following the treatment, the quality of the produced UPW met the standards (specific electric conductivity was < 1.0 × 10−3 µS cm−1 at 25 °C) and water production capacity increased; moreover, the run-down time of the mixed-bed ion-exchange resin significantly grew.

In Situ Measurement of Nitrate Flux and Attenuation Using a Soil Passive Flux Meter.

This work enhances our understanding of catchment-scale N budgets by demonstrating the modification and application of a simple method for direct in situ measurements of vadose zone nitrate leaching and attenuation. We developed a soil passive flux meter (SPFM) to measure solute leaching based on a modified design of ion-exchange resin columns, and we tested the design in numerical simulations, laboratory experiments, plot-scale field experiments, and a catchment-scale field deployment. Our design minimized flow divergence around the resin column to attain nearly 100% capture of surface applied tracers in plot- and catchment-scale deployments. We found that mixing resin with native soil and extending the column height 10 cm above the resin layer minimized divergence of soil water around the column, resulting in a field-measured convergence factor (χ) of 1.3 that was consistent with numerical simulations. For catchment-scale testing, SPFMs were used at nine sites in three dominant land uses (crop, pasture, and turf) with known N inputs in two deployments, one during the 4-mo wet season and an additional set during the 8-mo dry season, to obtain integral annual measures of soil nitrate fluxes. In situ measured nitrate leaching determined from the SPFMs was positively correlated with known N inputs ( = 0.55, < 0.05) and attenuation averaged 67% (± 24% SD) of inputs across all sites. Although N inputs explain a large portion of the variability, our results emphasize the importance of both inter- and intra-land use variability in landscape-scale N budgets.

Struvite production using membrane-bioreactor wastewater effluent and seawater

Wastewater phosphorus (P) released into natural water bodies such as lakes and rivers, can cause water pollution as a result of eutrophication. If this P is effectively removed from wastewaters and economically recovered for use as fertilisers, not only can the water pollution be controlled, but also reduce the anticipated global shortage of P. This scarcity will result from the natural phosphate rock reserve being exhausted. Three experiments were conducted using membrane-bioreactor effluent (MBR, 35 mg PO4/L) and reverse osmosis concentrate (ROC, 10 mg PO4/L) waters to supply phosphate, and sea water (1530 mg Mg/L) to supply Mg for the production of struvite. The phosphate in the MBR and ROC was concentrated approximately 15 times by adsorption onto an ion exchange resin column followed by desorption. Struvite was precipitated by mixing the desorbed solution with seawater and NH4Cl. The chemical composition and mineral structure of the precipitates agreed with those of the reference struvite. When Ca in seawater (300 mg Ca/L) was removed before mixing the water with MBR or ROC, the purity of the struvite improved.

Determination of Rhenium in Geological Samples by Isotope Dilution–Multicollector–Inductively Coupled Plasma-Mass Spectrometry with Novel Chromatographic Separation

ABSTRACTA method was developed to determine rhenium contents in geological samples using multicollector–inductively coupled plasma-mass spectrometry (MC–ICP-MS) and extraction with an ion-exchange resin. Samples were digested in Carius tubes and osmium was converted into volatile OsO4, which was purified by distillation and microdistillation. The purified Os contents and isotopic ratios were determined using negative thermal ionization mass spectrometry. After the distillation of Os, the samples were treated with HF, then 1.2 M HCl, and loaded on ion-exchange resin columns. Re was eluted using 0.75 M HNO3 and directly determined by MC–ICP-MS. This method was validated using a series of reference materials and the analytical Re data are consistent with the literature values. This method precision (relative standard deviation) ranged from 0.8 to 6%. The procedural blank and detection limit (3σ) of Re were 1.1 pg and 0.5 pg/g (for a sample size of 2g), respectively. These results indicate that the proposed method can be applied to determine trace Re in geological samples. Using Carius tube digestion combined with HF desilicification and redissolution, the Re and Os contents found in the soluble and insoluble phases of several reference materials indicated that the distributions of Re and Os were homogeneous and heterogeneous, respectively.

Application of Ion-Exchange Resin Column for Basic Development of Strontium-90/Yttrium-90 Generator for Preparation of Radiopharmaceutical Therapy

The aim of this study is to examine the possible use of ion-exchange resin on Dowex AG 50x8 in separating Y-90 from Sr-90 which then could be applied in the basic of manufacture of producing Sr-90/Y-90 generator for the production of radiopharmaceutical cancer therapy. The findings showed that a distributive coefficient of Sr-90 and Y-90 with HCl 6 N solvent showed that distributive coefficient of Sr-90 in cation-exchange resin on Dowex 50x8 was greater than Y-90. Y-90 in HCl 6 N solvent was more easily eluted, while Sr-90 was bound to resin.. In conclusion, resin on Dowex AG 50x8 with HCl 6 N elution solvent might be able to separate Y-90 from Sr-90 as the basis for Sr-90/Y-90 generator.

Flow injection determination of cyromazine in natural water samples using diperiodatoargentate(III)–H2SO4–chemiluminescence system

ABSTRACTA simple and sensitive chemiluminescence (CL) procedure is proposed for the determination of cyromazine (CYR) using flow injection technique. CYR has strong enhancing effect on the CL reaction of diperiodatoargentate-(III) complex (DPA) in H2SO4 medium. The CL intensity with solid phase extraction (SPE) technique and with and without using online ion exchange resin column (IERC; OH-form) was proportional to the concentration of CYR over the range 0.1–200, 10–1000 and 2–2500 µg L–1 (R2 = 0.9974, 0.9980 and 0.9990, n = 7 each), respectively. Under the conditions, the limits of detection (S/N = 3) 0.029, 2.5 and 0.5 µg L–1, relative standard deviations (n = 3) 1.9–3.6%, 1.4–2.7% and 1.0–3.0% and sample throughputs were 120, 80 and 120 h–1. The effect of reagents concentration, flow rate, sample loop volume, photomultiplier voltage and IERC length was optimised. The mean results for natural water samples analysed by the proposed method were not significantly different at 95% confidence limit with the previously reported HPLC method. Interference from chloride ions could be eliminated by using SPE procedure or incorporating an in-line IERC. The CL mechanism of DPA–H2SO4–CYR system was also discussed briefly.

Cation resin fixed-bed column for the recovery of valuable THAM reagent from the wastewater

Abstract Two commercial available cation resins, i.e. Amberlite IR-120 and Dowex HCR-W2, were tested as ion exchange adsorbents to investigate their isotherms, kinetics, breakthrough characteristics and regeneration on removal and recovery of tetra-methyl ammonium hydroxide (TMAH) from wastewater. Batch and column experiments were investigated to obtain experimental data for theoretical modelling and verify the column performance of the ion exchange process. The Langmuir isotherm represents better equilibrium behavior of both resins on TMAH uptake. The ion exchange kinetics follows the pseudo second order rate law also for both resins. Furthermore, breakthrough characteristics study shows the breakthrough curves follow the Thomas model and Yoon–Nelson model very well. The recovery efficiencies of TMAH were obtained as 99.6 and 98.0% from wastewater by ion exchange resin column by using 9 N HCl regeneration for Amberlite IR-120 and Dowex HCR-W2 resins, respectively. The comparative study on TMAH ion exchange removal by Amberlite IR-120 and Dowex HCR-W2 resins in fixed bed column suggested that Dowex HCR-W2 demonstrates higher ion exchange capacity than that of Amberlite IR-120 resin.

Ambient CO2 capture and storage in bioelectrochemically mediated wastewater treatment

This study reports that wastewater can be used to capture and store CO2 directly from ambient air and produce energy. The proof-of-concept system consisted of an ion exchange resin column that captures and concentrates ambient CO2 using a moisture-driven cycle. The concentrated CO2 was then transferred into a microbial electrochemical carbon capture (MECC) reactor for carbon sequestration and hydrogen production. Data from an average batch cycle showed that approximately 8mmol/L CO2 was captured in the MECC cathode when 0.14g/LCOD was removed in the anode. With 90% hydrogen conversion efficiency, the energy intensity and CO2 absorption from the process could be 11.3kJ/gCOD and 0.49gCO2/gCOD respectively. If the proposed process is applied, over 68milliontons of atmospheric CO2 can be captured yearly during wastewater treatment in the US, which equates to significant economic values if CO2 taxes were to be implemented more widely.

A universal aqueous-based antifouling coating for multi-material devices

Event Abstract Back to Event A universal aqueous-based antifouling coating for multi-material devices Sharon Goh1*, Yafei Luan2, Xiaojing Wang2*, Hong Chen2*, John L. Brash1 and Qiyin Fang1* 1 McMaster University, School of Biomedical Engineering, Canada 2 Soochow University, Polymer Science and Engineering, China Introduction: Preventing unwanted protein adsorption is important to improve implant biocompatibility, reduce biofouling, and control cell adhesion. A typical approach involves grafting polymers to alter surface chemistry. However, many surface modification protocols require harsh chemical conditions and solvents which may not be suitable for some materials. Thus, antifouling protocols need to consider the chemical stability of the substrate and, consequently, their applicability may be limited. This is of importance for biomedical devices which are composed of multiple classes of materials. Therefore, antifouling methods suitable for whole device modification are highly desirable [1],[2]. An aqueous-based polyethylene glycol (PEG) antifouling coating was previously developed using polydopamine (PDA) as a spacer [1]. PDA has been demonstrated to polymerize strongly onto virtually all material classes and readily forms covalent bonds with free amino groups.[3] However PEG grafting from solution may be sterically limited, leading to areas of exposed PDA available for protein binding. We sought to improve this method by backfilling the PDA-PEG coating with a non cell-adhesive protein, bovine serum albumin (BSA). A previous study on PDA-BSA coated substrates reportedly reduced cell adhesion compared to PDA [4]. We hypothesized that the combination of PEG and BSA may reduce fouling to a greater degree than PEG alone. Materials and Methods: Polydimethyl siloxane (PDMS), hydrophilic porous polycarbonate membranes (PC; 0.01 μm pore diameter), and borosilicate glass cover slips were incubated for 3 h with stirring in 2 mg/mL dopamine solution prepared in PBS, pH 8.5. The PDA coated surfaces were then incubated for 24 h in either (a): 10 mg/mL BSA (PBS, pH 7.4) at room temperature or (b): 5 mg/mL NH2-PEG-NH2 (MW 5000), (PBS, pH 8.5) at 37ºC or (c): (a) followed by (b) or (d): (b) followed by (a). Fibrinogen (Fg) was radiolabeled with I-125 using the ICl method and passed through an ion exchange resin column to remove free iodide. The surfaces were incubated in 1 mg/mL Fg solution in PBS (5% labelled) for 2 h, and rinsed with buffer. Adsorption was quantified from radioactivity measurements. Results and Discussion: Fg was used as a model protein to evaluate resistance to non-specific protein adsorption of the modified PDMS, glass, and PC. Adsorption data are shown in Figure 1. Consistent with previous reports [4], the PDA coated surfaces showed enhanced protein adsorption due to their ability to bind covalently to amino groups in Fg. Compared to the unmodified materials PEG modification was effective in reducing Fg adsorption only on PC. Interestingly, the PDA-PEG modified surfaces showed significantly higher Fg adsorption than the PDA-BSA, possibly due to the larger BSA molecules giving greater surface coverage. For all three substrates there was no significant difference in adsorption between PDA-BSA and PDA-BSA/PEG, possibly due to blockage of PEG attachment by the BSA. The lowest adsorption was seen on the PDA-PEG surfaces that were “backfilled” with BSA. These PDA-PEG/BSA surfaces showed reductions in Fg adsorption of 89%, 63%, and 55% for PC, glass, and PDMS, respectively. Figure 1. Fg adsorption on different substrates. SEM ± mean for n=6 replicates and two trials. Protein concentration = 1 mg/mL. Conclusions: Attachment of passivating moieties to a variety of material types using polydopamine as a bonding agent has been demonstrated. Backfilling PDA-PEG layers with albumin was shown to improve their antifouling properties. The modification was demonstrated on various types of materials, suggesting its utility as a universal antifouling coating. This strategy should be applicable to biomedical devices required to be non-fouling including implants and sensors. Mitacs Globalink; Government of Ontario

Urbanization in China changes the composition and main sources of wet inorganic nitrogen deposition.

Nowadays, nitrogen (N) deposition has become a growing global concern due to urbanization activities increasing the large amount of reactive N in the atmosphere. However, it remains unclear whether urbanization affects the composition and main sources of N deposition in rapidly urbanizing areas such as in China. One-year measurement of wet inorganic N deposition was conducted using ion-exchange resin (IER) columns in the range of 260 km from urban to rural areas in the Pearl River Delta (PRD) region, south China. An increasing pattern of wet inorganic deposition along the urbanization gradient was observed and it increased in the order: rural (15.26 ± 0.20 kg N ha(-1) year(-1)) < suburban/rural (21.45 ± 3.73 kg N ha(-1) year(-1)) < urban (31.16 ± 0.44 kg N ha(-1) year(-1)) < urban/suburban sites (34.15 ± 5.73 kg N ha(-1) year(-1)). Nitrate N (NO3 (-)-N) accounted for 53.5-79.1 % of total wet inorganic N deposition, indicating a significant negative correlation with distance from the urban core. Based on moss δ(15)N-values the main source of NO3 (-)-N was considered to be emitted from vehicles. Our results demonstrate that urbanization has large impacts on the regional pattern of wet inorganic N deposition. Thus, controlling NOx emission, especially vehicle emission will become an effective strategy for N pollution abatement in China.