Affinity adsorption of human vitamin K-dependent coagulation factor IX onto heparin-like poly (styrene sodium sulfonate) adsorbent

Adsorption of proteins on polymer material plays an important role in a number of fields, particularly in separation of biomolecules by chromatographic methods. The work reports here the synthesis of modified cross-linked polystyrene gel beads as a stationary phase in liquid chromatography for the purification of factor IX. Suitable chemical groups, such as sulfonate which confer this polymer heparin-like adsorbing property, were grafted on the aromatic ring of the hydrophobic matrix. This functional group was chosen on the basis of the biospecific molecular interactions between factor IX and its ligand particularly heparin in such manner to enhance its binding ability and efficacy. Adsorption of factor IX on to this functional polymer was performed under physiological conditions according two modes: non-competitive adsorption (adsorption of factor IX alone) and competitive adsorption (adsorption of factor IX in the presence of another vitamin-K dependent coagulation factors). The adsorbed factor IX content at the interface allows to establish the chemisorption isotherm curves. The adsorption rate in both cases was found to be significantly high and the affinity constants, estimated by the Langmuir model, were: 4.7 × 10⁸ and 4.1 × 10⁸ l/M respectively. Affinity chromatography on column using this functional polymer as a stationary phase confirms its high ability to adsorb factor IX at low ionic strength. Thus, the synthesized packing material gel functionalised by sulfonate group can be used advantageously as a heparin-like adsorbent in purification of factor IX.     

Adsorption behavior of caffeine as a green corrosion inhibitor for copper

Electrochemical and impedance experiments were carried out to evaluate the corrosion behavior of copper in aerated 0.1 mol L^? 1 H₂SO₄ solutions in the presence of three xanthine derivatives with similar chemical structures. The corrosion rate of copper was found to increase in the presence of theophylline and theobromine and decrease in the presence of caffeine. The adsorption and inhibitory effect of caffeine on copper surfaces in aerated 0.1 mol L^? 1 H₂SO₄ solutions were then investigated in detail by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), contact angle measurements, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and fluorescence experiments. The data obtained indicate that caffeine behaves as a cathodic-type inhibitor adsorbing onto the copper surface according to the Temkin isotherm, with the negative ?G°_ads value of ? 31.1 kJ mol^? 1 signifying a spontaneous adsorption process. The corrosion inhibition efficiency increased with caffeine concentration in the range of 1.0–10.0 mmol L^? 1. Furthermore, the EIS results obtained at the open-circuit potential and surface analysis (SEM, EDS and fluorescence) clearly demonstrated the adsorption of the organic compound onto the copper electrode. The contact angle measurements revealed the formation of a hydrophobic protective film. This film covers up to 72% of the total active surface, acts as a protective barrier and prevents interaction between the metal, water and oxygen molecules.     

Poly(hydroxyethyl methacrylate) based magnetic nanoparticles for plasmid DNA purification from Escherichia coli lysate

The aim of this study is to prepare poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine) [PHEMAH] magnetic nanoparticles for plasmid DNA (pDNA) purification from Escherichia coli (E. coli) cell lysate. Magnetic nanoparticles were produced by surfactant free emulsion polymerization. mPHEMAH nanoparticles were characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), electron spin resonance (ESR), thermogravimetric analyses (TGA) and transmission electron microscopy (TEM). Surface area, average particle size and size distribution were also performed. Specific surface area of the mPHEMAH nanoparticles was found to be 1180 m²/g. Elemental analysis of MAH for nitrogen was estimated as 0.18 mmol/g polymer. The amount of pDNA adsorbed onto the mPHEMAH nanoparticles first increased and then reached a saturation value at around 1.0 mg/mL of pDNA concentration. Compared with the mPHEMA nanoparticles (50 μg/g polymer), the pDNA adsorption capacity of the mPHEMAH nanoparticles (154 mg/g polymer) was improved significantly due to the MAH incorporation into the polymeric matrix. The maximum pDNA adsorption was achieved at 25 °C. The overall recovery of pDNA was calculated as 92%. The mPHEMAH nanoparticles could be used six times without decreasing the pDNA adsorption capacity significantly. The results indicate that the PHEMAH nanoparticles promise high selectivity for pDNA.     

As(V) removal from aqueous media using α-MnO2 nanorods-impregnated laterite composite adsorbents

We present a novel way of enhancing the utility of low cost readily available laterite by impregnating it with the α-MnO₂ nanorods, thus making a composite material suitable for the removal of As(V) from aqueous media. The composites were synthesized by two methods: (i) ball-milling of a physical blend of laterite with pre-synthesized MnO₂; and (ii) in situ formation of MnO₂ in the presence of laterite. The BET surface area of composites prepared by both methods was markedly higher compared to un-modified laterite, and the presence of MnO₂ in the composite was also confirmed by XRD analysis and TEM microscopy. The adsorption capacity for As(V) was found to be highly pH dependent and the adsorption kinetics followed a pseudo second-order kinetic model. The Langmuir adsorption isotherm was found to be the best model to describe the adsorption equilibrium of As(V) onto un-modified laterite as well both ball-milled and in situ formed composite. The adsorption capacities at room temperature and pH 7.0 were found to be 1.50 mg g^?1, 8.93 mg g^?1 and 9.70 mg g^?1, for un-modified laterite, ball-milled and in situ formed composite, respectively.     

Polymer electrolyte based dye-sensitized solar cell with rice starch and 1-methyl-3-propylimidazolium iodide ionic liquid

Biodegradable rice starch was used to prepare solid polymer electrolytes (SPEs) using sodium iodide salt. The polymer electrolytes are prepared using solution cast technique. 1-methyl-3-propylimidazolium iodide (MPII) ionic liquid was incorporated in the polymer electrolyte. The ionic conductivity of SPEs are measured and temperature-dependent behavior of SPEs studied. All the solid polymer electrolytes follow Arrhenius type of thermal activated model. The ionic conductivity increased after addition of MPII ionic liquid. The highest ionic conductivity of 1.20 × 10^− 3 S cm^− 1 is achieved upon addition of 20 wt.% of MPII ionic liquid. Structural properties of polymer electrolytes are studied with FTIR and XRD which confirmed complexation between polymer and ionic liquid. The polymer electrolytes are analyzed for thermal study using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Dye-sensitized solar cells (DSSC) are fabricated using polymer electrolytes and studied under Sun simulator. The highest energy conversion efficiency of 2.09% is attained after addition of 20 wt.% of MPII ionic liquid.     

Adsorption of gum Arabic on bioceramic nanoparticles

Surface modification agents can be used to tailor the surface chemistry and biological activity of bioceramic nanoparticles in very intriguing ways. However, the specific modes of interactions between macromolecules and nanoparticles can be difficult to characterize. The aim of this study was to investigate the adsorption of gum Arabic on hydroxyapatite (HAp) and magnetic nanoparticles (MNP) using the bicinchoninic acid (BCA) test. Gum Arabic (GA) is a natural gum that has been widely used as an emulsifying agent and shows promise for dispersing nanoparticles in aqueous solutions. The adsorption of GA onto HAp nanoparticles followed a Langmuir isotherm with an adsorption plateau occurring at 0.2 g GA/g HAp. The adsorption of GA onto MNP attained a maximum value of 0.6 g GA/g MNP, after which it decreased to approximately 0.2 g GA/g MNP. The maximum adsorption density of GA on both MNP and HAp is equivalent when normalized to the specific surface area (4 × 10^− 3 g GA/m²). Adsorbed GA molecules were displaced from the surface of HAp and MNP in the presence of phosphate ions.     

Preparation of biomorphic porous calcium titanate and its application for preconcentration of nickel in water and food samples

Biomorphic porous nanocrystalline-calcium titanate (SPCTO) was successfully prepared using the sol–gel method and with sorghum straw as the template. Characterization was conducted through XRD, SEM and FTIR. The ability of SPCTO to adsorb nickel ion in water was assessed. Elution and regeneration conditions, as well as the thermodynamics and kinetics of nickel adsorption, were also investigated. The result showed that the sorbent by the sol–gel template method was porous and has a perovskite structure with an average particle diameter of 26 nm. The nickel ion could be quantitatively retained at a pH value range of 4–8, but the adsorbed nickel ion could be completely eluted using 2 mol L^? 1 HNO₃. The adsorption capacity of SPCTO for nickel was found to be 51.814 mg g^? 1 and the adsorption behavior followed a Langmuir adsorption isotherm and a pseudo-second-order kinetic model. The enthalpy change (ΔH) of the adsorption process was 33.520 kJ mol^? 1. At various temperatures, Gibbs free energy changes (ΔG) were negative, and entropy changes (ΔS) were positive. The activation energy (E_a) was 25.291 kJ mol^? 1 for the adsorption. These results demonstrate that the adsorption was an endothermic and spontaneous physical process. This same method has been successfully applied in the preconcentration and determination of nickel in water and food samples with good results.     

Silanized polymeric nanoparticles for DNA isolation

The aim of this study is to prepare silanized polymeric nanoparticles for DNA isolation. Polymeric p(HEMA)-IMEO-PBA nanoparticles around 85.7 nm diameter, was obtained by surfactant free emulsion polymerization for DNA isolation. Synthesized nanoparticles for characterization studies were realized scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Zeta-size. Surface area, average particle size and size distribution were also performed. The surface area of synthesized silanized polymeric nanoparticles was 2460 m²/g. Synthesized polymeric nanoparticles were silanized with 3-(2-imidazoline-1-yl)propyl (triethoxysilane) (IMEO). After that, phenylboronic acid (PBA) which is DNA specific ligand were covalently binded to silanized polymeric nanoparticles. The amount of DNA adsorbed onto the p(HEMA)-IMEO-PBA nanoparticles first increased and then reached a saturation value at around 14.0 mg/mL of DNA concentration. The maximum adsorption was 672.41 mg/g silanized polymeric nanoparticles in the optimum adsorption medium. The maximum DNA adsorption was achieved at 4 °C. The overall recovery of DNA was calculated as 95%. In repetitive adsorption–desorption circles, it is observed not being important decrease in DNA adsorption capacities. The results were shown that silanized polymeric nanoparticles can be a good alternative for DNA isolation.     

Synthesis and characterization of amino acid containing Cu(II) chelated nanoparticles for lysozyme adsorption

Immobilized metal ion affinity chromatography (IMAC) is a useful method for adsorption of proteins that have an affinity for transition metal ions. In this study, poly(hydroxyethyl methacrylate-methacryloyl-l-tryptophan) (PHEMATrp) nanoparticles were prepared by surfactant free emulsion polymerization. Then, Cu(II) ions were chelated on the PHEMATrp nanoparticles to be used in lysozyme adsorption studies in batch system. The maximum lysozyme adsorption capacity of the PHEMATrp nanoparticles was found to be 326.9 mg/g polymer at pH 7.0. The nonspecific lysozyme adsorption onto the PHEMA nanoparticles was negligible. In terms of protein desorption, it was observed that adsorbed lysozyme was readily desorbed in medium containing 1.0 M NaCl. The results showed that the metal-chelated PHEMATrp nanoparticles can be considered as a good adsorbent for lysozyme purification.     

Corrosion inhibition of aluminum in hydrochloric acid solution by alkylimidazolium ionic liquids

The effects of newly synthesized three alkylimidazolium ionic liquids—1-butyl-3-methylimidazolium chlorides (BMIC), 1-hexyl-3-methylimidazolium chlorides (HMIC) and 1-octyl-3-methylimidazolium chlorides (OMIC)—on the corrosion of aluminum in 1.0 M HCl were investigated using potentiodynamic polarization, electrochemical impedance spectroscopy and weight loss methods. All measurements showed that the inhibition efficiency increased with increase in the concentration of inhibitor and the effectiveness of these inhibitors was in the order of OMIC > HMIC > BMIC. Polarization curves revealed that the studied inhibitors were mixed type inhibitors. The adsorption of the inhibitors on the aluminum surface obeyed Langmuir adsorption isotherm and had a physical mechanism. The effect of temperature on the corrosion behavior in the presence of 5 × 10^?3 M of inhibitors was studied in the temperature range of 303–333 K. The associated activation energy of corrosion and other thermodynamic parameters such as enthalpy of activation (ΔH), entropy of activation (ΔS), adsorption equilibrium constant (K_ads) and free energy of adsorption (ΔG_ads) were calculated to elaborate the mechanism of corrosion inhibition.     

PAN–PEO solid polymer electrolytes with high ionic conductivity

The transparent and flexible solid polymer electrolytes (SPEs) are fabricated from polyacrylonitrile–polyethylene oxide (PAN–PEO) copolymer. The formation of the copolymer is confirmed by Fourier-transform infrared spectroscopy (FTIR) and Gel permeation chromatography (GPC) measurements. The effects of acrylonitrile (AN) wt% content and M_n(PEO) on ionic conductivity are investigated by alternating current (ac) impedance spectroscopy. By controlling and adjusting the AN wt% content and doping PEO with high molecular weight, the ionic conductivity of SPEs is optimized. The ionic conductivity of PAN–PEO solid polymer electrolytes is found to be high 6.79 × 10⁻⁴ S cm⁻¹ at 25 °C with an [EO]/[Li] ratio of about 10, and are electrochemically stable up to about 4.8 V versus Li/Li⁺. The conductivity and interfacial resistance remain almost constant even at 80 °C.     

Poly(hydroxyethyl methacrylate-co-methacryloylamidotryptophane) nanospheres and their utilization as affinity adsorbents for porcine pancreas lipase adsorption

Novel nanospheres with an average size of 350 nm utilizing N-methacryloyl-(l)-tryptophane methyl ester (MATrp) as a hydrophobic monomer were prepared by surfactant free emulsion polymerization of 2-hydroxyethyl methacrylate (HEMA), (MATrp) conducted in an aqueous dispersion medium. MATrp was synthesized using methacryloyl chloride and (l)-tryptophane methyl ester. Specific surface area of the non-porous nanospheres was found to be 1902.3 m²/g. poly(HEMA–MATrp) nanospheres were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM). Average particle size and size distribution measurements were also performed. Elemental analysis of MATrp for nitrogen was estimated at 1.36 mmol/g nanospheres. Then, poly(HEMA–MATrp) nanospheres were used in the adsorption of porcine pancreas lipase in a batch system. Using an optimized adsorption protocol, a very high loading of 558 mg enzyme/g nanospheres was obtained. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The K_m value for immobilized lipase (16.26 mM) was higher than that of free enzyme (10.34 mM). It was observed that enzyme could be repeatedly adsorbed and desorbed without significant loss in adsorption amount or enzyme activity. These findings show considerable promise for this material as an adsorption matrix in industrial processes.     

Equilibrium and kinetics of cadmium adsorption from aqueous solutions using untreated Pinus halepensis sawdust

Untreated Pinus halepensis sawdust has been investigated as an adsorbent for the removal of cadmium from aqueous solutions. Batch experiments were carried out to investigate the effect of pH, adsorbent dose, contact time, and metal concentration on sorption efficiency. The favorable pH for maximum cadmium adsorption was at 9.0. For the investigated cadmium concentrations (1–50 mg/L), maximum adsorption rates were achieved almost in the 10–20 min of contact. An adsorbent dose of 10 g/L was optimum for almost complete cadmium removal within 30 min from a 5 mg/L cadmium solution. For all contact times, an increase in cadmium concentration resulted in decrease in the percent cadmium removal (100–87%), and an increase in adsorption capacity (0.11–5.36 mg/g). The equilibrium adsorption data were best fitted with the Freundlich isotherm (R² = 0.960). The kinetics of cadmium adsorption was very well described by the pseudo-second-order kinetic model (R² > 0.999).     

Adsorption intrinsic kinetics and isotherms of lead ions on steel slag

Batch experiments were carried out to investigate the kinetics of adsorption of lead ions by steel slag on the basis of the external diffusion, intra-particle diffusion and adsorption reaction model (pseudo-first-order, pseudo-second-order). The results showed that the controlling step for the adsorption kinetics changed with the varying experimental parameters. When the particle size of steel slag was larger than 120 mesh, intra-particle diffusion of Pb²⁺ was the controlling step, and when the initial concentration of Pb²⁺ was less than 150 mg L^?1 or the shaking rate was lower than 150 rpm, external diffusion of Pb²⁺ was promoted. Contrary to the former experimental conditions the adsorption reaction was the controlling step, and the adsorption followed second-order kinetics, with an adsorption rate constant of 13.26 g mg^?1 min^?1. The adsorption isotherm of Pb²⁺ with steel slag followed the Langmuir model, with a correlation coefficient of 0.99.     

Electrochemical hydrogen evolution of multi-walled carbon nanotube/micro-hybrid composite decorated with Ni nanoparticles as catalyst through electroless deposition process

Hydrogen evolution of multi-walled nanotube (MWCNT)/micro-hybrid polymer composite, decorated with Ni nanoparticles through electroless deposition process is studied by the electrochemical method. Cyclic voltammetry (CV) is utilized to clearly study the electrochemical hydrogen storage/evolution behavior of the composite through a potential window ranging from ? 1.60 to + 0.60 V (vs. Ag/AgCl). Hydrogen adsorption/desorption peaks are positioned at ? 1.52 and ? 0.05 V, respectively. Chronoamperometry is also applied to estimate active surface area (0.145 m² g^? 1) of the composite as well as the diffusion coefficient (3.4 × 10^? 11 m² s^? 1) of adsorbed hydrogen process. According to the chrono-charge/discharge technique, the capacity of fabricated Ni-MWCNT/micro-hybrid composite is estimated to be 2.98 wt.% during charging for a certain time (40 min).     

PHEMA cryogel for in-vitro removal of anti-dsDNA antibodies from SLE plasma

Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA) cryogel carrying DNA was used in the removal of anti-dsDNA antibodies from systemic lupus erythematosus (SLE) patient plasma. The PHEMA cryogel was prepared by bulk polymerization which proceeds in an aqueous solution of monomer frozen inside a plastic syringe. After thawing, the PHEMA cryogel contains a continuous matrix having interconnected macropores of 10–200 μm size. Pore volume in the PHEMA cryogel was 67.5%. Ester groups in the PHEMA structure were converted to imine groups by reacting with poly(ethyleneimine) (PEI) in the presence of NaHCO₃. Amino (? NH₂) content of PEI-modified PHEMA cryogel was determined as 82 mg PEI/g. Then, DNA was attached onto the PHEMA cryogel via amino groups (53.4 mg DNA/g cryogel). Anti-dsDNA-antibody concentration declined significantly from 780 IU/ml to 80 IU/ml with the time. The maximum anti-dsDNA-antibody adsorption amount was 70 × 10³ IU/g. Anti-dsDNA-antibodies could be repeatedly adsorbed and eluted without noticeable loss in the anti-dsDNA-antibody adsorption amount.     

Magnetic chitosan nanoparticles for removal of Cr(VI) from aqueous solution

A simple method was introduced to prepare magnetic chitosan nanoparticles by co-precipitation via epichlorohydrin cross-linking reaction. The average size of magnetic chitosan nanoparticles is estimated at ca. 30 nm. It was found that the adsorption of Cr(VI) was highly pH-dependent and its kinetics follows the pseudo-second-order model. Maximum adsorption capacity (at pH 3, room temperature) was calculated as 55.80 mg·g^? 1, according to Langmuir isotherm model. The nanoparticles were thoroughly characterized before and after Cr(VI) adsorption. From this result, it can be suggested that magnetic chitosan nanoparticles could serve as a promising adsorbent for Cr(VI) in wastewater treatment technology.     

Temperature-swing adsorption of proteins in water using N-isopropylacrylamide copolymer gel particles

The adsorption and desorption behaviors of bovine serum albumin (BSA) in water for temperature-responsive polymer gel particles have been investigated by the temperature-swing operation between 298 and 313 K, where the cationic N-isopropylacrylamide (NIPA) gels copolymerized with vinylbenzyl trimethylammonium chloride (VBTA) or 2-(dimethylamino)ethyl methacrylate (DMAEMA) were used. The NIPA-VBTA and the NIPA-DMAEMA copolymer gels adsorbed BSA while the NIPA homopolymer gel hardly adsorbed BSA, indicating that the copolymer gels adsorb BSA through the electrostatic attraction between the positively charged groups in the gels and the negatively charged BSA. The adsorption amounts for the NIPA-DMAEMA gels were smaller than those for the NIPA-VBTA gels. This may be because almost every VBTA group, which is a quaternary ammonium salt, can be positively charged in water, while only some of the tertiary amine DMAEMA groups are protonated in water. Moreover, it was found that both the copolymer gels with a large mesh size of the polymer network repeatedly adsorbed BSA at 298 K and desorbed some of pre-adsorbed BSA at 313 K by the temperature-swing operation. This BSA desorption may result from the decrease of the number of the positively charged groups accessible to BSA due to the shrinking of the constituent polymer chains.     

Removal of Congo Red from aqueous solution by cattail root

In this study, cattail root was used to remove Congo Red (CR) from aqueous solution. The effects of operation variables, such as cattail root dosage, contact time, initial pH, ionic strength and temperature on the removal of CR were investigated using batch adsorption technique. Removal efficiency increased with increase of cattail root dosage and ionic strength, but decreased with increase of temperature. The equilibrium data fitted well to the Langmuir model (R² > 0.98) and the adsorption kinetic followed the pseudo-second-order equation (R² > 0.99). Thermodynamics parameters such as standard free energy change (ΔG°), standard enthalpy change (ΔH°), and standard entropy change (ΔS°) were analyzed. The values of ΔG° were between ?7.871 and ?4.702 kJ mol^?1, of ΔH° was ?54.116 kJ mol^?1, and of ΔS° was ?0.157 kJ mol^?1 K^?1, revealing that the removal of CR from aqueous solution by cattail root was a spontaneous and exothermic adsorption process. The maximum adsorption capacities of CR on cattail root were 38.79, 34.59 and 30.61 mg g^?1 at 20, 30 and 40 °C, respectively. These results suggest that cattail root is a potential low-cost adsorbent for the dye removal from industrial wastewater.     

Amperometric choline biosensors based on multi-wall carbon nanotubes and layer-by-layer assembly of multilayer films composed of Poly(diallyldimethylammonium chloride) and choline oxidase

A layer-by-layer deposition technique combined with Multi-wall carbon nanotubes (MWCNTs) was employed for fabricating choline sensors. The terminals and side-walls were linked with oxygen-containing groups when MWCNTs were treated with concentrated acid mixtures. A film of MWCNTs was initially prepared on the platinum electrode surface. Based on the electrostatic interaction between positively charged polyallylamine (PAA) and negatively charged MWCNTs and poly(vinyl sulfate) (PVS), a polymer film of (PVS/PAA)₃ was alternately adsorbed on the modified electrode continuously to be used as a permselective layer. Then poly(diallyldimethylammonium) (PDDA) and choline oxidase(ChOx) multilayer films were assembled layer-by-layer on the pretreated electrode, so an amplified biosensor toward choline was constructed. The choline sensor showed a linear response range of 5 × 10^? 7 to 1 × 10^? 4 M with a detection limit of 2 × 10^? 7 M estimated at a signal-to-noise ratio of 3, and a sensitivity of 12.53 μA/mM with a response time of 7.6 s in the presence of MWCNTs. Moreover, it exhibited excellent reproducibility, long-term stability as well as good suppression of interference. This protocol could be used to immobilize other enzymes for biosensor fabrication.