Effect of bovine serum albumin on the functionality and structure of catanionic surfactant at air–buffer interface

Interaction of bovine serum albumin (BSA) with the solvent spread monolayer of a catanionic surfactant, octadecyltrimethylammonium dodecylsulfate, (C₁₈TA⁺DS^?) at the air–buffer interface was investigated by measuring the surface pressure with time and change in surface area. Dipalmitoylphosphatidylcholine (DPPC) was used as reference. Kinetics of BSA desorption from the interface to the buffer subphase, that of C₁₈TA⁺DS^? and DPPC through their interaction with BSA, were also studied at different BSA concentrations (in the subphase) and surface pressures. Surface pressure (π)–area (A) isotherms (at pH = 5.4, μ = 0.01, T = 298 K) revealed that the coacervate/DPPC monolayer becomes expanded in the presence of BSA at low π while their protein bound species are released into the subphase at high π. Film morphology, studied by epifluorescence microscopy (EFM) and atomic force microscopy (AFM), reveals that the sizes of the domains of both DPPC and coacervate decrease in the presence of BSA. Presence of BSA in the coacervate and DPPC monolayer was supported from AFM data analysis.     

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.     

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.     

Hydrothermal synthesis,characterization and electrical investigation of poly(para-phenylenediamine)/vanadium oxide nanocomposite nanosheets

Sheet-like mesoporous poly(paraphenylenediamine)/vanadium oxide nanocomposite has been synthesized by the hydrothermal process using the vanadium oxide V₂O₅ as inorganic precursor and paraphenylendiamine as reducing and a structure-directing agent. Such techniques as X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FTIR), Raman Spectroscopy, X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption/desorption isotherms (BET) have been used to characterize the structure, morphology and the texture of the material. The conductivity of the material was measured by complex impedance spectroscopy which increases from 72 × 10^?5 Ω^?1 cm^?1 at 298 K to 95 × 10^?4 Ω^?1 cm^?1 at 493 K. The Arrhenius diagram is not linear, it presents a rupture situated at 407 K and the activation energies’ average values are 0.044 eV and 0.13 eV.     

Hydrothermal synthesis of mesoporous VO2·½(H2O) nanosheets and study of their electrical properties

Layered sheet-like nanocrystalline VO₂·½(H₂O) has been synthesized by hydrothermal process using V₂O₅ as vanadium source and 2-phenylethylamine as a reducing agent and a structure-directing template. Techniques X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption/desorption isotherms have been used to characterize the structure, morphology and composition of the materials. Electrical conductivity measurements showed that the as synthesized VO₂·½(H₂O) nanosheets has a conductivity value which goes from 75 × 10^?6 Ω^?1 cm^?1 at 298 K, to 68 10^?5 Ω^?1 cm^?1 at 386 K with activation energy of 0.24 eV.     

Hydrothermal synthesis and magnetic properties of α-MnO2 nanowires

In the present study, one-dimensional (1D) α-MnO₂ nanowires with width of 50–60 nm, length about several micrometers have been successfully prepared under hydrothermal conditions in the presence of sodium carboxymethyl cellulose. The samples were characterized by X-ray diffraction, scanning electron microscope, superconducting quantum interference device and N₂ adsorption–desorption experiment. The magnetic measurement reveals that the α-MnO₂ nanowires exhibit a ferromagnetic behavior at 5 K and a paramagnetic behavior at 300 K. The N₂ adsorption–desorption experiment shows that surface area is 160.4 m² g^?1, which is even larger than those of mesoporous nanostructures. At the same time, the possible formation mechanism for the formation of α-MnO₂ nanowires has been proposed according to the experimental results.     

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).     

Adsorption of collagen to indium oxide nanoparticles and infrared emissivity study thereon

Adsorption of collagen to indium oxide nanoparticles was carried out in water–acetone solution at volumetric ratio of 1:1 with pH value varying from 3.2 to 9.3. As indicated by TGA, maximum collagen adsorption to indium oxide nanoparticles occurred at pH of 3.2. It was proposed that noncovalent interactions such as hydrogen bonding, hydrophilic and electrostatic interactions made main contributions to collagen adsorption. The IR emissivity values (8–14 μm) of collagen-adsorbed indium oxide nanoparticles decreased significantly compared to either pure collagen or indium oxide nanoparticles possibly due to the interfacial interactions between collagen and indium oxide nanoparticles. And the lowest infrared emissivity value of 0.587 was obtained at collagen adsorption of 1.94 g/100 g In₂O₃. On the chance of improved compatibility with organic adhesives, the chemical activity of adsorbed collagen was further confirmed by grafting copolymerization with methyl methacrylate by formation of polymer shell outside, as evidenced by IR spectrum and transmission electron microscopy.     

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.     

Fabrication and evaluation of a sustained-release chitosan-based scaffold embedded with PLGA microspheres

Nutrient depletion within three-dimensional (3D) scaffolds is one of the major hurdles in the use of this technology to grow cells for applications in tissue engineering. In order to help in addressing it, we herein propose to use the controlled release of encapsulated nutrients within polymer microspheres into chitosan-based 3D scaffolds, wherein the microspheres are embedded. This method has allowed maintaining a stable concentration of nutrients within the scaffolds over the long term. The polymer microspheres were prepared using multiple emulsions (w/o/w), in which bovine serum albumin (BSA) and poly (lactic-co-glycolic) acid (PLGA) were regarded as the protein pattern and the exoperidium material, respectively. These were then mixed with a chitosan solution in order to form the scaffolds by cryo-desiccation. The release of BSA, entrapped within the embedded microspheres, was monitored with time using a BCA kit. The morphology and structure of the PLGA microspheres containing BSA before and after embedding within the scaffold were observed under a scanning electron microscope (SEM). These had a round shape with diameters in the range of 27–55 μm, whereas the chitosan-based scaffolds had a uniform porous structure with the microspheres uniformly dispersed within their 3D structure and without any morphological change. In addition, the porosity, water absorption and degradation rate at 37 °C in an aqueous environment of 1% chitosan-based scaffolds were (92.99 ± 2.51) %, (89.66 ± 0.66) % and (73.77 ± 3.21) %, respectively. The studies of BSA release from the embedded microspheres have shown a sustained and cumulative tendency with little initial burst, with (20.24 ± 0.83) % of the initial amount released after 168 h (an average rate of 0.12%/h). The protein concentration within the chitosan-based scaffolds after 168 h was found to be (11.44 ± 1.81) × 10^? 2 mg/mL. This novel chitosan-based scaffold embedded with PLGA microspheres has proven to be a promising technique for the development of new and improved tissue engineering scaffolds.     

Purification of yeast alcohol dehydrogenase by using immobilized metal affinity cryogels

In this study, poly(2-hydroxyethyl methacrylate–glycidylmethacrylate) [poly(HEMA–GMA)] cryogels were prepared by radical cryocopolymerization of HEMA with GMA as a functional comonomer and N,N′-methylene-bisacrylamide (MBAAm) as a crosslinker. Iminodiacetic acid (IDA) functional groups were attached via ring opening of the epoxy group on the poly(HEMA–GMA) cryogels and then Zn(II) ions were chelated with these structures. Characterization of cryogels was performed by FTIR, SEM, EDX and swelling studies. These cryogels have interconnected pores of 30–50 μm size. The equilibrium swelling degree of Zn(II) chelated poly(HEMA–GMA)-IDA cryogels was approximately 600%. Zn(II) chelated poly(HEMA–GMA)-IDA cryogels were used in the adsorption of alcohol dehydrogenase from aqueous solutions and adsorption was performed in continuous system. The effects of pH, alcohol dehydrogenase concentration, temperature, and flow rate on adsorption were investigated. The maximum amount of alcohol dehydrogenase adsorption was determined to be 9.94 mg/g cryogel at 1.0 mg/mL alcohol dehydrogenase concentration and in acetate buffer at pH 5.0 with a flow rate of 0.5 mL/min. Desorption of adsorbed alcohol dehydrogenase was carried out by using 1.0 M NaCI at pH 8.0 phosphate buffer and desorption yield was found to be 93.5%. Additionally, these cryogels were used for purification of alcohol dehydrogenase from yeast with a single-step. The purity of desorbed alcohol dehydrogenase was shown by silver-stained SDS–PAGE. This purification process can successfully be used for the purification of alcohol dehydrogenase from unclarified yeast homogenates and this work is the first report about the usage of the cryogels for purification of alcohol dehydrogenase.     

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.     

Adsorption property and affinity chromatography of polystyrene derivative sorbent towards cow's milk xanthine oxidase

On the basis of the biospecific molecular recognition between complementary chemical groups of xanthine oxidase (XO) and their ligands particularly sulphated glycoaminoglycans and heparin. Poly (styrene chlorosulfonyl) particles modified by sulfonate sodium groups was synthesized and its adsorption property towards cow's milk XO was established. The adsorption of XO onto this functional polymer was performed in batch at 4 °C and at pH 6.0 during 30 min. of incubation. The adsorbed XO content at the interface allows establishing the chemisorption isotherm curve. The affinity association estimated from this adsorption isotherm according to the Langmuir equation was found to be significantly high in the magnitude of 1.25 × 10⁶ M^? 1. Affinity chromatography on column using this functional polymer as a stationary phase confirms its high ability to adsorb XO at low ionic strength. In fact, the xanthine oxidase of the crude extract is strongly adsorbed onto the sorbent and is eluted at high ionic strength with out any significant loss of its biological activity. The purified enzyme possesses a protein flavin ratio (PFR) of 6.05 with a specific activity of 1.78 UI/mg. On the other hand, the electrophoresis of XO fraction showed a single band with a molecular weight of about 150 kDa. Thus, the synthesized beads functionalized by sulfonate group could be used efficiently and advantageously in the purification of XO instead of other conventional chromatographic methods which need several steps.     

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.     

Removal,preconcentration and spectrophotometric determination of picric acid in water samples using modified magnetic iron oxide nanoparticles as an efficient adsorbent

A simple, fast and sensitive spectrophotometric method is developed for removal, preconcentration and determination of trace amounts of picric acid in water samples. Magnetic iron oxide nanoparticles (MIONPs) were synthesized and characterized by transmission electron microscopy (TEM). The magnetic nanoparticles were coated with cetyltrimethylammonium bromide (CTAB) and were applied for fast separation, preconcentration and spectrophotometric determination of picrate anion (the ion of picric acid) in an aqueous solution. The separation, preconcentration procedure is fast and will be completed in 2 min. Methanol is used for desorption of adsorbed picrate anion. The effects of important parameters such as pH of aqueous medium, CTAB dosage, adsorbent amount, temperature, electrolyte concentration, desorbing solvent and interfering ions on the adsorption of picrate anion were investigated. The method showed good linearity for the determination of picric acid in the concentration range of 0.02–1.00 μg mL^? 1 with a regression coefficient of 0.999. The limit of detection (LOD) is obtained to be 0.007 μg mL^? 1. The relative standard deviation (RSD) for 0.03 μg mL^? 1 and 0.8 μg mL^? 1 of picric acid were 3.98% and 1.97% respectively. Picric acid was separated, preconcentrated and determined successfully in spiked samples of Karoon River water.     

Possibilities of atomic hydrogen storage by carbon nanotubes or graphite materials

Atomic hydrogen storage by carbon nanotubes (CNTs) and highly oriented pyrolytic graphite (HOPG) has been studied using a flow catalytic reactor and an ultra-high vacuum surface science apparatus including scanning tunneling microscope (STM), respectively. Defect sites on CNTs as adsorption sites of atomic hydrogen are introduced by oxidation pretreatment using La catalyst. Pd catalysts are then deposited on CNT surfaces for dissociation of H₂ into atomic hydrogen, which spills over to the defect sites. In the best case, 1.5 wt% of hydrogen is stored in the defective CNT with Pd particles at 1 atm and 573 K. In temperature programmed desorption (TPD) experiments, H₂ starts to desorb at 700–900 K depending on the annealing temperatures of CNTs prior to hydrogen storage. On the HOPG surface, hot atomic hydrogen produced by dissociation of H₂ using tungsten wire desorbs from graphite terraces at 400–700 K, which is much lower than that on CNTs. It is possible that one can decrease the desorption temperature by changing the method of H₂ dissociation.     

Adsorption of Cr(VI) from aqueous solution by hydrous zirconium oxide

A type of ZrO₂·nH₂O was synthesized and its Cr(VI) removal potential was investigated in this study. The kinetic study, adsorption isotherm, pH effect, thermodynamic study and desorption were examined in batch experiments. The kinetic process was described by a pseudo-second-order rate model very well. The Cr(VI) adsorption tended to increase with a decrease of pH. The adsorption data fitted well to the Langmuir model. The adsorption capacity increased from 61 to 66 mg g^?1 when the temperature was increased from 298 to 338 K. The positive values of both ΔH° and ΔS° suggest an endothermic reaction and increase in randomness at the solid–liquid interface during the adsorption. ΔG° values obtained were negative indicating a spontaneous adsorption process. The effective desorption of Cr(VI) on ZrO₂·nH₂O could be achieved using distilled water at pH 12.     

Longitudinal and concurrent dimensional changes of cellulose aggregate fibrils during sorption stages

Atomic force microscopy (AFM) studies of the dimensional changes of cellulose microfibril materials, called cellulose aggregate fibrils (approx. 100 µm × 3 µm × 300 nm), exposed to two distinct relative humidities of 80% and 23% for 24 h and then suddenly subjected to 50% RH and 23 °C show that the fibrils are responsive to the surrounding environments in a nonspecific fashion. AFM images (10 µm × 10 µm) of the individual straight cellulose aggregate fibrils were taken as a function of elapsed time during both desorption and adsorption of moisture. The longitudinal distance between discrete natural defects observed on the cellulose aggregate fibrils as well as the width, cross-sectional area, and height of the cellulose aggregate fibril were measured from the AFM images. The length of the cellulose aggregate fibrils was found to have reduced after exposure to either high or low relative humidity, and then placement in ambient conditions. Over time in ambient conditions, the cellulose aggregate fibrils progressively relaxed to their original length during both desorption and adsorption of moisture. However, the relaxation rate during adsorption was faster than that during desorption. The possible explanations for this phenomenon are discussed including the sample preparation method, volume conservation, entropy elasticity, and free volume theory. The changes in the width, height, and cross-sectional area are also discussed.     

Oriented immobilized anti-LDL antibody carrying poly(hydroxyethyl methacrylate) cryogel for cholesterol removal from human plasma

Low density lipoprotein (LDL) cholesterol is a major ingredient of the plaque that collects in the coronary arteries and causes coronary heart diseases. Among the methods used for the extracorporeal elimination of LDL from intravasal volume, immunoaffinity technique using anti-LDL antibody as a ligand offers superior selectivity and specificity. Proper orientation of the immobilized antibody is the main issue in immunoaffinity techniques. In this study, anti-human β-lipoprotein antibody (anti-LDL antibody) molecules were immobilized and oriented through protein A onto poly(2-hydroxyethyl methacrylate) (PHEMA) cryogel in order to remove LDL from hypercholesterolemic human plasma. PHEMA cryogel was prepared by free radical polymerization initiated with N,N,N′,N′-tetramethylene diamine (TEMED). PHEMA cryogel with a swelling degree of 8.89 g H₂O/g and 67% macro-porosity was characterized by swelling studies, scanning electron microscope (SEM) and blood compatibility tests. All the clotting times were increased when compared with control plasma. The maximum immobilized anti-LDL antibody amount was 63.2 mg/g in the case of random antibody immobilization and 19.6 mg/g in the case of oriented antibody immobilization (protein A loading was 57.0 mg/g). Random and oriented anti-LDL antibody immobilized PHEMA cryogels adsorbed 111 and 129 mg LDL/g cryogel from hypercholesterolemic human plasma, respectively. Up to 80% of the adsorbed LDL was desorbed. The adsorption–desorption cycle was repeated 6 times using the same cryogel. There was no significant loss of LDL adsorption capacity.     

Immobilization of Acidithiobacillus ferrooxidans on sulfonated microporous poly(styrene–divinylbenzene) copolymer with granulated activated carbon and its use in bio-oxidation of ferrous iron

The immobilization efficiencies of Acidithiobacillus ferrooxidans cells on different immobilization matrices were investigated for biooxidation of ferrous iron (Fe^2 +) to ferric iron (Fe^3 +). Six different matrices were used such as the polyurethane foam (PUF), granular activated carbon (GAC), raw poly(styrene–divinylbenzene) copolymer (rawSDVB), raw poly(styrene–divinylbenzene) copolymer with granular activated carbon (rawSDVB-GAC), sulfonated poly(styrene–divinylbenzene) copolymer (sulfSDVB) and sulfonated poly(styrene–divinylbenzene) copolymer with granular activated carbon (sulfSDVB-GAC). The sulfSDVB-GAC polymer showed the best performance for Fe^2 + biooxidation. It was used at packed-bed bioreactor and the kinetic parameters were obtained. The highest Fe^2 + biooxidation rate (R) was found to be 4.02 g/L h at the true dilution rate (D_t) of 2.47 1/h and hydraulic retention time (τ) of 0.4 h. The sulfSDVB-GAC polymer was used for the first time as immobilization material for A. ferrooxidans for Fe^2 + biooxidation.