Investigation of lysozyme adsorption performance of Cu2+-attached PHEMA beads embedded cryogel membranes

Water-soluble polymeric particle embedded cryogels: Synthesis, characterisation and adsorption of haemoglobin

Making cryogels, which are among today’s accepted adsorbents, more functional with different methods, has been one of the subjects spent overtime. In this study, water-soluble poly(maleic anhydride-alt-acrylic acid) polymer embedded in poly(2-hydroxyethyl methacrylate) cryogels. Copper ions were then immobilised to this structure, and this polymer was used for adsorption of haemoglobin from aqueous systems. Adsorption interaction was carried out on an electrostatic basis, and approximately 448.62 mg haemoglobin/g polymer adsorption capacity value was obtained. It was found that the same material has managed to maintain its adsorption ability by 90.3% even after the use of it five times in the adsorption/desorption cycle. The adsorption interaction was determined to be appropriate for the Langmuir model by isotherm studies. The change in Gibbs free energy value was calculated as −2.168 kJ/mol.

α-Amylase Immobilized Composite Cryogels: Some Studies on Kinetic and Adsorption Factors

Stability of enzymes is a significant factor for their industrial feasibility. α-Amylase is an important enzyme for some industries, i.e., textile, food, paper, and pharmaceutics. Pumice particles (PPa) are non-toxic, natural, and low-cost alternative adsorbents with high adsorption capacity. In this study, Cu²⁺ ions were attached to pumice particles (Cu²⁺-APPa). Then, Cu²⁺-APPa embedded composite cryogel was synthesized (Cu²⁺-APPaC) via polymerization of gel-forming agents at minus temperatures. Characterization studies of the Cu²⁺-APPaC cryogel column were performed by X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), and Brunauer, Emmett, Teller (BET) method. The experiments were carried out in a continuous column system. α-Amylase was adsorbed onto Cu²⁺-APPaC cryogel with maximum amount of 858.7 mg/g particles at pH 4.0. Effects of pH and temperature on the activity profiles of the free and the immobilized α-amylase were investigated, and results indicate that immobilization did not alter the optimum pH and temperature values. k_cat value of the immobilized α-amylase is higher than that of the free α-amylase while K_M value increases by immobilization. Storage and operational stabilities of the free and the immobilized α-amylase were determined for 35 days and for 20 runs, respectively.

A new application of inorganic sorbent for biomolecules: IMAC practice of Fe3+-nano flowers for DNA separation

Selection of purification method and type of adsorbent has high significance for separation of a biomolecule like deoxyribonucleic acid (DNA). Nanoflowers are a newly improved class of adsorbent. Due to showing very structural similarity to plant flowers, they are named as nanoflowers. Herein, after synthesize of copper phosphate three hydrate nanoflowers [(Cu₃(PO₄)₂.3H₂O), CP-NFs], Fe³⁺ ions were attached to their surfaces. Obtained Fe³⁺-CP-NFs, before investigation of some adsorption parameters for DNA, they were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Some attained data from the results of adsorption experiments as follows: While maximum DNA adsorption on Fe³⁺-CP-NFs was found as an excellent value of 845.8 mg/g, nanoflowers without Fe³⁺ ions adsorbed DNA as only 25.3 mg/g. Optimum media conditions for DNA adsorption were observed at pH 7 and 25 °C with an initial concentration of 1.5 mg/mL DNA. Langmuir and Freundlich adsorption equations were applied to determine which adsorption model was appropriate, and it was seen that Langmuir model was fit with a R² of 0.9885.

Reducing arsenic and groundwater contaminants down to safe level for drinking purposes via Fe3+-attached hybrid column

Monitoring of groundwater is fundamentally important due to it has emerged as a major source of drinking water and also used for irrigation purposes in many places in the world. Arsenic contamination in surface water and groundwater resources is a major concern due to its presence at high concentration and associated adverse health effects. Thus, the remediation of As in water resources, alongside other chemical species including fluoride, lithium, vanadium aluminium and nitrate is necessary. We have designed a hybrid [polyethyleneimine (PEI)-supported Fe³⁺-attached poly-(HEMA-co-GMA)] column for the reduction of arsenic (III and V) and other groundwater chemicals from natural groundwater as a potential contribution to water resource management. Swelling behaviour and scanning electron microscopy (SEM) were performed for the characterization of hybrid material. For the optimization of experimental conditions, the effects of pH and initial arsenic concentrations on adsorption were studied using arsenic solutions. Maximum adsorption capacity in equilibrium was 11.44 and 5.79 mg/g polymer for As(III) and As(V), respectively at pH 7. The reduction of metalloids and other subsurface chemicals were carried out with natural groundwater samples obtained from local sources. The mean concentrations of arsenic were recorded between 44.96 and 219.04 μg/L and of which 71.3-95.4 % (0.32-1.22 mg/g) were removed. The average removals were determined as F^-1 50-86%, Li⁺ 43.2-99.7%, Al⁺³ 83.8-91.4%, NO₃^- 48.4-72.2% and V 91.3-95.7. Chemical-loaded hybrid columns were regenerated successfully 15 times with only a loss of 5% in adsorption capacity by 0.01 M NaCl^- treatment for potential adaptation into water industry. No pre-oxidation of As species was performed for the treatment of ground water samples prior to the hybrid column testing.

Preparation and Properties of Cryogel Based on Poly(2-hydroxyethyl methacrylate- co-glycidyl methacrylate)

The immobilized metal affinity cryogels based on poly(2-hydroxyethyl methacrylate- co-glycidyl methacrylate) (p(HEMA-GMA)) containing hydroxy and epoxy groups were prepared by free-radical copolymerization under cryogenic condition and then functionalized with iminodiacetic acid and chelated Cu²⁺, Ca²⁺, and Fe³⁺ ions to the p(HEMA-GMA) cryogel. The structures of p(HEMA-GMA) and immobilized metal-affinity cryogels were analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy. SEM results showed that the prepared cryogels had interconnected pores with the size of 30-100 μm. The performance of water swelling into the cryogels was fitted in Fickian diffusion. The adsorption property of cryogels was influenced by the immobilized ionic type, temperature, and adsorbate. The adsorption capacity of immobilized Cu²⁺ cryogel (p(HEMA)-Cu²⁺ (0.5 M) cryogel) was the highest in comparison with that of Ca²⁺ and Fe³⁺ affinity cryogels under the same condition. The maximum adsorption capacity of p(HEMA)-Cu²⁺ (0.5 M) cryogel for porcine pancreatic lipase was 150.14 mg/g at a higher temperature of 35 °C, whereas for bovine serum albumin, the maximum adsorption capacity was 154.11 mg/g at a lower temperature of 25 °C. The research of thermodynamics and kinetics indicated that the mechanism of the protein adsorption process corresponded to the Langmuir model and pseudo-second-order model.

Preparation and properties of cryogel based on poly(hydroxypropyl methacrylate)

A novel supermacroporous poly(hydroxypropyl methacrylate) (p(HPMA)) cryogel was synthesized by cryogelation method at -16 °C. In this synthesis process, HPMA was used as a monomer, and N,N'-methylenebisacrylamide (MBAAm) was used as cross-linker; the reaction was carried out in the presence of redox initiator pair N,N,N',N'-tetramethylene diamine (TEMED) and ammonium persulfate (APS). The effect of monomer concentration, cross-linker content, cooling rate, and dioxane co-solvent were determined with respect to the pore structure, mechanical behavior, swelling degree, and porosity of cryogel. The ESEM images indicate that the pore wall structure of cryogels was rough; moreover, small holes were present in the pore walls of cryogels. The result of compression test indicates that cryogels can be compressed by at least 80% without any breakdown. The result of swelling kinetics indicates that cryogels attain swelling equilibrium in 10 s. Furthermore, p(HPMA)-Cu²⁺ cryogel was prepared by loading Cu²⁺ ions on functionalized poly(hydroxypropyl methacrylate)-iminodiacetic acid (p(HPMA)-IDA) cryogel. We investigated the adsorption of bovine serum albumin (BSA) on cryogels. The results indicate that compared to Freundlich isotherm, Langmuir isotherm could more suitably describe the adsorption process of BSA on cryogels. Meanwhile, the adsorption capacity of p(HPMA)-Cu²⁺ cryogel was significantly greater than that of p(HPMA) cryogel. The maximum adsorption capacity of BSA on p(HPMA)-Cu²⁺ cryogel, which was treated with 1 M Cu²⁺ ions, was as high as 196.87 mg/g cryogel (equivalent to 20.48 mg/mL cryogel) at 25 °C and pH = 7.8; therefore, the maximum adsorption capacity of BSA on p(HPMA)-Cu²⁺ cryogel was 4.35 times higher than that of p(HPMA) cryogel. Thus, the adsorption capacity of cryogels was strongly influenced by Cu²⁺ concentration, moreover, temperature changes clearly affected the adsorption capacity of p(HPMA)-Cu²⁺cryogel. The adsorption capacity at 25 °C was twice as that at 15 °C. By calculating Gibbs free energy change (∆G) of adsorption, we found that the adsorption process was spontaneous; moreover, adsorption process occurred better at higher temperature.

O-carboxymethyl chitosan Schiff base complexes as affinity ligands for immobilized metal-ion affinity chromatography of lysozyme

We synthesized Ni²⁺-attached O-Carboxymethyl chitosan Schiff base complexes embedded composite cryogels (Ni²⁺-O-CMCS-CCs) by means of polymerization of gel-forming precursors at subzero temperatures. Prepared affinity cryogel showed excellent adsorption performance for lysozyme selected as model protein to test adsorption parameters, demonstrating an adsorption capacity of 244.6 mg/g (15.3 mg/g for Ni²⁺ minus O-CMCS-CCs), with fast adsorption equilibrium within 30 min and good reversibility. The performance of Ni²⁺-O-CMCS-CCs for lysozyme was also evaluated by SDS-PAGE, and a purification efficiency of 86.9% with 89.5% purification yield was determined. The swelling test, FT-IR, and SEM analysis were carried out for the characterization of Ni²⁺-O-CMCS-CCs. At the end of 35 adsorption-desorption cycles, there was no significant change in the adsorption capacity.

In situ chitin isolation from body parts of a centipede and lysozyme adsorption studies

Isolation of structurally intact chitin samples for biotechnological applications has gained much recent attention. So far, three-dimensional chitin isolates have been obtained from only diplopods and sponges. In this study, three-dimensional chitin isolates were obtained from the body parts of centipede Scolopendra sp. (antennae, head, forcipule, collum, trunk, trunk legs and last pair of legs) without leading to structural failure. FT-IR spectra of chitin isolates confirmed that chitin samples are in α allomorph. TGA, XRD and SEM analyses and lysozyme adsorption studies revealed that each chitin isolate had different thermal stability, crystallinity and surface characteristics. Among the chitin isolates, Cu(II)-immobilized forcipule chitin showed the highest affinity for lysozyme (54.1mg/g), whereas chitin from last pair of legs exhibited the lowest affinity (3.7mg/g). This study demonstrated that structurally intact chitin isolates can be obtained from the body parts of centipede Scolopendra sp. (antennae, head, forcipule, collum, trunk, trunk legs and last pair of legs) by using a simple chemical procedure. Also, it gives a biotechnological perspective to the organisms in the group of Chilipoda.

Hepatotoxic microcystin removal using pumice embedded monolithic composite cryogel as an alternative water treatment method

Microcystins are the most commonly encountered water-borne cyanotoxins which present short- and long-term risks to human health. Guidelines at international and national level, and legislation in some countries, have been introduced for the effective health risk management of these potent hepatotoxic, tumour-promoters. The stable cyclic structure of microcystins and their common production by cyanobacteria in waterbodies at times of high total dissolved organic carbon content presents challenges to drinking water treatment facilities, with conventional, advanced and novel strategies under evaluation. Here, we have studied the removal of microcystins using three different forms of pumice particles (PPs), which are embedded into macroporous cryogel columns. Macroporous composite cryogel columns (MCCs) are a new generation of separation media designed to face this challenging task. Three different MCCs were prepared by adding plain PPs, Cu(2+)-attached PPs and Fe(3+)-attached PPs to reaction media before the cryogelation step. Column studies showed that MCCs could be successfully used as an alternative water treatment method for successful microcystin removal.