Cryogel-supported titanate nanotubes for waste treatment: Impact on methane production and bio-fertilizer quality.

By reducing the cadmium (Cd(2+)) content in biomass used for bio-based products such as biogas, a less toxic bio-based fertilizer can be obtained. In this work, we demonstrate how a macroporous polymer can support titanate nanotubes, and we take advantage of its known selective adsorption behavior towards Cd(2+) in an adsorption process from real nutrient-rich process water from hydrolysis of seaweed, a pollutant-rich biomass. We show that pretreatment steps involving alteration in area-to-volume ratio performed in aerated and acidic conditions release the most Cd(2+) from the solid material.

Chromatographic adsorption of serum albumin and antibody proteins in cryogels with benzyl-quaternary amine ligands.

The preparation and characterization of mixed-mode adsorbents for a typical separation purpose are of great importance in bioseparation areas. In this work, we prepared a new monolithic cryogel with a combination of ion-exchange and hydrophobic functions by employing benzyl-quaternary amine groups. The fundamental cryogel properties, protein equilibrium adsorption isotherm and chromatographic adsorption in the cryogel were measured experimentally.

Improved arsenic(III) adsorption by Al2O3 nanoparticles and H2O2: evidence of oxidation to arsenic(V) from X-ray absorption spectroscopy.

We have investigated the oxidation of inorganic As(III) with H2O2 catalysed by Al2O3, using X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopy. The effects of different reaction conditions (pH, time and initial H2O2 concentration) were also studied as were the kinetics of the oxidation reaction. We demonstrated that As(III) was oxidized to As(V) in the presence of H2O2 and Al2O3.

Cryogelation of chitosan using noble-metal ions: in situ formation of nanoparticles.

One of the purposes of the project was to develop the method of preparation of 3D macroporous hydrogel with a structure of interconnected pores by the use of noncovalent interactions. The combination of chitosan and noble-metal complexes was investigated as cross-linking agents for the preparation of ionic cryogels (ICs). Furthermore, the treatment of the ICs containing gold complex by glutaraldehyde results in spontaneous formation of gold nanoparticles (AuNPs) and chemical cross-linking of the cryogel.

A thiol functionalized cryogel as a solid phase for selective reduction of a cysteine residue in a recombinant human growth hormone variant.

Site selective chemical modification is a preferred method, employed to prolong the circulation half-life of biopharmaceuticals. Cysteines have been used as attachment point for such modification, however, to be susceptible for chemical modification the involved thiol must be in its reduced form. Proteins often contain disulfides, which aid to maintain their tertiary structure and therefore must remain intact.

Γ-Al₂O₃-based nanocomposite adsorbents for arsenic(V) removal: assessing performance, toxicity and particle leakage.

The generation and development of effective adsorption materials for arsenic removal are urgently needed due to acute arsenic contamination of water sources in many regions around the world. In the search for these new adsorbents, the application of nanomaterials or nanocomposites, and especially the use of nanoparticles (NPs), has proven increasingly attractive. While the adsorptive performance of a range of nanocomposite and nanomaterial-based systems has been extensively reviewed in previously-published literature, the stability of these systems in terms of NP release, i.

Poly(hydroxyethyl methacrylate)-based composite cryogel with embedded macroporous cellulose beads for the separation of human serum immunoglobulin and albumin.

A novel super-macroporous monolithic composite cryogel was prepared by embedding macroporous cellulose beads into poly(hydroxyethyl methacrylate) cryogel. The cellulose beads were fabricated by using a microchannel liquid-flow focusing and cryopolymerization method, while the composite cryogel was prepared by cryogenic radical polymerization of the hydroxyethyl methacrylate monomer with poly(ethylene glycol) diacrylate as cross-linker together with the cellulose beads. After graft polymerization with (vinylbenzyl)trimethylammonium chloride, the composite cryogel was applied to separate immunoglobulin-G and albumin from human serum.

Evaluation of macroporous blood and plasma scaffolds for skeletal muscle tissue engineering.

The field of tissue engineering has a growing need for suitable scaffold materials to become attractive as a clinical therapy. To use a completely autologous construct to repair a damaged or diseased tissue is an appealing thought. As a model system, two types of scaffolds were prepared from biological fluids: blood and plasma.

Arsenite adsorption on cryogels embedded with iron-aluminium double hydrous oxides: possible polishing step for smelting wastewater?

Arsenic is among the most toxic elements and it commonly exists in water as arsenite (As(III)) and arsenate (As(V)) ions. As(III) removal often requires a pre-oxidation or pH adjustment step and it is a challenge to adsorb As(III) at circumneutral pH. In this study, iron-aluminium double hydrous oxides were synthesized and incorporated into cryogels.

Cryogelation of molecularly imprinted nanoparticles: a macroporous structure as affinity chromatography column for removal of β-blockers from complex samples.

In this work, a new macroporous molecularly imprinted cryogel (MIP composite cryogel) was synthesized by glutaraldehyde cross-linking reaction of poly(vinyl alcohol) (PVA) particles and amino-modified molecularly imprinted core-shell nanoparticles. The MIP core-shell nanoparticles were prepared using propranolol as a template by one-pot precipitation polymerization with sequential monomer addition. The characteristics of the MIP composite cryogel were studied by scanning electron microscopy (SEM) and texture analyzer.

Enzyme-catalyzed crosslinking in a partly frozen state: a new way to produce supermacroporous protein structures.

In this study a new way to produce supermacroporous protein structures was investigated. Enzyme-mediated crosslinking of gelatin or casein was performed in a partly frozen state, which yielded stable, protein-based cryogels. The reaction kinetics for the formation of cryogels were found to be fairly slow, most likely due to the low temperature (-12 °C) used or due to an increased viscosity owing to the cryo-concentration taking place.

Composite cryogel with immobilized concanavalin A for affinity chromatography of glycoproteins.

Composite cryogels containing porous adsorbent particles were prepared under cryogelation conditions. The composites with immobilized concanavalin A (Con A) were used for capturing glycoproteins. Adsorbent particles were introduced into the structure in order to improve the capacity and to facilitate the handling of the particles.

Porous protein-based scaffolds prepared through freezing as potential scaffolds for tissue engineering.

Successful tissue engineering with the aid of a polymer scaffold offers the possibility to produce a larger construct and to mould the shape after the defect. We investigated the use of cryogelation to form protein-based scaffolds through different types of formation mechanisms; enzymatic crosslinking, chemical crosslinking, and non-covalent interactions. Casein was found to best suited for enzymatic crosslinking, gelatin for chemical crosslinking, and ovalbumin for non-covalent interactions.

Oxidized dextran as crosslinker for chitosan cryogel scaffolds and formation of polyelectrolyte complexes between chitosan and gelatin.

Macroporous scaffolds composed of chitosan and using oxidized dextran as a crosslinker are produced through cryogelation. Introducing gelatin as a third component into the structure results in the formation of mesopores in the pore walls, which are not seen if gelatin is excluded. The mesoporous structure is explained by the formation of polyelectrolyte complexes between chitosan and gelatin before crosslinking takes place.

Cross-linking cellulose nanofibrils for potential elastic cryo-structured gels.

Cellulose nanofibrils were produced from P. radiata kraft pulp fibers. The nanofibrillation was facilitated by applying 2,2,6,6-tetramethylpiperidinyl-1-oxyl-mediated oxidation as pretreatment.

Formation of macroporous self-assembled hydrogels through cryogelation of Fmoc-Phe-Phe.

In this study, it was found that macroporous hydrogels were formed when self-assembly of fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Phe-Phe) peptides was induced using glucono-δ-lactone (GdL) in apparently frozen samples. Formed cryogels exhibited a heterogeneous structure with pore walls of densely packed fibres of assembled dipeptides and pores in the range 10-100 μm. Hydrogels formed from the same composition above the freezing point exhibited a homogenous structure without any apparent porosity.

An improved capillary model for describing the microstructure characteristics, fluid hydrodynamics and breakthrough performance of proteins in cryogel beds.

A capillary-based model modified for characterization of monolithic cryogels is presented with key parameters like the pore size distribution, the tortuosity and the skeleton thickness employed for describing the porous structure characteristics of a cryogel matrix. Laminar flow, liquid dispersion and mass transfer in each capillary are considered and the model is solved numerically by the finite difference method. As examples, two poly(hydroxyethyl methacrylate) (pHEMA) based cryogel beds have been prepared by radical cryo-copolymerization of monomers and used to test the model.

Preparation of macroporous cryostructurated gel monoliths, their characterization and main applications.

Cryostructuration platform renders it possible to form macroporous materials (known as cryogels) with a broad range of porosity, from structures with combination of meso- and macropores to structures with 100-μm sized macropores. When these materials are formed in the shape of monoliths (monolithic cryogels), they present a unique monolithic stationary medium for specific applications. This review summarizes the recent research on the preparation and characterization of cryostructurated monolithic cryogels for (bio)separation and points to some future perspectives.

Ultrafast Responsive Poly- (N-isopropylacrylamide) Gel Produced by Cryostructuring of Self-crosslinkable Polymer Microgels.

A macroporous material composed of closely aggregated particles was prepared by cryo-structuration of N-isopropylacrylamide-co-N-hydroxymethylacrylamide (NIPA-co-HMAm) particle suspensions. The formed structure was maintained by the formation of covalent bonds through self-crosslinking between the particles while the system was in a semi-frozen state thus avoiding the need to freeze-dry the sample. This resulted in macroporous structure composed of closely aggregated thermoresponsive particles which exhibit an ultrafast temperature response.

Modulating the porosity of cryogels by influencing the nonfrozen liquid phase through the addition of inert solutes.

The freezing of monomeric mixtures is known to concentrate solutes in a nonfrozen phase in the area surrounding the ice crystals. The concentration of such solutes is determined by the freezing temperature. Although salts or solvents do not directly react in the polymerization reaction, they do change the composition and properties of the nonfrozen phase.

Evaluation of selective composite cryogel for bromate removal from drinking water.

Bromate, which is a potential carcinogen, should be removed from drinking water to levels of less than 10 microg/L. A chitosan-based molecularly imprinted polymer (MIP) and a sol-gel ion-exchange double hydrous oxide (Fe(2)O(3) x Al(2)O(3) x xH(2)O) adsorbent (inorganic adsorbent) were prepared for this purpose. The sorption behavior of each adsorbent including sorption kinetics, isotherms, effect of pH and selective sorption were investigated in detail.

Modeling of protein breakthrough performance in cryogel columns by taking into account the overall axial dispersion.

A model considering the overall axial dispersion for describing protein adsorption and breakthrough in monolithic cryogel beds has been developed. The microstructure of cryogels was characterized by tortuous capillaries with a normal diameter distribution but a constant pore wall thickness. The axial dispersion within cryogel columns was described by using the overall axial dispersion coefficient, which can be easily obtained by matching the experimental breakthrough curves without adsorption or measuring residence time distributions (RTDs).

Building macroporous materials from microgels and microbes via one-step cryogelation.

Macroporous materials are prepared from microgels or microbes by one-step chemical cross-linking under semifrozen conditions. This avoids the use of freeze drying of the sample because a chemically stable structure is prepared under semifrozen conditions. Cryostructuration results in a material with pore walls composed of closely packed particles.