Characterization of a novel continuous supermacroporous monolithic cryogel embedded with nanoparticles for protein chromatography

A novel continuous supermacroporous monolithic cryogel embedded with nanometer-size particles was prepared by the radical cryogenic co-polymerization of acrylamide (AAm), N,N'-methylene-bis-acrylamide (MBAAm), allyl glycidyl ether (AGE) and the dispersed surfactant-stabilized Fe3O4 nanoparticles under the freezing-temperature variation condition in a glass column. This special separation matrix has interconnected supermacropores with pore size of 10-50 microm, which permit the free-passage of microbial cells or cell debris in the culture fluids and then is interest in downstream processes. The axial liquid dispersion coefficients of the new continuous supermacroporous monolithic bed at different liquid flow rates were obtained by measuring residence time distributions (RTDs) using tracer pulse-response method. The experimental results showed that the axial liquid dispersion within the bed was weak in a wide water flow rate of 0.5-15 cm/min. The axial dispersion coefficient was found to be increased exponentially with the increase of liquid flow rate. Chromatographic process of bovine serum albumin (BSA) in the cryogel monolithic bed was carried out to reveal the protein breakthrough and elution characteristics. Compared with other reported cryogel beds in literature, the protein adsorption capacity of the present cryogel bed was improved due to the embedded nano-sized solid adsorbents in the gel matrix. Microstructure morphology of the embedded nanoparticles in the cryogel and the gel matrix structure were also analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in this paper.     

Protein adsorption in porous adsorbent particles: A multiscale modeling study on inner radial humps in the concentration profiles of adsorbed protein induced by nonuniform ligand density distributions

Recently published results determined from molecular dynamics (MD) modeling and simulation studies have shown that the spatial distribution of the density of immobilized charged ligands in ion‐exchange porous adsorbent particles is most likely nonuniform and the adsorbent particles also exhibit local nonelectroneutrality. In this work, the functional forms of the nonuniform spatial distributions of the density of the immobilized ligands in four different porous adsorbent media that were determined by MD studies were employed in a macroscopic continuum model describing the transport and adsorption of a single protein in the porous particles of the four different adsorbent media. The results clearly show that inner radial humps in the concentration profiles of the adsorbed protein can occur when the spatial distribution of the density of the immobilized ligands in the porous adsorbent particles is nonuniform and also has local maxima or minima along the radial direction in the particle. The results also indicate that the rate at which the equilibrium condition is approached depends significantly on the functional form of the spatial distribution of the density of the immobilized ligands. When adsorption equilibrium has been reached, the concentration profile of the adsorbed protein exhibits the shape of the spatial distribution of the density of the immobilized ligands. The results suggest that the technique of confocal scanning laser microscopy could be used to measure the concentration profile of an adsorbed protein at equilibrium and this measurement could provide the spatial distribution of the density of the immobilized ligands, and such measurements could also be used for quality control of the adsorbent medium. The results in this work have also implications in the modeling, design, analysis, and quality control of systems involving biocatalysis. Furthermore, the results clearly indicate that it is very important to study the dynamic behavior of an adsorption system having a nonuniform spatial distribution in the density of the immobilized charged ligands and where (i) both monovalent and multivalent interactions between the single charged adsorbate and the immobilized charged ligands occur and (ii) the values of the pH and ionic strength are such that the electrophoretic effects are active.     

Immobilized trypsin on epoxy organic monoliths with modulated hydrophilicity: novel bioreactors useful for protein analysis by liquid chromatography coupled to tandem mass spectrometry

The development of epoxy organic monoliths with modulated hydrophilicity for the preparation of novel trypsin-based microreactors is reported. Porous polymer monoliths have been prepared using methacrylate chemistry triggered by γ-ray irradiation. In situ polymerization has been optimized and extended to medium and high polymer densities using glycidyl methacrylate (GMA) as reactive monomer as well as to the hydrophilic nature of the co-monomers (glyceryl monomethacrylate, GlyMA and acrylamide, AMD). Enzyme immobilization was smoothly achieved by passing a buffered trypsin solution through the columns kept at room temperature. The activities of the immobilized enzyme were characterized by the apparent Michaelis constant (K(m)) and the apparent maximum velocity (V(max)) of the reaction using a non chromogenic, low-molecular mass substrate N-α-benzoyl-l-arginine ethyl ester (BAEE). For the kinetic constants determination a new off-line chromatographic procedure was developed on purpose. The most efficient IMERs were obtained by immobilizing trypsin on monolithic skeleton prepared with hydrophilic monomers (GlyMA and AMD). One of the most promising bioreactor was applied to the digestion of model proteins with different molecular weight and complexity such as human serum albumin (HSA), β-casein and ribonuclease B (RNase B), and the produced peptides were analyzed by liquid chromatography-mass spectrometry. Using a digestion time of only 25 min the proteins were recognized by the database with satisfactory sequence coverage, which was 78.22, 49.76 and 80.68% for HSA, β-casein and RNase B, respectively.     

A novel method for the simple and simultaneous preconcentration of Pb2+, Cu2+ and Zn2+ ions with aid of diethylenetriamine functionalized SBA-15 nanoporous silica compound

A rapid method for the extraction and monitoring of nanogram level of Pb²⁺, Cu²⁺ and Zn²⁺ ions using uniform silanized mesopor (SBA-15) functionalized with diethylenetriamine groups and flame atomic absorption spectrometry (FAAS) is presented. The preconcentration factor of the method is 100 and detection limit of the technique is 5.5?ng?mL^?1 and 1.4?ng?mL^?1 and 0.1?ng?mL^?1 for Pb²⁺, Cu²⁺ and Zn²⁺ respectively. The time and the optimum amount of the sorbent, pH and minimum amount of acid for stripping of ions from functionalized SBA-15 were tested. The maximum capacity the functionalized SBA-15 was found to be 183.0 (±1.9) µg, 156.0 (±1.5) µg and 80.0 (±1.6) µg of Pb²⁺, Cu²⁺ and Zn²⁺/mg functionalized SBA-15, respectively.     

A novel microwave assisted reverse micelle fabrication route for Th (IV)‐MOFs as highly efficient adsorbent nanostructures with controllable structural properties to CO and CH4 adsorption: Design,and a systematic study

Reducing gas contaminants by affordable and effective adsorbents is a major challenge in the 21^st century. In the present study, thorium metal organic framework (Th‐MOF) nanostructures are introduced as highly efficient adsorbents. These compounds were manufactured via a novel route resulting from the development of microwave assisted reverse micelle (MARM) and ultrasound assisted reverse micelle (UARM) methods. The products were characterized utilizing XRD, SEM, TGA/DSC, BET, and FT‐IR analyses. Based on the results, the samples synthesized by MARM had uniform size distribution, high thermal stability, and significant surface area. Calculations using DFT/B3LYP indicated that the compounds have a tendency to the polymeric form, which could theoretically confirm the formation of Th‐MOF. Results of analysis of variance (ANOVA) showed that synthesis parameters played a critical role in the manufacturing of products with distinctive properties. Response surface methodology (RSM) predicted the possibility of creating Th‐MOF adsorbents with the surface area of 2579 m²/g, which was a considerable value in comparison with the properties of other adsorbents. Adsorption studies showed that, in the optimum conditions, the Th‐MOF products had high adsorption capacity for CO and CH₄. It is believed that the synthesis protocol developed in the present study and the systematic studies conducted on the samples which lead to products with ideal adsorption properties.     

Anchoring H3PW12O40 on aminopropylsilanized spinel‐type cobalt oxide (Co3O4‐SiPrNH2/H3PW12O40): A novel nanohybrid adsorbent for removing cationic organic dye pollutants from aqueous solutions

In this work, phosphotungstic acid (H₃PW₁₂O₄₀; PW₁₂) was chemically anchored on aminopropylsiloxane functionalized spherical Co₃O₄ nanoparticles (Co₃O₄–SiPrNH₂) and the resultant nanocomposite (Co₃O₄–SiPrNH₂/PW₁₂) was fully characterized. The results demonstrated successful anchoring of PW₁₂ on the surface of Co₃O₄–SiPrNH₂nanoparticles. The Co₃O₄–SiPrNH₂/PW₁₂ nanohybrid indicated a specific surface area of 42.14 m² g^?1, which was greater than that of pure PW₁₂ (ca. 5 m² g^?1). The adsorption efficiency of this novel adsorbent nanomaterial was evaluated for removing methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes from aqueous solutions. The hybrid nanomaterial exhibited a high adsorption rate and selective adsorptivity for the cationic MB and RhB dyes compared to those for anionic MO dye. The prepared hybrid nanomaterial removed over 98% of MB within 12 min. The effects of initial pH, contact time, adsorbent dosage, and temperature were investigated on the adsorption process. The adsorption capacity of nanohybrid for cationic MB dye was 38.46 mg g^‐1. Also, adsorption kinetics indicated that the adsorption by Co₃O₄–SiPrNH₂/PW₁₂ was well‐modeled using pseudo‐second‐order kinetic model. Finally, thermodynamic parameters revealed that the adsorption was endothermic and spontaneous. The adsorption rate and ability of the Co₃O₄–SiPrNH₂/PW₁₂ were enhanced as compared with Co₃O₄ and Co₃O₄–SiPrNH₂ samples due to enhanced electrostatic attraction intraction. The nanohybride was easily separated and reused without any change in structure. Thus, it could be a promising green adsorbent for removing organic pollutants in water.     

A novel heterogeneous nanocatalyst: 2‐Methoxy‐1‐phenylethanone functionalized MCM‐41 supported Cu(II) complex for C‐S coupling of aryl halides with thiourea

An environmentally friendly copper‐based catalyst supported on 2‐Methoxy‐1‐phenylethanone functionalized MCM‐41 was prepared and characterized by FT‐IR, FE‐SEM, TEM, XRD, EDX, BET and ICP techniques. The catalyst was applied for the C?S cross‐coupling reaction of aryl halides with thiourea. Corresponding products were produced in good yields in aerobic conditions. The catalyst could be recovered and recycled for several times.