Oxime-functionalized cryogel disks for catalase immobilization

Synthesis and DFT calculations of metal(II) oxime complexes bearing cysteine as coligand and investigation of their biological evolutions in vitro and in silico

New complexes with the formula of [ML(Cys)(H2O)2] were obtained as a result of the reaction between the oxime ligand [HL: 4-(4-bromophenylaminoisonitrosoacetyl)biphenyl], cysteine (Cys), and the metal(II) salts (Mn, Ni, Co, Zn, Cu). The newly synthesized compounds were characterized using conventional techniques such as molar conductance, magnetic measurements, elemental analysis, infrared spectroscopy, and thermal analysis (TGA/DTA). Based on the conductivity measurements in DMF, it was determined that the complexes were non-electrolytes. The TGA/DTA analysis was performed to examine the thermal stability and degradation behavior of all samples, and results demonstrated that metal oxides or sulfides formed as a result of the decompositions. In conjunction with other data obtained, the elemental analysis confirmed the octahedral coordination of the complexes with deprotonated oxime (O, O-donor) and amino acid (N, S-donor) ligands and two coordinated waters. The compounds' optimized geometries, molecular electrostatic potential diagrams, and frontier molecular orbitals were computed at the DFT/B3LYP level using the 6-311 G(d,p) and LANL2DZ basis sets. The antibacterial and DNA cleavage activities of all synthesized compounds were also screened, and molecular docking simulations were performed. According to the results of molecular docking studies conducted with three different proteins, the best interaction was found to be between HL-1HNJ with a binding energy of -9.5 kcal/mol. The stability of the HL-1HNJ complex was also verified by a molecular dynamics simulation performed for 50 ns.Communicated by Ramaswamy H. Sarma.

Biodegradation of environmental pollutants using catalase-based biocatalytic systems

The synergistic combination of biocatalysts and nanomaterials provides a new interface of a robust biocatalytic system that can effectively remediate environmental pollutants. Enzymes, such as catalase-based constructs, impart the desired candidature for catalytic transformation processes and are potential alternatives to replace conventional remediation strategies that have become laborious and somewhat inefficient. Furthermore, the controlled or uncontrolled discharge of various emerging pollutants (EPs) into water bodies is equally proportional to the fast-growing population and extensive urbanization. EPs affect the entire living being and continuously deteriorate the environmental system, directly or indirectly. The occurrence of EPs (even released after partial treatments, but still in bioactive forms) disturbs ecological integrity. Due to the ineffectiveness of in-practice traditional remediation processes, new and robust treatment measures as effective and sustainable remediation have become a meaningful goal. In this context, special attention has been shifted to engineering an enzyme (catalase)-based biodegradation system with immense prospects in environmental cleanup. The unique synergistic combination of nanomaterials (having multifunctional attributes) with enzymes of interest makes them a state-of-the-art interface that can further ameliorate bio-catalysis and biodegradation performance. This review covers current research and scientific advancement in developing and deploying catalase-based biocatalytic systems to mitigate several EPs from the environment matrices. The biocatalytic features of catalase, along with the mechanistic insight into H₂O₂ neutralization, several nano-based materials loaded with catalase, including nanoparticles (NPs), carbon nanotubes (CNTs), metal-organic frameworks (MOFs), polymeric-based composites, oxime-functionalized cryo-gel disks, electro-spun nanofibrous membranes, and other hybrid materials have also been discussed with suitable examples.

Invertase adsorption with polymers functionalized by aspartic acid

Today, the separation and purification processes are highly preferred over the affinity interactions in the scientific world. Among the materials used for this purpose, magnetic particles and cryogels are very popular. Both polymeric structures have their advantages and disadvantages. In this study, poly(2-Hydroxyethyl methacrylate-N-methacryloyl-L-aspartic acid), poly(HEMA-MAsp), magnetic microparticles, and cryogels were synthesized, and adsorption performances of both polymeric structures were investigated by using invertase from aqueous systems. Invertase (β-fructofuranoside fructohydrolase, EC 3.2.1.26) is a commercially important enzyme used in the food industry to obtain the product called invert sugar, which consists of a mixture of equivalent amounts of glucose and fructose. Therefore, it was preferred as a model enzyme in adsorption studies of polymeric structures. According to the results, 104.1 mg g−1 and 135.5 mg g−1 of adsorption capacity values were obtained for cryogel and magnetic microparticle forms, respectively. Increasing temperature slightly reduced the adsorption capacity of both polymeric structures. In the adsorption/desorption cycle studies performed five times with poly(HEMA-MAsp) polymers, both forms were found to have high reusable properties. It was determined that the activity of invertase immobilized on polymeric structures was preserved at a rate of 83.6% for the particle form and 89.2% for the cryogel form.

Immobilization and Characterization of Pectinase onto the Cationic Polystyrene Resin

In the present study, the immobilization of free pectinase onto polystyrene resin beads via crosslinking with glutaraldehyde was investigated. The immobilized pectinase was characterized by Fourier transform infrared spectroscopy and confocal laser scanning microscopy. After optimizing the immobilization conditions, the optimum pH of immobilized pectinase shifted from 8.0 to 8.5 and the optimum temperature shifted from 45 to 60 °C, showing its improved stability to temperature and pH compared with the free pectinase. The Michaelis-Menten constant K _m value of free and immobilized pectinase was determined to be 1.95 and 5.36 mM, respectively. The storage stability of immobilized pectinase was demonstrated with 36.8% of the initial activity preserved after 30 days at 25 °C. The reusability of the immobilized pectinase activity was 54.6% of its initial activity after being recycled six times. Therefore, based on the findings mentioned above, it can be inferred that this simple immobilization technique for pectinase appears to be promising for industrial applications.

Grafted carrageenan: alginate gel beads for catalase enzyme covalent immobilization

A new matrix formulation was devised for catalase immobilization. Carrageenan-alginate beads different ratios were developed and soaked into different ratios of CaCl₂-KCl as a hardening solution. The best formulation for loading capacity was selected, treated with polyethylene imine followed by glutaraldehyde and further studied. The best concentration of catalase for immobilization was 300U/ml and the best loading time was 6 h. The catalytic properties increased after immobilization and the immobilized catalase achieved optimum activity at a temperature range of 30-50 °C that was compared to the optimum activity of free catalase which occurred at 40 °C. Higher catalytic activity of immobilized catalase occurred at alkaline pHs than the free one which achieved optimum catalytic activity at neutral pH. A comparison between the kinetic parameters of immobilized and free catalase showed variation. The K _M and Vmax of the immobilized catalase were 2.4 fold and six times higher than those of free catalase. The results of the study indicate that the formulated matrix can be used as a good matrix for catalase enzyme in various industrial applications.

Cibacron blue F3GA incorporated immobilized metal chelate affinity sorbent as a high efficient affinity immobilization materials for catalase enzyme

Catalase is a metalloenzyme commonly found in almost all plant and animal tissues and catalyzes the conversion of hydrogen peroxide to less reactive molecules. It is used for the elimination of hydrogen peroxide in biological, biomedical, food and textile applications. For this purpose, a novel affinity sorbent [poly(methacrylic acid- N-isopropyl acrylamide-CB-Fe³⁺, (p(MAA-NIPAAM)-CB-Fe³⁺)] for the determination and it was first developed using MAA and NIPAAM monomers. After characterization with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray Photoelectron Spectroscopy (XPS), adsorption parameters were determined. Reusability of p(MAA-NIPAAM)-CB-Fe³⁺ sorbent was determined after by determining the appropriate desorption agent for desorption of adsorbed catalase in the developed sorbent. It was determined that catalase adsorption could be performed with 0.01 g of sorbent in 45 min. The maximum adsorption capacity for catalase adsorption was determined as 243.17 mg/g with the use of sorbent. The operational and storage stability of the immobilized catalase was found to be high as expected. The conversion of H₂O₂ can be successfully performed by the immobilized enzyme in the prepared sorbent. It has been proven that the affinity of catalase for its substrate is increased by immobilization.

Injectable Cryogels in Biomedicine

Cryogels are interconnected macroporous materials that are synthesized from a monomer solution at sub-zero temperatures. Cryogels, which are used in various applications in many research areas, are frequently used in biomedicine applications due to their excellent properties, such as biocompatibility, physical resistance and sensitivity. Cryogels can also be prepared in powder, column, bead, sphere, membrane, monolithic, and injectable forms. In this review, various examples of recent developments in biomedical applications of injectable cryogels, which are currently scarce in the literature, made from synthetic and natural polymers are discussed. In the present review, several biomedical applications of injectable cryogels, such as tissue engineering, drug delivery, therapeutic, therapy, cell transplantation, and immunotherapy, are emphasized. Moreover, it aims to provide a different perspective on the studies to be conducted on injectable cryogels, which are newly emerging trend.

Three-dimensional ordered magnetic macroporous metal-organic frameworks for enzyme immobilization

Metal-organic frameworks (MOFs) have been emerged as a promising support for immobilizing enzymes owing to the tunable porosity, high surface area, and structural diversity. However, most of these possess nanometer size and small pores, which are difficult to recover them from the reaction medium and present low immobilization efficiency and protein loading capacity, and high substrate diffusion limitations. Herein, a novel magnetic amino-functionalized zeolitic imidazolate framework-8 (ZIF-8) with 3D highly ordered macroporous structure was synthesized using the assembled polystyrene (PS) nanosphere monoliths as a template. Subsequently, catalase (CAT) molecules were immobilized on the surface of macroporous magnetic ZIF-8 and inside the macropores by precipitation, covalent binding and cross-linking. The resultant immobilized CAT showed high immobilization efficiency (58%) and protein loading capacity (29%), leading to 500% higher activity than the immobilized CAT on ZIF-8 (CAT/ZIF-8). Meanwhile, the immobilized CAT could be easily recovered with a magnet without obvious activity loss. The traditional CAT/ZIF-8 lost its activity after 6 cycles, whereas, the immobilized CAT retained 90% activity of its initial activity after reusing for 8 cycles, indicating excellent reusability. In conclusion, this study provides a facile and efficient approach to immobilize enzymes on/in MOFs with enhanced activity and excellent recyclability.

Antimicrobial magnetic poly(GMA) microparticles: synthesis, characterization and lysozyme immobilization

Micron-sized magnetic particles currently find a wide range of applications in many areas including biotechnology, biochemistry, colloid sciences and medicine. In this study, magnetic poly(glycidyl methacrylate) microparticles were synthesized by providing a polymerization around Fe(II)-Ni(II) magnetic double salt. Adsorption of lysozyme protein from aqueous systems was studied with these particles. Adsorption studies were performed with changing pH values, variable amount of adsorbent, different interaction times and lysozyme amounts. The adsorption capacity of the particles was investigated, and a value of about 95.6 mg lysozyme/g microparticle was obtained. The enzyme activity of the immobilized lysozyme was examined and found to be more stable and reusable compared to the free enzyme. The immobilized enzyme still showed 80% activity after five runs and managed to maintain 78% of its initial activity at the end of 60 days. Besides, in the antimicrobial analysis study for six different microorganisms, the minimum inhibitory concentration value of lysozyme immobilized particles was calculated as 125 μg/mL like free lysozyme. Finally, the adsorption interaction was found to be compatible with the Langmuir isotherm model. Accordingly, it can be said that magnetic poly(GMA) microparticles are suitable materials for lysozyme immobilization and immobilized lysozyme can be used in biotechnological studies.

Reactive Green 5-Decorated Polyacrylamide/Chitosan Cryogel: An Affinity Matrix for Catalase

Acrylamide/chitosan-based cryogel was fabricated, and a triazine dye, Reactive Green 5, was attached to the cryogel by nucleophilic substitution to build a dye affinity support for adsorption of catalase enzyme. Characterization of cryogel was performed using FTIR, SEM, EDX, BET, and swelling test. Synthesized cryogel beared pores with ~ 200 μm in size and the surface area of 11.8 m²/g. Maximum catalase adsorption was (17.6 ± 0.29 mg/g) measured at pH 4.0 and 25 °C. The adsorption sites on the cryogel were saturated at 0.75 mg/mL enzyme concentration. Increased ionic strength caused a decrease in adsorption capacity. Desorption of catalase from cryogel was enabled using 0.5 M NaSCN solution. Consecutive adsorption experiments were carried out fifteen times to evaluate the reusability of the cryogel. Thermal, storage, and operational stabilities of immobilized catalase were higher than the free one. The data produced implicate that catalase-adsorbed dye-affinity cryogel may be used for H₂O₂ detection or removal when necessary. Graphical Abstract.

Designing and investigation of photo-active gellan gum for the efficient immobilization of catalase by entrapment

A photo-active gellan gum (Gel) derivative was developed by amide bond combination with trans-4-[p-(amino)styryl]pyridine (SP). The SP-Gel was cross-linked by UV curing via the intermolecular 2π + 2π cycloaddition of the inserted SP-CH=CH- moieties. The chemical structure of the obtained photo-crosslinkable biopolymer was investigated before and after the UV curing and the progress of the performed 2π + 2π cycloaddition-based cross-linking was detected via UV-visible light spectra. SP-Gel was evaluated as a polymeric matrix for the immobilization of catalase via entrapment technique. The synthesized biopolymer was mixed with the catalase and molded in the form of membranes that were UV cured to encapsulate the enzyme. The membranes were able to entrap 0.75 mg/cm² with retained activity reached above 95%. The immobilized catalase displayed higher thermal stability and higher resistance toward the environmental pH disturbances compared to the free enzyme. Also, despite the observed lower catalase-H₂O₂ affinity upon the entrapment that was indicated from the performed kinetic studies, the reusability and storage stability experiments revealed the economic value of the entire process by preserving around 95% and 83% of the initial catalase activity after the fifth and tenth operation cycles, respectively.

Characterization of biocompatible pig skin collagen and application of collagen-based films for enzyme immobilization

Based on the excellent biocompatibility of collagen, collagen was extracted from pig skin by acid-enzymatic method. The films were prepared by the self-aggregation behavior of collagen, and the catalase was immobilized by adsorption, cross-linking and embedding. The experiment investigated the effects of glutaraldehyde on the mechanical properties, external sensory properties, and denaturation temperature of the films. The results showed that self-aggregating material could maintain the triple helix structure of pig skin collagen. The self-aggregation treatment and cross-linking treatment can improve the mechanical properties to 53 MPa, while the glutaraldehyde cross-linking agent can increase the denaturation temperature of the pig skin collagen self-aggregating membrane by 20.35% to 84.48 °C. This means that its application to immobilized catalase has better stability. The comparison shows that the catalase immobilized by the adsorption method has strong activity and high operational stability, and the cross-linking agent glutaraldehyde and the initial enzyme concentration have a significant effect on the immobilization, and the activity can reach 175 U g-1. After 16 uses of the film, the catalase was completely inactivated. This study provides a reference for the preparation of a catalase sensor that can be used to detect hydrogen peroxide in food by a catalase sensor.

Redefining the chemistry of super-macroporous materials: when dendritic molecules meet polymer cryogels

Dendritic cryogels modify the functionality and properties against conventional cryogels and improve the Immunoglobulin G (IgG) adsorption.

Supermacroporous Composite Cryogels in Biomedical Applications

Supermacroporous gels, called cryogels, are unique scaffolds that can be prepared by polymerization of monomer solution under sub-zero temperatures. They are widely used in many applications and have significant potential biomaterials, especially for biomedical applications due to their inherent interconnected supermacroporous structures and easy formation of composite polymers in comparison to other porous polymer synthesis techniques. This review highlights the fundamentals of supermacroporous cryogels and composite cryogels, and then comprehensively summarizes recent studies in preparation, functionalization, and utilization with mechanical, biological and physicochemical features, according to the biomedical applications. Furthermore, conclusions and outlooks are discussed for the use of these promising and durable supermacroporous composite cryogels.

Effect of immobilization on the activity of catalase carried by poly(HEMA-GMA) cryogels

Hydrogen peroxide is converted by catalase to molecular oxygen and water to remove oxidative stress. In this study, catalase immobilization was performed using poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) (poly(HEMA-GMA)) cryogels with different amounts of GMA. Catalase adsorption capacity of 298.7 ± 9.9 mg/g was achieved at the end of 9 h using the poly(HEMA-GMA)-250 cryogel. Kinetic parameters and the inhibitory effects of pesticides such as 4,4'-DDE and 4,4'-DDT on the activity of free and immobilized catalase enzyme were investigated. While the V_max value of the immobilized enzyme was reduced 4-fold compared to the free enzyme, in the case of the comparison of the K_M values, the affinity of the immobilized enzyme was increased by 1.94 times against the substrate. The inhibitory effect of 4,4'-DDT pesticide was found to be higher for the immobilized and free enzyme. NaCl (1 M, pH: 7.0) solution was used for desorption of the adsorbed catalase enzyme. A desorption ratio of 96.45% was achieved. The technique used in this study is promising regarding for the immobilization of catalase enzyme to increase the operational activity. Therefore, poly(HEMA-GMA) cryogels have the potential to be used for immobilization of catalase enzyme in the fields of biology and biochemistry.