Catechol modification and covalent immobilization of catalase on titania submicrospheres

Catalase immobilization: Current knowledge, key insights, applications, and future prospects - A review

Catalase (CAT), a ubiquitous enzyme in all oxygen-exposed organisms, effectively decomposes hydrogen peroxide (H2O2), a harmful by-product, into water and oxygen, mitigating oxidative stress and cellular damage, safeguarding cellular organelles and tissues. Therefore, CAT plays a crucial role in maintaining cellular homeostasis and function. Owing to its pivotal role, CAT has garnered considerable interest. However, many challenges arise when used, especially in multiple practical processes. "Immobilization", a widely-used technique, can help improve enzyme properties. CAT immobilization offers numerous advantages, including enhanced stability, reusability, and facilitated downstream processing. This review presents a comprehensive overview of CAT immobilization. It starts with discussing various immobilization mechanisms, support materials, advantages, drawbacks, and factors influencing the performance of immobilized CAT. Moreover, the review explores the application of the immobilized CAT in various industries and its prospects, highlighting its essential role in diverse fields and stimulating further research and investigation. Furthermore, the review highlights some of the world's leading companies in the field of the CAT industry and their substantial potential for economic contribution. This review aims to serve as a discerning, source of information for researchers seeking a comprehensive cutting-edge overview of this rapidly evolving field and have been overwhelmed by the size of publications.

Oxidase mimicking Co/2Fe MOF included biosensor for sialic acid detection

A facile amperometric biosensor that included oxidase mimicking Co/2Fe metal-organic framework (MOF) for sialic acid (SA) detection was prepared. Amperometric SA biosensor was constructed on a gold screen-printed electrode via immobilization of Co/2Fe MOF and N-acetylneuraminic Acid Aldolase (NANA-Aldolase) enzyme, respectively. NANA-Aldolase enzyme converts free SA into pyruvate and N-acetyl-d-mannosamine. After this conversion, oxidase mimicking Co/2Fe bimetallic MOF converts pyruvate into acetylphosphate and O₂ into H₂O₂. Investigation of analytical characteristics resulted with the linear range of 0.02 mM-1.00 mM of SA concentration with limit of detection value of 0.026 mM. Sample application studies with developed SA biosensor were carried out with GD3 ganglioside and HeLa cancer cell lines which have high SA concentrations while A549 cell lines were also used as control group. Before detecting free SA, the bound SA was freed from SA sources where every step was monitored via electron impedance spectroscopy. Then, free SA was successfully detected with the amperometric SA biosensor and as a result, more practical and accurate system was developed.

Oxime-functionalized cryogel disks for catalase immobilization

Catalase is a protective enzyme against oxidative stress and converts hydrogen peroxide into water and molecular oxygen. In the current study, catalase immobilization was applied onto the oxime-functionalized cryogel disks. Cryogel disks were produced by free radical polymerization. After cutting as circular disks, oxime ligand (4-biphenylchloroglyoxime, BPCGO) was attached and oxime-functionalized cryogel disks were obtained. After optimization of several immobilization parameters such as pH, initial catalase concentration, temperature and ionic strength, maximum catalase load was detected as 261.7 ± 11.2mg/g for cryogel disk at pH5.0. Activity studies indicated that immobilization enhanced the enzyme activity in basic pH region, the temperature range of 15-35°C and at ionic strengths between 0.2 and 1.0M NaCl. Km was detected as 9.9 and 11.0mM and V_max was 357.1 and 769.2μmol min^-1 for free and immobilized catalase, respectively. k_cat and Km/k_cat values showed that immobilization enhanced the catalytic efficiency. Storage stability experiments demonstrated that immobilization increased the usability period. Furthermore, catalase desorption was achieved by 1.0M NaSCN at pH8.0 successfully and catalase adsorption capacity of oxime-functionalized cryogel disk was decreased by 9.9% at the end of 5 adsorption-desorption cycle.

Synthesis and formulation of functional bionanomaterials with superoxide dismutase activity

Layered double hydroxide (LDH) nanoparticles were prepared and used as solid support for superoxide dismutase (SOD) enzymes. Structural features were studied by XRD, spectroscopic methods (IR, UV-Vis and fluorescence) and TEM, while colloidal stability of the obtained materials was investigated by electrophoresis and light scattering in aqueous dispersions. The SOD quantitatively adsorbed on the LDH by electrostatic and hydrophobic interactions and kept its structural integrity upon immobilization. The composite material showed moderate resistance against salt-induced aggregation in dispersions, therefore, heparin polyelectrolyte was used to improve the colloidal stability of the system. Heparin of highly negative line charge density strongly adsorbed on the oppositely charged hybrid particles leading to charge neutralization and overcharging at appropriate polyelectrolyte loading. Full coverage of the composite platelets with heparin resulted in highly stable dispersions, which contained only primary particles even at elevated ionic strengths. Our results indicate that the developed bionanocomposite of considerable enzymatic function is a suitable candidate for applications, wherever stable dispersions of antioxidant activity are required for instance in biomedical treatments or in chemical manufacturing processes.

Durable defense: robust and varied attachment of non-leaching poly"-onium" bactericidal coatings to reactive and inert surfaces

Developing antimicrobial coatings to eliminate biotic contamination is a critical need for all surfaces, including medical, industrial, and domestic materials. The wide variety of materials used in these fields, from natural polymers to metals, require coatings that not only are antimicrobial, but also contain different surface chemistries for covalent immobilization. Alkyl "-onium" salts are potent biocides that have defied bacterial resistance mechanisms when confined to an interface. In this feature article, we highlight the various methods used to covalently immobilize bactericidal polymers to different surfaces and further examine the mechanistic aspects of biocidal action with these surface bound poly"-onium" salts.

Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles as a potential candidate to eliminate intracellular reactive oxygen species

Horseradish peroxidase-immobilized magnetic mesoporous silica nanoparticles (MMSNs-HRP) have been synthesized by a NHS/EDC coupling between the amino groups of horseradish peroxidase (HRP) and the carboxyl groups on the MMSNs surface. It is found that the immobilized HRP on MMSNs still retain high activity and the MMSNs-HRP can eliminate the reactive oxygen species (ROS) in Chinese hamster ovary (CHO) cells induced by the addition of H2O2 aqueous solution. Further, the fluorescent MMSN-HRP-CD nanoparticles have been prepared by attaching biocompatible, fluorescent carbon dots (CDs) to MMSNs-HRP. We have also investigated the effect of an applied magnetic field on cellular uptake of MMSNs-HRP-CDs and found that the internalization of MMSNs-HRP-CDs by CHO cells could be enhanced within 2 hours under the magnetic field. This work provides us with a novel and efficient method to eliminate ROS in living cells by using HRP-immobilized nanoparticles.

Inorganic materials as supports for covalent enzyme immobilization: methods and mechanisms

Several inorganic materials are potentially suitable for enzymatic covalent immobilization, by means of several different techniques. Such materials must meet stringent criteria to be suitable as solid matrices: complete insolubility in water, reasonable mechanical strength and chemical resistance under the operational conditions, the capability to form manageable particles with high surface area, reactivity towards derivatizing/functionalizing agents. Non-specific protein adsorption should be always considered when planning covalent immobilization on inorganic solids. A huge mass of experimental work has shown that silica, silicates, borosilicates and aluminosilicates, alumina, titania, and other oxides, are the materials of choice when attempting enzyme immobilizations on inorganic supports. More recently, some forms of elemental carbon, silicon, and certain metals have been also proposed for certain applications. With regard to the derivatization/functionalization techniques, the use of organosilanes through silanization is undoubtedly the most studied and the most applied, although inorganic bridge formation and acylation with selected acyl halides have been deeply studied. In the present article, the most common inorganic supports for covalent immobilization of the enzymes are reviewed, with particular focus on their advantages and disadvantages in terms of enzyme loadings, operational stability, undesired adsorption, and costs. Mechanisms and methods for covalent immobilization are also discussed, focusing on the most widespread activating approaches (such as glutaraldehyde, cyanogen bromide, divinylsulfone, carbodiimides, carbonyldiimidazole, sulfonyl chlorides, chlorocarbonates, N-hydroxysuccinimides).