IMMOBILIZATION OF LEVANSUCRASE: STRATEGIES AND BIOTECHNOLOGICAL APPLICATIONS

Activity and stability comparison of immobilized NADH oxidase on multi-walled carbon nanotubes, carbon nanospheres, and single-walled carbon nanotubes

Objective: This study aims to evaluate the importance of endodontic root canal sealers in filling cavities and irregularities in root canals with the primary goal of minimizing or eliminating bacterial residues. Despite this crucial objective, it's noteworthy that several conventional sealers have been linked to adverse effects, such as impaired wound healing, inflammation, and bone resorption. Therefore, there is a constant search for an optimal sealer that can effectively mimic the properties of lost tissue while maintaining an acceptable level of biological, physicochemical and biocompatible properties. The present study analyzes bioceramic cement's properties in endodontics through a comprehensive review of the available literature. Also, to evaluate the beneficial properties and characteristics of the biomaterials highlighted in this work. Methods: The present study used a systematic review approach to conduct a comprehensive literature search to find relevant publications on bioceramic cement properties in the endodontics field. Articles were retrieved using MeSH keywords and digital searches of journal websites. The selected studies were examined to extract data on sealability, bioactivity, pH, cytotoxicity, color change, radiopacity, edge adaptation, adhesive strength, antibacterial properties and biocompatibility. Results: The results of the reviewed research show that bioceramic endodontic cement has favorable properties for the therapeutic treatment of root canals. The literature highlights the material's biocompatibility, low cytotoxicity, bioactivity, radiopacity, appropriate pH value, favorable edge adaptation, high adhesive strength, practical sealability, antibacterial properties and minimal color change. Conclusion: Research results to date indicate that biomaterials used in endodontics have beneficial properties for root canal therapy and mimicking natural tissue regeneration. The beneficial properties of these materials, such as their biocompatibility, bioactivity, radiopacity, pH stability, edge conformability, adhesion strength, sealability and antibacterial properties, make it a promising replacement for traditional sealers. Further studies are needed to investigate the extended clinical effectiveness of the above intervention and to refine its composition to improve the outcomes associated with endodontic therapies.

Biodiesel production through transesterification is heavily reliant on catalysts, which play a significant role in the process. One of the major challenges in biodiesel production is selecting an appropriate catalyst. Both chemical and biological catalysts have been extensively researched for use in transesterification, each with its own set of advantages and disadvantages. Biocatalysts, particularly enzymes, have several desirable qualities that make them superior to chemical catalysts. These qualities include homogeneity, biocompatibility, biodegradability, and environmental acceptability. Lipases and phospholipases, with their specificity and regio- and enantioselectivity, are particularly useful in promoting the esterification and transesterification of carboxylic esters during biodiesel production. However, despite these benefits, the high cost of enzymes and the need for recycling contribute to higher production costs. Whole cell-based catalysts derived from various microbes have lower efficiency in the presence of an oily substrate, which reduces the biodiesel yield. However, immobilizing enzymes on a solid matrix has shown promise in improving enzyme stability, reusability, and the ability to survive in extreme temperature and pH environments. Several immobilization methods are available, such as physical adsorption, covalent bonding, entrapment, encapsulation, and cross-linking. It is worth exploring the interactions between biocatalysts and carriers, and also attempting to enhance enzyme features through immobilization or co-immobilization, and the use of whole cells to produce biodiesel more efficiently.

The goal of biodiesel production is to obtain a clean, biodegradable, and renewable fuel. Industrial-scale processes use homogeneous and heterogeneous chemical catalysts. These are efficient but require the use of very pure reagents and complex product purification steps or processing conditions under high temperature and pressure. Enzymatic catalysis, in contrast, using lipases as biocatalysts, is an alternative that produces a better-quality product under less extreme conditions. Since free lipases are not reusable, it is necessary to immobilize them to stabilize them and allow their reuse over several reaction cycles. This informative review presents various methods of lipase immobilization (physical adsorption, ionic bonding, covalent bonding, entrapment, encapsulation, and cross-linking) as well as their advantages and disadvantages, followed by a comparative study. Articles from 2010 to 2022 were used for bibliometry to show that the topic is still relevant. The immobilization methods are classified into two main groups, physical and chemical, according to the enzyme-support interaction. Among these methods, ionic bonding is recommended, because in addition to this process being easily achievable, lipases immobilized this way are more stable and reusable. In summary, the production of biodiesel from immobilized lipases is in line with sustainable development and respect for the environment.

Study on the activity and stability of urease immobilized onto nanoporous alumina membranes

Enzyme immobilization refers to the process of attaching or confining enzymes onto a solid support or within a matrix, often made of polymers or other materials. This immobilization creates a stable and controlled environment for the enzyme to interact with substrates and perform catalysis. The primary goal of enzyme immobilization is to enhance enzyme stability, reusability, and activity under specific conditions, making them more practical and efficient for various biotechnological, industrial, and medical applications.
 Immobilization methods can vary widely, including physical adsorption, covalent bonding, entrapment within matrices, encapsulation, crosslinking, and more. These methods provide a means to control the interactions between the enzyme and the surrounding environment, affecting factors such as substrate accessibility, enzyme orientation, and stability.
 Due to their ease of fabrication and superior structural adaptability, polymer compounds in a variety of physical forms, including beads, films, fibers,and coatings,have become popular as supportive materials for enzyme immobilization. For enzyme immobilization, a number of natural polymers, including agar, agarose, alginate, dextran, chitosan,and carrageenan, as well as synthetic polymers, such as polyamides, polystyrene, and polyacrylamide, are often employed as a carrier system. The immobilization offers a cost-effective system for various applications in biotechnology, industry, and research.

Enzyme immobilization on a solid matrix is nowadays widely employed, particularly in the food and pharmaceutical industries, in biomedical applications such as biosensors, immunological test systems, and in the production of fine chemicals. The conventional method of enzyme immobilization includes adsorption due to electrostatic and hydrophobic adhesion and covalent binding by internal cross-linkage of enzymes on a solid support. The immobilization of enzymes can offer several advantages including repeated usage of enzyme thereby reducing the cost of the enzyme, ease of product separation, and improvement in enzyme stability. The used tea, an abundant renewable source, can be applied as solid matrix for enzyme immobilization. In the present investigation, the immobilization of alkaline protease was studied on used tea. Immobilized enzyme showed better thermal stability than the free enzyme. Optimum conditions of immobilization investigated include temperature, pH and storage stability, and also reusability. The best result of immobilization yield (34%) and immobilization efficiency (45%) was found with 300 mg of solid matrix. The immobilized enzyme was activity even after eight cycles of repeated use.

Immobilizing and positioning patients for radiotherapy

Innovative multiple nanoemulsion (W/O/W) based on Chilean honeybee pollen improves their permeability, antioxidant and antibacterial activity

The aim of this work is to investigate phenol removal by immobilized peroxidase extracted from cauliflower stem. Peroxidase was partially purified by membrane filtration and diafiltration. Almost four-fold increase in the measured activity of partially purified peroxidase was obtained. The enzyme was then immobilized on to the surface of regenerated cellulose ultrafiltration membrane (molecular weight cut-off 30 kDa) using a dead-end filtration unit. Three different immobilization methods (physical adsorption, cross-linking and covalent-bonding using glutaraldehyde as a membrane activator) were tested. The immobilization and enzymatic reaction efficiency were evaluated in terms of the immobilization yield, the enzyme leakage from the system, the phenol removal and the permeate flux. Results showed that the immobilization methods did not much affect the permeate flux of the membrane. The peroxidase immobilization by covalent-bonding on regenerated cellulose membrane produced the highest immobilization yield and the lowest enzyme leakage. The immobilized enzymatic reaction efficiency on phenol removal was 100% at operational time 60 min and reduced to 96.4% at 600 min.

Stability analysis of Bacillus stearothermophilus L1 lipase immobilized on surface-modified silica gels

Carnitine can be considered a conditionally essential nutrient for its importance in human physiology. This paper provides an updated picture of the main features of carnitine outlining its interest and possible use. Particular attention has been addressed to its beneficial properties, exploiting carnitine’s properties and possible use by considering the main in vitro, in animal, and human studies. Moreover, the main aspects of carnitine-based dietary supplements have been indicated and defined with reference to their possible beneficial health properties.

Graphene-based materials have been shown to have advantageous properties in biomedical and dental applications due to their high mechanical, physiochemical, antibacterial, and stem cell differentiating properties. Although graphene-based materials have displayed appropriate biocompatible properties when used in implant materials for orthopedic applications, little research has been performed to specifically test the biocompatibility of graphene for dental applications. The oral environment, compared to the body, varies greatly and must be considered when evaluating biocompatibility requirements for dental applications. This review will discuss in vitro and in vivo studies that assess graphene's cytotoxicity, antibacterial properties, and cell differentiation ability to evaluate the overall biocompatibility of graphene-based materials for dental applications. Particle shape, size, and concentration were found to be major factors that affected overall biocompatibility of graphene.

Optical fibre reflectance sensors for the detection of heavy metal ions based on immobilised Br-PADAP

Aspergillus niger NRC 107 xylanase and beta-xylosidase were immobilized on various carriers by different methods of immobilization, including physical absorption, covalent binding, ionic binding, and entrapment. The immobilized enzymes were prepared by physical adsorption on tannin-chitosan, ionic binding onto Dowex-50W, covalent binding on chitosan beads through glutaraldehyde, and entrapment in polyacrylamide had the highest activities. In most cases, the optimum pH of the immobilized enzymes were shifted to lower than those of free enzymes. The optimum reaction temperature of immobilized xylanase was shifted from 50C to 52.5-65C, whereas that of immobilized beta-xylosidase was shifted from 45C to 50-60C. The Km values of immobilized enzymes were higher than those of native enzymes. The operational stability of the immobilized enzymes was evaluated in continuous operation in packed-bead column-type reactors. The enzymes covalently bounded to chitosan showed the highest operational stability. However, the enzymes immobilized by physical absorption or by ionic binding showed a low operational stability. The enzymes entrapped in polyacrylamide exhibited lower activity, but better operational stability.