# The Biocatalytic Degradation of Organic Dyes Using Laccase Immobilized Magnetic Nanoparticles
## 1 Introduction  
The economy and development of the present world are essentially dependent on the industries. However, the other face of industrial development is the pollution of the environment, due to the release of toxic materials associated with different industries [1]. The presence of these materials is a great risk to the living ecosystem, because of their confirmed mutagenic and carcinogenic properties [2, 3]. So, these harmful materials must be removed safely from different environmental systems. Dyes that are released into the environment through different printing and textile activities are an example of these dangerous pollutants [4, 5]. These dyes were removed from contaminated industrial wastewater viaseveral biological and chemical methods. Attention is drawn to using biological methods, including enzymes, instead of chemical methods, due to limitations such as the discharge of harmful by-products, high cost, and ineffective purification [6]. These dyes' biodegradation is extensively investigated, using several peroxididases and oxidases [7; 8; 9]. The increase enzyme is a multi-copper oxidase that is formed by several plants and fungi, and can oxidize different types of dyes in an eco-friendly and effective way [10]. However, the lacase's weak stability and difficult reusability limit its application in the water treatment from such contaminants [11]. Besides the non-reusability and low stability of soluble lacase, it is very sensitive towards denaturing agents that retard its function and hinder its use in real sample applications. These problems can be resolved by the lacase hold method on different types of supports, to enhance enzyme stability. Different carriers are used to support the lacase enzyme, and improve its catalytic efficiency and stability, and this process is known as immobilization. The immobilization of different biomolecules and enzymes is achieved by using many approaches, such as encapsulations, entrapment, crosslinking, adsorption, and covalent bonding [12]. The enzyme immobilization was reached using different types of materials, including inorganic materials (silica, metal oxides, and clays) [13; 14; 15], organic materials (natural and synthetic polymers) [16; 17], and hybrids (joining organic and inorganic materials) [18]. Among all the materials used, nanomaterials are widely used due to their exceptional properties [19; 20; 21; 22; 23; 24], such as high surface area, ease of synthesis, low cost, and ease of modification that can enhance the enzymatic activity. Many studies reported the successful immobilization of lacase on the surface of nanomaterials, to improve its stability and catalytic properties, for the removal of the dye from aqueous media. For instance, free lacase was successfully immobilized with improved properties and reused on the surface of green synthesized ZnO and MnO nanoparticles for the degradation of alizarin red S dye [25]. From nanomaterials, magnetic nanoparticles are the most used and favored as support for enzymes, due to their magnetic behavior that allows the magnetic separation from the reaction medium, using an external magnet. For example, a magnetic amino-functionalized metal-organic framework (Fe\({}_{3}\)O\({}_{4}\)-NH\({}_{2}\)@MIL-101(Cr)) was successfully used for the immobilization of lacase, for the biodegradation of Reactive Black 5 (RB) and alizarin red S (AR) dyes in water [26], while a magnetic nanocomposite (Fe\({}_{3}\)O\({}_{4}\)/chitosan) was used for the successful immobilization of manganese peroxidase, for the removal of orange 16 and methylene blue [27]. The implantation of some heavy metals with the magnetic nanoparticles significantly enhances their immobilization efficiency for lacase, besides applied operability. Additionally, several heavy metals, such as cobalt, calcium, zinc, and copper, were reported in many works to improve the lacase activity [28]. Especially, copper ions at low concentrations serve as lacase modulators more than other heavy metals [29].