Liposomes and Microencapsulated Enzyme Preparations

Introduction

Enzymes are biological macromolecules that can catalyze a large number of biochemical reactions in minute quantities and with high efficiency, and under mild conditions required for their action. Therefore, enzymes are widely used as a biocatalyst in the processing of food, production of pharmaceutical products, preparation of biosensors, manufacture of hygiene products and detergents, and biological experiment kits. However, enzymes are less tolerant of environmental conditions and can be easily destroyed. Therefore, the protection and targeted delivery of the enzyme is a key step toward its application, and this can be achieved by microencapsulating preparations of the enzyme. Numerous studies have shown that liposomes are excellent tools for achieving enzyme microencapsulation.

Classification

Microencapsulation of enzymes allows them to be applied to a wide range of temperatures and pH values to enhance their catalytic activity and have higher production yields. Enzymes can be entrapped in the core or membrane of liposomes depending on their hydrophilic/hydrophobic nature so that they can resist environmental stresses through a layer of liposomal protection. Some enzymes are anchored on the surface of liposomes as shown in Fig. 1; meanwhile, surface modifications of liposomes ensure the conjugation of enzymes on their surface. Liposomes can be loaded with different enzymes, mainly oxidoreductase and hydrolase classes.

Fig 1. An illustration of liposomal structure and entrapment/anchoring of enzymes. (Mohammadi A, 2021)

Oxidoreductase Enzymes

The class of redox enzymes includes mainly

• Catalase
• Glucose oxidase
• Laccase

Catalase, which is mainly used in food packaging, preservation, and cheese production, has also been reported to be encapsulated in liposomes formed by cisplatin (IV)-drug-binding phospholipids for clinical cancer therapy. By encapsulating catalase into liposomes, its activity and stability can be improved. Encapsulation of peroxidase in a liposome made of cisplatin. Glucose oxidase is derived from microorganisms and has a wide range of applications in the food, beverage, pharmaceutical, clinical, chemical, and biotechnology industries, where it can increase food shelf life and improve flavor. Laccase, which oxidizes phenolic and non-phenolic lignin-related substrates and other environmental contaminants, has been used in bakery products to reduce the time it takes for dough to reach its peak and accelerate dough breakdown. Its microencapsulation by liposomes improves activity and stability.

Hydrolase Enzymes

Hydrolytic enzymes include alpha-amylase, amyloglucosidase, beta-galactosidase, flavorase, lipase, trypsin, etc. Alpha-amylase is a common enzyme used in many industrial processes such as starch liquefaction, baking, textile design, detergent, and bioethanol production. The microencapsulation of liposomes improves their stability. Amyloglucosidases are used in several industries, such as wastewater treatment, detergents, baking, and natural sweeteners. Compared to the free form, the liposome-loaded enzyme is very stable and reusable and maintains a certain level of activity. β-D-galactosidase or lactase is used in many processing practices such as food, dairy, and fermentation industries as well as environmental processes. Encapsulation by liposomes improves their tolerance to temperature and pH, improves the flavor of foods when added to liposomes, and possesses high activity even after liposome cracking. Flavor enzymes have internal and external peptidase activity and are mainly used in cheese production and to accelerate cheese ripening, which can enhance the flavor of food products. Encapsulation of cheese ripening enzymes in liposomes can increase the speed of cheese ripening and result in better texture, odor, and taste while reducing the cost of product storage. Lipase is widely used in various processes such as the petroleum industry, baking industry, dairy products, etc. Its encapsulation by liposomes results in increased activity and reduced catalytic time.

Example

Some emulsion foods require the addition of antioxidants, but natural antioxidants are less active, and the use of liposome-encapsulated enzymes allows them to be positioned at specific sites thereby increasing their effective concentration and acting as antioxidants.

Some dairy products require lactase supplementation to meet the needs of lactose intolerant people, but adding lactase directly to food can cause fermentation and affect the taste of the food. However, loading with liposomes ensures the localized release of lactase and prevents enzyme side reactions.

Enzymes are also commonly used to promote cheese ripening. To reduce the degradation of cheese proteins by enzymes, they are wrapped in liposomes and dispersed evenly in the cheese, then rennet is added to form a clot in which the liposomes are netted and subsequently broken, allowing the release of enzymes and thus accelerating cheese ripening.

About Us

BOC Sciences can design a variety of liposome products containing the most complex compounds. Our scientists can customize liposomes of any size and concentration in any volume to meet your different needs. We can conduct the entire proposal from liposome design to PK modeling.

Reference

1. Mohammadi A; et al. Liposomal/Nanoliposomal Encapsulation of Food-Relevant Enzymes and Their Application in the Food Industry. Food and Bioprocess Technology. 2021, 14(1): 23-38.