An ideal immobilization method should employ mild chemical conditions which allow for large quantities of enzyme to be immobilized to provide a large surface area for enzyme-substrate contact within a small total volume, minimize barriers to mass transport of substrate and product and provide a chemically and mechanically robust system. Different immobilization methods have been performed including covalent attachment, physical entrapment or encapsulation and adsorption. Entrapment or encapsulation inside a solid matrix usually results in a low enzymatic reaction rate because substrates have to diffuse into the matrix to interact with the entrapped enzyme. In contrast, adsorption is a much simpler way to immobilize enzymes and maintain their activity under mild experimental conditions. However, the stability of adsorption is affected by a combination of factors, such as pH, ionic strength, temperature, surface tension, charges, and matrix. Most previous studies used particles made of synthetic polymer, inorganic, or metallic materials as substrates to adsorb proteins which could severely limit their potential in vivo biomedical/clinical applications. The characteristics of the matrix are of paramount importance in determining the performance of the immobilized enzyme system. Ideal support properties include physical resistance to compression, hydrophilicity, inertness toward enzymes ease of derivatization, biocompatibility, resistance to microbial attack, and availability at low cost. Supports can be classified as inorganic and organic according to their chemical composition. The organic supports can be subdivided into natural and synthetic polymers. The physical characteristics of the matrices such as required particle diameter, water soaking capacity, mechanical strength, and compressible ability will be of major importance for the performance of the immobilized systems and will determine the type of reactor used under technical conditions i.e., stirred tank, fluidized, fixed beds. In particular, pore parameters and particle size determine the total surface area and thus critically affect the capacity for binding of enzymes. Nonporous supports show some diffusing limitations but have a low loading capacity. Therefore, porous supports are generally preferred due to their preferred larger surface area allows for maximal enzyme loading and greater stability towards persisting environment conditions. Porous supports should have a controlled pore distribution in order to optimize capacity and flow properties as well. Despite of having many advantages of inorganic carriers (e.g., high stability against physical, chemical, and microbial degradation), most of the industrial applications are used organic matrices for enzyme immobilization. An excellent matrix is agarose gel/beads which has been extensively used for immobilization/encapsulation of enzymes in modern and upcoming laboratory practices. In addition to its high porosity makes it suitable for desired proteins/enzymes as well as its hydrophilic character and ease of derivatization are very important factor for its maximal use as chosen matrix for modern enzyme/protein immobilization techniques.
About Author / Additional Info:
Dr. Kirti Rani,
Assistant Professor (II),
Amity Institute of Biotechnology,
Amity University Uttar Pradesh, Noida,
Sec-125, Gautam Buddha Nagar, Noida-201303 (UP), India.
Off. Phone no: +120-4392946
Mobile no: +9990329492
Email ID: email@example.com, kirtisharma2k@rediffmail.