ELECTROSPUN NANOFIBERS FOR ENZYME IMMOBILIZATION

An enzyme is a kind of protein with a catalytic function. As a biological catalyst it has many merits,including a quick reaction rate, mild reaction conditions, and strong substrate specifificity, and the enzyme itself can be degraded by microorganisms, so it meets the requirements of green chemistry. Thus enzymes have been widely applied in various fifields, such as food, medicine, light industry, agriculture, etc. Nevertheless, the advanced structure of the enzyme renders it very sensitive to environmental conditions, like pH, temperature, metal ions, and organic solvents. Changes in these environmental conditions may lead to a loss of activity in free enzymes. Moreover, free enzymes cannot be recycled after a reaction and have no reutilization, which restrict practical applications. The rise of enzyme immobilization techniques since the 1950s can improve the stability and reutilization of enzymes and also give benefifits in reducing the cost, protecting the environment, automatic continuous production, and many other aspects. Hence enzyme immobilization techniques provide broad prospects for the application of enzymes (Hanefeld et al., 2009).

The properties of immobilized enzymes are mainly depended on the immobilization methods and carrier materials used. The properties of carrier materials can directly affect the catalytic activity of immobilized enzymes (Krajewska, 2009). In recent years researchers have conducted extensive studies on enzyme immobilization utilizing different carrier materials, including activated carbon (Kumar et al., 2009), nanoparticles (Kumar et al., 2014), gelatin (Shen et al., 2011), magnetic microspheres (Miao et al., 2016), ordered mesoporous materials (Deka et al., 2015), hydrophilic microfifiltration membranes (Liu et al., 2006), etc. Among all these carrier materials, nanomaterials have attracted increasing attention in the fifield of enzyme immobilization due to their multiple advantages of large specifific surface area, small mass transfer resistance, large enzyme loading ability, etc. It is known that as carrier materials for enzyme immobilization, nanoparticles and carbon nanotubes can improve enzyme loading volume and catalytic activity. However, the stability of the enzymes immobilized on these materials is not satisfactory and the immobilized enzymes are diffificult to recycle from the reaction system, restricting their use in the fifield of enzyme immobilization.

Because electrospun nanofifibrous membranes have advantages of large specifific surface area, rich structure, long lasting, easy separation recycling, etc., many scholars use them to study the immobilization of enzyme molecules. As the carrier of immobilized enzymes, an electrospun nanofifibrous membrane gives suffificient contact of enzymes with substrates and could effectively enhance the catalytic effificiency and reusability of enzymes, thus it has been considered a potential enzyme immobilization matrix with broad application prospects. Enzyme immobilization is now a hot research topic in the application fifields for electrospun nanofifibers (Wang et al., 2009). This chapter brieflfly introduces research progress on enzyme immobilization strategies for electrospun nanofifibers, and then highlights recent advances of enzyme -immobilized electrospun nanofifibers used in various application fifields. It concludes with a summary of current and future research efforts and opportunities in the development of electrospun nanofifibers for enzyme immobilization.

Paper link：https://www.sciencedirect.com/book/9780323512701/electrospinning-nanofabrication-and-applications