Immobilization of urease enzyme on chitosan/polyvinyl alcohol electrospun nanofibers

Abstract

Electrospun nanofibers have gained much attention for enzyme immobilization due to their high surface‐to‐volume ratio. In this study, urease was immobilized on chitosan/poly(vinyl alcohol) (PVA) nanofibers by both adsorption and crosslinking methods. In order to obtain nanofibers with more desirable properties, solutions with different ratios of chitosan and PVA were electrospun and crosslinked using glutaraldehyde. Comparing SEM images of the nanofibers, before and after immersing them in phosphate buffer, it was shown that higher chitosan content leads to more stable fibers. So, the solution with the chitosan to PVA ratio of 40:60 was used for enzyme immobilization. Then, the effects of initial protein concentration, temperature, incubation time, and method of immobilization were investigated to reach the highest enzyme activity. Under similar immobilization conditions, covalently immobilized urease showed higher activity, compared to uncrosslinked immobilized enzyme. Besides, it retained 30% of its initial activity after 10 times usage. So, this method was chosen for further investigation. Not only the activity of the immobilized enzyme was much higher than the free enzyme in a wide range of pH and temperature, but also stability of the immobilized enzyme was improved. Immobilized urease was then used to remove thiourea which is a toxic compound. Findings indicated 60% hydrolysis of initial thiourea in 12 h. In conclusion, the findings showed that chitosan/PVA nanofibers are suitable candidates for the immobilization of urease.

Immobilized Urease Vector System Based on the Dynamic Defect Regeneration Strategy for Efficient Urea Removal

“…Urease, an oligomeric nickel-containing enzyme, serves as a catalyst for the hydrolysis of urea into carbon dioxide and ammonia. However, the limitation lies in the nonreusability of the free enzyme. , Consequently, immobilization techniques can be employed to tether urease onto a carrier material, facilitating its separation and reuse while simultaneously enhancing its bioavailability. − But the research on immobilized urease primarily focuses on biosensing and water purification while investigations regarding urea clearance within the human body are comparatively limited. − …”

A robust and efficient lipase based nanobiocatalyst for phenothiazinyl-ethanol resolution

“…18 Polyvinyl alcohol attracts particular interest for wound dressings, since it is highly hydrophilic and can be easily cross-linked. 19 Taking into account these properties, a combination of the two polymers may lead to electrospun nanofibers with improved properties (increased mechanical strength, thermal stability and swelling ability [20][21][22][23][24][25] ) as a matrix for enzyme immobilization.…”

“…Taking into account these properties, a combination of the two polymers may lead to electrospun nanofibers with improved properties (increased mechanical strength, thermal stability and swelling ability 20–25 ) as a matrix for enzyme immobilization.…”