Abstract:
This research is aimed to study the efficiency of using polystyrene/polystyrene-comaleic anhydride electrospun fibers as a supporting material for lipase immobilization. It is found from the study for the optimum conditions in preparing e-spun fibers from polymer blends of PS:PSMA with mixing ratio at 4:1 and 1:1 that voltage (kV) : distance between needle and collector (cm) : concentration of polymer solution (%w/w) has significant effect on fiber morphology. The suitable conditions, in which smooth surface with bead-free fibers are obtained, for 4:1 and 1:1 PS/PSMA are 6:11:15 and 8:10:12, respectively. Suitable solvents for preparing these PS/PSMA blends are mixed solvent of DMF and THF at mixing ratio 2:1 and 1:1, respectively. It is found from using these e-spun mats for lipase immobilization that e-spun mat of 1:1 PS/PSMA provides the highest immobilization efficiency. Its protein loading and hydrolysis activity (U/mg support) are higher than those of 4:1 PS/PSMA and 1:0 PS/PSMA, respectively. From the re-usability test with hydrolysis reaction, while the immobilized enzyme on 1:1 PS/PSMA is possibly re-use for 6 times, the immobilized lipase on e-spun PS/PSMA with PSMA content less than 50% can be re-used much less. Pre-treatment of e-spun mat with alcohol can improve protein loading for ~ 2.7x. Efficiency of lipase immobilization on commercial support as NKA (PS bead) is also studied in comparison with e-spun mat. Results show that shape (form) of the supporting materials has an influence on the immobilization efficiency. Immobilized enzyme of NKA has lower protein loading but much higher activity (U/mg lipase) than that of e-spun mats.