Preparation of a Cu(II)-PVA/PA6 composite nanofibrous membrane for enzyme immobilization

PVA/PA6 composite nanofibers were formed by electrospinning. Cu(II)-PVA/PA6 metal chelated nanofibers, prepared by the reaction between PVA/PA6 composite nanofibers and Cu2+ solution, were used as the support for catalase immobilization. The result of the experiments showed that PVA/PA6 composite nanofibers had an excellent chelation capacity for Cu2+ ions, and the structures of nanofibers were stable during the reaction with Cu2+ solution. The adsorption of Cu(II) onto PVA/PA6 composite nanofibers was studied by the Langmuir isothermal adsorption model. The maximum amount of coordinated Cu(II) (q(m)) was 3.731 mmol/g (dry fiber), and the binding constant (K(l)) was 0.0593 L/mmol. Kinetic parameters were analyzed for both immobilized and free catalases. The value of V(max) (3774 μmol/mg·min) for the immobilized catalases was smaller than that of the free catalases (4878 μmol/mg·min), while the K(m) for the immobilized catalases was larger. The immobilized catalases showed better resistance to pH and temperature than that of free form, and the storage stabilities, reusability of immobilized catalases were significantly improved. The half-lives of free and immobilized catalases were 8 days and 24 days, respectively.