Self-assembled hybrid nanomaterials with alkaline protease and a variety of metal ions

Abstract

Enzyme immobilization is a well-known essential process to improve enzyme stability and enable the industrial reuse of enzymes for more reaction cycles. In this work, we used alkaline protease and a variety of metal ions (Cu²⁺, Zn²⁺, Mn²⁺ and Ag⁺) to synthesize hybrid nanomaterials by self-assembly method respectively, but only two kinds of hierarchical flower-like hybrid nanomaterials were formed. These hybrid nanomaterials' structures were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. Compared with free alkaline protease, two kinds of hybrid nanomaterials exhibited higher enzyme activity (∼927% for alkaline protease–Cu₃(PO₄)₂·3H₂O hybrid nanomaterials, ∼201% for alkaline protease–Zn₃(PO₄)₂·4H₂O hybrid nanomaterials). Enzyme concentration could affect the size and petal density of nanomaterials, so that hampered mass transfer. Furthermore, we concluded that the formation of flower-like hybrid nanomaterials was influenced by atomic radius and the outermost electron orbit of metal ions. These findings have great significance in the synthesis of the hybrid nanomaterials.