Multilayer petal-like enzymatic-inorganic hybrid micro-spheres [CPO-(Cu/Co/Cd)3(PO4)2] with high bio-catalytic activity

Abstract

CPO, a versatile enzyme, has limitations in industrial applications due to its poor stability and the difficulty of reuse. The preparation of stable immobilized enzymes with high catalytic activity is therefore desirable, but remains a challenge. A facile preparation of a series of enzyme-inorganic hybrid micro-spheres [chloroperoxidase (CPO)-(Cu/Co/Cd)3(PO4)2] and its application in the decolorization of crystal violet is reported in this work. All the hybrid micro-spheres show a multilayer petal-like structure. The formation of hybrid micro-spheres were proposed via four stages: crystallization, in-situ coordination, self-assembly and size growth. The process was entropy-driven, and there was a competition between precipitation of phosphate and coordination of M2+ with amide groups of CPO. The introduction of excess of chloride ions retarded the phosphate from precipitating by forming [MCl4]2− complexes, while simultaneously promoting the coordination of M2+ with amide groups. These hybrid materials showed high bio-catalytic activity in the decolorization of crystal violet. The decolorization efficiency reached 99.66%, 98.44% and 98.05% just within 3min using CPO-Cu3(PO4)2, CPO-Cd3(PO4)2 and CPO-Co3(PO4)2 respectively. They also have good thermal stability, and can keep 52.89% catalytic activity after 8 cycles of use.CPO-inorganic hybrid micro-spheres [chloroperoxidase (CPO)-(Cu/Co/Cd)3(PO4)2] is promising in the treatment of waste water containing crystal violet. It also has potential application for treatment of other soluble organic dyes in industrial wastewater.