Construction of nano-composites by enzyme entrapped in mesoporous dendritic silica particles for efficient biocatalytic degradation of antibiotics in wastewater

Dendritic silica particles (DSP) with center-radial vertical pore were prepared for entrapping chloroperoxidase (CPO) to construct CPO@DSP. This enzymatic composite is very stable in the presence of heat and organic solvents, remaining 90.74% activity at 80 degrees C after 3 h while the free CPO can keep only 14.28% activity at the same condition. Moreover, it was found the pore size of DSP can influence the catalytic activity of the composite. The pore should keep the accessible internal areas for the substrates besides accommodating the enzyme itself. A novel amyloid-like protein nanofilm formed by phase transition lysozyme (PTL) was coated around the surface of CPO@DSP (expressed as PTL-CPO@DSP), and then the PTL was cross-linked with another layer of CPO through glutaraldehyde to construct CPO@PTL-CPO@ DSP. In this way, the CPO was widely distributed both in mesoporous channel and on the surface of DSP simultaneously. Both the enzyme loading and the reuse of CPO@PTL-CPO@DSP was greatly improved compared with CPO@DSP. After 20 cycle of use, CPO@PTL-CPO@DSP can maintain over 80% of its original activity. CPO@PTL-CPO@DSP were very efficient when applied in the degradation of the antibiotic levofloxacin and rifaximin in wastewater. Over 88% of both antibiotics can be degraded within 30 min at concentration of 20 mu g.mL(-1) in wasterwater.