Sustainable biodegradation of antibiotic residues in aqueous environment using OXA-48 β-lactamase encapsulated in spherical mesoporous covalent organic frameworks

The prevalence of antibiotics in natural aquatic environment has become an emerging class of organic pollutants, impacting both aquatic ecosystems and human health. Herein, spherical mesoporous covalent organic frameworks (SMCOF) was successfully synthesized and employed in the immobilization of OXA-48 β-lactamase through pore adsorption, in which 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde were utilized as the node and linker, respectively. Structural characterization demonstrated that OXA-48 was successfully adsorbed into the pores of SMCOF, achieving a loading capacity of 546.81 mg/g. Meanwhile, OXA-48@SMCOF maintained the catalytic activity of 62.08 % and 104.98 % after the treatment at 50 °C (pH of 7.4) and 37 °C (pH of 11) for 30 min, respectively. Further, all the catalytic activities of OXA-48@SMCOF remained above 88 % after the incubation in the presence of various organic solvents or proteinase K for 1 h. Moreover, OXA-48@SMCOF retained 53.78 % and 41.18 % of original activity after 15 cycles of reuse and 10 days of storage, respectively, indicating its favorable reusability and storage stability. In the application of degrading antibiotics in lake water samples, OXA-48@SMCOF demonstrated superior degradation performance compared to free OXA-48, attributing to the protective effect of SMCOF. Overall, the present study provides a promising technique to construct high performance immobilized enzymes, which is beneficial for the future application of OXA-48@SMCOF in the degradation of antibiotics during water treatment process.