Construction of new enzyme reactor based on aptamer functionalized magnetic nanoparticles conjugated organic framework (COF) for acetylcholinesterase immobilization has been an enabling endeavor in this work. The aptamer against acetylcholinesterase was selected through a method based on capillary electrophoresis in one round. A new magnetic COF material rich of carboxyl groups was firstly synthesized, and its surface was then modified with the selected aptamer through covalently linking. Acetylcholinesterase was immobilized to fabricate the enzyme reactor Fe 3 O 4 @COF-Apt-AChE through the high affinity and specificity with its binding aptamer. The as constructed enzyme reactor was comprehensively characterized and the key factors that affected its catalysis efficiency were investigated in detail. Owing to the surface modification of the magnetic COF materials by aptamer for acetylcholinesterase immobilization, the immobilized enzyme exhibited improved substrates affinity. What’s more, good reusability (more than 8 times) and prolonged stability (enzyme activity still kept at 90% after 42 days) were also achieved. Finally, the enzyme reactor could be applied in AChE inhibitors screening, which expanded its application capability. The proposed protocol not only paves a new way for fabrication of novel aptamer functionalized magnetic COF materials as enzyme reactors, but also indicates a broadened application of the integration of aptamer and its enzyme.
Lei Chen,Yanting He,Zhixian Lei,Chenling Gao,Qing Xie,Ping Tong,Zian Lin
Core-shell structured magnetic covalent organic framework (Fe 3 O 4 @COF) nanocomposites were synthesized via a facile approach at room temperature and explored as an absorbent for magnetic solid-phase extraction (MSPE) of bisphenols (BPs) from human serum sample. The as-prepared Fe 3 O 4 @COF nanocomposites with core-shell structure possessed high specific surface area (181.36 m 2 /g), uniform mesoporous size (~ 3.6 nm), high saturation magnetization (42.7 emu/g), and excellent thermal and chemical stability, rendering it as an ideal adsorbent with high adsorption efficiency and size selectivity. The experimental parameters influencing extraction efficiency, including adsorbent dosage, extraction time, pH and ion strength, desorption solvent and time, were investigated in detail. Taking these advantages together, a simple, fast, effective and sensitive method that MPSE followed by HPLC-MS, was proposed to detect five BPs, which exhibited good linearity (r > 0.9982) within the concentration ranges of 0.1–50 μg/L. Moreover, the low detection limits (1.0–78.1 ng/L), signal-to-noise ratio (S/N = 3), the high enrichment factors (56–95 fold), and good recoveries (93.0–107.8%) with relative standard deviations (RSDs) less than 3.4% for inter-day and 6.9% for intra-day were achieved. The developed method was also successfully applied to the analysis of trace BPs in human serum sample, which demonstrated the most promising potential of the Fe 3 O 4 @COF nanocomposites as good adsorbent in sample pretreatment.
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