Size-controlling preparation of covalent organic framework nanospheres for electrochemical impedimetric aptasensing of oxytetracycline

Covalent organic framework (COF) nanospheres with controlled size of-500 and-1100 nm were successfully prepared by adjusting the HOAc amount in the synthetic system. The as-synthesized COFs have large conjugate aromatic skeleton, excellent stability, abundant pore, and uniform morphology. These advantages of COFs are benefit for immobilizing aptamers to fabricate the targeted electrochemical aptasensor. The commonly used oxytetracycline (OTC) is an analytic model to explore the sensing performance of the COF-based aptasensor, indicating that the smaller COF (-500 nm) is more conducive to acquiring the sensitive sensor than that of the larger COF (-1100 nm). Moreover, the limitation of detection of the COF (-500 nm)-based aptasensor is calculated to be 7.4 fg mL-1 using the response impedance signal. Additionally, the aptamer-based biosensor has fine reproducibility, good stability, excellent specificity, and available usability even in real samples.

Automated summary

Covalent organic framework (COF) nanospheres with controlled size of -500 and -1100 nm were successfully synthesized by adjusting the amount of HOAc in the reaction system. The resulting COFs exhibited a large aromatic skeleton, high stability, abundant pores, and uniform morphology. These COF-based advantages were utilized to immobilize aptamers for fabricating targeted electrochemical aptasensors. The sensing performance of the COF-based aptasensors was evaluated using oxytetracycline (OTC) as an analytical model, and it was found that the smaller COF (-500 nm) was more sensitive than the larger COF (-1100 nm). Furthermore, the COF (-500 nm)-based aptasensor demonstrated a detection limit of 7.4 fg mL-1 using the impedance signal, and showed excellent reproducibility, stability, specificity, and usability in real samples.