A reusable aptasensor based on the dual signal amplification of Ce@AuNRs-PAMAM-Fc and DNA walker for ultrasensitive detection of TNF-α

The early monitoring of TNF-α has important clinical significance for newborn disease screening. Therefore, a reusable electrochemical aptasensor based on CeO2@Au nanorods-PAMAM-ferrocene (Ce@AuNRs-PAMAM-Fc) and enzyme-free DNA walker technology was developed for the ultrasensitive detection of TNF-α. To amplify the signal, Ce@AuNRs was prepared by in situ synthesis of gold nanoparticles on the surface of CeO2NRs and connected with PAMAM-COOH and Fc-COOH to form Ce@AuNRs-PAMAM-Fc. As signal tags, Ce@AuNRs-PAMAM-Fc could catalyze the redox reaction of H2O2 with the changes in current signals. In addition, the enzyme-free DNA walker technology was used to continuously cleave the signal probe to achieve the dual-amplification of the signal. The developed aptasensor could detect TNF-α in the range of 2 to 2 × 106 pg/mL, with a detection limit of 0.6 pg/mL. It is worth mentioning that the combination of DNA walker and strand displacement technology made the aptasensor reused up to 7 times, greatly reducing the detection cost. In summary, the highly sensitive and reusable aptasensor is a promising strategy for the early screening of neonatal diseases.