A label-free and selective electrochemical aptasensor for ultrasensitive detection of Di(2-ethylhexyl) phthalate based on self-assembled DNA nanostructure amplification

Abstract

• An electrochemical aptasensor was constructed to detect Di(2-ethylhexyl) phthalate. • The aptasensor has the advantages of easy operation, label-free and low cost. • Utilizing self-assembly of DNA nanostructures for amplifying detection signal. • The aptasensor shows wide linear range and low detection limit of 0.04 ng mL −1 . • The aptasensor shows good reproducibility and high selectivity for DEHP assay. Di(2-ethylhexyl) phthalate (DEHP) is an endocrine disrupting compound that is often used as a plasticizer and tends to migrate in the environment and accumulates in the human body causing harm to humans. Thus, a simple, label-free, enzyme-free, high selective and ultrasensitive electrochemical aptasensor has been constructed for detection of DEHP based on the self-assembly of DNA nanostructure signal amplification strategy in this paper. The DNA-junction nanostructure is made of hairpin 1 (HP1), hairpin 2 (HP2), hairpin 3 (HP3) and quarter sequence (QS). Without DEHP, the electrochemical detection response is very low. Only when the aptamer binds to the target and detaches from the electrode surface, the DNA-junction is trapped on the electrode surface, enhancing the electrochemical signal. This is because the DNA-junction nanostructure is rich in guanine, which is able to adsorb more methylene blue (MB) for the purpose of enhancing the detection signal. The linear detection range of the obtained aptasensor is 0.1 ng mL −1 to 5000 ng mL −1 and the limit detection is 0.04 ng mL −1 . Finally, the proposed aptasensor has been applied to analyze DEHP in real samples, laying the foundation for its utilization in environmental water samples and food safety.