Highly sensitive colorimetric aptasensor for 17β‐estradiol detection in milk based on the repetitive‐loop aptamer.

Trace of 17β‐estradiol (E2) contamination in food has been a concern for its negative impacts on human health, leading to the need for an E2‐monitoring system. This work reported a new simple, sensitive, and colorimetric E2 detection based on the designed repetitive‐loop aptamer and gold nanoparticles (AuNPs). The designed aptamers (L2–L5) exhibited a higher binding capability to E2 than the original truncated aptamer (L1). Although L3–L5 aptamers exhibited the highest binding capability, only L3‐aptasensor demonstrated the sensitive detection of E2 in a range of 0.05−0.8 nM, with the limit of detection at 13.1 pM. The developed L3‐aptasensor was 7.7‐folds more sensitive for E2 detection than the L1‐aptasensor. It selectively detected E2, but not the other tested chemicals with similar structures: progesterone, genistein, diethylstilbestrol, bisphenol A, and chloramphenicol. The L3‐aptasensor efficiently detected E2 spiked in milk samples within the precision acceptance criterion of recovery rates (100.1%−113.0%) and the relative standard deviations (5.24%−11.06%). These results demonstrated the development of a new aptasensor based on the designed repetitive‐loop aptamer that could enhance E2‐detection sensitivity and be potentially used for detecting E2 in milk samples with high accuracy and reliability. [ABSTRACT FROM AUTHOR]