LAUSR

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 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. -New aptasensor for E2 detection was developed using the designed aptamer with a repetitive-loop structure. -The developed aptasensor exhibits the limit of detection for E2 of 13.1 pM, which is 7.6 and 381.7 folds more sensitivity than the reported truncated and full-length aptasensors, respectively. -The developed aptasensor efficiently detected E2 spiked in milk samples with acceptable accuracy and reliability according to the AOAC standard. This article is protected by copyright. All rights reserved.