Tailored microenvironment of functional DNA enables highly robust blood estradiol tests

Monitoring estradiol (E2) levels in the blood is crucial for obtaining reliable hormone levels necessary for assessing overall reproductive and cardiovascular health. While existing techniques like mass spectrometry and chemiluminescence immunoassays offer high sensitivity and selectivity, they are often complex, costly, and suffer from issues, such as cross-reactivity and limited biostability. Herein, we present a DNA-based method for E2 detection in blood, which mitigates the matrix effect using engineered DNA microenvironments. We demonstrate that incorporating heparin significantly enhances the binding between aptamers and E2 using fluorescence and electrochemical assays. Additionally, the presence of non-charged polymer on electrode surface reduces the apparent dissociation constant by over 70-fold, enabling us to design assays that overcome the dynamic range limitations of surface binding assays. Our method proves reliable for monitoring E2 levels in clinical samples, including those from women undergoing hormone replacement therapy, assisted reproductive technology, and throughout the menstrual cycle. Overall, our work presents a promising approach for E2 testing in blood and underscores the critical role of the DNA local environment in target recognition within biological settings.