Ultrahigh-Sensitivity Detection of 17β-Estradiol

Abstract

17β-estradiol (E2), a vital female sex hormone, plays a crucial role in female reproductive cycles and secondary sexual characteristics. The quantification of E2 concentration in human blood and urine samples is essential because a deviation from physiological levels of E2 indicates the development of diseases and abnormalities such as precocious puberty, breast cancer, weight gain, abnormal menstruation, osteoporosis, and infertility. In addition, the detection of E2 in food and the environment has gained widespread interest because of its role as an endocrine disruptor (environmental hormone) that can perturb physiological processes. E2 is used as a drug for hormone therapy. Various E2 detection technologies for diagnosing relevant human diseases, drug screening, and environmental monitoring have been demonstrated in studies. In this article, we have reviewed technological strategies developed for E2 detection with ultrahigh sensitivity, with a limit of detection comparable to several pg/mL or lower. We observed that gold nanoparticles (AuNPs) were used as nanoplatforms for signal amplification, which enabled ultrahigh sensitivity in most studies. Signal amplification was facilitated by AuNP characteristics such as the versatility of surface biochemistry, exceedingly large surface-to-volume ratio, surface plasmonic activity, luminescence quenching ability, and biocompatibility. These techniques have been used to detect E2 in food, water, human serum, and urine with ultrahigh sensitivity. We summarize the working principles of E2 detection strategies that allow ultrahigh sensitivity and provide an approach for future work required for the elucidation of practical applications of these technologies.