The apparent increase in hormone-induced cancers and disorders of the reproductive tract has led to a growing demand for new technologies capable of detecting nanogram per liter level endocrine disruptors. Scientists in China invented an ultracompact optical fiber biosensor displaying superfine plasmonic spectral combs and enhanced by conjugate-induced bio-amplification, which showed the limit of detection down to 1.5 ng l-1 estradiol equivalent concentration. The technique has the potential to revolutionize environmental and health monitoring.