Analyte‐Gated Plasmonic Hot‐Carrier Current for Ultrasensitive Biosensing

ABSTRACT

We report the first optoelectronic biosensor that employs plasmonic hot carriers for signal transduction. Hot‐carrier generation and transfer were driven by plasmonic hot spots formed through biomarker‐mediated attachment of gold nanoparticles to a gold film. As proof of concept, a device was developed for quantitative detection of 17β‐estradiol (E2), a key biomarker for early diagnosis of precocious puberty in pediatric patients. The sensor enabled ultrasensitive detection of trace E2, even in human urine, with a limit of detection of ≈13 aM (3.5 ag/mL), to the best of our knowledge, the lowest reported to date. In contrast to conventional plasmonic biosensors based on local refractive index change, which are inherently limited for low‐molecular‐weight analytes, this platform uses plasmon‐generated hot carriers and thus achieves ultrahigh sensitivity for small molecules such as E2 (≈272 Da). These results establish plasmonic hot carriers as a promising transduction mechanism for scalable and multiplexed bio‐ and chemical sensing platforms.