Fiber-based SERS biosensor as a tool for monitoring of contaminants in environmental water.

In fifteen words or less, explain the significance of this contribution (Novel Aspect).: Fiber-based SERS biosensor enables portable, real-time detection of trace contaminants directly in environmental water.

Abstract Text:

Endocrine-disrupting chemicals (EDCs) are emerging as a significant threat to humans, wildlife, and aquatic ecosystems. Estradiol, one of the most potent natural estrogens, is frequently detected in municipal wastewater and agricultural runoff. Even at ultra-trace levels, estradiol can disrupt the endocrine system, leading to various types of cancer and reproductive dysfunctions in humans. Current detection methods rely on sampling and analysis in a centralized lab, limiting the understanding of contamination sources/timing and quick intervention. In this study, we present a duplex aptamer-based biosensor for the in-situ detection of estradiol in water (our target medium being river water). The sensor integrates DNA aptamers on an optical fiber functionalized with silver-coated gold nanoparticles, serving as a surface-enhanced Raman scattering (SERS) active platform. These optical fibers facilitate the transmission of both the excitation laser and the resulting SERS signal, enabling remote detection. The sensor operates using a simple dip-and-detect approach, allowing one-pot assays by directly immersing the sensor into the sample. The proposed sensor can detect estradiol with a detection limit of 34 nM in solution (≈ 9 ppb). In addition to the detection of estradiol, we also studied the impact of salt ions (Na, Mg) concentration on the sensor performance to assess its application in specific environmental waters. We show how this fiber-optic sensor can be an effective tool for real-time environmental monitoring of EDCs such as estradiol in aquatic systems.