A novel aptamer sensor based on layered tungsten disulfide nanosheets and Au nanoparticles amplification for 17β-estradiol detection

Abstract

The required routine monitoring of the endocrine-disrupting compounds in real samples demands for cost-effective, selective and sensitive detection methods. Layered tungsten disulfide (WS₂) nanosheets are a type of two-dimensional, covalent-network solid material with remarkable structural and electronic properties that have attracted increasing interest in recent years. In this work, WS₂ nanosheets are prepared by a one-step sonication-assisted exfoliation method and characterized using X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. A novel aptamer-based label-free electrochemical biosensor for 17β-estradiol is fabricated with the aptamers immobilized on the WS₂ nanosheets/Au nanoparticle-modified glassy carbon electrode through Au–S interaction. After blocking with bovine serum albumin, the aptamer probe is then bound with the addition of 17β-estradiol to form the estradiol/aptamer complex on the electrode surface, which leads to a significant decrease in peak current. The change in the peak current has a good linear relationship with 17β-estradiol concentration in the range of 1.0 × 10⁻¹¹ to 5.0 × 10⁻⁹ M, with a detection limit of 2.0 × 10⁻¹² M (3σ/S). The aptamer sensor exhibits high sensitivity and remarkable reproducible analytical performance, and has been successfully applied for the determination of 17β-estradiol in serum and water samples with the recovery of 96.0–104.2%. The layered WS₂ nanosheet/Au nanoparticle film thus, acts as an efficient platform for the assembling of bio-probes and will be extended to other analytes such as protein and DNA and RNA electrochemical biosensing.