Biomarker detection for disease diagnosis via versatile Ag₂S nanowires as electrochemical sensor and SERS substrate

The present study for the first time opens up new applications of versatile Ag₂S as an enzyme–free electrochemical sensor and a surface–enhanced Raman scattering (SERS) substrate in addition to its widespread use in organism and cell imaging, protein and volatile organics detection, and so forth. Ag₂S exhibits outstanding performance in the detection of the uric acid (UA) and the methylene blue (MB) with high sensitivity and wide detection range from 10⁻⁷ M to 10⁻³ M. This is on the one hand attributed to Ag₂S in this work engineered into the nanowired (NW) structure, of which the large surface area is in favor of the interface with those analytes. Additional contribution originates on the other hand from the fast charge transfer kinetics between the Ag₂S NWs and the analytes, allowing the Ag₂S NWs to efficiently accept/donate the electrons from/to UA/MB, which in turn manifest as either the charge flow or the Raman scattering clearly seen in the cyclic voltammogram, amperometric plot and Raman spectrum, respectively.