Ag@ZIF-67 decorated cotton fabric as flexible, stable and sensitive SERS substrate for label-free detection of phenol-soluble modulin

Although strategies of compositing noble materials and Zeolitic imidazolate frameworks (ZIFs) have been used to enhance the performance of ZIF-based surface-enhanced Raman scattering (SERS) substrates, the enhancement process still remains unclear and the sampling process with powder-form substrates is challenging for practical applications. In this study, a flexible SERS substrate with silver (Ag) nanoparticle decorated ZIF-67 as the active materials and cotton fabric as the supporting framework is developed with a facile method in two steps. The proposed flexible SERS substrate not only can reduce difficulties during the sampling process, but also expands future applications for sampling towards irregular target substances. Meanwhile, the enhancement mechanism has been investigated by using Methylene Blue to probe the molecular interactions. The constructed SERS substrate shows the highest enhancement factor of 6.25 × 10⁶ and an excellent detection sensitivity with a limitation of detection (LoD) of 10^–14 M/L. Because of its excellent performance in SERS tracing, the proposed SERS substrate shows exceptional ability in detecting and identifying phenol-soluble modulins and is considered to be a label-free approach that requires no adding markers/tags or antibodies. The proposed substrate expands the potential applications of SERS technology for rapid detection of bacterial toxins during clinical diagnoses and treatment.

Graphic abstract

Ag decorated ZIF-67 particles are anchored onto cotton fabric to fabricate flexible SERS substrates. The proposed flexible SERS substrate achieves high SERS activity with high enhancement factor, low LoD, good reproducibility and stability. The flexible SERS substrate shows great potential in detection and identification of Phenol-soluble modulin.