Three-dimensional liquid freestanding membranes for reproducible and robust SERS detection

Surface-enhanced Raman scattering (SERS) is a highly sensitive and molecule-specific analytical technique with broad applications in biomedicine and chemistry. However, the poor reproducibility caused by the non-uniform distribution of “hot spots” in conventional substrates has hindered its further development and practical use. In this work, stainless-steel carriers with different pore sizes were employed to construct free-standing membranes (FSMs) by combining them with nanoparticle suspensions. The influence of pore size on FSM formation was systematically investigated. Specially, SERS detection of 10 −5  M rhodamine 6G as a model analyte, relative standard deviations was as low as combined 1.7% demonstrating excellent signal reproducibility. When applied to embryo culture media, relative standard deviations values of 7.76% and 7.49% were obtained for FSMs derived from high-quality and low-quality embryos, respectively. The proposed FSM fabrication method is highly reproducible, simple, and cost-effective, offering a promising strategy for optimizing and extending the practical applications of SERS.