Ultrafast laser-driven confined interfacial coalescence of Au nanoparticles for ultrasensitive SERS via enhancement of aromatic ring vibrational modes

Realizing Au-based SERS substrates via laser-driven confined interfacial coalescence. • Achieving high sensitivity (detectable concentration ≤ 10 −18 M) for the SERS test. • Revealing specific vibrational modes of aromatic ring functioning in SERS detection. In this study, a picosecond laser-driven interfacial coalescence method is developed for realizing highly sensitive and uniform Au-based surface-enhanced Raman scattering (SERS) substrates via enhancement of aromatic ring vibrational modes, achieving an ultralow detection limit of 10 −18 M toward aromatic-ring-containing dyes and an exceptional enhancement factor of 1.83×10 12 . The confined environment restricts liquid Au flow, generating interfacial vortices within ∼100 nm region and leading to the formation of high-density nanoparticles with excellent SERS performance. The enhancement mechanism is found to strongly correlate to the concentration, particularly at low concentration (<10 −8 M), the selective single-molecule-level enhancement of aromatic ring vibrational modes under sub-monolayer adsorption allows highly sensitive detection of five specific dyes and pigments with aromatic-ring (Rhodamine 6 G, Malachite Green, Alizarin Red, Carmine Red, and Indigo), confirming its broad applicability for trace molecular detection. The Au-based SERS substrate exhibits remarkable uniformity with a relative standard deviation of 5.74% and retains stable SERS activity for over 1 year under ambient conditions. This work establishes a scalable, cost-effective laser-based manufacturing paradigm for high-performance SERS sensors, offering exceptional sensitivity, reproducibility, and stability. The method enables ultralow-concentration detection of aromatic molecules via enhancement of aromatic ring vibrational modes, demonstrating versatility across cultural heritage preservation, environmental monitoring, and biomedical diagnostics. A laser-induced confined interfacial coalescence strategy is developed to fabricate high-density, uniform Au nanoparticles for SERS substrates, allowing precise control of nanoparticle size, shape, and distribution. This enables selective adsorption and ultrahigh sensitivity, providing a versatile and scalable platform capable of cultural heritage analysis while also applicable to environmental, food, and biomedical molecular detection. Download: Download high-res image (220KB) Download: Download full-size image