Liquid Interfacial SERS Analyzer with Built-In Self-Reporting on Carborane-Tailored Self-Assembled Nano-Buoy Arrays

The spontaneous assembly of nanoparticles at liquid–liquid interfaces (LLIs) to form uniform and defect-free SERS substrates has garnered considerable attention in analytical sensing. However, the soft nature of these interfaces imposes stringent requirements on LLI structural design, necessitating both interfacial stability and tunable structure–performance relationships. Here, we developed a molecularly tailored LLI-SERS platform using carborane (CBT)-stabilized AgNPs as buoyant probes (AgNP@CBT). Spherical CBT modification of AgNPs created an effective steric coating to guarantee reliable SERS analysis with subnanometer precision, while endowing the nanoparticles with cation-enrichment capability to enhance the assembly stability of AgNP@CBT in a large-scale fashion by reducing interfacial tension. Meanwhile, the Raman signal at 2576 cm⁻¹, originating from CBT located in the silent region, provided the LLI-SERS platform with a stable inner reference to self-calibrate in real time for variations of the interfacial environment, further improving the accuracy of detection. This strategy was highly versatile and successfully employed for two potential applications: real-time monitoring of hydroxyl radical (^∙OH) generation from the photocatalytic activity of nano-ZnO, and in vivo tracking the variation of hypochlorous acid (ClO⁻) in the seizure mice brains via combination with a microdialysis technique.