Nanopillar-Assisted SERS Chromatography

Practical implementation of surfaced enhanced Raman spectroscopy (SERS) sensing is hindered by complexity of real-life samples, which often requires long and costly pretreatment and purification. Here, we present a novel nanopillar-assisted SERS chromatography (NPC-SERS) method for simultaneous quantitation of target molecules and analysis of complex, multicomponent fluids, e.g., human urine spiked with a model drug paracetamol (PAR). Gold-coated silicon nanopillar (AuNP) SERS substrates and a centrifugal microfluidic platform are tactfully combined, which allows (i) a precise and fully automated sample manipulation and (ii) spatial separation of different molecular species on the AuNP substrate. The NPC-SERS technique provides a novel approach for wetting the stationary phase (AuNP) using the "wicking effect", and thus minimizes dilution of analytes. Separation of PAR and the main human urine components (urea, uric acid, and creatinine) has been demonstrated. Quantitative detection of PAR with ultrawide linear dynamic range (0-500 ppm) is achieved by analyzing the spreading profiles of PAR on the AuNP surface. NPC-SERS transforms SERS into a sensing technique with general applicability, facilitating rapid and quantitative detection of analytes in complex biofluids, such as saliva, blood, and urine.