Handcrafted silver substrates boost surface plasmon resonance for ultra-sensitive lipid analysis

Abstract

Lipid monitoring plays a crucial role in biomedical research, particularly in the areas of cardiovascular health, metabolic disorders and nutrition. However, direct and highly sensitive detection of lipids poses significant challenges due to the interference of high SERS background noise in lipid samples. In this study, we present a SERS platform for the quantitative analysis of lipids. By harnessing the Surface Plasmon Resonance (SPR) effect of nanostructured grooves and leveraging deuterium oxide, a remarkable enhancement of in-situ Raman signals originating from cholesterol is achieved. This approach yielded an impressive average enhancement factor of 7.3 × 105 and a detection limit of 1.9 × 10−4 mg/mL, highlighting the exceptional sensitivity and precision of our method. We have obtained high quality, in-situ SERS signals for six distinct lipid molecules. Rapid identification of lipid samples in mixed systems has been achieved through the combination of characteristic peak analysis and PCA-LDA, including the detection of SERS signals from lipids in milk. Notably, univariate monitoring of in-situ cholesterol in human serum was successfully achieved for the first time using deuterium water as an internal standard. In addition, silver substrate demonstrated outstanding reproducibility, maintaining consistent SERS activity even after more than 10 repetitions. Therefore, this platform offers the distinct advantages of high sensitivity, specificity and cost-effectiveness for lipid detection. These findings enable dietary management and blood lipid monitoring, and therefore hold crucial implications for the early prevention of lipid-related disorders and diseases.