Gold Deposited Plant Leaves for SERS: Role of Surface Morphology, Wettability and Deposition Technique in Determining the Enhancement Factor and Sensitivity of Detection

摘要

Fabrication of eco-friendly, low cost, sensitive and reproducible surface enhanced Raman scattering substrates is of utmost importance for chemical and biological analysis. In this regard, we fabricated plant leaf based substrates by depositing gold nanoparticles onto the leaf surfaces of different plants. The naturally occurring micro/nanostructures on the surface of the plant leaves influences the deposition of Au nanoparticles and leads to the formation of electromagnetic hot spots. The fabricated leaf based substrates were compared for its performance with the substrates where the leaf surfaces were sputter coated with Au plasma. It was observed that the surface morphologies of different leaf surfaces tend to influence the performance of the substrates. Upon comparison of the enhancement factors obtained from the different substrates, a qualitative correlation between the surface morphology and wettability of the leaf surface with performance can be established. In the drop casted samples, the Au nanoparticles got clustered nicely in three-dimensional nanofold structures present on the leaf surfaces and the obtained SERS intensity could be directly correlated to the wettability (hydrophobicity) of the leaf substrates. Further, we demonstrated that the designed substrate can be used for sensitive analysis of a Raman active analyte up to sub nanomolar concentrations.