SERS Chips Containing Internal Standard MoS₂ for Quantification of Analytes

Raman spectroscopy with Surface-enhanced Raman scattering (SERS) is one of the most selective, sensitive, and rapid methods for detecting target analytes. Recently, research for adjusting SERS to many fields such as food toxicity, biomolecules, and hazardous substances is being actively implemented. However, SERS has limitations for exact quantification, due to various factors such as spot variation, absence of standard, and reproducibility. Thus, research for integrating ‘internal standard material’ into the SERS chip has been conducted. It showed the possibility of calculating the ratio of ‘Raman intensity of analyte’ to the ‘Raman intensity of internal standard material’, which is supposed to be consistent within the controlled condition.<br/>Here, we propose a ‘MoS₂@Gold nanostructure SERS chip’, in which the MoS₂ was used as the internal standard for the intrinsic Raman characteristic peak. Existing materials for the internal standard of SERS chips were mostly produced in form of particles or flakes, which may occur spot variation. By integrating the MoS₂ grown in film form, the uniformity and controllability of the substrate could be highly refined. Gold is located at both the top and bottom of the MoS2 in the form of film and nanogrid, which could increase the SERS effect on both MoS₂ and the analyte. This sandwiched structure resulted in a 10^-9M LOD of Rhodamine 6G (R6G) and a linear relationship between the Raman intensity and the concentrations of the analytes within the standard deviation of less than 4%, with the correction factors. Through the results of the linear relationship, the MoS₂@Gold nanostructure SERS chip developed in this research proposes future alternatives to the sensors on universal fields with a qualitative, quantitative, and quick method.