Researchers led by YANG Liangbao from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences (CAS) have developed a surface-enhanced Raman spectroscopy method to automatically capture target molecules in AgNP/MoS₂ nano-pockets, which enables highly sensitive and long-duration dynamic detection of some chemical reaction processes.

The results were published in Analytical Chemistry and selected as the cover page.

Surface-enhanced Raman spectroscopy (SERS) is a type of molecular spectroscopy with fast, highly sensitive, and fingerprint-like identification properties.

"This study is based on our previous SERS studies," said Prof. YANG Liangbao, "which we have been doing for years."

In the experiment, the researchers covered a large-area monolayer nanoparticle film with a two-dimensional material MoS₂, creating an AgNP/MoS₂ nano "pocket". This nano "pocket" was then placed on the target molecules to be tested.

Using a multi-physics field model and finite element simulation method, they analyzed the electric field enhancement distribution of the AgNP/MoS₂ nano "pocket" structure in both solution and air, as well as the dynamic process of solution evaporation.

They found that the nano "pocket" not only possessed a high density of hotspots, but also had the ability to actively capture molecules. Compared to a single-layer Ag NP film, the addition of MoS₂ slowed down the evaporation of the solution, widened the window of SERS detection, and further enhanced the electric field. This structure enabled high sensitivity and stability in dynamic SERS detection for up to eight minutes.

In addition, this structure can be used to detect anti-tumor drugs and monitor structural changes of xanthine in serum.

According to the researchers, the related methods are expected to be more applicable to the in-situ detection of substance transformations or other chemical reaction kinetics in biological systems.

This study was funded by the Research Instrument and Equipment Development Program of CAS, the National Natural Science Foundation of China, and the Natural Science Research Program of Anhui Province.

Front cover of Analytical Chemistry. (Image by CHEN Siyu)

(top) AgNP/MoS₂ nano-pockets" formed by assembling a large-area monolayer nanoparticle film at the liquid-liquid interface (bottom) in a large-area monolayer nanoparticle film covered with the two-dimensional material MoS₂. (Image by CHEN Siyu)