Novel SERS Method Captures Target Molecules in Nanofilms

Researchers in China have developed a new Surface-Enhanced Raman Spectroscopy (SERS) method for active capture of target molecules in small gaps between multiple layers smaller than 3 nm.

The method is based on previous research by the team at Hefei Institutes of Physical Science, Chinese Academy of Sciences using SERS for automatic capture of target molecules in single-layer nanofilm hotspots. In a paper published in the journal Advanced Optical Materials, the team validated the technique by detecting the substance changes occurring during sperm–oocyte binding. 

SERS is a molecular spectroscopy with fast, highly sensitive and fingerprint recognition properties. Compared to the traditional dry state SERS method, however, the new technique allowed the target molecule to enter the hot spot more effectively and reduced the detection limit by 2-3 orders of magnitude. The team achieved this using nano-capillary pumping action to automatically capture the target molecules into a smaller gap.

This method therefore provides a new means for target molecules to actively enter naturally interbedded smaller gaps and provides essentially unlimited possibilities for SERS detection.

Led by Professor Yang Liangbao, the group constructed a natural three-layer silver nanoparticle film structure with small interbedded gaps of 1-3 nm and a large number of hot spots by a liquid-liquid interface assembly method, which effectively increased the number of hot spots. Due to the nano-pumping effect generated by these smaller gaps, the target solution could spontaneously move upwards through the nano-gaps, and the small gaps actively captured the target molecules making the signals of the target molecules dramatically amplified for sensitive detection.

The method provided a platform for trace dynamic detection and was successfully applied to track material changes during sperm-egg cell binding.

The results open up new methods for the active transport of target molecules to optimal hotspots and were expected to enable ultra-sensitive detection or monitoring of biological systems in the direction of material transformation, cell behavior or chemical kinetic process studies.