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Progress in the research of highly sensitive enhanced Raman sensing technology in Suzhou Institute of medical technology

Highly sensitive trace gas sensing has important practical significance in environmental pollution research and human volatile organic compounds (VOCs) detection. So far, a variety of analytical techniques have been used for gas detection, but most of them have the disadvantages of high cost, complex operation, time-consuming analysis process and so on. As a powerful trace molecular detection tool, surface enhanced Raman scattering (SERS) can greatly enhance the Raman scattering signal of target molecules by using the surface plasmon resonance and charge transfer effect of substrate. It has the characteristics of high sensitivity, simplicity, rapidity, non-destructive and specific fingerprint recognition, and has advantages in the field of gas sensing.  

Recently, Zhang Zhiqiang, a researcher at Suzhou Institute of biomedical engineering technology, Chinese Academy of Sciences, and sun Jiaojiao, a doctoral student, developed a three-dimensional rose branched SERS substrate with ultra-high sensitivity (bigaunp/Au/ZnO/P). In this study, researchers prepared nano zinc oxide (ZnO) – Gold (AU) three-dimensional heterostructures on polyvinylidene fluoride (PVDF) films by combining chemical growth and micro nano processing. The enhancement principle is that the three”hot spots” of gold nanoparticles (AuNPs) on the surface of adjacent nanorods, adjacent AuNPs on the surface of the same nanorod and the junction point between gold layer and AuNPs jointly improve the electromagnetic enhancement effect, The charge transfer between Au and ZnO generates high-density charges, forms an internal electric field, and excites the chemical enhancement effect of ZnO nanorods.  

The detection limit of p-mercaptobenzoic acid (P-MBA) molecule on the SERS substrate is 10-13m, and its enhancement factor is as high as 2.27 × 107, with good uniformity and repeatability (RSD & lt; 4%). In addition, PVDF membrane has porous characteristics, and the filtration detection program can be used to improve the collision efficiency between the target analyte and SERS”hot spots”, which is conducive to the efficient enrichment of gas molecules.  

Taking putrescine and cadaverine as examples, researchers verified the detection performance of the three-dimensional flexible SERS substrate in gas sensing. By modifying P-MBA sensing monolayer on SERS substrate, putrescine and cadaverine were selectively captured by amide reaction, and high sensitive quantitative detection of low concentration gas molecules was realized (putrescine detection limit:1.26) × 10-9m, detection limit of cadaverine:2.5 × 10-9m), 2-3 orders of magnitude higher than the detection limit reported in similar studies, which proves the application potential of the SERS sensor in practical gas sensing.  

In view of the porous characteristics and excellent enhancement performance of the three-dimensional flexible SERS substrate, integrating it with microfluidic device and portable Raman spectrometer to build a SERS rapid detection system is expected to realize the efficient capture and enrichment of bacteria, viruses and pollutants in aerosols, and give full play to the technical advantages of the three-dimensional substrate in the field of highly sensitive detection of aerosols.  

Relevant research results are published on Analytical Chemistry under the title of ultra sensitive SERS analysis of liquid and gaseous putrescine and cadaverine by a 3D rosettelike nanostructure modified flexible population substrate. The research work has been supported by the National Natural Science Foundation of China, the prospective project of key R & D industries in Jiangsu Province, and the R & D project of scientific research instruments and equipment of the Chinese Academy of Sciences.  

Construction method of SERS sensing substrate based on three-dimensional rose branch and detection strategy of organic gas molecules