Shulou(Shulou.com)11/24 Report--

CTOnews.com, November 1, according to the official website of the Institute of Oceanography of the Chinese Academy of Sciences, recently, the international academic journal "Surfaces and Interfaces" reported that the Institute of Oceanography of the Chinese Academy of Sciences and the Institute of Physics of the Chinese Academy of Sciences have prepared a surface-enhanced Raman scattering (SERS) substrate of seven-star ladybug-like silver nanoparticles, which can detect 10-6 M ethanolamine phosphate molecules under simulated high pressure with good sensitivity and pressure resistance. It provides a new method for in-situ detection of low concentration microbial metabolites in deep sea in the future.

CTOnews.com attached to the official website of the Chinese Academy of Sciences (excerpt):

Due to the extremely complex deep-sea environment, deep-sea in-situ exploration is faced with great challenges. In the previous work, using the self-developed deep-sea Raman probe system, the research team successfully realized the in-situ detection of fluid temperature, composition (such as CO2, SO42-/HSO4- and H2), minerals and overlying biota physical and chemical parameters of hydrothermal vents at high temperatures (up to 450℃).

However, there is a lack of detection methods for the related metabolites and intermediates of some macromolecules in the deep sea, especially the metabolites and intermediates of various microorganisms living in the deep sea extreme environment. At the same time, there are no in situ detection methods for extracellular metabolites of deep-sea microorganisms in the world. Traditional detection methods, such as color measurement, liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR), can not detect multi-components at the same time, which is time-consuming, high cost and low sensitivity. The detection limit of laser Raman can only reach millimoles, which seriously hinders the detection of metabolites or intermediates of low concentration deep-sea microorganisms by laser Raman technology. Therefore, the in situ detection of extracellular metabolites in the deep sea is very difficult and faces great challenges.

Surface-enhanced Raman scattering (SERS) is mainly derived from the enhancement of local electromagnetic fields near precious metal (silver and gold) nanoparticles, so it has the ability of ultra-sensitive and rapid detection of trace molecules, and the detection limit can reach nanomole or even pico-moles. However, most of the widely used SERS substrates are liquid sol materials, and the solid SERS substrates are easy to oxidize and fall off under high pressure, so they can not be used in deep-sea in-situ exploration.

Fig. 1 schematic diagram of the preparation process of SERS substrate (a); and SERS enhancement mechanism (b)

Fig. 2 SEM image of SERS substrate (the distribution of silver nanoparticles on the surface is similar to the pattern on the back of Coccinella septempunctata) therefore, the research team used high temperature annealing process to heat-treat the silver-coated quartz, successfully prepared silver nanoparticles SERS substrate material similar to Coccinella septempunctata, showed good crystal orientation, and achieved the detection of 10-6 M ethanolamine phosphate at 11 MPa. The developed SERS substrate material has strong oxidation resistance and can withstand the deep-sea high pressure environment, which ensures the success of the in-situ exploration voyage of the South China Sea cold spring ecosystem in 2022, which not only meets the needs of deep-sea in-situ exploration, but also is suitable for the detection of extreme industrial environment.

Fig. 3 (a) SERS spectra of ethanolamine phosphate of different concentrations; (b) calibration curve of ethanolamine phosphate; (c) comparison of SERS spectra of L-tryptophan, L-threonine and N-acetyl-L-phenylalanine; (d) SERS spectra of ethanolamine phosphate and typical interferers.

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