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Manufacture of Anisotropic Ag and Au@Ag Nanostructures for Quick Detection of Rhodamine 6G used in Food Preservation at Low Concentrations

Description: Nowadays, Rhodamine 6G organic pigments used in the tanning industry and garment are being used to preserve and colorize food indiscriminately which is very harmful to human health We have fabricated two-component metal nanostructures (Au@Ag) which have flat plates with big “hot pots”. We designed a high surface-enhanced Raman scattering (SERS) coefficient which can detect the Rhodamine 6G pigment at a low concentration of 10-8M (0.01ppm). We have successfully manufactured the complex of Anisotropic Ag and Au@Ag Nanostructures for Quick Detection of Rhodamine 6G used in Food Preservation at Low Concentration

The manufacture of anisotropic Ag and Au@Ag nanostructures consists of 3 stages: Stage 1: Fabrication of spherical silver nanoparticles with the size of approximately 6-10n. Stage 2: Formation of sheet anisotropic silver nanostructures with LED-assisted photochemical method Stage 3: Fabrication of the gold layer around the silver plates by the redox method. The reaction continues as the amount of gold precursors continues to increase, so the thickness of the gold crust will depend on the amount of gold salt added Our result have shown that: After measuring UV-Vis absorption spectra in the wavelength range from 300 nm to 1100 nm on Jassco V770, we determined the shape of the nanoparticles that were fabricated. Our partivles have only 1 peak at a wavelength of 601 nm, which shows that gold has completely coated silver, creating homogeneous Au@Ag. - The post-fabricated particles were excited by LED (wavelength of about 520 nm) at a power of 1.2 mW/cm2. Depending on the LED projection time, the shape and size of the silver nanoparticles will vary . We have show that our Au@Ag nanoparticles are mainly triangles. These are the samples 50 minutes after LED irradiation and coated with gold We use EDS to analyze and evaluate the content of elements in the sample. The results show that we have been successful in fabricating Au@Ag nanostructures with LED-assisted photochemical method. Au@Ag nanoparticles contain 24.16% by weight of silver at the core and accounting for 33.15% of the total particles, while the gold weight is 75.84% in the shell and accounting for 66.85% of the total particles. This once again confirms that we have succeeded in fabricating Au@Ag nanostructures by LED-assisted photochemical method The experimental results show that LED projection time has a great influence on the development of nanostructures. When the LED projection time increased, the preferred quadrupole oscillations appeared, leading to the AgNPs developing anisotropic and forming triangular nanoparticles. Observing, we see that the color of the samples changes from light yellow to moss green when the LED light starts for 25 minutes, then becomes dark green when the projection time reaches 85 minutes. The color variation of the solution is due to the plasmon changing surface effect as the size and shape of the nanoparticles change We use absorption spectroscopy and TEM, SEM images to investigate the effect of the gold precursor on the formation of Au@Ag nanostructures Rhodamine 6G analyte diluted at different concentrations from 10-4 M to 10-8 M was tested with a base of Au@Ag nanopods. The results of this experiment showed that triangular and Au@Ag nanostructures are well used to make SERS substrates to detect Rhodamine 6G dye residue at a concentration of 10-8 M. It has been shown that silver nanoplates and Au@Ag nanostructures can be used as sensor probes with high sensitivity in the detection of Rhodamine 6G substances at low concentrations Conclusion - We have successfully fabricated triangular flat-plate silver nanostructures with an average side size of about 45-50 nm and a thickness of 14-16 nm and Au@Ag nanoplates. - A process for the fabrication of anisotropic silver and Au@Ag nanostructures and to be able to control its size and shape based on modification of fabrication technology parameters is envisaged. - Low concentration (10-8 M) of Rhodamine 6G colorant was detected for all three nanostructures fabricated. The results are particularly interesting when the Au@Ag plates give the best reinforcement coefficient when compared to the two triangular plain silver nanostructures. - The above results show that Ag and Au@Ag nanostructures can act as nanosensors to detect Rhodamine 6G colorant residues at a concentration of 0.01ppm (or 10-8 M). This is a strong point and advantage of the fast, simple, and cheap cost of nanotechnology to detect Rhodamine 6G at low concentrations

Organisation: RESEARCH INSTITUTE OF CREATIVE EDUCATION

Innovator(s): Tran Huong Tra, Nguyen Phung Duy Anh, Do Quang Huy, Hoang Thu Huyen, Ly Khac Tiep

Category: Biotechnology

Country: Vietnam

Gold Award