Study On The Formation Mechanism Of Gold Nanoparticles In Plant Extracts And It's Application In The Detection Of Dopamine And Cu²⁺

Gold nanoparticles(AuNPs)have exhibited promising applications in the fields of biological medicine and food detection due to their unique optical,Surface Plasmon Resonance(SPR)and biocompatibility properties.And these characteristics can be adjusted by controlling the size and morphology.This main works are exploring more biological sources for the synthesis of AuNPs,and these AuNPs can be directly used for the Visual detection of dopamine(DA)and copper ions(Cu²⁺).The main research contents and results are as follows:(1)The S-AuNPs prepared from Spirulina extract were combined with UV-Vis spectroscopy to realize the quantitative and Visual detection of DA.The synthesis of S-AuNPs and the Visual detection mechanism of DA were also discussed.The spirulina extract was used as reductant and protectant to synthesize the wine-red S-AuNPs sol with uniform particles and good dispersion.The color of the S-AuNPs sol changed from wine-red to blue after the addition of DA.It can be used to Visually detect DA.UV-Vis spectroscopic analysis showed that when the concentration of DA was in the range of 5-40?M,there was a good linear relationship with the ratio of A ₆₉₀/A ₅₂₀:Y=0.02744X-0.00296,and the correlation coefficient is 0.9827,LOD is 2.02?M.(2)G-AuNPs were prepared in the Green tea extract.The synthesis process of G-AuNPs was affected by the addition of DA.Combined with UV-Vis spectroscopy can realize the quantitative determination of DA.Green tea extract contains polyphenols and other poly-hydroxyl substances,and HAu Cl₄can be reduced to prepare G-AuNPs.Using UV-Vis,the absorption peak of the synthesized gold nanoparticles(G-DA-AuNPs)with the addition of DA gradually red shifted and became wider.In the range of 50?250?M for DA,there was a good linear relationship between SPR absorption wavelength and concentration of DA:Y=0.108X+524.2,and the correlation coefficient was 0.9927,LOD is 8.51?M.(3)The gold nanoparticles(P-AuNPs)with average particle size of 18?20nm were prepared from Padina australis extract and UV-Vis spectroscopy were used to realize the Visualization and quantitative detection of Cu^2+..The synthesis and detection mechanism were discussed.P-AuNPs prepared from the extract of Padina australis extract had good dispersion and their sol color was wine-red.After the addition of Cu²⁺,the color of sol changes.With the increase of Cu²⁺concentration,the color of P-AuNPs sol changed from wine red to purple and then to blue,and the corresponding UV-Vis SPR absorption peak gradually broadened and showed a red shift.In the range of 0?40?M,the SPR of P-AuNPs sol was linear with A ₆₆₀/A ₅₁₈:Y=0.0138X+0.1664,and the correlation coefficient was 0.9905,LOD is 0.62?M.