Study On Green Synthesis Of Metal Nanoparticles From Ginkgo Biloba Extract And Its Application

Metal nanoparticles have been widely used in the fields of information,environment,biology,medicine and catalysis because of their unique properties.At present,metal nanoparticles are mainly prepared by chemical,physical and biological methods.The green synthesis of metal nanoparticles by plants in biological methods has the advantages of simple process,wide sources of materials,green products and safe and reliable processes.In order to further expand the plant source of green synthesis of metal nanoparticles by plant method,this paper selects cheap and easily available ginkgo biloba extract as reducing agent and capping agent to successfully synthesize metal nanoparticles.The specific contents and results are as follows:（1）The current situation and progress of metal nanoparticles synthesis by plant green method were reviewed.The kinds of plants for metal nanoparticles synthesis were summarized.The reaction mechanism of this method and the application prospect of metal nanoparticles were analyzed.（2）AgNPs/GBE was successfully synthesized with ginkgo biloba extract as reductant and capping agent and Ag NO₃ as precursor.The effects of different process conditions on AgNPs/GBE were investigated by single factor method.The results showed that three factors,including reaction temperature,p H value of solution and Ag NO₃ concentration,had significant effects on the synthesis of AgNPs/GBE.The single factor method showed that the optimum process conditions for the synthesis of AgNPs/GBE were 80℃,p H is 10,and Ag NO₃ concentration is 0.04mol mol·L^-1.The synthesis process of AgNPs/GBE was further optimized by response surface methodology.The optimal conditions were as follows:time 80 min,dosage of ginkgo biloba extract 4 m L,temperature 80.389℃,p H 10.154,Ag NO₃ concentration 0.043mol·L^-1.（3）PdNPs/GBE was synthesized with PdCl₂ as precursor.Three main factors affecting the synthesis of PdNPs/GBE,including reaction temperature,p H value of reaction solution and concentration of precursor Pd Cl₂,were determined by single factor method,and the synthesis conditions of PdNPs/GBE were further optimized by response surface methodology.Through the monitoring of ultraviolet visible spectrophotometer,it was found that the SPR absorption peak of Pd Cl₂ at 306nm and420nm decreased continuously until completely disappeared,which was due to the disappearance of Pd⁺and the formation of PdNPs/GBE.The analysis of PdNPs/GBE particle size by laser particle size analyzer shows that the particle size is mainly distributed between 3.54 nm and 16.52 nm.（4）AuNPs/GBE was synthesized with HAuCl₄ as precursor.The synthesis process of AuNPs/GBE was optimized by single factor experiment and response surface methodology.The particle size of AuNPs/GBE was measured by Nano-ZS90 laser particle size analyzer.The average particle size of AuNPs/GBE was 13.92nm calculated from the statistical results of particle size.Through TEM,it can be clearly seen that the particles of AuNPs/GBE are evenly distributed,and their appearance is spherical or ellipsoidal,without agglomeration.In order to further study the simulated peroxidase activity of AuNPs/GBE,the color reaction model of H₂O₂-TMB system was used for testing,and the detection limit of glucose was finally calculated as 5.7×10-6 mol·L^-1.