Research On Colloidal Gold And Colloidal Silver Prepared From Licorice Extract And Their Application

Objective:In order to provide a new development direction for the green preparation of gold and silver nanoparticles,this study quickly synthesized gold and silver nanoparticles with good dispersion and uniform particle size by green reduction method.This method is simple,efficient,clean and non-toxic.In order to provide theoretical basis and technical support for the large-scale rapid detection of Glycyrrhizin content,this study applied the prepared colloidal gold to an immunochromatographic system,and established a new technology for rapid detection of Glycyrrhizin by immunochromatography based on a competitive method.The technology has the characteristics of low cost and high sensitivity.In this study,the antibacterial effect of colloidal silver was evaluated to lay a foundation for the research of nano antibacterial agents.This study evaluated the antioxidant activity of colloidal gold and colloidal silver,and provided some guidance for their antioxidant application in medicine and food fields.Methods:In this study,we adopted the green reduction method,using chloroauric acid as the gold-containing precursor and silver nitrate as the silver-containing precursor,using licorice extracts Glycyrrhizin,L-arabinose and Ferulic acid as reducing agents and stabilizer,quickly synthesize gold and silver nanoparticles with good dispersibility and uniform particle size without adding other reducing agents and stabilizers.The prepared Glycyrrhizin-colloidal gold was applied to an immunochromatographic system and an immunochromatographic test strip for rapid detection of Glycyrrhizin content was developed.The Oxford cup punching method and filter paper diffusion method were used to explore the antibacterial properties of the colloidal silver prepared in this study against Escherichia coli and Staphylococcus aureus.ability.Using UV-Vis spectrophotometry,with ascorbic acid as the positive control,the prepared colloidal gold and colloidal silver were tested for the antioxidant activity of scavenging hydroxyl radicals and DPPH radicals to evaluate their antioxidant activity.Results:Glycyrrhizin-colloidal gold and silver,Ferulic acid-colloidal gold and silver and L-arabinose colloidal gold and silver were successfully prepared and characterized.In this study,a colloidal gold immunochromatographic test paper was successfully prepared for the rapid detection of Glycyrrhizin content.The detection limit of the test strip was 25 ng·m L^-1,and it only had specific binding to Glycyrrhizin.The detection limit remained unchanged for one year at room temperature.The detection results are in line with high performance liquid chromatography.The prepared colloidal silver was used to inhibit the growth of bacteria,and the inhibitory activities of each sample on Escherichia coli were as follows:L-arabinose-colloidal silver>Ferulic acid-colloidal silver>Glycyrrhizin-colloidal silver.The inhibitory activities against Staphylococcus aureus were as follows:Glycyrrhizin-colloidal silver>L-arabinose-colloidal silver>Ferulic acid-colloidal silver.Hydroxyl radical and DPPH radical scavenging experiments were performed on colloidal gold,colloidal silver and their corresponding reducing agents.The results showed that the scavenging ability of the samples on DPPH radical was ascorbic acid>Ferulic acid-colloidal silver>Ferulic acid-colloidal gold>L-arabinose-colloidal gold>L-arabinose-colloidal silver>L-arabinose solution;The scavenging ability of hydroxyl radical was Glycyrrhizin-colloidal gold>Glycyrrhizin-colloidal silver>Ascorbic acid>L-arabinose-colloidal silver>Ferulic acid-colloidal gold>Ferulic acid-colloidal silver>L-arabinose-colloidal gold.Conclusion:In this study,gold and silver nanoparticles with uniform particle size and good dispersibility were successfully prepared from licorice extract,and they were applied in the fields of immunochromatography system,antibacterial and antioxidant activities,respectively.The immunochromatographic test paper developed in this study for the rapid detection of Glycyrrhizin acid content is simple and efficient,with high sensitivity,good specificity,strong stability and accurate results,and is suitable for large-scale rapid screening of Glycyrrhizin content.The colloidal silver synthesized in this study has a certain bacteriostatic effect on Escherichia coli and Staphylococcus aureus.Among them,L-arabinose-colloidal silver has the best antibacterial effect on Escherichia coli,and Glycyrrhizin acid-colloidal silver has the best antibacterial effect on Staphylococcus aureus.Among the colloidal gold and colloidal silver obtained in this study,Glycyrrhizin-colloidal gold has the highest scavenging ability to hydroxyl radicals,and Ferulic acid-colloidal silver has the highest scavenging ability to DPPH radicals.