Antibacterial Properties Of Au(Ⅰ)complex And Its Application In The Detection Of Antibiotics And Ascorbic Acid

Metal complexes are increasingly widely used in the fields of pharmaceutical industry,chemical analysis,separation and purification.The Au(Ⅰ)complex has a d10closed-shell electronic structure.The entire complex molecule is in an oxidized state,and the geometric configuration of the Au(Ⅰ)complex is changeable,with unique thermodynamic and kinetic properties.It is not only used in fluorescence detection,industrial catalysis,but also used in fields such as anti-tumor,antibacterial,protein inhibitor and other biomedical fields.In this paper,Au(Ⅰ)-Met complex was synthesized by HAu Cl4 and methionine,and its antibacterial activity was explored,and it was applied to the degradation and detection of β-lactam antibiotics and the detection of ascorbic acid.Study on the antibacterial properties of Au(Ⅰ)complexes.Bacterial growth curves at different Au(Ⅰ)-Met concentrations indicate that Au(Ⅰ)-Met has a good antibacterial effect.The minimum inhibitory concentration(MIC)of Au(Ⅰ)-Met against S.aureus and E.coli are 21.7 μmol/L and 39.0 μmol/L,respectively,and the minimum bactericidal concentration(MBC)for S.aureus and E.coli are 26.0 μmol/L and 43.4 μmol/L.The bactericidal kinetics further shows that Au(Ⅰ)-Met has highefficiency bactericidal performance,and the complete killing time for both S.aureus and E.coli is 0.5 h.In addition,Au(Ⅰ)-Met has a wide range of bacteriostasis and has inhibitory effects on Bacillus subtilis,P.aeruginosa and Candida albicans.Compared with traditional antibiotics,bacteria will not develop resistance to Au(Ⅰ)-Met.In addition,within the effective inhibitory concentration range,the cytotoxicity of Au(Ⅰ)-Met is almost negligible.At the same time,this article discussed the antibacterial mechanism of Au(Ⅰ)-Met in detail,and found that Au(Ⅰ)-Met has enzymatic activity that can induce the increase of ROS in bacterial cells,thereby killing the bacteria.In addition,Au(Ⅰ)-Met can also cause bacterial cell membrane damage and DNA damage,and finally proved that bacteria internalize Au(Ⅰ)-Met through clathrin-mediated endocytosis.Based on the Au(Ⅰ)complex to degrade β-lactam antibiotics and detect ampicillin.Firstly,it explored the degradation mode of Au(Ⅰ)-Met for three β-lactam antibiotics.Secondly,using the characteristic that only AMP degradation can produce fluorescent substances under acidic conditions,a sensor system for detecting AMP was constructed.A series of characterization of the solution before and after the reaction of AMP,PG,CFX and Au(Ⅰ)-Met.UV spectrum,Gaussian simulation calculation,and XPS spectrum show that all three can be degraded by Au(Ⅰ)-Met,and the degradation process contains hydrolysis and oxidative degradation.The fluorescence diagram shows that only AMP can produce fluorescence under acidic conditions.under alkaline conditions,in addition to AMP,CFX also produces fluorescence.By comparing the mass spectra of the above solutions,it is found that the degradation product that produces fluorescence is 2-hydroxy-3-phenylpyrazine.Under acidic conditions,the concentration of AMP in the sample was quantified by the fluorescence of the reactant,and a method for fluorescence detection of AMP was constructed.The detection conditions were optimized,and the optimal conditions were 0.2 mmol/L Au(Ⅰ)-Met,70 ℃,30 min,and p H=1.0.Under the optimal conditions,the fluorescence intensity has a good linear relationship with the AMP concentration in the range of 0.042-33.3 μmol/L,the lowest detection limit(3σ/S)is0.015 μmol/L,and the method has good specificity and selectivity.In addition,this method successfully detected AMP concentrations in veterinary drugs and seawater samples.Based on Au(Ⅰ)complex dual-mode ratio method for the detection of ascorbic acid.The Au(Ⅰ)-Met/OPD system is used to detect AA based on the ratio colorimetry and ratio fluorescence method.The sensing mechanism mainly involves three steps:Au(Ⅰ)-Met oxidizes OPD to produce OPDox;AA inhibits the production of OPDox,and at the same time is oxidized to DHAA by Au(Ⅰ)-Met;The produced DHAA combines with OPD to form DFQ.As the concentration of AA increases,the color of the solution gradually changes from yellow to colorless,and the fluorescent color gradually changes from yellow to blue.Under the best experimental conditions,the absorbance ratio A340/A445 value and the fluorescence ratio F425/F555 have a good linear relationship with the AA concentration in the range of 0.1-100 μmol/L,and the lowest detection limit(3σ/S)is 0.09 μmol/L and 0.04 μmol/L,respectively.The system has good selectivity to AA.The system was used to analyze human serum samples with AA added.The recovery rates of the two ratio methods for AA were96.26-107.56 % and 97.41-105.67 %,which further confirmed Au(Ⅰ)-The feasibility of Met/OPD sensing system in practical application.