Research On Synthesis, Antibacterial And Antibacterial Mechanism Of The Rare Earth Complex

In this paper, we have synthesized a series of complexes of rare earth elements,and the physical and chemical nature of the Rare Earth Complexes were measured as well as the antibacterial properties. In addition the antibacterial mechanism of the rare earth elements were preliminarily explored.Eu(α-NMA)3phen·H2O,Tb(α-NMA)3phen·H2O,La(α-NMA)3phen Gd(α-NMA)3phen·H2O,Y(α-NMA)3phen Eu(α-NAA)3phen,Tb(α-NAA)3phen,La(α-NAA)3phen,Y(α-NAA)3phen,Gd(α-NAA)3phen,Eu(β-NAA)3phen,Tb(β-NAA)3phen,La(β-NAA)3phen,Y(β-NAA)3phen,Gd(β-NAA)3phen·H2O were synthesized using the rare earth Eu Tb La Y Gd,the first ligandα-naphthoic acid,β-naphthoic acid,α-naphthaleneacetic acid,β-naphthalene acetic acid and the second ligand 1,10-phenanthroline.The 19 kinds of rare earth complexes were dry white powder, and exhibited good thermal stability.The antibacterial spectrum of the rare earth complexes was determined by the filter paper diffusion method, and the results showed that the antibacterial activity of them to different types of strains was stronger than the pure rare earth ions and the ligands, which with broad-spectrum anti-bacterial properties; Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, yeast, skin bacteria andBacillus subtilis were selected as representatives, the antibacterial capacity of the rare earth complexes and its ligands was determined by the filter paper diffusion method.The results showed that the inhibition zone diameter of the rare earth chlorides and the acidic ligands was equal to or less than 10 mm basically, which had no apparent inhibitory effect; while the inhibition zone diameter of the ligand phen was about 11～21 mm,the inhibition zone diameter of the rare earth complexes was about 15～28.5 mm, which illustrated that phen and the complexes all had better antibacterial effect. Yet,when the concentration were same,the antibacterial effect of the complexes was better than that of the phen. We also found that one kind of complexes could display different antibacterial effects against different strains, and when the acidic ligands changed, the antibacterial effect of the complexes would change accordingly. Finally, the MIC and the MBC of the rare earth complex were determined as the MIC is 43.5μg/ml and the MIB is 87μg/ml.The changes of the the shape of the strains were observed before and after the treatment of the complex to confirm whether the complexes could affect the cell surface structure; And according to the principle that the rare earth elements could send out fluorescence under the UV excitation, a preliminary positioning to the role of cell position was observed by using Fluorescence inverted microscope and found that the rare earth complexes could be attached to the the cell surface. The rare earth ions, phen and the complexes could damage the shape of the cell by observing with SEM and the rare earth ions and the complexes could also absorb on the cell surface while the phen could not, which was accordance with the result of the Fluorescence inverted microscope. The above results indicated that the rare earth maybe damage the cell surface or the membrane or enzymes and so on.