We describe a simple one-pot thermal decomposition method for the production of a stable colloidal suspension of narrowly dispersed superparamagnetic Fe_(3)O_(4)-Ag core-shell nanostructures.These biocompatible nanost...We describe a simple one-pot thermal decomposition method for the production of a stable colloidal suspension of narrowly dispersed superparamagnetic Fe_(3)O_(4)-Ag core-shell nanostructures.These biocompatible nanostructures are highly toxic to microorganisms.Antimicrobial activity studies were carried out on both Gram negative(Escherichia coli and Proteus vulgaris)and Gram positive(Bacillus megaterium and Staphylococcus aureus)bacterial strains.Efforts have been made to understand the underlying molecular mechanism of such antibacterial actions.The effect of the core-shell nanostructures on Gram negative strains was found to be better than that observed for silver nanoparticles.The minimum inhibitory concentration(MIC)values of these nanostructures were found to be considerably lower than those of commercially available antibiotics.We attribute this enhanced antibacterial effect of the nanostructures to their stability as a colloid in the medium,which modulates the phosphotyrosine profile of the bacterial proteins and arrests bacterial growth.We also demonstrate that these core-shell nanostructures can be removed from the medium by means of an external magnetic field which provides a mechanism to prevent uncontrolled waste disposal of these potentially hazardous nanostructures.展开更多
基金the Department of Science and Technology(DST)New Delhi,India through the Ramanna Fellowship Scheme(No.SR/S2/RFCMP-01/2005)+2 种基金One of the Authors(A.K.V)is thankful to DST,New Delhi,for the FTPYS projectThe authors are also grateful to the Microbiology Department of Sir.P.P.Institute of Science,Bhavnagar University,Bhavnagar,for providing the culturesSpecial thanks are due to Dr.D.Srivastava,Scientist,CS&MCRI,Bhavnagar,for his help in TEM measurements.
文摘We describe a simple one-pot thermal decomposition method for the production of a stable colloidal suspension of narrowly dispersed superparamagnetic Fe_(3)O_(4)-Ag core-shell nanostructures.These biocompatible nanostructures are highly toxic to microorganisms.Antimicrobial activity studies were carried out on both Gram negative(Escherichia coli and Proteus vulgaris)and Gram positive(Bacillus megaterium and Staphylococcus aureus)bacterial strains.Efforts have been made to understand the underlying molecular mechanism of such antibacterial actions.The effect of the core-shell nanostructures on Gram negative strains was found to be better than that observed for silver nanoparticles.The minimum inhibitory concentration(MIC)values of these nanostructures were found to be considerably lower than those of commercially available antibiotics.We attribute this enhanced antibacterial effect of the nanostructures to their stability as a colloid in the medium,which modulates the phosphotyrosine profile of the bacterial proteins and arrests bacterial growth.We also demonstrate that these core-shell nanostructures can be removed from the medium by means of an external magnetic field which provides a mechanism to prevent uncontrolled waste disposal of these potentially hazardous nanostructures.
