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Antimicrobial activity of fluorescent A g nanoparticles
Author(s) -
Bera R.K.,
Mandal S.M.,
Raj C.R.
Publication year - 2014
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12222
Subject(s) - antimicrobial , nanoparticle , fluorescence , bacillus megaterium , biophysics , staphylococcus epidermidis , aspergillus niger , fluorescence microscope , candida albicans , escherichia coli , antibacterial activity , bacteria , chemistry , particle size , staphylococcus aureus , microbiology and biotechnology , nanotechnology , biology , materials science , biochemistry , organic chemistry , physics , quantum mechanics , gene , genetics
The antimicrobial activity of fluorescent A g nanoparticles of 1·5 nm ( nA g‐ F s) is demonstrated and compared with the other A g nanoparticles of different shapes and size. The antimicrobial activity was evaluated using G ram‐positive ( S taphylococcus epidermidis NCIM 2493 and B acillus megaterium ) and G ram‐negative bacteria ( P seudomonas aeruginosa ATCC 27853 and E scherichia coli ) and fungal strains ( C andida albicans and A spergillus niger ). Insights into the possible mechanism were investigated using fluorescence microscope and cytoplasmic materials release assay. The fluorescence microscopic measurements show that the nA g‐ F s are localized at the centre of the cell, and 50% decrease in the fluorescence intensity was observed upon 2‐h incubation. Maximum cytoplasmic release was observed with spherical A g nanoparticles of 10 nm. Although the nA g‐ F shows minimum cytoplasmic release, it has the highest activity. The microbial killing effect of nA g‐ F s is actually originates from its intracellular activity. The antimicrobial activity of nA g‐ F s is significantly higher than the other synthesized nanoparticles of different shapes and size. The activity of the nanoparticles has been rationalized by considering the shape, size and surface structure of the particles. Significance and Impact of the Study This study aims to demonstrate the size and shape‐dependent antimicrobial activity of Ag nanoparticles. It is shown for the first time that the fluorescent Ag nanoparticles of 1·5 nm have superior antimicrobial activity with respect to the larger particles. The shape and size of the particles actually control their activity. The smaller particles can easily penetrate the cell wall and have pronounced activity. These findings may be useful in the development of potential antimicrobial agents.