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On the Enhanced Antibacterial Activity of Antibiotics Mixed with Gold Nanoparticles

GL Burygin12, BN Khlebtsov1, AN Shantrokha2, LA Dykman1, VA Bogatyrev12 and NG Khlebtsov12*

Author affiliations

1 Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13 Prospekt Entuziastov, 410049, Saratov, Russia

2 Saratov State University, 83 Ulitsa Astrakhanskaya, 410026, Saratov, Russia

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Citation and License

Nanoscale Research Letters 2009, 4:794-801  doi:10.1007/s11671-009-9316-8

Published: 21 April 2009


The bacterial action of gentamicin and that of a mixture of gentamicin and 15-nm colloidal-gold particles onEscherichia coliK12 was examined by the agar-well-diffusion method, enumeration of colony-forming units, and turbidimetry. Addition of gentamicin to colloidal gold changed the gold color and extinction spectrum. Within the experimental errors, there were no significant differences in antibacterial activity between pure gentamicin and its mixture with gold nanoparticles (NPs). Atomic absorption spectroscopy showed that upon application of the gentamicin-particle mixture, there were no gold NPs in the zone of bacterial-growth suppression in agar. Yet, free NPs diffused into the agar. These facts are in conflict with the earlier findings indicating an enhancement of the bacterial activity of similar gentamicin–gold nanoparticle mixtures. The possible causes for these discrepancies are discussed, and the suggestion is made that a necessary condition for enhancement of antibacterial activity is the preparation of stable conjugates of NPs coated with the antibiotic molecules.

Colloidal-gold nanoparticles; Gentamicin; Drug delivery; Antibacterial activity; Agar-well-diffusion method; Minimum inhibitory concentration; Maximum tolerant concentration; Atomic absorption spectroscopy