Nano Express

Nanoscale Research Letters

, Volume 4, Issue 8, pp 794-801

Open Access This content is freely available online to anyone, anywhere at any time.

On the Enhanced Antibacterial Activity of Antibiotics Mixed with Gold Nanoparticles

  • G. L. BuryginAffiliated withInstitute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of SciencesSaratov State University
  • , B. N. KhlebtsovAffiliated withInstitute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences
  • , A. N. ShantrokhaAffiliated withSaratov State University
  • , L. A. DykmanAffiliated withInstitute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences
  • , V. A. BogatyrevAffiliated withInstitute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of SciencesSaratov State University
  • , N. G. KhlebtsovAffiliated withInstitute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of SciencesSaratov State University Email author 

Abstract

The bacterial action of gentamicin and that of a mixture of gentamicin and 15-nm colloidal-gold particles on Escherichia coli K12 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.

Keywords

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