Functional gold nanoparticles as potent antimicrobial agents against multi-drug-resistant bacteria

Abstract

We present the use of functionalized gold nanoparticles (AuNPs) to combat multi-drug-resistant pathogenic bacteria. Tuning of the functional groups on the nanoparticle surface provided gold nanoparticles that were effective against both Gram-negative and Gram-positive uropathogens, including multi-drug-resistant pathogens. These AuNPs exhibited low toxicity to mammalian cells, and bacterial resistance was not observed after 20 generations. A strong structure-activity relationship was observed as a function of AuNP functionality, providing guidance to activity prediction and rational design of effective antimicrobial nanoparticles.

Keywords: MDR E. coli; MRSA; antimicrobial agents; gold nanoparticles; mode of action; structure−activity relationship; uropathogens.

Figure 1

Molecular structures of functional ligands on AuNPs.

Figure 2

MIC values (nM) of AuNPs bearing different hydrophobic surface ligands against laboratory E. coli DH5α. Log P represents the calculated hydrophobic values of the end groups.

Figure 3

PI staining showing NP 3 (C10-AuNP)-induced bacterial cell membrane damage. Scale bar is 5 μm.

Figure 4

Hemolytic activity of NP 3 at different concentrations. HC50 was estimated to be ∼400 nM (as denoted by the red cross in figure).