Laser thermal ablation of multidrug-resistant bacteria using functionalized gold nanoparticles

Abstract

The issue of multidrug resistance (MDR) has become an increasing threat to public health. One alternative strategy against MDR bacteria would be to construct therapeutic vectors capable of physically damaging these microorganisms. Gold nanoparticles hold great promise for the development of such therapeutic agents, since the nanoparticles exhibit impressive properties, of which the most important is the ability to convert light into heat. This property has scientific significance since is exploited to develop nano-photothermal vectors to destroy bacteria at a molecular level. The present paper summarizes the latest advancements in the field of nanotargeted laser hyperthermia of MDR bacteria mediated by gold nanoparticles.

Keywords: antibiotic resistance; bacteria; gold nanoparticles; photo-thermal ablation.

Figure 1

Scanning electron microscope images of MSSA. Notes: (A) Backscattered electron images of MSSA treated with PBG vehicle, nonfunctionalized GNPs, or fGNPs. (B) Secondary electron images showing MSSA treated with fGNPs and then sham exposed or exposed to pulsed laser irradiation at 532 nm. Red arrows indicate damaged bacterial cells. Copyright © 2015. Dove Medical Press. Reproduced from Millenbaugh NJ, Baskin JB, DeSilva MN, Elliot WR, Glickman RD. Photothermal killing of Staphylococcus aureus using antibody-targeted gold nanoparticles. Int J Nanomedicine. 2015;10:1953–1960. Abbreviations: fGNPs, functionalized GNPs; GNPs, gold nanoparticles; MSSA, methicillin-sensitive Staphylococcus aureus; PBG, phosphate buffered saline containing 1% bovine serum albumin and 10% glycerol.

Figure 2

Gold–silver core–shell nanoparticles stabilized with aspartame proposed by Fasciani et al. Notes: Reprinted with permission from Fasciani C, Silvero MJ, Anghel MA, Argüello GA, Becerra MC, Scaiano JC. Aspartame-stabilized gold–silver bimetallic biocompatible nanostructures with plasmonic photothermal properties, antibacterial activity, and long-term stability. J Am Chem Soc. 2014;136(50):17394–17397. Copyright © 2014 American Chemical Society. Abbreviation: AuNP@Ag@Aspartame, aspartame-stabilized gold–silver nanostructures.

Figure 3

Proposed mechanism for shape-selective recognition and killing of microorganisms by Borovička et al. Notes: Reprinted with permission from Borovička J, Metheringham WJ, Madden LA, Walton CD, Stoyanov SD, Paunov VN. Photothermal colloid antibodies for shape-selective recognition and killing of microorganisms. J Am Chem Soc. 2013;135(14):5282–5285. Copyright © 2013 American Chemical Society.

Figure 4

Transmission electron microscopy images (magnification: 30,000×) representing PA3 – antibody–nanorod conjugates interactions. Notes: (A) PA3 – ligand-free nanorods; (B) PA3-coated antibody–nanorod conjugates (electrostatic attraction); and (C) PA3-coated antibody–nanorod conjugates (covalent coupling using 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide chemistry). Scale bar =500 nm. Reprinted with permission from Norman RS, Stone JW, Gole A, Murphy CJ, Sabo-Attwood TL. Targeted photothermal lysis of the pathogenic bacteria, pseudomonas aeruginosa, with gold nanorods. Nano lett. 2008;8(1):302–306. Copyright © 2008, American Chemical Society.

Figure 5

TEM images of (A) VRE, (B) PDRAB, and (C) VRSA produced after incubation with Au@van in PBS. TEM images of (D) VRE, (E) PDRAB, and (F) MRSA produced after incubation with unmodified gold nanoparticles in PBS. Notes: Copyright © 2007. Future Medicine Ltd. Reproduced from Huang W, Tsai P, Chen Y. Functional gold nanoparticles as photothermal agents for selective-killing of pathogenic bacteria. Nanomedicine. 2007;2(6):777–787. Abbreviations: MRSA, methicillin-resistant Staphylococcus aureus; PBS, phosphate-buffered saline; PDRAB, pandrug-resistant Acinetobacter baumannii; TEM, transmission electron microscopy; VRE, vancomycin-resistant enterococci; VRSA, vancomycin-resistant Staphylococcus aureus.