Gold Nanorods Embedded in Polymeric Film for Killing Bacteria by Generating Reactive Oxygen Species with Light

Abstract

For the first time, anisotropic gold nanorods (AuNRs) were embedded with a photosensitizer dye (crystal violet) in polyurethane (PU) matrix to create the effective antimicrobial film, capable of killing Gram-negative bacteria on its surface when exposed to white light. The dye, when activated with white light, interacts with the AuNRs to generate reactive oxygen species (ROS), which kill bacteria. With a proper control of the aspect ratio (2.1−2.4) and coating of the AuNRs, the film can be tuned to reduce the bacteria population of one to four orders of magnitude (1-log to 4log) under 11 klux of light, for an exposure to light between 1 to 3 h. Particularly it could reduce 10 4 cfu/cm 2 to the level of 1−5 cfu/cm 2 in 3 h of light exposure. This was a desired performance for use on hospital surfaces. In addition, the system showed antimicrobial effect only when exposed to light, which eliminated the concern for a cumulative toxic effect on subjects exposed to the material for a long period of time and limited the time given to the bacteria to develop resistance against the system. Furthermore, this process of sterilization could be carried out by a commercially available white light lamp, which when in use did not interrupt the normal routine operation of the environment.

Study of the Effect of Anisotropic Gold Nanoparticles on Plasmonic Coupling with a Photosensitizer for Antimicrobial Film

“…It has been shown from previous work that the electrostatic interaction brings the dyes and the AuNRs together. 15 The overlapping between the absorption of the SPR peaks of AuNRs indicated by the simulation and the dye absorption confirm that all the components of the spectra, can participate in the plasmonic coupling with the dye. Thus, when located in close proximity inside the polymeric matrix boost the ROS production of the antimicrobial film.…”

“…14 This method uses 15 mL of a solution containing 9:1 acetone to nanoparticles dispersion (1.5 O.D. ; approximatively 0.65 mM of Au 0 , the optimum concentration based on our previous study 15 ) to swell 30 cm 2 polymeric matrix. The swelling process required an overnight incubation under moderate magnetic stirring, in order to obtain a uniform deposition of the particles.…”

“…[31][32][33] The fluorescein quenching was used in this work to quantify the ROS production of the films. 15 The test was performed on a solution containing 0.13 µM (50 µg/mL) of sodium fluorescein alkalinized with 5 mM NaOH. 31,32 This solution was exposed to light for 1 h on the surface of the film in a similar set up with the antimicrobial tests.…”

Gold Nanoparticles: Can They Be the Next Magic Bullet for Multidrug-Resistant Bacteria?

“…In a recent study [ 70 ], gold nanorods (AuNRs) were embedded with a photosensitizer dye crystal violet (CV) in a polyurethane (PU) matrix to fabricate an effective antimicrobial film. This film was capable of eradicating Gram-negative bacteria E. coli on its surface when exposed to white light.…”

“…Gold nanoparticles of different shapes and sizes are able to generate reactive oxygen species (ROS) by themselves under a suitable photoactivation source [ 81 , 82 ]. However, in our literature review, we found that AuNPs were linked to a photosensitizer in most of the APDT systems [ 70 , 75 , 78 ]. According to the previously discussed APDT approaches, there is good scientific evidence that combining gold nanoparticles with a photosensitizer has a synergism effect and would perform better in terms of ROS generation.…”