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 4-log) under 11 klux of light, for an exposure to light between 1 to 3 h. Particularly it could reduce 104 cfu/cm2 to the level of 1–5 cfu/cm2 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.
Highlights
With the emerging of antibiotic resistant bacteria, the development and maintenance of sterile environments is becoming a necessity for hospitals and food manufactures
The weight of infections caused by multidrug resistant bacteria, on the US health system, is of 55 billion USD per year,[1] and projections estimate an impact on the world economy for trillions USD yearly by the 2050.2 Infections from drug resistant bacteria are often contracted in environments where bacteria are exposed to drugs with frequent and incomplete cycles of disinfections, in hospitals or food processing facilities
We have reasoned that the activity of the film derives from the interaction between the excited state of the crystal violet (CV) dye and the AuNRs both encapsulated in the PU film
Summary
With the emerging of antibiotic resistant bacteria, the development and maintenance of sterile environments is becoming a necessity for hospitals and food manufactures. Tests performed in hospitals around the world have shown that chemical based routine cleaning is not thorough enough to achieve the required sterility standards in more than 40% of the surfaces in close contact with patients.[11−13] To improve the efficiency of cleaning processes, noncontact sterilization methods utilizing reactive gas or UV light have been introduced. These methods have a Received: April 26, 2019 Accepted: May 13, 2019 Published: May 14, 2019
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