Abstract
In this study, the photothermal-induced bactericidal activity of phospholipid-decorated gold nanorods (DSPE-AuNR) suspension against Pseudomonas aeruginosa planktonic and biofilm cultures was investigated. We found that the treatment of planktonic culture of Pseudomonas aeruginosa with DSPE-AuNR suspension (0.25–0.03 nM) followed by a continuous laser beam exposure resulted in ~6 log cycle reduction of the bacterial viable count in comparison to the control. The percentage reduction of Pseudomonas aeruginosa biofilm viable count was ~2.5–6.0 log cycle upon laser excitation with different concentrations of DSPE-AuNR as compared to the control. The photothermal ablation activity of DSPE-AuNR (0.125 nM) loaded into poloxamer 407 hydrogel against Pseudomonas aeruginosa biofilm resulted in ~4.5–5 log cycle reduction in the biofilm viable count compared to the control. Moreover, transmission electron microscope (TEM) images of the photothermally-treated bacteria revealed a significant change in the bacterial shape and lysis of the bacterial cell membrane in comparison to the untreated bacteria. Furthermore, the results revealed that continuous and pulse laser beam modes effected a comparable photothermal-induced bactericidal activity. Therefore, it can be concluded that phospholipid-coated gold nanorods present a promising nanoplatform to eradicate Pseudomonas aeruginosa biofilm responsible for common skin diseases.
Highlights
Biofilms are functional consortia of sessile microorganisms encased within a self-generated extracellular polymeric matrix composed of polysaccharides; proteins and DNA [1,2]
The results demonstrated that treatment of Pseudomonas aeruginosa with DSPE-AuNR suspension (0.125–0.03 nM) followed by a continuous laser beam excitation (CW, 3W cm−2 ) effected an extra ~5.0 log cycle reduction in bacterial viable count compared to the treatment using DSPE-AuNR alone, Figure 2A,B
Pseudomonas aeruginosa biofilms (24, 48 and 72 h) demonstrated resistance to DSPE-AuNR treatment, where it caused a non-significant decrease in viable count upon treatment under dark conditions even at the highest tested concentration; 0.25 nM
Summary
Biofilms are functional consortia of sessile microorganisms encased within a self-generated extracellular polymeric matrix composed of polysaccharides; proteins and DNA [1,2]. Biofilms exhibit distinct architectural; phenotypic and biochemical characteristics [3,4] that give them advantages over their planktonic counterparts in terms of virulency; pathogenicity and resistance to antimicrobial agents [1,4]. The biofilm trait of high antimicrobial resistance to antibiotics and disinfectants is a multifactorial and is attributed to slow antibiotic penetration, reduced microbial growth rates, persisters and unique physiology [5,6]. Biofilm-derived infections are aggressive, persistent and difficult to treat. Pseudomonas aeruginosa is among the most common colonizers of infected wounds and is an abundant biofilm former [9]. Biofilms are a protected mode of growth presenting a major problem in infection treatment due to high recalcitrance to Molecules 2019, 24, 2661; doi:10.3390/molecules24142661 www.mdpi.com/journal/molecules
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
