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Background: Antimicrobial photodynamic therapy (aPDT) and antimicrobial photothermal therapy (aPTT) are promising local and effective alternative therapies for antibiotic resistant bacterial infections and biofilms. Combination of nanoparticles and organic photosensitizers offer a great opportunity to combine PDT and PTT for effective eradication of both planktonic bacteria and their biofilms. In this work, photo-induced antibacterial activity of indocyanine green (ICG), 3-aminopropylsilane coated superparamagnetic iron oxide nanoparticles ([email protected]) and ICG loaded [email protected] were evaluated on planktonic cells and biofilms of gram-negative ( E.coli , K.pneumoniae , P.aeruginosa) and gram-positive ( S.epidermis) bacteria .
Results: A relatively low dose of ICG (25 mg/mL) and SPIONs (0.425 mg/mL nanoparticle) in combination with a single, short (10 min) laser irradiation at 808 nm with 1150 mW of power were used in this study. No dark toxicity of the agents or antibacterial effect of the laser irradiation were observed. The charge of the particles did not provide a significant difference in their penetration to gram-negative versus gram-positive bacterial strains or their biofilms. [email protected]/laser treatment completely eliminated P.aeruginosa and provided 7-log reduction in the colony forming unit (CFU) of E.Coli, but was not effective on the other two bacteria . This is the first example for antibacterial phototoxicity of this nanoparticle. ICG/laser and [email protected]/laser treatments provided complete killing of all planktonic cells . Successful eradication of all biofilms were achieved with ICG/laser (3.2-3.7 log reduction in CFU) or [email protected]/laser treatment (3.3-4.4 log reduction in CFU). However, an exceptionally high, 6.5-log reduction as well as a dramatic difference between ICG versus ICG/[email protected] treatment was observed in K.pneumoniae biofilms with [email protected]/laser treatment. Investigation of the ROS production and increase in the local temperature of the biofilms that were subjected to phototherapy suggested a combination of aPTT and aPDT mechanisms for phototoxicity, exhibiting a synergistic effect when [email protected]/laser was used.
Conclusions: This approach opens an exciting and novel avenue in the fight against drug resistant infections by successfully utilizing the antimicrobial and antibiofilm activity of low dose FDA approved optically traceable ICG and a relatively low cost clinically acceptable iron oxide nanoparticle to enable effective aPDT/aPTT combination, induced via short-duration laser irradiation at a near-infrared wavelength.
Keywords
Indocyanine green, SPION, photothermal therapy, photodynamic therapy, 16 combined therapy, biofilm
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This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 12 May, 2020
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Nanoscience
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: Antimicrobial photodynamic therapy (aPDT) and antimicrobial photothermal therapy (aPTT) are promising local and effective alternative therapies for antibiotic resistant bacterial infections and biofilms. Combination of nanoparticles and organic photosensitizers offer a great opportunity to combine PDT and PTT for effective eradication of both planktonic bacteria and their biofilms. In this work, photo-induced antibacterial activity of indocyanine green (ICG), 3-aminopropylsilane coated superparamagnetic iron oxide nanoparticles ([email protected]) and ICG loaded [email protected] were evaluated on planktonic cells and biofilms of gram-negative ( E.coli , K.pneumoniae , P.aeruginosa) and gram-positive ( S.epidermis) bacteria .
Results: A relatively low dose of ICG (25 mg/mL) and SPIONs (0.425 mg/mL nanoparticle) in combination with a single, short (10 min) laser irradiation at 808 nm with 1150 mW of power were used in this study. No dark toxicity of the agents or antibacterial effect of the laser irradiation were observed. The charge of the particles did not provide a significant difference in their penetration to gram-negative versus gram-positive bacterial strains or their biofilms. [email protected]/laser treatment completely eliminated P.aeruginosa and provided 7-log reduction in the colony forming unit (CFU) of E.Coli, but was not effective on the other two bacteria . This is the first example for antibacterial phototoxicity of this nanoparticle. ICG/laser and [email protected]/laser treatments provided complete killing of all planktonic cells . Successful eradication of all biofilms were achieved with ICG/laser (3.2-3.7 log reduction in CFU) or [email protected]/laser treatment (3.3-4.4 log reduction in CFU). However, an exceptionally high, 6.5-log reduction as well as a dramatic difference between ICG versus ICG/[email protected] treatment was observed in K.pneumoniae biofilms with [email protected]/laser treatment. Investigation of the ROS production and increase in the local temperature of the biofilms that were subjected to phototherapy suggested a combination of aPTT and aPDT mechanisms for phototoxicity, exhibiting a synergistic effect when [email protected]/laser was used.
Conclusions: This approach opens an exciting and novel avenue in the fight against drug resistant infections by successfully utilizing the antimicrobial and antibiofilm activity of low dose FDA approved optically traceable ICG and a relatively low cost clinically acceptable iron oxide nanoparticle to enable effective aPDT/aPTT combination, induced via short-duration laser irradiation at a near-infrared wavelength.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
The full text of this article is available to read as a PDF.
This is a list of supplementary files associated with this preprint. Click to download.
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