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Updated: May 10, 2026
An In Vitro Model to Study the Effect of 5-Aminolevulinic Acid-mediated Photodynamic Therapy on Staphylococcus aureus Biofilm
Published on: April 16, 2018
Impact of PVC microplastics in photodynamic inactivation of Staphylococcus aureus and MRSA
Alessandra Ramos Lima1, Kamila Jessie Sammarro Silva2, Antônio Sérgio Nakao Aguiar3
1Laboratory of Environmental Biophotonics, São Carlos Institute of Physics, University of São Paulo, São Carlos, SP, Brazil
Abstract:
Photodynamic processes have found widespread application in therapies. These processes involve photosensitizers (PSs) that, when excited by specific light wavelengths and in the presence of molecular oxygen, generate reactive oxygen species (ROS), that target cells leading to inactivation. Photodynamic action has gained notable attention in environmental applications, particularly against pathogens and antibiotic-resistant bacteria (ARB) that pose a significant challenge to public health. However, environmental matrices frequently encompass additional contaminants and interferents, including microplastics (MPs), which are pollutants of current concern. Their presence in water and effluents has been extensively documented, highlighting their impact on conventional treatment methods, but this information remains scarce in the context of photodynamic inactivation (PDI) setups. Here, we described the effects of polyvinyl chloride (PVC) microparticles in PDI targeting Staphylococcus aureus and its methicillin-resistant strain (MRSA), using curcumin as a PS under blue light. The presence of PVC microparticles does not hinder ROS formation; however, depending on its concentration, it can impact bacterial inactivation. Our results underscore that PDI remains a potent method for reducing bacterial concentrations in water and wastewater containing ARB, even in highly contaminated scenarios with MPs.
Insights
Photodynamic inactivation (PDI) effectively reduces bacteria, including antibiotic-resistant strains, even with microplastic contamination. This study shows polyvinyl chloride microparticles impact bacterial inactivation by PDI but do not prevent reactive oxygen species generation.
Area of Science:
- Environmental Science
- Microbiology
- Photochemistry
Background:
- Photodynamic inactivation (PDI) uses photosensitizers (PSs) and light to generate reactive oxygen species (ROS) for pathogen inactivation.
- Antibiotic-resistant bacteria (ARB) and microplastics (MPs) are significant environmental contaminants.
- The impact of MPs on PDI efficacy against bacteria is not well understood.
Purpose of the Study:
- To investigate the effect of polyvinyl chloride (PVC) microparticles on PDI efficacy against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA).
- To assess ROS generation in the presence of PVC microparticles during PDI.
- To evaluate PDI as a treatment for ARB in MP-contaminated water.
Main Methods:
- Photodynamic inactivation experiments were conducted using curcumin as a photosensitizer and blue light.
- Staphylococcus aureus and MRSA were exposed to PDI in the presence of varying concentrations of PVC microparticles.
- Reactive oxygen species (ROS) generation was measured to assess its correlation with bacterial inactivation.
Main Results:
- PVC microparticles did not inhibit ROS formation during PDI.
- The concentration of PVC microparticles influenced the bacterial inactivation rate.
- PDI demonstrated potent bacterial reduction capabilities even in the presence of high MP concentrations.
Conclusions:
- PDI remains an effective strategy for eliminating ARB in water and wastewater, even when contaminated with microplastics.
- The presence of PVC microplastics can modulate PDI's antibacterial efficacy.
- Further research is needed to fully elucidate the interactions between MPs and PDI processes.
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