Assessment and Characterization of Some New Photosensitizers for Antimicrobial Photodynamic Therapy (aPDT).

Laura Monica Dascalu (Rusu),Sorina Sava,Rahela Carpa,Doina Prodan,Irina Ciotlaus,Ioana Baldea,Radu Chifor,Violeta Popescu,Marioara Moldovan,Mindra Eugenia Badea

doi:10.3390/ma13133012

Abstract

The novelty of this study consists on the formulation and evaluation of five complex experimental natural photosensitizers (PS): gel with oregano essential oil (O), gel with methylene blue (AM), gel with a mixture of essential oils (Thieves-H), gel with arnica oil and curcuma extract (CU) and gel with frankincense essential oil (T), used as photosensitizing agents (PS) in antimicrobial photodynamic therapy (aPDT) in the control of microbial biofilm in oral cavity. The experimental PS were characterized by gas chromatography-mass spectrometry (GC-MS), Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, cytotoxicity assay, antimicrobial effect and scanning electron microscopy (SEM). The IR spectra of the experimental PS with essential oils exhibit absorption bands due to the presence of water and glycerol in high quantities. The studied compounds had a reduced cytotoxic effect on cell cultures. The lowest cytotoxic effect was observed in experimental PS with oregano essential oil and methylene blue PS. Essential oils with proven antibacterial capabilities used in experimental PS confer antibacterial activity to the gels in which they are incorporated, an activity that may be more efficient use of a PDT therapy. Single bacteria were detected mainly by SEM after 12 h, while aggregate bacteria and micro colonies dominated the samples at 48 h.

Highlights

Bacteria that grow in biofilms adhere to the surface of the tooth, where they multiply and form micro colonies embedded in an extracellular polymeric matrix, which includes water and nutrient channels
We aimed to identify and quantify the antibacterial effect of the natural experimental photosensitizers and control sample, on examples of two classes of bacteria: Gram positive (Staphylococcus aureus ATCC 25923) and
Experimental PS contain nanocapsules, which include an organic phase based on essential oils, with the active principle wrapped in a fine film of polycaprolactone (PLC) to ensure controlled release of the active substance through the diffusion phenomenon

Summary

Introduction

Bacteria that grow in biofilms adhere to the surface of the tooth, where they multiply and form micro colonies embedded in an extracellular polymeric matrix, which includes water and nutrient channels. Biofilms that colonize dental surfaces are among the most diverse and complex biofilms that exist in Nature. There are more than 700 bacterial species that can lead to periodontal disease. The most common method of treating periodontal disease is the mechanical removal of periodontal biofilms. Antimicrobial agents are used for periodontal treatments, but biofilm species have developed several mechanisms of resistance to this. Removal of oral microflora and the struggle to maintain antimicrobial agents concentrated in the oral cavity leads to problems associated with the use of these antimicrobial agents [1,2,3,4]

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Conclusion