Enhancing the Antibacterial Effect of Erythrosine-Mediated Photodynamic Therapy with Ethylenediamine Tetraacetic Acid

At a Glance

Metadata	Details
Publication Date	2024-02-26
Journal	THE JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY
Authors	MinKi Choi, Haeni Kim, Si Young Lee, Juhyun Lee
Institutions	Gangneung–Wonju National University
Analysis	Full AI Review Included

6CCVD Technical Documentation & Analysis: High-Power Photodynamic Therapy Optics

Executive Summary

This research highlights the synergistic effect of Ethylenediamine Tetraacetic Acid (EDTA) and Erythrosine-mediated Photodynamic Therapy (PDT) for enhanced eradication of Streptococcus mutans biofilm, a critical application in pediatric dentistry. The findings necessitate high-performance optical and thermal management components, areas where 6CCVD’s MPCVD diamond excels.

Core Achievement: The combined EDTA + PDT treatment achieved a significantly heightened antibacterial effect, reducing the bacterial count to 1.41 Log₁₀ CFU/mL, compared to 4.10 Log₁₀ CFU/mL for PDT alone (p < 0.0001).
Mechanism: EDTA’s chelating properties remove the dentin smear layer, allowing the photosensitizer (Erythrosine) to penetrate deeper into the biofilm, thereby increasing PDT efficacy.
Critical Component: The study utilized a high-power LED light source (385-515 nm) operating at an intense output of 2000 mW/cm².
Material Requirement: Sustaining 2000 mW/cm² output requires superior thermal dissipation and optical transparency in the blue/green spectrum (385-515 nm), making MPCVD diamond ideal for optical windows and heat spreaders in next-generation PDT devices.
6CCVD Value Proposition: We provide custom, high-purity Single Crystal Diamond (SCD) optical windows and Polycrystalline Diamond (PCD) heat sinks necessary to maintain the stability and efficiency of high-irradiance LED systems used in advanced clinical PDT.

Technical Specifications

The following hard data points extracted from the study define the operational parameters for the high-power PDT system:

Parameter	Value	Unit	Context
Light Source Type	LED (VALO™)	N/A	Used for Photodynamic Therapy (PDT)
Wavelength Range	385 - 515	nm	Blue/Green visible spectrum
Light Output Power Density	2000	mW/cm²	”Extra power mode” requirement
Irradiation Time	17	s	Duration of light exposure
Irradiation Energy Density	Max 34	J/cm²	Calculated maximum energy delivered
Photosensitizer Concentration	20	µM	Erythrosine concentration
Chelating Agent Concentration	17	%	EDTA solution concentration
Lowest Bacterial Count (EDTA + PDT)	1.41 ± 1.49	Log₁₀ CFU/mL	Highest antimicrobial efficacy
Specimen Dimensions	6.0 x 3.0 x 2.0	mm	Bovine dentin substrate size

Key Methodologies

The experimental success relies on precise control over chemical application and high-intensity light delivery. 6CCVD focuses on supporting the hardware required for steps 3, 5, and 6.

Substrate Preparation: Dentin specimens (6.0 mm x 3.0 mm x 2.0 mm) were sectioned using low-speed diamond disks and polished to 1000 grit.
Biofilm Formation: S. mutans suspension (1.0 x 10⁸ CFU/mL) was incubated on specimens for 24 h at 37°C under 5% CO₂.
Photosensitizer Preparation: 20 µM Erythrosine solution prepared in phosphate-buffered saline (PBS), requiring light shielding (silver foil) due to photosensitivity.
EDTA Application: 17% EDTA solution applied for 1 min to remove the smear layer and enhance dentin permeability.
PDT Protocol: 40 µL of 20 µM Erythrosine applied for 3 min, followed by 17 s of light irradiation.
Light Delivery System: 385 - 515 nm LED source positioned 1 mm from the target, delivering 2000 mW/cm².
Efficacy Analysis: Bacterial counts (CFU) and Confocal Laser Scanning Microscopy (CLSM) using LIVE/DEAD KIT (green for live, red for dead bacteria).

6CCVD Solutions & Capabilities

The high power density (2000 mW/cm²) and specific wavelength range (385-515 nm) required for effective PDT necessitate materials with exceptional optical clarity and thermal conductivity. 6CCVD provides the advanced MPCVD diamond components essential for manufacturing robust, high-performance clinical PDT devices.

Applicable Materials

Application Requirement	6CCVD Material Recommendation	Key Capability Match
High-Power LED Heat Sinks	Thermal Grade PCD or SCD	Highest thermal conductivity (up to 2000 W/mK) ensures stable operation and longevity of the 2000 mW/cm² LED chip.
Optical Windows/Lenses	Optical Grade SCD	Excellent transparency across the required 385-515 nm spectrum with minimal absorption or scattering losses.
Custom Apertures/Filters	Optical Grade PCD	Can be manufactured in large formats (up to 125 mm diameter) and precisely laser-cut to define the irradiation area (e.g., 6.0 mm x 3.0 mm spot size).
Integrated Sensors/Contacts	Boron-Doped Diamond (BDD)	Potential for integrating electrochemical sensors or robust, conductive contacts directly onto the optical assembly.

Customization Potential

The successful replication and scaling of this high-irradiance PDT technology depend on custom component manufacturing, a core strength of 6CCVD:

Custom Dimensions: We offer PCD plates and wafers up to 125 mm in diameter, allowing for the fabrication of large-format optical assemblies or heat spreaders tailored to clinical device geometry.
Precision Polishing: To ensure maximum light transmission and minimize scattering losses at the high power density used (2000 mW/cm²), 6CCVD provides ultra-smooth polishing:
- SCD surfaces with Ra < 1 nm.
- Inch-size PCD surfaces with Ra < 5 nm.
Integrated Metalization: For direct chip bonding or creating electrical contacts on the heat sink, 6CCVD offers in-house metalization services, including Ti/Pt/Au, W, and Cu layers, ensuring reliable thermal and electrical interfaces for the high-power LED array.

Engineering Support

The synergy between EDTA and PDT relies on precise light delivery and stable power output. 6CCVD’s in-house PhD team specializes in optimizing diamond material properties for demanding optical and thermal applications. We can assist engineers and scientists in selecting the optimal diamond grade (SCD vs. PCD) and thickness (0.1 µm to 500 µm) to maximize efficiency and reliability for similar Photodynamic Therapy (PDT) and Biofilm Eradication projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

This study evaluated the additive impact of ethylenediamine tetraacetic acid (EDTA) on erythrosine-mediated photodynamic therapy (PDT) against Streptococcus mutans (S. mutans) biofilm by measuring colony-forming units and applying confocal laser scanning microscopy. Fifty-six bovine incisors, free from dental caries or structural defects, were utilized in this study. Dentin specimens were created by cutting with a low-speed diamond disk under a continuous flow of water, resulting in dimensions of 6.0 mm × 3.0 mm × 2.0 mm. The specimens were categorized into 4 groups: Control, EDTA, PDT, and EDTA + PDT. S. mutans ATCC 25175 was employed to establish biofilm on the dentin specimens. A 17% EDTA solution was applied for 1 min. For PDT, erythrosine served as the photosensitizer. Finally, a light-emitting diode source (385 - 515 nm) was employed in this study. The PDT group exhibited a significantly lower bacterial count than both the control and EDTA groups (p < 0.001). The EDTA + PDT group demonstrated a significantly reduced bacterial count compared to the other 3 groups (p < 0.001). This study demonstrated that EDTA enhances the antimicrobial efficacy of PDT on S. mutans biofilm. Even at a low concentration of photosensitizer, the combination of EDTA and PDT yields a significant antibacterial effect.

Tech Support

Original Source

DOI: https://doi.org/10.5933/jkapd.2024.51.1.32

References

2007 - Dental caries: from in-fection to prevention
2015 - Topical PDT in the treatment of benign skin disease: Principles and new applications