Investigation of a Blue Light LED Device to Suppress Wound Pathogens Using a Collagen-Based Synthetic Skin Model

Summary

A 405 nm blue light LED device demonstrates antimicrobial efficacy against a broad range of wound pathogens when evaluated on a collagen-based synthetic skin model. This simplified in vitro approach offers a reproducible and ethically viable alternative for early-phase evaluation of light-based antimicrobial therapies.

Abstract

Conventional wound management is increasingly challenged by the rise of antimicrobial resistance and the cytotoxic side effects of traditional agents. Phototherapy, particularly using blue light (BL), offers a promising non-invasive and non-contact alternative. This study evaluated the antimicrobial efficacy and safety of a 405 nm BL-LED device against a broad spectrum of medically important wound pathogens using a collagen-based synthetic skin model, emphasizing the novelty of applying this platform for light-based antimicrobial testing. This synthetic skin provides a more realistic environment, mimicking the structure and topography of human skin. Light uniformity mapping showed consistent irradiance across a 10 cm diameter (30.14 ± 0.78 mW/cm²). The device achieved a substantial fluence-dependent microbial log reduction of up to 3.5 at 27 J/cm², demonstrating efficacy considerably higher than that reported in similar studies. Its broad-spectrum activity was confirmed against ESKAPE pathogens and Candida albicans, a significant advantage for managing polymicrobial wound infections. A key finding was the differential susceptibility among species, with Klebsiella pneumoniae exhibiting the highest susceptibility while Staphylococcus aureus proved most resistant. This is likely due to variations in microbial envelope structure and photosensitive molecule content, which affect the reactive oxygen species (ROS). Optical transmission experiments and surface versus embedded-colony analyses revealed no statistical significance, suggesting the potential application of BL to inhibit pathogens beneath the skin. Infrared spectroscopy confirmed that BL exposure, even at high fluences (108 J/cm²), caused no detectable chemical or conformational degradation of the collagen matrix, unlike the damaging effects observed with germicidal UV-C control. Finally, a unique evaluation in an aerosol chamber demonstrated that BL treatment reduced microbial deposition on surfaces by over 95%, highlighting its potential for mitigating nosocomial infections. These findings demonstrate the suitability of skin-mimicking substrates as an accessible alternative for evaluating BL in preclinical testing, thereby eliminating the need for animal models.

Introduction

Wound infections pose a persistent challenge and significant burden on the global healthcare system and affect the quality of life of patients. Wound healing is often complicated by microbial infections that delay the closure of cutaneous wounds, resulting in lesions and chronic wounds predominantly in elderly and diabetic populations. Conventional wound management strategies rely on antibiotics, antiseptics, chemicals, and natural bioactive agents that primarily suppress wound-causing organisms. While these traditional methods are effective in speeding up the healing process by reducing inflammatory cells and enhancing the number of fibroblasts¹

Protocol

1. Preparation of synthetic skin samples

A collagen-based synthetic skin model (VITRO-Skin) sheet was cut into rectangular swatches measuring 5.0 cm × 2.5 cm under aseptic conditions in a biosafety cabinet. Each swatch was placed into a sterile Petri dish and stored at 4 °C until use. Prior to inoculation, the samples were equilibrated to room temperature and hydrated in a humidity chamber according to the manufacturer's instructions to mimic the hydration level of human skin.

2. Preparation of microbial cultures

American Type Culture Collect....

Results

Antimicrobial efficacy of blue light LED and UV-C against wound pathogens
The blue light LED device (405 nm), operated at an intensity of 30 mW/cm² for 15 min, demonstrated significant antimicrobial efficacy against all tested wound pathogens on synthetic skin models (Figure 5). Among the tested species, Klebsiella pneumoniae showed the highest susceptibility to blue light, with a mean log reduction of 3.4 in viable cell counts. Conversely, Staphylococcus au.......

Discussion

This study demonstrates the significant antimicrobial potential of a 405 nm Blue Light LED (BL-LED) device against a panel of clinically relevant wound pathogens tested on collagen-based synthetic skin models. The BL-LED exposure at a fluence of 27 J/cm² achieved up to a 3.5-log reduction in microbial load (Figure 6), exceeding the antimicrobial performance reported in several earlier studies^6,7,17

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Acinetobacter baumannii	ATCC The Global Bioresource Center	ATCC 19606
Blue Light - Light Emiiting Diode	Violumas	N/A	BL-LED is a prototype thus does not have a Catalog number
Candida albicans	ATCC The Global Bioresource Center	ATCC 10231
Enterobacter aerogenes	ATCC The Global Bioresource Center	ATCC 13048
Escherichia coli	ATCC The Global Bioresource Center	ATCC 25922
Fourier Transform InfraRed  (FT-IR) Spectrophotometer Nicolet iS5	Thermo Scientific	IQLAADGAAGFAHDMAZA	OMNIC Software is used for Analysis
FT-IR Nicolet iS5 iD1 Direct Beam Transmission Module (Base Adaptor)	Thermo Scientific	IQLAADGAAGFAJAMAYX
FT-IR Nicolet iS5 iD7 Diamond Attenuated Internal Refraction Module	Thermo Scientific	IQLAADGAAGFAJAMBFN
Incubator	Percival Scientific	9330.01.06L
IR theromometer	Thermo Fisher Scientific	06-664-254
Klebsiella pneumonia	ATCC The Global Bioresource Center	ATCC 13883
Phosphate-Buffered Saline	Thermo Fisher Scientific	AM9624	PBS Catalog number (Thermo Fisher Scientific)
Pseudomonas aeruginosa	ATCC The Global Bioresource Center	ATCC 27853
Sabouraud Dextrose Agar	BD Difco	DF0109-17-1	SAB Catalog number (BD Difco)
Staphylococcus aureus	ATCC The Global Bioresource Center	ATCC 25923
Tryptic Soy Agar	BD Difco	DF0369-17-6	TSA Catalog number (BD Difco)
Tryptic Soy Broth	BD Difco	DF0370-17-3	TSB Catalog number (BD Difco)
UV-LED	Violumas	N/A	UV-LED is a prototype thus does not have a Catalog number
UV-VIZ Spectrophometer (Genesys 10 UV Scanning)	Thermo Scientific	335907P
Vitro-Skin	MEDELINK	SKU24000	Vitro-Skin