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An Antimicrobial Fabric Using Nano-Herbal Encapsulation of Essential Oils

Published: April 7th, 2023



1School of Engineering Technology and Applied Sciences (SETAS), Centennial College

Antimicrobial lab coats prevent the cross-contamination of pathogen accumulation and accidental bio-spills. Here, we describe the protocol for developing a skin-friendly antimicrobial fabric using nano-herbal encapsulation and modified standard tests to precisely evaluate the efficacy and suitability for typical usage of the lab coat.

Lab coats are widely used in biohazard laboratories and healthcare facilities as protective garments to prevent direct exposure to pathogens, spills, and burns. These cotton-based protective coats provide ideal conditions for microbial growth and attachment sites due to their porous nature, moisture-holding capacity, and retention of warmth from the user's body. Several studies have demonstrated the survival of pathogenic bacteria on hospital garments and lab coats, acting as vectors of microbial transmission.

A common approach to fix these problems is the application of antimicrobial agents in textile finishing, but concerns have been raised due to the toxicity and environmental effects of many synthetic chemicals. The ongoing pandemic has also opened a window for the investigation of effective antimicrobials and eco-friendly and toxic-free formulations. This study uses two natural bioactive compounds, carvacrol and thymol, encapsulated in chitosan nanoparticles, which guarantee effective protection against four human pathogens with up to a 4-log reduction (99.99%). These pathogens are frequently detected in lab coats used in biohazard laboratories.

The treated fabrics also resisted up to 10 wash cycles with 90% microbial reduction, which is sufficient for the intended use. We made modifications to the existing standard fabric tests to better represent the typical scenarios of lab coat usage. These refinements allow for a more accurate evaluation of the effectiveness of antimicrobial lab coats and for the simulation of the fate of any accidental microbial spills that must be neutralized within a short time. Further studies are recommended to investigate the accumulation of pathogens over time on antimicrobial lab coats compared to regular protective coats.

The protective white coat is a mandatory personal protective equipment (PPE) item in microbiology laboratories and healthcare facilities, and it protects from direct exposure to pathogens, spills, and burns. These cotton coats promote microbial growth due to many factors-the woven fabric provides attachment sites and aeration, cotton and starch used in the manufacturing process along with exfoliated epithelial cells from the user supply nutrients, and the proximity to the user gives warmth and moisture. The accumulation of microbes on textiles can also cause health problems such as allergies and nosocomial infection, unpleasant odors, and fabric deterioration

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1. Preparation of nanoparticles

  1. Nano-herbal encapsulation
    1. Prepare 50 mL of 1% (v/v) acetic acid.
      CAUTION: Glacial acetic acid is an irritant, which can cause severe skin burns and eye damage. Wear a full-length lab coat, nitrile gloves, and goggles, and work under a fume hood.
    2. Prepare chitosan solution (1.2% w/v) by dissolving 0.6 g of chitosan flakes (medium molecular weight) in 50 mL of 1% acetic acid (prepared above). Agitate overnight (O/N) at room temperatu.......

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Initial screening of the synthesized NPs
Following the two-step oil-in-water emulsion technique16, the bioactive compounds (carvacrol and thymol) were successfully encapsulated in chitosan. This was confirmed by UV-Vis spectrophotometry for the peak absorption of the respective bioactive compounds compared to controls, which were the chitosan NPs without any bioactive compounds. The constituted NPs were homogeneous and stable over 12 months at 4 °C. The initial screenin.......

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The antimicrobial efficacy of biocides is conventionally tested by quantitative assays, such as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), in which the bacteria are immersed in an antimicrobial liquid for 24 h. However, these assays are not suitable for coated fabrics, where the liquid interface is lacking and the biocides are diffused slowly along the fabric fibers. Therefore, many standard fabric tests have been established, such as AATCC 147, ISO 20645, AATCC 100, and JIS L 19.......

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This study was funded by "Applied Research, Innovation and Entrepreneurship Services" (ARIES), Centennial College, Canada.


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NameCompanyCatalog NumberComments
Acetic acidMillipore Sigma64-19-7
Antibiotic base agarBD DifcoDF0270-17-4Also known as Antibiotic Medium 2
Antibiotic seed agarBD DifcoDF0263-17-3Also known as Antibiotic Medium 1
Blood Agar (Nutrient Agar with 5% Sheep Blood)Donated by CFIA
Bromcresol Purple Lactose AgarDonated by CFIA
Candida albicansATCC The Global Bioresource CenterATTC 10231
CarvacrolMillipore Sigma282197 (CAS# 499-75-2)
Centrifuge  Allergra X-22R CentrifugeBeckman CoulterModel # X-22RRefrigerated. Wait at least 20 min or until the temperature reach the set low value (e.g., 4 °C) as the refrigeration takes time.
Chitosan Medium Molecular Weight (CS)Millipore Sigma448877 (CAS # 9012-76-4)
Clamshell Heat PressIntivaIM1200
Escherichia coli (E. coli)ATCC The Global Bioresource CenterATTC 23725
IncubatorThermo Scientific1205M34
Letheen BrothBD DifcoDF0681-17-7Used to neutralize antimicrobial effects. Product from different manufacturers may require to add Polysorbate 80, which is already added in Difco product.
Milli Q waterMillipore SigmaZR0Q16WWDeionized water
Mueller-Hinton AgarBD DifcoDF0252-17-6
Pentasodium tripolyphosphate (TPP)Millipore Sigma238503 (CAS# 7758-29-4)
Phospahte Buffered Saline (PBS)Thermo ScientificAM9624
Pseudomonas aeruginosaATCC The Global Bioresource CenterATTC 9027
Sabouraud Dextrose AgarBD DifcoDF0109-17-1
Shaking incubator/ Thermo shakerVWRModel# SHKA2000
Staphylococcus aureusATCC The Global Bioresource CenterATTC 6538
ThymolMillipore SigmaT0501 (CAS# 89-83-8)
Trypticase Soy AgarBD Difco236950
Trypticase Soy BrothBD Difco215235
Tween 80Millipore SigmaSTS0204 (CAS # 9005-65-6)
UV-Vis SpectrophometerThermo ScientificGENESYS 30 (840-277000)

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