What's in your clothing | Antimicrobial textiles

Antimicrobial textiles are textiles that are manufactured with nanoparticles, natural antimicrobial agents, and/or have actual antimicrobial compounds embedded in the fabric. The goal of these textiles is to kill or inhibit the growth of microorganisms such as bacteria, yeast, fungi, and viruses. The textiles are used for clothing in addition to numerous other uses such as filters, towels and cleaning products, food packages, and healthcare products. I noticed after COVID with face mask use and production, there appeared to be a keen interest in these textiles. Read more...

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Topics

• What are antimicrobial textiles?

• What is the goal of antimicrobial textiles?

• How do antimicrobials in clothing affect our skin?

• How do microorganisms on clothing affect our skin?

• How do antimicrobials in textiles work?

• What types of antimicrobial finishes are there?

• What are the uses of antimicrobial textiles?

• Are there any skin conditions associated with the biome?

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Photo: Wix

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What are antimicrobial textiles?

Antimicrobial textiles are textiles that are manufactured with nanoparticles, natural antimicrobial agents, and/or have actual antimicrobial compounds embedded in the fabric. The goal of these textiles is to kill or inhibit the growth of microorganisms such as bacteria, yeast, fungi, and viruses. The textiles are used for clothing in addition to numerous other uses such as filters, towels and cleaning products, food packages, and healthcare products. I noticed after COVID with face mask use and production, there appeared to be a keen interest in these textiles.

What is the goal of antimicrobial textiles?

The goal of antimicrobials in textiles can be vast. They can serve to reduce the transmission of pathogens via materials such as healthcare worker clothing, towels, bedsheets in hospitals, hats, car seats, earbuds, curtains that separate hospital beds or in hotel rooms, carpets, mops, etc. Antimicrobials in textiles can also serve a role in reducing the tendency of microbes to overgrow on textiles subject to moisture such as tents, tarps, and umbrellas- this reduces the tendency for these fabrics to be degraded over time as well as in odor control. Constantly laundering textiles is not always feasible in many circumstances.

How do antimicrobials in clothing affect our skin?

Before jumping into the antimicrobials used in clothing, let's talk about microbes and your clothing and how they interact with your skin.

I always talk about how your skin is your body’s first line of defense against the environment from an immune perspective and for regulating body temperature. Ultimately most of your skin’s body surface area comes into contact with textiles during some point of the day or night - through clothing, bed linens, upholstery, etc.

We do know that our skin maintains an acidic pH - somewhere between 4.5 and 5. Why? To make it unfavorable for microbes to grow and exist. This pH favors the growth of certain bacteria that can serve to benefit our skin.

Now clothing and textiles in contact with our skin can have their own microhabitat of microorganisms. Some microorganisms can even break down textiles such as Aspergillus, Penicillium, and Microsporum, and bacterial genera Bacillus, Streptomyces, and Pseudomonas.

Microbes on clothing can contribute to odor, and irritation, and impact the integrity of our textiles.

Synthetic fibers can be a little more resistant to the impact of microbial attachment and growth whereas natural fibers may actually serve as a source for their overgrowth. However, synthetics may harbor more oils and residues that can contribute to an accumulation over time. Some bacteria attach more easily to textiles than others. For example, Staphylococcus adheres more easily than E coli.

Bacteria prefer rougher surfaces and residues to attach to - so if there are more crevices for bacteria to hide they may prefer these surfaces. Remember that lice can also preferentially attach to seams.

How do microorganisms on clothing affect our skin?

We know that microorganisms live on and interact with our skin, but what about our clothes?

Our clothes can have one of 4 possible interactions with microorganisms of our skin:

1. No effect

2. Alter our skin biome

3. Alter sweat production or trigger unpleasant odor by impacting our skin’s natural balance

4. Transfer disease

The main bacterial phyla found in textiles include Firmicutes, Actinobacteria, and Proteobacteria are also of known importance to the human skin microbiome. Staphylococcus and Micrococcus are common with the armpits or axillae dominated by Staphylococcus and Corynebacterium. Corynebacterium is one of the main odor-causing bacteria. The longer the garment is worn- the higher the concentration of the bacteria present.

These bacteria and organisms can impact our health. Healthcare uniforms can harbor MRSA and VRE amongst other potential pathogens and staph and enterococci can live on these surfaces for months. There have been cases of transmission of pathogens from healthcare workers to patients where it was necessary to not only decontaminate the clothing but also the washing machine that served as a reservoir for the bacteria. Even after clothes are washed, they tend to be rapidly recontaminated even within 3 hours of wear.

How do antimicrobials in textiles work?

Enter the world of antimicrobial textiles. If we cannot launder the textiles constantly knowing they are recontaminated rapidly, then the theory with antimicrobial textiles is that there can be agents embedded in the textiles used to kill the microbes or finishes that prevent their adhesion.

Antimicrobials in fabrics are classified as

• Leaching or non-leaching

• Biostatic or biocidal

• Anti-bacterial, anti-viral, or anti-fungal

Leaching antimicrobials are embedded in the fabric and intended to slowly come out or “leach” onto the microbe to kill it. Examples of this include silver nanoparticles embedded in cotton and loomstate textiles.

Nonleaching describes antimicrobials chemically bonded to the fabric and do not leave the fabric. They offer long-lasting protection and are non-toxic to microbes. Examples of this include metallic silver, silicone, and copper used in polyurethane. For cellulose fibers, chitosan, and for cotton treatment antimicrobial agents such as triclosan, glucapon, and sodium pentaborate. These tend to be preferred because the antimicrobial properties tend to last and are safer for skin contact.

What types of antimicrobial finishes are there?

Let’s start with nanoparticles. We discussed this concept with my video on flame retardants. For antimicrobial finishes, silver nanoparticles can kill many microbes without direct toxicity to human skin cells. They have antiviral activity (even to covid). Titanium, tin, zinc, gold, and copper have also been used. Some of these metals directly penetrate bacterial cell walls while others can release ions to interfere with bacterial overgrowth.

There are natural compounds that have been used as antimicrobials in textiles. Curcumin, honey, natural dyes, and pigments can be used. Curcumin damages bacterial cell membranes, while honey can serve to either lower the pH or actually produce peroxide.

Cyclodextrins are oligosaccharides that have a hydrophilic outer surface and a lipophilic central cavity that can damage bacterial membranes. Lignin coatings have activity against Staphylococcus epidermidis. Chitosan from chitin offers anti-odor properties with antibacterial activity against S. aureus, E. coli, and Listeria monocytogenes. Halogens have been used with activity against S. aureus and E. coli.

Curcumin from turmeric is commonly used as a non-toxic natural dye for wool and cotton with sustained pigment and antimicrobial benefits after laundering. Silk is considered to have natural antimicrobial properties but a limited range. It can be treated with natural dyes to increase the spectrum of activity. Mordants are used while dying textiles to help fix the dye to the fabric. These have been studied to enhance the antimicrobial properties of textiles.

Action	Agent	Mode of action	Types of textiles	Effect on skin
​Antibacterial	​Nanoparticles: Silver Copper Zinc Cobalt Titanium	​Damage cell wall/ cell membrane Inhibition of the synthesis of cell wall/membrane resulting in cell leakage and cell death Inhibition of DNA/RNA, protein synthesis Inhibition of specific metabolic processes within the cell	​Cotton Silk Flax Wool Polyester	​Zinc pyrithione: significant reduction in bacteria counts on skin Silver chloride with Titanium had no effect on skin bacterial counts Silver treated textiles did not impact skin microbiome Silver treated polyester did not reduce odor and did not reduce skin bacterial counts over 2 days Over 12 weeks of wearing silver impregnated textiles, women in particular had a change in their skin microbiome with more diverse bacterial species Silver is not highly absorbed in the skin and does not trigger a significant inflammatory reaction
	Quaternary ammonium compounds
	Triclosan	Minor effect on overall bacterial content of skin but did reduce Staphylococcus
	Natural
	​Bamboo
	​Chitosan	​Possibly changes cell membrane permeability		​Pronounced effect on Staphylococcus aureus more so than Staphylococcus epidermidis
	​Alginate
	​Vitamins
	​Oils
​Antifungal	Guanazole, silver and zinc		Cotton	​Aspergillus niger Fusarium chlamydosporum Penicillium
	Zinc nanoparticles		Cellulose fibers	​Aspergillus. niger, Geotrichum candidum and Phanerochaete chrysosporium
Antiviral	Quaternary ammonium compounds
	Triclosan
	Polyhexamethylene biguanide
	N-halamines
	Polypyrrole
	Chitosan
	Natural dyes Graphene materials
	Nanoparticles: Copper Silver Zinc

What are the uses of antimicrobial textiles?

In healthcare, these materials can be used in wound care, help deliver medications to the skin, and help manage some skin conditions such as atopic dermatitis and fungal infections.

In apparel, I’m seeing lots of brands marketing antimicrobial clothing. These are found in baby clothing, bras, underwear, socks, and workout apparel. Antimicrobial textiles in sports apparel have the potential to produce less odor but in practice may not be as effective as we think.

They are used in space craft given the inability to wash clothing.

The challenge posed by the use of antimicrobial-treated personal protective equipment (PPE) is that the metals used in textiles can be released into landfills.

Are there any skin conditions associated with the biome?

Dermatologic conditions associated with dysbiosis of the biome:

1. Atopic dermatitis

2. Seborrheic dermatitis

3. Acne

4. Alopecia

5. Psoriasis

6. Candidal infections

7. Rosacea as it relates to Demodex mites

8. Dermatophytosis

Dermatologic condition	​Role of biome	Antimicrobial textiles	Effect on biome	Effect on skin
​Atopic dermatitis	​Excess colonization of Staph aureus triggering inflammatory response	​Zinc-oxide treated textile	Antibacterial against Staphylococcus aureus and Klebsiella pneuomoniae	Rapid improvement of severity of atopic dermatitis Decreased pruritus Improved sleep quality
		Silver treated cotton textile	Antibacterial against Staphylococcus aureus	Reduced symptoms of atopic dermatitis
		Alkoxysilane quaternary ammonium coated silk fabric	No specific antibacterial effect noted	Some improvement in lesions of atopic dermatitis
		Chitosan coated pajamas	Inhibited Staphylococcus aureus while promoting growth of other Staph species	​Improved disease severity
​Healthcare associated infections		Copper oxide impregnated textiles		Reduced the number of antibiotic treatment initiations Reduced the number of fever days Reduced antibiotic usage in hospitalized chronic ventilator-dependent patients
Dermatophytosis	Trichophyton rubrum, Trichophyton mentagrophytes, and C. albicans	Didecyldimethylammonium chloride (DDAC), poly-hexamethylenbiguanide, copper and two silver chloride concentrations	All samples showed a clear inhibition of C. albicans, activity against Trichophyton sp. varied significantly; for example, DDAC completely inhibited T. rubrum growth, whereas T. mentagrophytes growth remained unaffected even in direct contact with the fibres.
		​Non-woven textiles containing polyhexamethylene biguanide (PHMB) mixed with sophorolipid	Textiles containing PHMB significantly reduced CFU of fungi in healthy volunteers to levels comparable to soap washing.