Abstract:

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The use of particles extremely small in sizethan cells -- is emerging as a powerful complement in Bio-Nanotechnology.Silver is one of the most famous antimicrobial substances. Nano-technologymakes it possible to expand the surface area of Silver particles markedly. Thesurface area is directly proportion to the drug action.

The antimicrobial activity of Silver ion is welldefined in nano science. Anti-microbial mechanisms of Nanosilver are differentaccording to the species of bacteria. Silver ion rapidly kills microbes byblocking the cell respiration pathway or breaking outer cell wall. The speed ofaction is almost instantaneous once the Silver reaches the microbe. Theefficacy of microbe killing is based not only on the amount of Silver ion present, but likely also the presence of other Silver radicals generated by a Silver releasing product.

Nano-silver basedantimicrobial fabrics have many technical applications in medical, hygiene, protection, sport, and industrial markets. Nano-silver based antimicrobial fabrics are used inwound dressings. Now a day it is compared in terms of ''zone of inhibition''and ''kill rate'' of bacteria which are both related to the antibacterialactivity. Metallic Silver, Silver oxides, and Silver salts are well-known tohave antimicrobial properties; but the slow-release systems of metallic silver,do not give high zone of inhibition neither high kill rate because of limitedavailability of Silver ions in such metallic systems. But slightly solubleNano- silver salt crystals possess broad-range of antimicrobial properties.1

The minimum inhibitoryconcentrations (MIC), minimum bactericidal concentrations (MBC), zone ofinhibition, and killing curves are important with clinically relevant bacteria.

Key words: Nano- silver, Anti-microbial, Woundcareproduct.

1.0   Introduction

Nano-silver basedwoundcare products come under Non implantable materials classification ofmedical textile. Nano-technology is emerging a potent technology. Nanotechnologyis the design, characterization, production and applications of structures,devices and systems by controlling shape and size at the nanometer scale.2Nano-silver is part of Nano-technology. Nano-silver has wide range ofapplications like dressing burns, scald, and acne. It also wide range ofapplication daily use like panty liners, sanitary towels and pants. It is principally used as anti-microbial agent. Nano-technology expanded its surface area at nanometerscale. The markedly expand the surface area of silver particles, increasing their contact with bacteria or fungi, and vastly improving its bactericidaland fungicidal effectiveness.

Nano-silver is extensively used in wound careproduct because of its potent anti-microbial effect. Nano-silver isincorporated in suitable textile and used for woundcare. In combination ofNano-silver and textile, Nano-silver provides an anti-microbial protection andtextile acts as an external barrier.

2.0 HistoricalPerspective

In ancient times, the first metals discoveredand used were Gold, Silver and Copper. Silver have been generally recognizedfor centuries for its medicinal purposes. Silver has been used as a medicineand preservative by many cultures throughout history. The Greeks and othersused silver vessels for water and other liquids to keep them fresh.

S.No.

Culture

Application

1.            

The Greeks

Silver vessels to keep water and other liquids fresh.

2.            

Roman

stored wine in Silver urns to prevent spoilage

3.            

Egyptian

The reference of Silver is mentioned in ancient Egyptian writings

4.            

Chinese

Silver chopsticks

5.            

Indian

Silver is used in small amounts as a tonic, elixir or rejuvenative agent for patients debilitated by age or disease.

 

3.0 Materials:

3.1 Nano-silver: Nano-technology is offering silver nanopowders with mean particle sizes available from 25 to 30 nm. The particles are characterized by spherical morphology and strong crystalline.

The x-ray diffraction (XRD), transmission electron microscopy (TEM), and BET surface area analysis are the characterization techniques. TEM will show the shape, and size distribution of nano particles.

SEM images of treated fabrics will indicate silver Nano- particles dispersed on the surfaces of specimens. ICP-MS will inform the residual concentration of silver particles on fabrics.

For the characterization, differential scanning calorimetry (DSC) and wide-angle X-ray diffractometer (WAXD) will be used for analysis of structure, thermal and crystallization behavior of the fibers.

3.2 Comparisons of Silver Content 3

Silver Content of Dressings

Proprietary Name

Ag content (mg/100cm2)

Silverlon

546

Calgitrol Ag

141

Acticoat

105

Contreet Foam 

85

Contreet Hydrocolloid 

32

Aquacel Ag  

8.3 

SilvaSorb  

5.3 

Actisorb Silver 220 

2.7 

3.3 Substrate material:

1.       Cotton

2.       Viscose

3.       Silk

4.       Polyamide fiber

5.       Hydrogel

6.       Hydrophilic polyurethane foam

7.       Alginates

The selection of suitable substrate depends upon many factors like designing of woundcare products, type of wound, target population, water vapor permeability, air permeability, thickness, area density, bulk density, bursting strength, abrasion resistance and fabric strength.

4. Methods

4.1 Activity of Nano-silver:

Silver has been known for his a potential anti-microbial action. It is active against Gram positive bacteria and Gram- negative bacteria. The silver release is also effective against fungi including Candida and Aspergillus. The minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC), zone of inhibition, and killing curves are import to determine with clinically relevant bacteria.

Recently its beneficial effect on wound comes in picture because of Nanotechnology. Nanotechnology amplifies surface of Silver. Drug action is directly proportion to the surface of drug. Recent clinical data with the use of a pure silver delivery system, which can maintain both anti-microbial control and provide an ideal wound healing environment, have been very positive, especially when compared to the use of the topical antibiotic cream, silver sulfadiazine (or antibiotic solutions).

An important concern in the design of new dressings is their ability to fight microbial infection. Many dressings now exploit 'bioactive' properties to promote healing and control infection. These include the now well-known sustained release iodine and silver dressings (e.g. Iodosorb, Actisorb Silver 220). Actisorb Plus is an activated charcoal cloth impregnated with silver. It is reported to absorb bacteria, which are then inactivated by the silver4.

 

The antimicrobial activity of silver depends upon the silver ions and other silver radicals generated by a silver releasing product. The action of silver ion is well defined. Antimicrobial mechanisms of nanosilver were different according to the species of bacteria. From the result, Silver nano particles will be available as a good antibiotic alternative.

The proteomic data revealed that a short exposure of E. coli cells to antibacterial concentrations of nano-Ag resulted in an accumulation of envelope protein precursors, indicative of the dissipation of proton motive force. Consistent with these proteomic findings, nano-Ag was shown to destabilize the outer membrane, collapse the plasma membrane potential and deplete the levels of intracellular ATP

. 5

 

4.2 Wound Healing activity of Nano-silver 6:

The anti-inflammatory effect of Silver ion on a wound is well defined since longtime. Recently with the new concepts on wound healing, the major focus of wound healing has been on the relationship between tissue destruction by a group of collagenase enzymes known as METALLOPROTEINASES (MMP) and tissue synthesis which is stimulated by growth factors.

Current Concepts

1. An excess of MMP activity has been reported in burn wounds and in chronic wounds.

2. Action of the MMPs is dependent on the availability of free Zinc.

3. Silver decreases surface Zinc which could decrease excess MMP activity and increasing healing rate.

4. Recent findings indicate that silver decreases MMP activity.

5. The fact that silver increases wound surface calcium should stimulate epithelialization.

A quantitative assay can be done by using collagenase MMP-1, MMP-8; and MMP-13). As MMP-2 and MMP-9 have related activities (gelatinase), they are anticipated to behave similarly and produce results similar to those obtained for the collagenase tested.

Some study also revealed that the sustained-release silver foam dressing showed statistically significant advantages in odour reduction and pain relief as well as the clinical ease of use of the dressing.

4.3 Methodology of incorporation Nano-silver into fabric:

Silver can be applied simply and quickly by immersion or soaking in a bath, by vaporization, or by adding to a wash after the rinse cycle. The different binders are used for binding Silver into the fabric like PVA.

Some of methods of incorporating nano-silver are mentioned below

Traditional coating technologies like padding, spraying

Surface treatments by silver in hydrogel.

Silver ion incorporation into material compounds.

Surface-engineered nanostructures like Autocatalytic/Electroless, Vapor Deposition, and Ionic Plasma Deposition (IPD).

4.4 Designing of Advance wound care product:

 

All new woundcare products are multilayer. The wound contact layer should be non adhesive. Nano-silver should be incorporated in wound contact layer. Middle layers should be absorbing layer. It should be absorbs the wound exudates. The outer layer protects wound from the external environment.

Nano silver base woundcare products are an advanced active wound care product. It is advance because it covers, protects, and provides moist environment for wound healing. It is active woundcare products because it stimulates wound healing.

5.0   Evaluation of Nano-silver based woundcare product:

The selection and timing of a particular test will differ from one product to another product. Evaluation of Woundcare product is mention below

1.       Performance tests

2.       Microbiological tests

3.       Silver release studies

4.       In-vitro and in vivo tests

5.       Clinical testing

1. Performance tests:

1.       Water vapor permeability

2.       Air permeability

3.       Rate of absorption

4.       Total absorption capacity

5.       Water repellency

6.       Sinking time

7.       Wicking rate

8.       Drain test

9.       Abrasion test

2. Microbiological tests:

A) American Association of Textile Chemists and Colorists (AATCC)

• Method 100- Antibacterial finishes on textile materials.

• Method 147-

  Antibacterial activity assessment of textile materials: parallel streak method

B) American Society for Testing Materials (ASTM)

1.

      

E-01 Standard Test Method for Determining the Antimicrobial Activity of Immobilized Antimicrobial Agents under Dynamic Contact Conditions

 

C) Government, corporate and other test methods

2.       JIS L-, Testing method for antibacterial activity of textiles.

Contact us to discuss your requirements of China Silver Antimicrobial Fabric Supplier. Our experienced sales team can help you identify the options that best suit your needs.

3.       Anti-algal assessment on textiles and polymers

4.       Bacterial Identification

5.       Minimum Inhibitory Concentrations (MIC)

D) Other Test methods

• USP Antimicrobial Preservative Effectiveness

• Dow Corning Corporate Test Method

• Kirby Bauer Standard Antimicrobial Susceptibility 

2. Silver Ion Release Studies:

Ionic Silver Release from Silver Woundcare product will be measure by inductively coupled plasma spectroscopy released in tryptic soy broth at 37oC.

4. In-vitro and in vivo study:

The selection and timing of a particular in-vitro and in-vivo test will depends upon the aim and objective of woundcare product. For example, wound healing, It will be carried on animals like albino rats to know the wound healing rate and other parameters according to designing of the woundcare product. Using a modified Walker-Mason technique, burn wounds will be induced on rats by exposing an area of dorsal skin to boiling water for 12 seconds. Burn sites will be evaluated according to objectives of study.

 

Other Testing

Bottom of Form

1)Preliminary screening of raw materials, i.e. cytotoxicity, hemolysis.

2) Biocompatibility tests of woundcare components, per the FDA Modified ISO Matrix.

3) Release and audit testing, e.g., Bacterial Endotoxin Testing.

Pyrogen Test (USP <151>)

Bacterial Endotoxin Test (USP<85>)

Safety Test, General (USP <85>)

Safety Test, Biologics (USP <88>)

Systemic Injection Test (USP <88>/ISO -11)

Abnormal Toxicity

Intracutaneous Reactivity Test (USP <88>/ISO -10)

Implantation Test - 1, 4, 12, 26, 52 Weeks (USP <88>/ISO -6)

Histology of Implant Sites (ISO -6)

Primary Skin Irritation (ISO -10)

Skin Sensitization, Maximization Method (ISO -10)

Skin Sensitization, Closed Patch Test (ISO -10)

Biological Reactivity Tests, in vivo (USP<88>) {Class Plastics Testing}

Cytotoxicity testing

Hemocompatibility testing: (ISO -4)

Mutagenicity testing (ISO -3)

Mucosal irritation testing: (ISO -10)

General toxicology studies

Specialized Test like Antibody Production test

5. Clinical Trial-

Design-

Single /Double blind

Parallel or cross design

Randomized control Trial (RCT)

Placebo control

Parameter for wound assessment-

The parameters for wound assessment is mentioned bellow

• Wound healing

• Comfort

• Pain

• Anti-microbial effect

• Ease for use

 

1. Wound healing:

The main parameter of wound or chronic ulcer is wound healing rate. The assessment of wound healing is often subjective so there is a need to develop a standard methodology to enable accurate comparisons between treatment outcomes and the accumulation of a reliable body.

Wound site measurement techniques

The purpose of any wound measurement is to monitor the progress of healing through changes in the length, width, area or volume of a wound. This can be done using the following techniques:

1. Simple measurement by tapes or ruler

2. Wound tracing

3. A Kundin gauge

4. Moulds

5. Scaled photographs

6. Planimetrics

7. Computerized stereophotogrammetry

2. Comfort- It will evaluate all performance of woundcare product during nursing.

3. Pain: Wound pain was rated by the patient using a visual analog scale during dressing removal, application, and 2 hours after application.

4. Antimicrobial effectiveness: Antimicrobial effectiveness can be evaluated by quantitative burn wound biopsies performed before and at the end of treatment.

5. Ease for use: Ease of use was rated by the nurse providing wound care.

6.0 Warning

It should not be used on patients with a known sensitivity to silver. In addition, silver has repeatedly been shown to be non-toxic to human cells. Toxicity occurs from the complexes used to deliver silver such as nitrate and sulfadiazine.

7.0 Regulations-

For Nano-silver based woundcare products, FDA Marketing Clearances is required

1.       US FDA-

Section 510(k) of the Food, Drug and Cosmetic Act requires those device manufacturers who must register to notify FDA, at least 90 days in advance, of their intent to market a medical device. This is known as Premarket Notification - also called PMN or 510(k).

2.       FDA, India-

We have to reregister the Nano-silver based woundcare product for marketing.

More details, you can log on http://cdsco.nic.in

8.0 Conclusion:

Nano-silver based woundcare product falls under the Non implantable materials classification of medical textile. It is the ideal woundcare product .It combat with infections and also promotes wound healing by decreasing MMP activity and increasing wound surface calcium that stimulate epithelialization. Silver has constantly been shown to be non-toxic to human cells.

 

Associated Data

Data Availability Statement

Data are available in public resource.

Abstract

Antimicrobial textiles are functionally active textiles, which may kill the microorganisms or inhibit their growth. The present article explores the applications of different synthetic and natural antimicrobial compounds used to prepare antimicrobial textiles. Different types of antimicrobial textiles including: antibacterial, antifungal and antiviral have also been discussed. Different strategies and methods used for the detection of a textile&#;s antimicrobial properties against bacterial and fungal pathogens as well as viral particles have also been highlighted. These antimicrobial textiles are used in a variety of applications ranging from households to commercial including air filters, food packaging, health care, hygiene, medical, sportswear, storage, ventilation and water purification systems. Public awareness on antimicrobial textiles and growth in commercial opportunities has been observed during past few years. Not only antimicrobial properties, but its durability along with the color, prints and designing are also important for fashionable clothing; thus, many commercial brands are now focusing on such type of materials. Overall, this article summarizes the scientific aspect dealing with different fabrics including natural or synthetic antimicrobial agents along with their current functional perspective and future opportunities.

Graphic abstract

Keywords:

Antimicrobial, Fabric, Textile, Antibacterial, Clothing

Introduction

Textiles are omnipresent and play an essential part in human society. Cloths may contain certain types of microbes, which has been recently discussed as clothing microbiology and the effect and interaction of cloths with human skin microflora [1]. Coatings of natural antimicrobial agents on the textiles or fabrics date back to ancient times, when the Egyptians used spices and herbal coatings on cloths to prepare the mummy wrap. Traditionally, the Chinese used bamboo fibers, which contained an antimicrobial compound called &#;Bamboo-kun&#; for housing structure. Bamboo fibers have also been explored for their natural antibacterial and antifungal properties, which are mediated by 2&#;6-dimethoxy-p-benzoquinone and dendrocin [2]. Application of antibiotics developed during the Second World War; at the same time, the use of antimicrobials to prevent textiles from rotting was also in demand. Tents, tarpaulins and truck covers were required to be protected from microbial attack during heavy rain and snow that would destroy fibers and also increase the chances of infection. To protect the fabric from microbial colonization and increase their durability, several military fabrics were treated with antimony salts, copper and a mixture of chlorinated waxes, which not only stiffened the fabrics but also gave them a distinct odor [3]. During initial times, the side effects of these antimicrobials were not considered, however, more attention was paid toward the adverse effects of these chemicals on the environment and health. The concept of safer antimicrobial compounds and textiles came into existence following the publication of Rachel Carson&#;s book Silent Spring in . Different sectors including ecologists, scientists, industrialists and chemists worked collectively to produce eco-friendly antibiotics [4].

In the present era, antimicrobial textiles are very helpful in hospitals, environment and places that are prone to microbes, which are baleful. The clothes are worn by the patients, healthcare workers and doctors may have a lot of microbes present on them, which can be transmitted easily from one person to another. Commercial opportunities abound for antimicrobial fabrics whenever it is about controlling the spread of infectious microorganisms [5]. Antimicrobial textiles can be termed based on their specificity against microbes, i.e., antibacterial, antifungal, or/and antiviral. Several antimicrobial textiles may also act against bacteria, fungi and viruses simultaneously. Some chemicals may be used to target a broad range of microbes and are generally termed as antimicrobial [6]. In common public area including hotels, restaurants, or trains such type of fabric is highly demanded, e.g., the towel which is used to mop up fluids, curtain and carpet could be a source of infection. There are also noticeable unfulfilled requirements for odor control, which is another expanding research area in this field. The textile may contain several microorganisms that are anathema and may transfer from an infected person to others. The only possible and effective way for reducing the microbial load from textile is by continuous laundering of clothes but this case is not possible in hospitals where there are continuous shifts. On the other hand, another way to reduce the chances of microbial infection from one person to others through the textile is by developing antimicrobial textiles. These antimicrobial textiles may also be useful for the people involved in sanitary-related work and those who are working in sewage treatment, where there is a high risk of getting infected. Surface modification of the textile including electrospinning, nanotechnologies, plasma treatment, polymerization, microencapsulation and sol&#;gel techniques has been done to impart some novel functional properties to textile, e.g., water-repellent, flame-retardant and antibacterial activity [7].

Antimicrobial winter wear is gaining importance as these clothes are not washed frequently and rarely exposed to sunlight. These clothes are generally stored for a longer time, which may enable the growth of microbes and thus antimicrobial type fabric may be an appropriate option. Similarly, the antimicrobial textiles may also be useful in those places where non-plastic bags are used. Food packaging which generally involves degradable material is safer for the environment as well as does not affect the food properties, however, the concept of antimicrobial coating in such wrappers is important to reduce the growth of pathogenic and food spoilage microbes. Primarily, the antimicrobial textile is required by the following sectors along with the appealing combination of color, print and design:

• Apparel: caps, jackets, sanitary pads, sportswear, undergarment, winter wear

• Commercial: carpets, covering for seats, window, vehicle, etc.; dusting cloths, military fabric, tent, uniform

• Health care: bandage, earbuds, scrub, mask, lab coats, protective kits

• Households: bedding, carpet, cover, curtains, mop, pillows, towel

The present work deals with the recent update in the development and applications of antimicrobial textile. A word cloud has been prepared using this article to portray the essence of the whole article (Fig.  ).

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Active antimicrobial agents

Nanoparticles

Among different compounds, nanoparticle-based coatings are quite common in both natural as well as synthetic textiles. Silver nanoparticles (AgNPs) possess strong toxicity toward a broad range of microbes with lower toxicity toward human cells along with long-term durability and increased dyeability. Silver (Ag) nanomaterials are well recognized for their self-cleaning and antimicrobial activity [8]. AgNPs (~&#;10 nm in size) have also demonstrated antiviral activity against SARS-CoV-2 (the causative virus of COVID-19) [9]. Besides silver, other metals and metal oxide nanoparticles including titanium, tin, zinc, gold and copper have also been applied on different natural as well as synthetic textiles. As suggested the antimicrobial activity of functionalized CuONPs coated textile materials against Gram-positive and Gram-negative bacteria can be attributed to three main mechanisms, i.e., the release of copper ions, the direct contact of CuO NPs with bacteria and the production of reactive oxygen species [10].

Biosynthesis and applications of nanostructured inorganic materials have got its importance in the development of antimicrobial textile. Selenium brooms were synthesized using almond skin extract showed time-dependent changes in the morphology from NPs in 15 s to selenium brooms in 45 min. Cotton-coated fabric with these structures exhibited activity against Bacillus subtilis [11]. Functional eco-friendly nanohybrid material synthesized using oligochitosan (obtained from crab shells) and nano-silica (obtained from rice husk) was resistant against Phytophthora infestans fungal attack, which points toward advanced research in the green agricultural application [12].

Agglomeration prevention, desired morphology and uniform size of nanoparticles have always been challenging in the NPs-related studies. Capping with ligands is generally used to overcome such challenges. Several natural capping agents have been used and are also well coated on the fabric. Seaweed capped zinc oxide nanoparticles (SW-ZnO NPs) were coated on cotton fabric using pad-dry-cure technique, which demonstrated its antibacterial against both Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Escherichia coli and Klebsiella aerogenes) bacteria [13]. Similarly, another natural capping agent, date seed extract was used to prepare capped ZnO NPs, which also demonstrated the antimicrobial activity and UV protectant property in cotton fabric [14]. Amino-capped TiO2 NPs coated functional cotton fabric was fabricated using two-step sol&#;gel and hydrothermal method demonstrated an effective antibacterial activity against S. aureus and E. coli [15].

Cellulose-based fabric requires pre-activation or pre-treatment to attain efficient stability of the NPs on the surface. Some human skin friendly bio-adhesive chemicals or methods need to be explored to develop a durable functional textile. Simultaneous sonochemical deposition of ZnO NPs using an enzymatic cross-linked phenolic network of gallic acid demonstrated high antibacterial efficiency even after several washing cycles in hot water [16].

Natural compounds

In addition to curcumin, there are many natural active agents have been extracted and used to develop antimicrobial fabric. Application of plant extract, essential oils as well as animal products, e.g., honey, have also been used in fabrics for managing wound infections. Several natural dyes, pigments and mordants have also been explored for their antimicrobial activity.

Sustainable antimicrobial textile finishing may be developed by using some natural compounds like cyclodextrins. These cyclic oligosaccharides have a hydrophilic outer surface and a lipophilic central cavity. Application of cyclodextrin and its derivatives (α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin) are increasing in the textile industry [17]. Lignin provides resistance against microbial attack in plants. This dark-colored phenolic compound is generally removed during the processing to get cellulose fibers. A lignin-coated fabric made from sugarcane bagasse exhibited antibacterial activity against Staphylococcus epidermidis. The lignin coating concentration was based on its MIC, which suggested that the bacterial growth could be inhibited to prevent further propagation within 6 h of contact [18]. Chitosan is often used in antimicrobial textile preparation and processing because of its antimicrobial and anti-odor property. Chitosan is a cationic polysaccharide, which is obtained by alkaline deacetylation of chitin. Application of chitosan hydrogel on cellulosic fabric imparted antibacterial activity against S. aureus, E. coli and Listeria monocytogenes [19]. Contrarily, a report suggested that the antimicrobial properties were not significantly affected by chitosan when the cotton and polyester fabrics were coated in a combination of silica sols and chitosan [20]. However, edible chitosan/pectin-based silver nanoparticle films from natural biodegradable polymers demonstrated effective antibacterial activity against E. coli. These antimicrobial films may increase the shelf life of the products and may be used for food packaging purpose [21].

Other chemicals and treatments

Halogens have been used in the treatment of fabric to impart antimicrobial property. Functional fibers having highly effective antibacterial property was fabricated by the introduction of an N-halamine structure on a polydopamine-based coating. N-halamine functionalized polydopamine-based coatings exhibited antibacterial activity against S. aureus and E. coli [22]. Halogenated phenols, e.g., chlorophenols have also been used in antimicrobial textile finishes. Active polymers based on biguanides (polycationic amines) may destroy the bacterial cell by electrostatic attractions [23]. Cotton fabrics were coated with silicon and nitrogen-containing compound, poly [3-(5,5-cyanuricacidpropyl)-siloxane-co-trimethyl ammoniumpropyl siloxane chloride] with phytic acid by layer-by-layer assembly (Cotton-PEI/(PCQS/PA)30-Cl). The treated cotton fabrics reduced 100% E. coli and S. aureus within 1 min of contact time [24].

Plasma treatment has been proposed as a low-cost and chemical-free method to modify the surface properties of different fabrics for incorporating eco-friendly rechargeable antimicrobial finishing. Cotton fabric treated with nitrogen plasma after padding with 5,5-dimethylhydantoin (pad-plasma-dry-cure) and chlorinated with sodium hypochlorite improved its antibacterial property against S. aureus [25]. Deposition of silver nanoparticles on plasma-activated surface exhibited antimicrobial property [26]. Similarly, dielectric barrier discharge plasma-treated polyamide 6,6 fabric showed higher Ag NPs deposition [27].

Natural fabric, antimicrobial dyes and pigments

Traditionally the natural dyes and pigments were used for fabric staining, which not only gives color but also acts as an antimicrobial agent. Curcumin (1,7-bis(4-hydroxy-3-methoxy)-1,6-heptadiene-3,5-dione), an active ingredient in turmeric is commonly used as non-toxic natural dye. Fabric like wool and cotton have been well stained with curcumin and also investigated for their antimicrobial activity. As demonstrated by pad dyeing using curcumin onto wool and cotton imparted both, color as well as antimicrobial property. This treatment was also found to be highly resistant to common laundering practices as compared to the untreated one [69, 70]. Cotton and other natural fibers exhibit excellent antimicrobial property when treated with natural compounds. Silk is considered to have natural antimicrobial property; however, it may not affect wide range of microbes. On the other hand, treatment with natural dyes like curcumin, or obtained from Terminalia catappa, Morinda citrofolia, Tectona grandis, Artocarpus heterophyllus, etc. have successfully imparted a significant level of antimicrobial activity against microorganisms [71].

Besides plants, microbial pigments have also been developed to dye cotton, glace cotton, silk and rayon. A red pigment isolated from Rhodonellum psychrophilum contained a mixture of 2-methyl-3-butyl-prodigine, prodigiosin, 2-methyl-3hexyl-prodigine, 3, 4-Didehydrorhodopsin, anhydrorhodovibrin, alloxanthin and tetradecanoyl-hexadecanoyl compounds. This pigment demonstrated antibacterial against E. coli, S. aureus and antiyeast activity against C. albicans and S. cerevisiae [72].

Sometimes alum or metal-based mordants such as salts of chromium, aluminum, iron, copper, stannous and tin along with solvents like petroleum ether, ethyl acetate, acetone and methanol are used to intensify the dying process. However, extensive use of these mordants may not be considered eco-friendly. On the other hand, several natural mordants including bark extracts, essential oils, tannic acid, sumac, gall nuts, neem oil, oleic, stearic acids, etc. are also in use [73]. The application of natural mordant is continuously being explored to enhance the dying process along with its antimicrobial activity. Wool and silk fibers pretreated with neem oil retained higher color when dyed with chlorophyll, saffron red and yellow natural dyes natural as compared to untreated fibers [74]. Similarly, natural mordant myrobalan has also been used along with a natural dye extracted from Opuntia ficus-indica fruit on the silk fabric to enhance its antimicrobial property [75].

Besides natural or synthetic mordants, experiments with natural dyes obtained from Green walnut shells and Neem leaves suggested that the increased concentration of dyes also enhanced the antimicrobial property of the silk fabric [76, 77]. A number of synthetic dyes have also been investigated for their antimicrobial activity. However, they are not considered as skin or environmental friendly.

Synthetic and blended fabric

Synthetic fibers including acrylic, nylon, polyester, polypropylene and tetrafluoroethylene may have some antimicrobial properties, which can further be enhanced through the treatment of antimicrobial compounds [78]. 3-Allyl-5,5-dimethylhydantoin (ADMH) was grafted on several popular textiles like nylon, polyester, acrylic, polypropylene and natural fabrics to increase their antimicrobial property [79].

Antimicrobial agents and their incorporation into the fabric depend upon the type of textile materials and fibers. Chemical as well as physical properties of the fibers including their thickness diameter and processing conditions, antimicrobial compounds can be integrated using different methods and techniques. These compounds can be added directly into a fiber during its synthesis or into the fiber sheath during extrusion or may be applied on the fibers once they are manufactured through dip coating, polymer coating, spray application, or by introducing into the spin finish. In the case of nonwoven products, antimicrobials can be incorporated either during the bonding or during finishing processes. On the other hand, knitted or woven textiles are typically treated through exhaust and pad-dry-cure method [80].

Graphene&#;modified performance textile for personal clothing has been suggested to have a high level of antimicrobial activity and can be economic as well as comfortable. This graphene-based textile includes graphene 81 and graphene 82 nanomaterials impregnated fabrics. On the basis of their properties, these materials have been suggested for the fabrication of improved personal protective equipment (PPE) [81]. Cotton/elastane fabrics used for clothing achieved a significant level of antimicrobial property when treated with quat-silane [65]. Nylon 6 was containing copper nanoparticles (size 40&#;60 nm) were physisorbed on a modified surface by grafting mPEG. The treated fabric demonstrated its activity against pathogenic bacteria and also ensured cytocompatibility [82]. Hybrid coatings based on ZnO, Ag:ZnO/chitosan, 3-glycidyloxypropyltrimethoxysilane and tetraethoxysilane prepared by sol&#;gel method were applied on pure cotton and cotton/polyester (50/50%) textiles using &#;pad-dry-cure&#; technique demonstrated a significant level of antimicrobial activity [83].

Antimicrobial textiles for dermatological applications

Antimicrobial textile materials are used for different purposes including first aid, in clinical and hygienic practice. These antimicrobial textiles may also be used as bio-functional textiles, which are produced by integrating advanced pharmaceutical nanocarriers to conventional textiles in order to provide wearable drug delivery systems. These bio-functional textiles are promising products that may improve the dermal penetration with lower toxicity risk [84]. Antimicrobial textile materials can be used as a suitable matrix for different active substances facilitating their gradual release. Beside antimicrobial substances, these textiles may be used as carrier in aromatherapy, atopic dermatitis, painkillers, hormone therapy, melanoma, psoriasis treatment, etc. [85]. Recent study suggested that lyocell and antimicrobial silver-impregnated textiles are promising on common atopic dermatitis [86]. Adhesion and penetration ability of Ag NPs on cotton fabric suggested them to be used as dressing material for wound healing. These highly efficient antimicrobial cotton fabrics also demonstrated no toxic effect on human cells [87]. Cotton wound dressing has been developed to treat skin fungal infections. This cotton wound dressing contained Ketoconazole and β-cyclodextrin that demonstrated a controlled and slow release of these antifungal compounds to kill skin fungus namely C. albicans and A. niger [88].

Antimicrobial textile in functional design

Antimicrobial clothes are innovative, growing and highly competitive in the apparel industry. These antimicrobial textiles have been used to fight bacteria in an innovative way, where fashion and design are the prime importance. However, awareness and use of such products may be limited. A study on the buying behavior of antimicrobial apparel such as baby clothes, socks and underwear in Bangkok metropolitan revealed that the buying majorities were female, mostly employed and aged between 32 and 38 years [89]. As breathable, antibacterial and antimicrobial breast support, bra and related apparel were much demanded by the woman's apparel industry; a breast support system has been patented. This design consists of a support member having an outer surface and an inner surface. This support member comprises at least one antibacterial and one antimicrobial material along with at least one anti-absorbent material or a combination thereof [90]. Besides this, men's designer antimicrobial undergarments are also in use. A patent on men's underwear included four 140D antimicrobial nylon yarns in a weaving process. It also involved drawing a graph by graphic software and slackening the density of the crotch by using an overlapping function, so that the slackened crotch was combined with the added 140D antimicrobial yarns and the stitch uplifting weave to form a bag [91].

Antimicrobial sportswear is also in demand as it may be useful in preventing microbial growth and sweating odor. Sensory analysis on sportswear with odor-controlling property revealed that odor-control textile may smell less intense than similar polyester samples [92]. A flexible antimicrobial sleeve has been patented, which eliminates any germ transferred from the wearer to the sleeve by coughing or sneezing. This sleeve was designed to be worn by children on the elbow over their existing clothes. The design permitted a frictional fit that allowed the wearer easy application and removal without limiting the motions [93].

The application of antimicrobial clothing is not just limited to routing use, but it also seems to have a potential role in diverse fields. Recently, an evaluation analysis on developing antimicrobial textile for long-duration space flight has been carried out. The space travel system is generally free from microbes and there are quite lesser chances of microbial growth in the spacesuit. However, the garments in space are worn for a longer time and only a few garments are taken on a mission due to the lack of laundry facility. Contact with human skin may allow the growth of microbes and there are no options available for efficient washing of clothes. The use of antimicrobial textile in space travel may eliminate or reduce the need for garment washing [94].

Recently, the COVID-19 pandemic has generated a significant increase in the production and use of metal nanoparticles-based antiviral textile including face masks, gloves, protective suits, shoes, etc. Mismanagement in the disposal of such types of personal protective equipment may lead to a long-term negative effect in environments [95]. Sometimes leaching of metals for the nanometal-based textile can be used to calculate the amount of metal released in the disposal phase of such textile products during landfill treatment [96].

Antimicrobial textile in fashion design

Antimicrobial textiles have been used in the areas of health care, hygiene, medical devices, sportswear, innerwear, food packaging, storage, thermal and mechanical protection, automotive textiles, heating, ventilation and air conditioning, air filters, and water purification systems. They are also used to protect healthcare personnel with functional clothing as well as fabrics all around the home, including socks, mattresses, baby diapers, coverings and now in face masks as well. Antimicrobial textiles are quite popular with sportswear or active fashion wear. In the global and Indian fashion market, sportswear or active-wear is in gaining high popularity. Perhaps this shift is due to people's interest in different looks for different sports events inspired by various celebrities such as new gymnasium looks or casual active-wear. In recent time, we can also find many celebrities coming up with their sports or active-wear fashion brands such as HRX&#;lifestyle brand by Hrithik Roshan, SKULT&#;athleisure fashion brand by Shahid Kapoor or One8 x Puma and One8 Commune by Virat Kohli collaboration with Puma and there are many such names. Hence, these sports garments using specialized fibers, yarns, engineering design of fabric with various chemical finishes. In a textile preferable used for sport application, moisture and heat management are the key issues that have to be ensured for appropriate thermophysiological and tactile comfort and further due to the COVID-19 pandemic the demand for antimicrobial textiles in active sportswear is enormously increased [97]. Some examples of the textile and apparel companies/brands using antimicrobial fabrics are as follows:

• Brooks Brothers (USA), Antibacterial fabric for underwear

• Louvolite (England), Antimicrobial curtain fabric for window coverings

• Medline (USA), Antimicrobial fabric for medical devices

• Plastisan (Spain), Antimicrobial shower curtains

• QuietWear (USA), Anti-odor apparel for hunting

• St. Croix (USA), Antibacterial fabric for apparel

• EcoMed (Australia), Antibacterial hospital curtains

• Coleman Aerobed (USA), Antimicrobial air mattresses

• Sea to Summit (Australia), Antimicrobial sleeping bag liners and air mattresses

While certain global brands are claiming to use antimicrobial fabrics such as diesel claims that their new denim has virus-fighting capabilities [98], according to sources, it has the capacity to disable over 99 percent of viral activity within two hours of contact. &#;London-based Apposta promises its dress shirts&#; fabric inhibits &#;hosting bacteria and viruses, including COVID-19,&#; and &#;reduces the likelihood and speed of contaminations, transmissions by destroying bacteria and viruses on contact&#; [99]. The Lululemon active sportswear brand, one of their lines called &#;Silverescent,&#; products that boast of their antimicrobial properties through the use of silver threads. Companies like Dow Microbial Control, Microban, Lululemon, Under Armour, etc., manufacture products that guarantee sweat stain-free and bacteria-killing technology. Lululemon uses X-Static technology, which embeds 99.9% pure silver in its fibers. Companies rely on the chemical energy and reactions in their materials to deliver their antimicrobial qualities [100].

Companies such as Donear Industries, Welspun India Ltd, RSWM Ltd (Mayur), Arvind Ltd, Vardhman Textiles and D' Décor have launched antiviral fabrics for the garment manufacturing industry and home furnishing products. These fabrics are almost 15 to 20 percent higher in cost than the fabrics with no such treatment. Liva sub-brand of Aditya Birla group claims Antimicrobial protection is a special viscose-based fabric that inhibits the growth of microbes (Bacteria and Viruses) on Apparels & Home-Textiles and kills them to the extent of 99% effective even after 50 washes [101].

Conclusion and future directions

Synthetic as well as natural fabrics have been used for antimicrobial textiles development. Antimicrobial properties can be introduced by application of chemicals, metal-based NPs, plant & animal-derived compounds, dyes and mordants. The coated fabrics may show a narrow or broad range of antibacterial properties against bacteria, fungi and viruses. MIC and IC50 values can be used to evaluate the amount of antimicrobial compound to be coated, which affects the efficiency and price of prepared textiles. Synthetic chemicals and metal nanoparticles-based antimicrobial textiles are effective but also seem to be a threat toward damaging the environment as there is very limited information available about the exact impact of chemicals that can leach into the environment. Thus, future research must be directed toward exploring the potential for natural antimicrobial agents. As the application of domestic antimicrobial textiles is increasing, there must be a well-planned and managed system for the disposal and treatment of antimicrobial textiles. A consistent and robust solution is a must so that this should not become a problem like plastic waste management.

Authors' Contributions

RG drafted antimicrobial agent part, SS drafted application and fashion-related part, and RKS conceptualized, edited and finalized the manuscript.

Data Availability

Data are available in public resource.

Declarations

Conflicts of interest

Not applicable

Consent for publication

Yes.

Consent to participate

Yes.

Footnotes

Publisher's Note

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