History of Antimicrobial Finish

During world war II, when cotton fabric was extensively used for tent age, tarpaulins and truck covers, these fabrics need to be protected from rotting caused by microbial attack. This was particularly a problem in the south pacific campaigns, where much of the fighting took place under jungle like conditions. During the early 1940’s, the US army quartermaster Crops and collected and complied data on fungi, yeast and algae isolated from textiles in topical and subtropical areas throughout the world (Lee , Hwang & Kim, 2009). 

Cotton duck, webbing and other military fabrics were treated with mixtures of chlorinated waxes, copper and antimony salts that stiffened the fabrics and gave them a distinct odor. At the time potential polluting effects of the application 

materials and toxicity related issue were not a major consideration. After world war II, and as late as the mid-to-late 1950’s fungicides used to cotton fabrics were compounds such as 8-hydroxyginoline salts, copper napthenate, copper ammonium fluoride and chlorinated phenols. As the government and industrial firms became more aware of the environment and workplace hazards these compounds caused. Alternative products were sought. 

Microbial growth on textile leads to odor development, mildew growth derived discoloration up to the loss of functional properties (elasticity and tenacity) For that reason already in the seventeenth century ship cloth was conserved by tanning with iron salt solutions (Brown color) . The use of hygienically effective substance today is related to body tight worn garment and sports textiles, mattresses and socks. Especially cellulosic fibers are in the first place cotton are targeted fibers for antimicrobial functionalization. 

Microbes:

A microorganism or microbe is a microscopic living organism, which may be single- celled or multicellular Microorganisms i.e. bacteria, fungi, mildew, mold and yeasts are found everywhere in nature, even in hostile environment. The human is usually crowded with innumerablemicroorganisms. A suitable temperature, moisture, dust and receptive surface provide perfect conditions for their growth .In favorable conditions certain bacteria can grow from a single germ to millions in a very short period of time. They can double every 20-30 seconds in a warm and mosit microclimate that has plenty of food for them e.g. perspiration and other body secretions, skin particles, fats and left overs from worn-out threads 

Type of microbes that attack textile materials

Microbes are the tiniest creatures not seen by the naked eyes. They include a variety of micro-organisms like bacteria, fungi, algae and virus. Further, subdivisions in the bacteria family are Gram positive (staphylococcus aurous), Gram negative (E-coli), Spore bearing or non-spore bearing type. Some specific types of bacterial are pathogenic and cause cross infection. Fungi, molds or mildew are complex organisms with slow growth rate. They are part of our everyday live and found everywhere in the environment and on our bodies. 

Attack of Textile Materials by Microbes

Natural Fibers

Textiles made from natural fibers are generally more susceptible to biodeterioration than are the synthetic (man-made) fibres. This is because their porous hydrophilic structure retains water, oxygen and nutrients, providing perfect environments for bacterial growth. Products such as starch, protein derivatives, fats and oils used in finishing of textiles can also promote microbial growth. Micro-organisms may attack the entire substrate, that is the textiles fibres or may attack only one components of the substrate, such as plasticizer contained therein, or grow on dirt that has accumulated on the surface of a product. Nevertheless, even mild surface growth can make a fabric look unattractive by the appearance of unwanted pigmentation. Heavy infestation which results in rotting and breakdown of the fibres and subsequent physical changes such as loss of strength or flexibility may cause the fabric to fail in service. 

Materials by microbes

People are totally concern over the problems of odour, staining, deterioration, and human health condition such as allergies or infectious disease (Tables 1)

Table 1: Some of common microbes and their influence

Application of antimicrobials by leaching technology: 

The vast majority of antimicrobials work by leaching or moving from the surface on which they are applied. This is the mechanisms used by leaching antimicrobials to poison a microorganism. Such chemicals have been used for decades in agricultural application with mixed results. Besides affecting durability and useful life, leaching technologies have potential to cause a variety of other problems when used in garments. These include their negative effects because; they can contact the skin and potentially affect the normal skin bacteria, cross the skin barrier, and/or have the potential to cause rashes and other skin irritations. 

Effects of microbes on textile and human beings: 

Although microbes can be useful in many ways, for example in brewing, baking and biotechnology, they can also be harmful to both textile and humans. Different substances added to textiles, such as size, hand modifiers, antis tats, thickeners, lubricants and dirt as well as grease, sweat and dead skin from the human body provide a great source of nourishment for microorganisms. Following are some of the possible effects microorganisms on textiles; 

§ Bad odor

§ Discoloration

§ A slick slimy handle

§ Loss of functional properties like elasticity and tensile strength

§ Decrease in the life of the textiles, especially cotton and wool

The effect on human health is much more vast than the effect on textile. Most of the microbes involve diseases. Some of them do cause the prevention of some diseases. Bacteria associated with the human body outnumber body cells by ten to one. In most causes the bacteria that cause sickness are that bacteria that normally inhibit the body. They are picked up from the atmosphere. Some of the effect that are caused by microbes on human being is pointed out below : Various types of infectious diseases such as plague, tuberculosis, anthrax, malaria etc. 

§ Food poisoning and water caused diseases

§ Damage of building materials

§ Bad odor

Antimicrobial component: 

Normal home-washing of textiles, which is generally under mild conditions, does not completely remove the microbes. In order to eliminate microbes, very severe laundering conditions, e.g. a temperature 95°c and strong detergent followed by bleach, are essential. Any surviving microbes can quickly multiply again at each further wearing. This can be avoided by the application of antimicrobial (Mahesh, Manjunatha Reddy, & VijayaKumar, 2011). 

In this research chitosan is used as antimicrobial agent. This have been investigated as an antimicrobial material against a wide range of target organism like algae, bacteria, yeasts and fungi in experiments involving invivo and in vitro interactions with chitosan in different forms ( solution, film and composites ). Chitosan is considered to be a bactericidal ( kills the live bacteria or some fraction) or bacteriostatic ( hinders the growth of bacteria but does not imply whether or not bacteria are killed), often with no distinction between activities. The exact mechanism is not fully understood and several other factors may contribute to the antimicrobial action (Lourenço et. al., 2013). 

Chemical composition of turmeric: 

Table 2.2: Chemical composition of turmeric

Chemical structure of turmeric extracts compound and curcumin 

Figure 2.1: Structure of turmeric extracts

R' =R''= H: Curcumin 

R = OMe; R´=H; R''=H: Demethoxycurcumin 

R = R'= R''=H:Bis-demethoxycurcumin 

R =OMe; R'= OH;R''= H:(1E,6E)-1-(4-Hydroxy-3-methoxyphe- nyl)-7-(3,4-ihydroxyphenyl)-1,6-heptadiene-3,5-dione 

R = R'= R''=OMe:5'-MethoxycurcuminAntibacterialpropertiesoftreated 

Required for an antibacterial agent:

Textile material in particular, the garments are more susceptible to wear and tear. It is important to take into account the impact of stress strain, thermal and mechanical effects on the finished substrates. The following requirements need to be satisfied to obtain maximum benefits out of the finish. Durability to washing, dry cleaning and hot pressing. Selective activity to undesirable microorganisms. Should not produce harmful effects to the manufacturer, user and the environment. Should comply with the statutory requirements of regulating agencies (Mandroli & Bhat, 2013). 

Compatibility with the chemical processes. Easy method of application.No deterioration of fabric quality Resistant to body fluids.Resistant to disinfections/ sterilization. 

Safety, non-toxicity for human health and the environment and also biodegradability are required for an antibacterial agent. 

Durability of Antimicrobial Textiles

Temporary antimicrobial properties in textiles are easy to achieve in finishing but readily lost in laundering. Temporary antimicrobial textiles are useful only for disposal materials. Durable antimicrobial function is quite challenging to achieve and can last more than 50 machine washes (Murthy, Soumya, & Srinivas, 2015). 

Mechanisms of antimicrobial finishes: 

Despite the long list of requirements, a variety of chemical finishes have been used to produce textiles with demonstrable antimicrobial properties. These products can be divided into two types based on the mode of attack on microbes. One type consists of chemicals that can be considered to operate by a controlled-release mechanism. The antimicrobial is slowly released from a reservoir either on the fabric surface or in the interior of the fibre. This ‘leaching’ type of antimicrobial can be very effective against microbes on the fibre surface or in the surrounding environment (Naz, et. al., 2010). However, eventually the reservoir will be depleted and the finish will no longer be effective. In addition, the antimicrobial that is released to the environment may interfere with other desirable microbes, such as those present in waste treatment facilities. The second type of antimicrobial finish consists of molecules that are chemically bound to fiber surfaces. These products can control only those microbes that are present on the fiber surface, not in the surrounding environment. ‘Bound’ antimicrobials, because of their attachment to the fiber, can potentially be abraded away or become deactivated and lose long term durability. Antimicrobial finishes that control the growth and spread of microbes are more properly called biostats, i.e. bacteriostats, fungi stats. Products that actually kill microbes are biocides, i.e. bacteriocides, fungicides. This distinction is important when dealing with governmental regulations, since biocides are strongly controlled (Rachana, S., & Venugopalan, P. (2014). 

Antimicrobial effects:

Turmeric extract and the essential oil of Curcuma longa (turmeric) inhibit the growth of a variety of bacteria, parasites, and pathogenic fungi. A study of chicks infected with the caecal parasite Eimera maxima demonstrated that diets supplemented with 1-percent turmeric resulted in a reduction in small intestinal lesion scores and improved weight gain. Another animal study, in which guinea pigs were infected with either dermatophytes, pathogenic molds, or yeast, found that topically applied turmeric oil inhibiteddermatophytes and pathogenic fungi, but neither curcumin nor turmeric oil affected the yeast isolates. Improvements in lesions were observed in the dermatophytes and fungi-infected guinea pigs, and at seven days post-turmeric application the lesions disappeared. Curcumin has also been found to have moderate activity against Plasmodium falciparum and Leishmania major organisms (Singh & Jain, 2011). 

Chitosan:

Chitosan is a deacetylated derivate of chitin, which is a natural polysaccharide mainly derived from the shells of shrimps. Chemically, it can be designated as poly-β-(1→4)-D-glucosamine or poly-(1,4)- 2-amido-deoxy-β-D-glucose (Tiwari, et. al., 2009). In addition to its antimicrobial activity, chitosan has some important advantages such as non-toxicity, biocompatibility and biodegradability (Lertsutthiwong & Rojsitthisak, 2011). 

The antimicrobial efficiency of chitosan depends on its average molecular weight, degree of deacetylation and the ratio between protonated and unprotonated amino groups in the structure It is believed that chitosan of a low molecular weight is more antimicrobially active than chitosan oligomers. The efficiency also increases with increased deacetylation, which can exceed 90%. An important disadvantage of chitosan is its weak adhesion to cellulose fibers, resulting in a gradual leaching from the fiber surface with repetitive washing. To enable chitosan to bind strongly to cellulose fibers, various crosslinking agents are used, including mostly polycarboxylicacids . In the presence of a crosslinking agent, hydroxyl groups of chitosan and cellulose can form covalent bonds with carboxyl groups of polycarboxylic acid in an esterification reaction or with hydroxyl groups of imidazolidinone in an etherification reaction, thus leading to the formation of a crosslink between chitosan and cellulose. This greatly improves durability and wash resistance (Ungphaiboon, et. al., 2005). 

Benefit of antimicrobial textiles:

A wide range textile product is now a available for the benefit of the consumer. Initially, the primary objective of the finish was to protect textiles from being affected by microbes particularly fungi. Uniforms, tents, defense textile and technical textiles, such as, geo-textiles have therefore all been finished using antimicrobial agents. Later, the home textiles, such as, curtains coverings and bath mats came with antimicrobial finish. The application of the finish is now extended to textile used for outdoor, health care sector, sports and leisure (Zemljic, et. al., 2014).