**3.3.3 Cyclodextrin**

Cyclodextrins are toroidal-shaped cyclic oligosaccharides with a hydrophilic outer surface and an internal hydrophobic hollow interior, which can entrap a vast number of lipophilic compounds into their hydrophobic cavity, depending on their size and molecular structure. The remarkable ability of cyclodextrins to include hydrophobic compounds has been exploited in several fields, spanning from pharmaceuticals to cosmetics, from food manufacturing to commodity

In textile field, a novel functional surface treatment of cotton based on the permanent fixation of cyclodextrin on fabric is receiving increased attention. Some literatures have demonstrated that cyclodextrin fixed to cotton did not affect the hydrophilic properties of cellulose and the immobilized cavities of cyclodextrins did not lose their complexing power to form inclusion complexes with other molecules. (Wang & Cai, 2008)

CDs and their derivatives have been used in the textile domain since the early 1980s. The permanent binding of CDs onto textile fibers offers the advantage that the inclusive properties of CDs towards bioactive molecules become intrinsic to the modified fibers.( El Ghoul et al, 2008)

Fig. 10. TEM micrographs of chitosan-PBA particles stained for an appropriate period with 2% PTA solution. (A) Well-defined core-shell particles that consist of PBA cores and chitosan shells; (B) soft PBA-chitosan particles, which deform easily when in contact with

1. Polycationic structure of chitosan which can be expected to interact with the predominantly anionic components (lipopoly-saccharides and proteins of microorganism surface) resulting in changes in permeability which causes death of the

2. The chitosan on the surface of the cell can form a polymer membrane which prevents

3. The chitosan of lower molecular weight enters the cell, binding to DNA and inhibits

4. Since chitosan could adsorb the electronegative substance in the cell and flocculate them, it disturbs the physiological activities of the microorganism leading to death of

Cyclodextrins are toroidal-shaped cyclic oligosaccharides with a hydrophilic outer surface and an internal hydrophobic hollow interior, which can entrap a vast number of lipophilic compounds into their hydrophobic cavity, depending on their size and molecular structure. The remarkable ability of cyclodextrins to include hydrophobic compounds has been exploited in several fields, spanning from pharmaceuticals to cosmetics, from food

In textile field, a novel functional surface treatment of cotton based on the permanent fixation of cyclodextrin on fabric is receiving increased attention. Some literatures have demonstrated that cyclodextrin fixed to cotton did not affect the hydrophilic properties of cellulose and the immobilized cavities of cyclodextrins did not lose their complexing power

CDs and their derivatives have been used in the textile domain since the early 1980s. The permanent binding of CDs onto textile fibers offers the advantage that the inclusive properties of CDs towards bioactive molecules become intrinsic to the modified fibers.( El

to form inclusion complexes with other molecules. (Wang & Cai, 2008)

Several mechanisms were proposed for the antimicrobial activity by chitosan:

cell by inducing leakage of intracellular components.

nutrients from entering the cell.

the cells**. (**El-tahlawy et al, 2005)

RNA and protein synthesis.

**3.3.3 Cyclodextrin** 

Ghoul et al, 2008)

manufacturing to commodity

each other.

#### **4. 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. 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 fibre surfaces. These products can control only those microbes that are present on the fibre surface, not in the surrounding environment. 'Bound' antimicrobials, because of their attachment to the fibre, 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, fungistats. 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.

Fig. 11. Controlled release antimicrobials

Antibacterial Agents in Textile Industry 403

20645 are based on the agar diffusion test and ISO 11721 is a burial test (part 1 for the determination of an antimicrobial finish and part 2 for the determination of the long-term resistance). The main difficulties of these tests are mostly poor reproducibility of the test results and often insufficient correlation between laboratory results and actual conditions in the field. Careful attention to detail and trained laboratory personnel are essential for

A more rapid test method, developed by the British Textile Technology Group in the late 1980s, is based on adenosine triphosphate (ATP) luminescence. The growth of

against

and

amount

positive

is

around the textile.

One method involves

*Aspergillus niger* in

quantitative

Rapid qualitative method for determining antibacterial activity of treated textile materials

both Gram-positive and Gram-negative bacteria. Treated material is placed in nutrient agar that is streaked with test bacteria. Bacterial growth is determined visually after incubation. Antibacterial activity is demonstrated by zones of inhibition on

Quantitative method for determining the degree of antimicrobial activity of treated textiles. The

of bacterial growth in inoculated and incubated textiles is determined through serial dilutions and subsequent inoculations of sterile agar. Gram

Four methods for determining the antifungal assessment on textile properties of treated textiles.

testing fabric properties after burial in soil that contains fungi. In a second method, cellulose fabric

plate and the subsequent growth visually determined. The third method exposes textiles to

Methods are given for the qualitative and

determination of antibacterial activity and the qualitative evaluation of antifungal properties of carpet samples using procedures and materials similar to those in the above test methods.

textiles; exposed to *Chaetomium globosum* in an agar

an agar plate and visually determines any fungal growth. The fourth method uses a humidity jar to expose textiles to mixture of fungi spores. Any growth on the textile is visually determined.

and Gram-negative bacteria are used.

accurate and repeatable results from these methods.( Schindler & Hauser, 2004)

microorganisms is assessed by firefly bioluminescent detection and ATP analysis.3

**AATCC test method Comments** 

Antibacterial activity of textile

147(agar plate test)

test method 30

method 174

materials: parallel streak method; test method

Antibacterial finishes on textile materials,

Antifungal activity, assessment on textile materials: mildew and rot resistance of textiles;

Antimicrobial activity assessment of carpets; test

Table 1. Comparison between different AATCC test methods

assessment of: test method 100

Textiles with biostatic properties, however, are subject to fewer regulations. The actual mechanisms by which antimicrobial finishes control microbial growth are extremely varied, ranging from preventing cell reproduction, blocking of enzymes, reaction with the cell membrane (for example with silver ions) to the destruction of the cell walls and poisoning the cell from within. In Figure 11 and 12 the chemical structures of some of antimicrobial agents are shown.

$$\begin{array}{c} \mathbf{C} \mathsf{H}\_{3} \mathbf{C} \mathsf{H}\_{2} \\\\ \mathbf{C} \mathsf{H}\_{2} \mathbf{O} \end{array} \quad \begin{array}{c} \mathbf{C} \mathsf{H}\_{3} \quad \mathsf{C} \mathsf{H}\_{2} \\\\ \mathbf{C} \mathsf{H}\_{3} \end{array}$$

Fig. 12. Bound antimicrobials
