Chitosan Derivatives - Promising Sustainable Biopolymers for Quality Healthcare Textiles

and CMTMCC. CMTMCC modified fabric exhibited best antimicrobial activity. TMCC and CMTMCC treated fabric showed more wicking height (cm) comparatively than chitosan treated fabric. Moisture absorption and moisture liberation, swelling and water vapor permeability of treated fabric were investigated. Thermal stability of treated fabric was also studied. All these characteristics support the TMCC and CMTMCC treated fabric could be the valuable materials for medical textile sector.


Introduction
The consumers are now increasingly aware of the hygienic lifestyle and there is necessity and expectation for high quality healthcare textiles. That's why it is one of the most important, continuously expanding and growing fields in technical textiles. Healthcare textiles represent structurally designed and accomplished for a new health and hygiene-related textiles products for the well-being of mankind which applications is diverse, ranging from hospitals, hotels to personal care products.
Because of their importance, a number of chemicals have been employed to impart antimicrobial activity to textile materials. These chemicals include inorganic salts, organometallics, phenols and thiophenols, onium salts, antibiotics, heterocyclic compounds with anionic groups, nitro compounds, urea and related compounds, formaldehyde derivatives, amines and synthetic dyes [1]. However, with the public's enhanced awareness of eco-safety, there has been considerable debate about their use, because majority of such agents are toxic to humans and are not environmentally friendly.
In addition, another big concern is that some of these agents are being increasingly resisted by microbial pathogens. Therefore, the role of textile finishers has now become increasingly demanding and has strengthened the interest in alternative ecofriendly and biodegradable finishing agents [2][3][4][5].
Chitosan is the deacetylated derivative of chitin that is the second most abundant polysaccharide found on earth next to cellulose. When chitin is deacetylated over about 60% it becomes soluble in dilute aqueous acids and is referred to as chitosan. Chitin is the main component in the shells of crustaceans, such as shrimp, crab [6][7][8][9]. Huge amounts of crab and shrimp (prawn) shells have been abandoned as wastes by worldwide seafood companies. This has led to considerable scientific and technological interest in chitin and chitosan as an attempt to utilize these renewable wastes. The applications of chitosan include uses in a variety of areas, such as pharmaceutical and medical applications, paper production, textile dyeing and finishing, fiber formation, wastewater treatment, biotechnology, cosmetics, food processing, and agriculture [10,11].
There is a greater demand for antimicrobial finishes on textile goods. Chitosan, a natural biopolymer, has many chemical attributes, especially its cationic nature, to make it an interesting candidate for these applications. However, the major problems of chitosan are its loss of the antimicrobial activity under alkaline conditions due to its loss of the cationic nature. But chitosan derivatives will overcome that problem due to retain antimicrobial activity in wide range of pH that could have a strong economic, social, and environmental impact, especially in our country.
In view of these ecological, environmental concerns and to overcome the drawback of chitosan, we are going to explore chitosan derivatives which will in turn help to develop next generation healthcare textiles. This will be followed by a focus on some recent developmental works pertaining to antimicrobial finishing of textiles using various "green chemistry" approaches in order to provide safe and novel antimicrobial textiles for aesthetic, hygienic, and healthcare applications in the near future. The specific objectives of the present project are: preparation of sustainable chitosan derivatives from prawn shell waste, modification of cotton fabric with chitosan derivative and antimicrobial assessment and different characterization of modified cotton fabric as for healthcare textiles. The prepared chitosan and its derivatives will be applied on cotton fabric and the modification will be confirmed using FTIR, TGA and DTA techniques. As quality healthcare textile, antimicrobial test, water vapor transmission rate, swelling test, and tensile strength of finished and unfinished cotton fabric will be investigated.

Methods
Processing of Prawn Shell Waste: Prawn shell was collected, washed, dried, and ground to 40-60 mesh using a hammer mill.
The ground prawn shell was then ready for a series of chemical treatment for extraction of chitin. Through a set of chemical treatments demineralization, de-protenization and decolouration of chitin was obtained. Later deacetylation of chitin gave chitosan [12,13].
Preparation of TMC: TMC was synthesized through nucleophilic substitution with CH 3 I as a reagent, sodium iodide as catalyst and sodium hydroxide (NaOH) as base with N-methyl pyrrolidone (NMP) as solvent [14].

Yield Percentage of Chitin, Chitosan and its Derivatives
The percentage yield was calculated from the ratio of the dried raw sample and the weight of obtained product. This obtained percentage yield is shown in Table 1. The yield percentage of chitosan, TMCC and CMTMCC was 66.5, 102 and 93 % respectively.

FTIR Analysis
In the FTIR spectrum of the prepared chitosan shown in Figure   1a, there were two absorption peaks at 1631 cm -1 and 2919 cm -1 , which correspond to the N−H bending of the primary amine, and the presence of hydroxyl groups respectively. Obvious changes of the FTIR spectra are observed after quaternization of chitosan with methyliodide. In the FTIR spectrum of TMCC, a characteristic peak at 1460 cm -1 indicates the C-H bending of trimethyl ammonium group thus shows evidence of the quaternary ammonium salt group. It should be also noted that the N−H bending (1630 cm -1 ) of the primary amine disappeared due to the change of the primary amine to the secondary aliphatic amine [16]. A new peak at 1740 cm -1 was also attributed to the quaternary ammonium in TMCC which is shown in Figure 1b. In addition, the spectrum shows a broad band at around 3400 cm 1 , probably due to the increased number of hydroxyl groups. The FTIR spectrum of the CMTMCC is shown in Figure 1c.

Surface Morphology
Surface morphology of the unmodified and modified cotton fabric were evaluated using three dimensional images getting from scanning electron microscope Figure 3. Unmodified cotton fabric exhibits regular surface as well as no adherence. Besides modified fabrics were overlaid with mentioned modifier which reveals little bit irregular, or microstructure roughness helps to increase surface area as well as antimicrobial functionality [17]. Conglomerated granule was evidently visible on the fiber surface which proofs the attachment of applied modifier on the fabric. of the cell to alter cell permeability. But the problem is that it has lower solubility above pH 6 and also its lower attachment capacity on cotton fabric [20]. For TMCC, the mechanism of antimicrobial activity using on cotton fabric is almost similar to chitosan. The slight difference in antimicrobial activity of chitosan and TMCC is due to having positive charge in nitrogen atom and its higher solubility in water than chitosan.  The antimicrobial action is believed to occur when the compounds are absorbed onto the bacterial cell surface, increasing the permeability of the lipid cell membrane and causing death through the loss of essential cell materials. In addition, these derivatives of chitosan are generally more active against grampositive and gram-negative bacteria than chitosan. This effect is believed to be due to adsorption of the polymers onto the bacterial cell surface and membrane with subsequent disruption of membrane integrity. Antimicrobial activity generally increases as the content of the quaternary ammonium moiety increases comparatively than chitosan. CMTMCC has better antimicrobial activity than chitosan and TMCC. Here the mechanism is approximately same to them but the difference is that the attachment capacity of CMTMCC (MIC=5.8mg/L for E. coli and 3.3 mg/L for S. aureus) is more than chitosan and TMCC on the cotton fabric.

Wicking, Moisture Absorption, Moisture Liberation and Swelling Test Result
Wicking Test: Wicking is the spontaneous flow of a liquid in a porous substrate, driven by capillary forces. Because capillary forces are caused by wetting, wicking is a result of spontaneous wetting in a capillary system. The wicking test results for untreated cotton fabric, chitosan, TMCC and CMTMCC modified cotton are given in Table 3. Untreated cotton fabric shows lower wicking height than the treated cotton fabrics due to the absence of the coating of chitosan, TMCC, and CMTMCC having channel like structure on cotton fabric. Chitosan and its derivatives show higher wicking height (cm). TMCC and CMTMCC have also higher wicking height (cm) comparatively than chitosan treated fabric. The reason for this is TMCC and CMTMCC have channel like structure same as chitosan and also have the presence of positive charge which helps to attract water molecules. hydroxyl groups that attract water molecules and hydrogen bond with the cellulose [21]. Ability to retain a liquid in the fabric is known as absorption. Absorption consists of several parts, first the fiber surface is wetted and the liquid is transported into the voids between the fibers and are absorbed into the fibers and diffuse [22]. The moisture absorption test results are given in Table 3 Table   3. Untreated fabric can easily liberate moisture because of having low capillaries. On the other hand, chitosan, TMCC, and CMTMCC treated cotton fabrics have channel like structure and for this it is unable to moisture liberation.
Swelling Test: Moisture/liquid transport in textile fabrics is one of the critical factors affecting physiological comfort. In conditions where wearers sweat a lot (e.g. high-level bodily activity), it is not only desirable for the fabric next to the skin to absorb liquid rapidly but also to transport it through the fabric promptly to avoid the discomfort of the fabric sticking to the skin. The comfort afforded by textile fabrics can be improved by understanding the liquid transport mechanism [23]. The swelling capacity of an antibacterial fabric plays an important role in the antibacterial activity, wound healing capacity, and for biomedical application due to their high water/solvent holding capacity. They can further absorb a slight to moderate amount of the wound exudates by swelling which helps in fast healing of the wound. The swelling test results are list in Table 3. Swelling % of untreated fabric is lower than others because of lacking the cross-linked channel structure to hold water for being swollen. Then the swelling capacity of CMTMCC is more than others for having not only the presence of hydrophilic groups in the film networks -as like as chitosan and TMCC which assist in improving the swelling characteristic of the fabric but also N atom containing positive charge and higher attachment capacity to the fabric.

Water Vapor Permeability (WVP) Test
Bolton studied a variety of dressings and determined that a WVTR of about 840 g/m 2 /day is required to maintain a moist wound surface [24]. Water Vapor permeability occurs mainly for having different vapor pressure on both sides of the cotton fabrics.
The WVP test results are given in     It can be seen that the initial decomposition temperature of unmodified cotton fabric is 225 O C as shown in Table 6. Also, for DSC curve it is observed that there is a exothermic peak at 450°C which corresponds the burning of the char present in cotton fabric during oxidation. Figure  The initial decomposition temperature of chitosan cotton fabric is 310OC as shown in Table 6. Now from Figure 5c it is obtained that at 50°C phase transition is occurred, at 80°Can endothermic peak is appeared due to melting behavior and at 340°C another endothermic peak is occurred for the same at 50°C. In this Figure the Initial decomposition temperature was 315°C. And Initial decomposition temperature of CMTMCC modified cotton was 290°C as shown in Table 6. antimicrobial activities that will be used in hospitals, hotels and personal cares textiles as not only fashion and comfort but also safeguard for human health without disturbing environment. At the same time, the project will help to utilize the by-product or wastage of prawn processing industries.