http://informahealthcare.com/mnc ISSN: 0265-2048 (print), 1464-5246 (electronic) J Microencapsul, 2014; 31(5): 461–468 ! 2014 Informa UK Ltd. DOI: 10.3109/02652048.2013.879927

RESEARCH ARTICLE

Chitosan microencapsulation of various essential oils to enhance the functional properties of cotton fabric Amjed Javid1, Zulfiqar Ali Raza1, Tanveer Hussain1, and Asma Rehman2 Journal of Microencapsulation Downloaded from informahealthcare.com by University of Newcastle on 08/29/14 For personal use only.

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Chemistry Research Laboratory, National Textile University, Faisalabad, Pakistan and 2National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan Abstract

Keywords

The present study dealt with emulsive fabrication of chitosan microcapsules encapsulating essential oils in the present of bio/surfactant. The size distribution, morphology and stability of microcapsules were examined by using advanced surface characterisation techniques. At cetyl trimethyl ammonium bromide (CTAB) concentration of 330 mg/L, the smallest average size of microcapsules was observed as12.8 mm; whereas with biosurfactant at 50 mg/L, the microcapsules of smallest average size of 7.5 mm were observed. The fabricated microcapsules were applied on a desized, bleached and mercerised cotton fabric by using pad-dry-cure method by using a modified dihydroxy ethylene urea as a cross-linking agent. The cross-linking was confirmed by using scanning electron microscopy and Fourier transform infrared spectroscopy techniques. The antibacterial activity of finished fabric was evaluated using the turbidity estimation method. The stiffness and wrinkle recovery properties of the treated fabric were also investigated by using the standard methods. In general, antibacterial activity of treated fabric increased with the increase in chitosan and essential oil concentrations, whereas stiffness increased with increase in concentration of chitosan but decreased with increase in essential oil concentration.

Antibacterial activity, emulsion, FTIR, microencapsulation, particle size, SEM

Introduction Functionalisation of textiles is an approach to improve the native properties as well as to impart new functions in the textile products. The functional finishes impart new properties such as UV resistance, photo-catalytic activity, flame retardency, antibiotic, antistatic, antimicrobial activity and wrinkle recovery to the fabrics (Gowri et al., 2010; Ammayappan et al., 2011; Sunder and Nalankilli, 2012; Gulrajani, 2013). With the increased public awareness, people are becoming more conscious about health and hygiene-related issues. It is necessary to protect the people from cross infection caused by the pathogens. The problem of cross infection becomes prominent in the case of textile materials such as pillow cases, bed sheets, drapes, gowns and masks which are frequently used in hospitals. These materials may carry microorganisms which may transfer to patients, hospital staff and visitors (Thelagavath and Kannaian, 2008). Natural fibres such as cotton, wool and silk are more susceptible to microbial attack than synthetics as their porous and hydrophilic structure retains more moisture, oxygen and nutrients required for microbial growth (Abo-Shosha et al., 2008). The textile substrates finished with antimicrobial agents are hygienically safe products when worn next to the skin. In the last few decades, many synthetic antimicrobial agents such as triclosan, metals and their salts, organometallics, phenols and quaternary ammonium compounds

Address for correspondence: Zulfiqar Ali Raza, Chemistry Research Laboratory, National Textile University, Faisalabad – 37610, Pakistan. Tel: +92 41 9230081. Fax: +92 41 9230098. E-mail: [email protected]

History Received 19 April 2013 Revised 27 November 2013 Accepted 2 December 2013 Published online 4 February 2014

have been developed. These compounds are bactericidal in nature and may cause skin irritation and eco-toxicity (Joshi et al., 2009). Chitosan derived from chitin by a deacetylation reaction is a biodegradable, biocompatible and non-toxic molecule. It has antimicrobial activity against a broad spectrum of organisms (Ye et al., 2005). Essential oils are a mixture of a variety of aromatic compounds. Due to the presence of volatile aromatic compounds, essential oils cause fragrance and provide protection from microbes (Vimal et al., 2013). They have different pharmaceutical and sedative effects due to their pleasant fragrance. Hence, essential oils could be applied on the textile materials to fulfill the psychological, sedative and emotional requirements of human body and to obtain antimicrobial textile products (Buckle, 2002; Wang and Chen, 2005). During microencapsulation, tiny particles of solid, liquid or gas are entrapped as core material inside a shell material. The core materials may include drugs, proteins, antimicrobial agents, hormones, dyes, flame retardants, phase change materials and fragrances while the formation of shell constitutes natural or synthetic polymers, metal or inorganic oxides. The potential applications of microencapsulation could be found in different types of finishes such as insect repellents, antimicrobial agents, aroma, antibiotics, flame retardants, cosmetic textiles, polychromic, thermo-chromic and many more (Palanikkumaran et al., 2010). The size and zeta potential of chitosan microcapsules might depend upon the weight ratio of core-, shell- and coating materials, surfactant, anti-adherence, and other process conditions (Huanbutta et al., 2008). Although most essential oils are antimicrobial, yet they did not gain attention as antimicrobial agents due to their volatile nature leading to poor lasting effect. To enhance their durability, chitosan

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could be used to encapsulate the essential oils. The aim of the present study is to achieve both antibacterial and performance characteristics of fabric in which microcapsules of chitosan were prepared with separate eucalyptus and sandal wood oils in the presence of bio/surfactant. These microcapsules were characterised physico-chemically and applied on the cotton fabric. The treated fabric was examined for antibacterial and physio-chemical characteristics.

Materials and methods

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Materials Desized, bleached and mercerised 100% cotton woven fabric (surface mass density 130 g/m2; warp and weft yarn counts 40/1 Ne; 100 ends and 80 picks per inch, and CIE whiteness 80) was obtained from Chenab Ltd. (Faisalabad, Pakistan). Chitosan, obtained from crab shells with 490% purity and degree of deacetylation of 90% was purchased from Bio Basic Inc. (Markham, Canada) and acetic acid from Acros Organics (Fair Lawn, NJ). Cetyl trimethyl ammonium bromide (CTAB) and NaOH were purchased from MP Biomedicals, LLC (Santa Ana, CA) and nutrient broth from Aqua Medic Inc. (Michigan, MI). All the chemicals were of analytical grade and used without further purification. Knittex RCT (cross-linking agent) and Knittex catalyst MO (catalyst) were donated by Huntsman (Salt Lake City, UT), and eucalyptus and sandalwood oils were purchased from the local market. Rhamnolipid surfactant (biosurfactant) was obtained from bacterial culture as reported earlier (Raza et al., 2009). All the solutions were prepared in deionised water.

homogeneous emulsions. In another set of experiments, 25, 50 or 100 biosurfactant mg/L were added, replacing CTAB. The emulsions were further mechanically shaked at 2000 rpm for 15 min to convert the bulk oils into micro-sized particles which were stabilised in aqueous system. The emulsions were then dripped into 0.75% (w/w) NaOH solution with slow stirring to precipitate the microcapsules, which were allowed to stabilise for 24 h and then filtered through Whatmann filter paper No. 42. The microcapsules were washed thoroughly with deionised water to remove any traces of NaOH or other impurities. Finally, the microcapsules were obtained in the form of aqueous dispersion to apply on cotton fabric. The details of the experimental design are given in Table 1. Microcapsule size measurement Average sizes of chitosan-based microcapsules were measured by using a Zeta sizer (ZEN 3600, Malvern Instruments, Worcestershire, UK). Application of microcapsules The microcapsules dispersion was diluted, if required, by adding deionised water. Low temperature cross-linking agent (modified dihydroxy ethylene urea; 40 g/L) catalysed by Knittex catalyst MO (10 g/L) was used to bind the microcapsules on the cotton fabric. The fabric was immersed in the dispersion for 1 min and squeezed at a pick up of 85–90%, followed by drying at 100  C for 2 min and curing at 125  C for 1 min at stenter.

Bacterial strains Bacterial strains of Escherichia coli and Staphylococcus aureus for antibacterial study were kindly donated by the culture collection centre of NIBGE, Faisalabad, Pakistan.

Phase contrast microscopy The aqueous dispersions of microcapsules were visualised by using an Olympus CX41 (Tokyo, Japan) optical microscope at a magnification of  100.

Preparation of chitosan/essential oil microcapsules Microcapsules of chitosan were prepared by emulsion method. Three concentrations of chitosan (3.33, 6.67 and 13.33 g/L) were separately vortexed vigorously in 1% aqueous acetic acid solution for 1 min to obtain homogeneous solutions. Then various concentrations of essential oil (eucalyptus or sandalwood) 10, 30, 60 g/L and CTAB 160, 330 and 500 mg/L were added to the chitosan solutions and vortexed for 1 min to produce

Scanning electron microscopy (SEM) The morphology of the microcapsules bound on the cotton fabric was analysed using a scanning electron microscope (JSM-5910, JEOL, Tokyo, Japan). Each sample was coated with sputtered gold, fixed in the sample holder and examined at an acceleration voltage of 10 kV and over developed for 10 min to enhance the contrast.

Table 1. Preparation of microcapsules through emulsification method at various concentrations of chitosan, essential oil, CTAB surfactant and biosurfactant. Code CES CES CES CES CES CES CES CES CES CES CES CES CES CES CES CES

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16

Chitosan, g/L (±SD)

Essential* oil, g/L (±SD)

Chitosan to oil ratio

CTAB, mg/L (±SD)

Biosurfactant, mg/L (±SD)

6.67 ± 0.10 13.33 ± 0.20 6.67 ± 0.10 13.33 ± 0.20 3.33 ± 0.05 6.67 ± 0.10 6.67 ± 0.10 6.67 ± 0.10 6.67 ± 0.10 13.33 ± 0.20 3.33 ± 0.05 6.67 ± 0.10 3.33 ± 0.05 6.67 ± 0.10 6.67 ± 0.10 6.67 ± 0.10

– 10.00 ± 0.20 10.00 ± 0.20 30.00 ± 0.60 10.00 ± 0.20 30.00 ± 0.60 30.00 ± 0.60 30.00 ± 0.60 30.00 ± 0.60 60.00 ± 0.60 30.00 ± 0.60 60.00 ± 1.20 60.00 ± 1.20 30.00 ± 0.60 30.00 ± 0.60 30.00 ± 0.60

NA 1:0.75 1:1.5 1:2.25 1:3.0 1:4.5 1:4.5 1:4.5 1:4.5 1:4.5 1:9.0 1:9.0 1:18.0 1:4.5 1:4.5 1:4.5

330.00 ± 6.60 330.00 ± 6.60 330.00 ± 6.60 330.00 ± 6.60 330.00 ± 6.60 – 160.00 ± 3.20 330.00 ± 6.60 500.00 ± 10.00 330.00 ± 6.60 330.00 ± 6.60 330.00 ± 6.60 330.00 ± 6.60 – – –

– – – – – – – – – – – – – 25 ± 0.5 50 ± 1.0 100 ± 1.5

Note: SD, standard deviation; NA, not applicable. *Eucalyptus or sandalwood.

DOI: 10.3109/02652048.2013.879927

FTIR spectroscopy The presence of oils in the chitosan microcapsules on the treated fabric was determined by using an Attenuated Total ReflectanceFourier transform infrared spectroscopy (ATR-FTIR, Bruker Tensor 27) at wavelengths between 500 and 4000 cm1. The ATR-FTIR was equipped with ZnSe grid that allows recording the FTIR spectra directly on a specimen placed on grid without any special preparation. Forty scans from each sample were collected and superimposed at a resolution of 4 cm1.

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Measurement of antibacterial activity of fabric A dispersion of nutrient broth was prepared by adding 8.0 g of it in 1 L of deionised water. The fresh inoculum was prepared by transferring a loop-full of separate E. coli and S. aureus species in 25 mL nutrient broth media in Erlenmeyer flasks and incubated in orbital shaker at 100 rpm and 37  C for overnight. The quantitative estimation of antibacterial activity was carried out by turbidometric method (Miraftab et al., 2011). In this method, the killing curves of replicate cultures grown in glass tubes are drawn for the measurement of related bacterial viability. An aliquot of 9 mL of prepared nutrient broth medium was transferred to 20 mL screw capped glass tubes and autoclaved at 121  C for 15 min. The freshly prepared inoculum was used for the measurement of antibacterial activity of fabric samples. The fabric samples, each of 0.1 g weight, were added in the glass tubes. An aliquot of 20 mL of the bacterial culture diluted up to 105 was used for the inoculation of the glass tubes containing the nutrient broth and fabric sample. These glass tubes were placed in an incubator at 37  C for 24 h. The control tubes were incubated with bacterial suspension but inserted with untreated cotton fabric. The turbidity of culture medium was measured at 600 nm using a UV–Vis spectrophotometer (Spectra 22, LaboMed, Inc., Los Angeles, CA).

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dimensions. In this study, the solid phase chitosan was used as the shell material and liquid phase essential oil as the core material. Moreover, the desirable capsulated finish, essential oil in this case, could be controlled and released depending on various physico-chemical and environmental conditions. Whereas, other methods of microcapsules fabrication do not provide such a wide range of productivity and applicability. Effect of essential oil/chitosan concentrations on the average size of microcapsule During the preparation of essential oil/chitosan microcapsules, a decrease in average size of the microcapsules was observed at chitosan concentration of 6.67 or 13.33 g/L on increasing the essential oil concentration from 10 to 30. However, an increase in size was noted on further increase in essential oil concentration up to 60 g/L. The smallest microcapsules of diameter 12.9 mm were found at chitosan and eucalyptus oil concentrations of 6.67 and 30 g/L, respectively; whereas at 3.33 chitosan g/L, a continuous increase in the average size of microcapsules was observed with increase in eucalyptus oil concentration. It is attributed to the average size of microcapsule dependence upon the ratios of aqueous phase to oil, chitosan to oil and chitosan to aqueous phase. At 3.33 g chitosan/L, increased average microcapsular size was observed with increase in eucalyptus oil concentration. This might be due to decrease in

Measurement of fabric stiffness The stiffness of cotton fabric was measured by using the standard test method ASTM-D1388. It is based on the cantilever bending principle. Briefly, a rectangular fabric sample was placed on the smooth horizontal platform with a weighed slide on it. The fabric with weighed slide was moved forward at constant speed. It bent due to its own weight as it projected from the smooth surface. The movement of fabric was stopped when it touched the bending angle indicator. The length of the fabric strip was measured in centimetres. Measurement of crease recovery of fabric

Figure 1. Effect of essential oil and chitosan concentrations on average Zeta size of microcapsules at CTAB concentration of 330 mg/L. Chitosan with eucalyptus oil (g/L): 3.33 (—m—), 6.67 (– –m– –), 13.33 (. . .m. . .) and chitosan with sandalwood oil (g/L): 3.33 (——), 6.67 (– –– –), 13.33 (. . .. . .).

The ability of the treated fabric to recover from creasing was analysed according to the standard test method ISO 2313:1972. Briefly, a fabric specimen was folded to make a crease between the two glass plates under a load of 2 kg for 1 min. After the removal of load, the specimen was allowed to relax for 1 min. The one end of the specimen was fixed in the spring loaded clamp while the other end was free to recover its original uncreased shape. The clamp was rotated slowly to make the free end in the vertical position. Deflection of the rotating clamp was measured in terms of angle which was the measurement of crease recovery of cotton fabric. The crease recovery of fabric was measured both in warp- and weft-wise. All the experiments were conducted in three independent replicates and the results reported are the average of three concordant readings.

Results and discussion The emulsion method enables us to fabricate dual phase soft micro-structures of chitosan-based microcapsules of required

Figure 2. Effect of CTAB surfactant (––) and biosurfactant (–m–) concentrations on average Zeta size of microcapsules with essential oil (30 g/L) chitosan (6.67 g/L).

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the ratio of aqueous phase to oil. Nevertheless in the case of chitosan (6.67 or 3.33 g/L), the minimal average size microcapsules were obtained at eucalyptus oil concentration of 30 g/L as shown in Figure 1. The ratios of chitosan to oil were set as 1.0:0.75 and 1.0:2.25 and 1.0:4.5. The ratio of chitosan (6.67 g/L) to oil of 1.0:4.5 resulted in the minimum average microcapsule size; below this ratio, oil particles made aggregation due to less availability of chitosan to form shell over oil particles; whereas at higher ratio the chitosan formed the layers over the oil particles to enlarge the size of microcapsule as a whole. The average microcapsule size for the concentration of chitosan 13.33 g/L exhibited the same trend as with 6.67 g chitosan/L. Jiamrungraksa and Charuchinda (2010) reported that the microcapsule size increased significantly on increasing the essential oil concentration encapsulated in sodium alginate of fixed concentration. Wang et al. (2009) also found that the size of the microcapsules reduced when the ratio of essential oil to aqueous phase decreased. Effect of bio/surfactant concentration on average size of microcapsule With the chemical surfactant, microcapsules of minimal size (12.8 mm) were achieved at 330 mg CTAB/L whereas the rhamnolipid biosurfactant produced microcapsules of as lower size as 7.5 mm at 50 mg biosurfactant/L, as shown in Figure 2. The presence of bio/surfactants in oil/aqueous media above their critical micelle concentration (CMC) resulted in self-aggregation to fabricate microcapsules of chitosan-entrapping essential oil. Optical microscopy of microcapsules Morphology of microcapsules of chitosan was investigated by capturing the optical micrographs of microcapsules after their precipitation in alkaline media, then washing and dispersing in the deionised water (Figure 3). Optical micrographs show that the microcapsules fabricated in different morphologies and shapes majorly spherical with minimum aggregation in them. The microcapsules with non-uniform size were observed with clear distinction between shell and core materials. Such non-uniformity of size might be due to the partial agglomeration of oil particles before encapsulation, especially when concentration of essential oil was high. Scanning electron microscopy of cotton fabrics Figure 4 shows the SEM images of untreated and treated cotton fabrics with microcapsular dispersions. The images of the microcapsules confirmed the prevalence and adhesion of microcapsules effectively to the surface of cotton fabric.

Figure 3. Optical micrographs of microcapsules with chitosan (6.67 g/L), eucalyptus oil (10 g/L) (a) and sandalwood oil (30 g/L) (b) at CTAB concentration of 330 mg/L and magnification 100.

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The microcapsules were uniformly distributed on the fabric surface and no agglomeration was found. FTIR of cotton fabrics The FTIR spectrum exhibited absorption value at 3336 cm1 due to the presence of hydroxyl group in the cellulose structure and a peak at 2894 is due to C–H stretching (Figure 5a). The absorption value at 3400 cm1 is assigned to the amino group of chitosan (Figure 5b). The peak at the wave number 1158 cm1 shows the presence of C–O–C stretching. The spectrum shows aromatic C–H bending at 1500–1700 cm1. The spectrum exhibits the peaks of hydroxyl and amine groups of modified dihydroxy ethylene urea at 3300–3500 cm1 (Figure 5c). The main components of essential oils are a-pinene, b-pinene, a-phellandrene, 1,8-cineole, limonene, terpinen-4-ol, aromadendrene, epiglobulol, piperitone and globulol which consists of the groups of ¼C–H, C¼O, etc. The absorption value at 1723 cm1 is due to the presence of the carbonyl group of essential oils. The band at 1598 cm1 is due to the ¼C–H stretching (Figure 5d). The stronger absorption value in all spectra is observed at 2860–2911 cm1 due to C–H stretching. Antibacterial activity of treated cotton fabrics The antibacterial activity of the fabric treated with microcapsules of chitosan with essential oils is graphically represented in Figure 6. The untreated fabric exhibited a higher turbidity resulting in lower bacterial resistance. The concentration of chitosan had remarkable effect on bacterial resistance. The maximum bacterial resistance was observed at chitosan to oil ratio of 1:4.5. With the increase in chitosan concentration from zero to 6.67 g/L, the antibacterial activity first enhanced and then reduced on reaching a higher value of 13.33 g/L. The minimal size microcapsule (12.8 mm) fabricated at the above-mentioned chitosan to oil ratio (1:4.5) might have facilitated their easy adsorption onto bacterial cell wall. The larger size microcapsules above and below this ratio might have found difficulty in adsorption resulting in reduced antibacterial activity. The treated fabric showed greater resistance against S. aureus as compared to E. coli. Zhang et al. (2003) reported that a reduced bacterial growth at lower concentration might be due to the lower availability of cationic sites leading to the more adsorption and reduced antibacterial activity. At higher concentrations the increased viscosity of the solution might form a thick coating and result in lower adsorption of chitosan into the bacterial cell. Due to higher concentration, a coating might be formed on the cell which reduce the surface interactions and lower the antibacterial activity.

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Figure 4. SEM images of untreated cotton fabric (a), and treated cotton fabric with chitosan, (6.67 g/L), CTAB (330 mg/L) and sandalwood oil (30 g/L) (b), or eucalyptus oil (30 g/L) (c) at magnification  1000 with respective higher magnification  10 000 (inset c).

The concentration of essential oil (Figure 6b) had significant effect on the antibacterial activity of the fabric. An increase in oil concentration resulted in the decreased absorption value and increase in the antibacterial activity. In the case of biosurfactants, the highest antibacterial activity was exhibited for 7.5 mm-sized essential oil encapsulated chitosan microcapsules were fabricated at biosurfactant concentration of 50 mg/L (Figure 6c), i.e. approximately at the CMC of biosurfactant. Vanit et al. (2010) observed that the clove oil showed very little activity at lower concentration. An increase in concentration causes the enhanced resistance against microorganisms. Arici et al. (2005) analysed that the potential of essential oils to resist microorganisms became more effective on increasing the concentration of oil. Bending length and crease recovery of treated cotton fabrics The treated fabric was evaluated for performance characteristics like bending length and crease recovery. The bending length of the fabric prior to finishing treatment was also measured to analyse the effect of chemical agents. The bending length of treated fabric along both warp and weft directions increased with the increase in chitosan to oil ratio. The effect of chitosan concentration on fabric bending length is shown in Figure 7(a). As the concentration of chitosan increased, the greater amount of chitosan microcapsules might have deposited into the interstices of the fabric leading to limit the inter fibre movements and eventually resulting in increased bending length. A significant increase in bending length was observed after finish application, which is attributed to the stiffening behaviour of cross-linking agent as it generated the cross-links between the adjacent fibres. The cross-linked fibres were unable to move upon the fabric

deformation resulting in an enhanced bending length. A decrement in bending length was observed with the increase in oil concentration as shown in Figure 7(b). The increase in oil concentration enhanced the oil contents in the microcapsules to make the fabric softer. Figure 8 depicts the effect of chitosan and oil concentrations on the crease recovery of cotton fabric. The increase in crease recovery angle both along warp and weft directions was observed with the increase in chitosan concentration. Cotton fibres containing large number of hydroxyl groups undergo creasing problems due to the snarling of cellulose macromolecules, when twisted, rubbed, washed or worn. Chitosan forms a network between the fibres to reduce the snarling and eventually causing to improve the crease recovery of the treated fabric. The crosslinking agent also exhibited a significant effect to enhance the crease recovery angle by cross-linking the hydroxyl groups of cotton fibres. The graphical representation shows that the oil concentration did not cause any remarkable change in the creaseresistant behaviour of the fabric. As essential oil was entrapped in the microcapsule of chitosan, it did not exhibit any direct interaction with the hydroxyl groups of cellulose.

Conclusions The present study investigated that the size of microcapsule of chitosan with essential oils was affected by varying the concentrations of chitosan, essential oil and surfactant/biosurfactant. The concentration of biosurfactant used to obtain smaller size microcapsule is quite less than the concentration of chemical surfactant CTAB. The concentration of essential oil and chitosan both affect the antibacterial activity of fabric. The antibacterial activity of fabric increases with the increase in chitosan

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Figure 5. FTIR spectra of untreated (a), and treated cotton fabric with chitosan (b), with chitosan and cross-linker (c), and with chitosan, cross-linker and eucalyptus oil (d).

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Figure 6. Effect of chitosan (a) and essential oil (b) concentrations on the antibacterial activity of treated cotton fabric at essential oil (30 g/L) and chitosan (6.67 g/L), respectively, at CTAB (330 mg/L), and effect of biosurfactant concentration (c) against E. coli (eucalyptus oil) (—m—), S. aureus (eucalyptus oil) (– –m– –) E. coli (sandalwood oil) (——) and S. aureus (sandalwood oil) (– –– –).

Figure 7. Effect of chitosan (a, b) and essential oil (c, d) concentrations on the bending length of treated cotton fabric at eucalyptus oil (30 g/L) and chitosan (6.67 g/L), respectively, at CTAB (330 mg/L). Warp (eucalyptus oil) (—m—), weft (eucalyptus oil) (– –m– –), Warp (sandalwood oil) (——), Weft (sandalwood oil) (– –– –).

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Figure 8. Effect of chitosan (a) and essential oil (b) concentrations on the fabric crease recovery of treated cotton fabric at essential oil (30 g/L) and chitosan (6.67 g/L), respectively, in the presence of Knittex RCT (40 g/L) and CTAB (330 mg/L). E ¼ Eucalyptus oil and S ¼ Sandalwood oil.

concentration up to a limit and then decreases. An increase in antibacterial activity is observed with the increase in essential oil concentration. The concentration of chitosan has direct relation with stiffness and wrinkle recovery characteristics of fabric. The presence of essential oil decreases the stiffness but has no effect on wrinkle recovery.

Acknowledgements The authors acknowledge NIBGE, Faisalabad, for donating bacterial strains and help in completing a part of research in its laboratories.

Declaration of interest The authors declare no conflicts of interests. The authors alone are responsible for the content and writing of this article. The authors acknowledge the financial support of R&D Division of NTU, Faisalabad.

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Chitosan microencapsulation of various essential oils to enhance the functional properties of cotton fabric.

The present study dealt with emulsive fabrication of chitosan microcapsules encapsulating essential oils in the present of bio/surfactant. The size di...
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