9

CHAPTER 2

CURATIVE MEDICAL TEXTILES REVIEW

2.1 INTRODUCTION

The curative textiles arena is the highlighted newborn area of

medical textiles. Though the literature specific to the curative textiles is not

rich, there have been many research works related to textiles coated with

herbal products and chemicals. Curative textiles are a merger between textiles

and curative components. Curative textiles can be broadly classified into two

types: curative function performed by the regular textile material and textiles

augmented with external curative components. The curative components

could either be a natural product or a synthetic compound. The era of multi-

functional textiles started with the introduction of antimicrobial textiles.

Compounds with antimicrobial activity would add an additional functionality

to the textile material. But such textiles cannot be considered as curative

textiles as their role is mainly preventive in nature and their support is only

secondary to the healing process. In case of curative textiles, the role played

by the multi-function textiles is vital and primary.

The developments in the field of coated textiles were made possible

due to the development in the coating and processing technologies. The

coating method is crucial in order to deliver the coated component in the right

way. Starting from dip-dry and pad-dry-cure processes to the recent nano

particle-coating process, there has been an enormous improvement in the

field. With the advent of concepts such as eco-friendliness and bio-

10

compatibility herbal products are being preferred over synthetic chemical

compounds. The herbal components have also low side effects compared to

the synthetic chemicals. The extraction methods used in the herbal medicinal

system have vastly grown. Sophisticated instruments and precise characterizations

have been put in place. Since herbal medicines are related to human health, a

high degree of accuracy is required in their characterization. Advanced

chromatography and spectrometry techniques are being used at all levels.

Application of curative textiles and their evaluation is also of equal

importance. Though the necessity for the evaluation is high, there are only a

few methods available for the evaluation. The need for innovation in the

evaluation methods for the curative textiles has to be addressed.

2.2 MEDICAL TEXTILES

Medical textile is one of the emerging areas in the field of technical

textiles. Sanitary napkins, incontinence diapers, surgical bandages, wound

dressings, healthcare textiles, sutures, vascular grafts, heart valves, artificial

tendon, artificial joints, artificial kidneys are examples of medical textiles.

Surgical bandages and various dressings are classical examples of textiles

used in the treatment of ailments. Developments in textile based dressings

with self-healing property have been tried by coating them with several

chemical and natural products thus making them take the functional role

(Gupta et al 2010). Dressings such as adhesive dressings, collagen dressings,

composites, hydrogel and hydrocolloid dressings, alginate based dressings,

burn therapy dressings are commercially available.

2.3 SURGICAL BANDAGES

Surgical Bandages are also called as Medical Devices. Bandages

could be elastic as well as non-elastic. Based on the function and properties

11

bandages can be classified into three major categories namely, fixation,

support and compression. Fixation bandages are elastic in nature and they are

used to hold the dressings or medicaments in place. Support bandages are

used to provide support to tissues and ligaments. Compression bandages can

be classified again depends on the amount of compression it produces.

2.3.1 Compression Bandages

Compression therapy is used in treating phlebological and

lymphological disorders such as varicose veins, leg ulcers, eczema and

oedema (Bleckena et al 2005) and other musculoskeletal disorders. The most

common practice used by medical practitioners in the compression therapy is

the usage of compression bandages. Based on the amount of compression

required for the treatment, the stretch of the bandage is determined. Resting

pressure applied on the affected part by bandage creates compression enabling

the venous pressure to be regulated. The blood flow in the vein is controlled

and there by the disorders is managed. Use of compression bandages in the

treatment of venous ulcers has been reviewed thoroughly (Cullum et al 1997;

Lee et al 2006). Such bandages come under Class 1 medical devices.

Compression bandages are classified based on four important aspects such as

pressure, number of layers, components and elastic properties (Partsch et al

2008). Elastic compression crepe bandages are termed ―long stretch

bandages‖ and the elasticity, as per DIN 61632 standards, is defined as the

percentage elongation of the material following application of a force of

10 N/cm width of the bandage. The pressure developed beneath a

compression bandage is governed by the tension in the fabric that is exerted

when the bandage is applied. One way of creating fabric tension is by using

the stretch yarns and the other method is by using textured and crimped

inelastic yarns (Cooper et al 1965) and thus extensibility of the bandage plays

the major role in imparting pressure and is an indication of the ability of

compression.

12

2.3.2 Fixation Bandages

Fixation bandages are simple elastic bandages and take the profile

of the body part and are also called as ―Contour bandages‖. They have high

elasticity and have open structure. They are normally applied as a second

layer over a wound dressing. They are multi-purpose bandages and can be

used for various bandaging applications.

2.3.3 Narrow Weaving

This form of weaving is used normally for tapes and bandage

fabrics. The width of the fabric ranges from 1 cm to 20 cm. The loom is also

called as needle loom due to its weft insertion mechanism which involves a

reciprocating needle on a cam. The warp yarns can be let off from beams as

well as from creels. The weft is inserted as a double-pick. The selvedge can

also be secured at one end by a crotchet stitch using a binder yarn and a

needle. The looms are capable of high-speed weft insertion with 900 double

picks per minute.

2.3.4 Coated Bandages and Coating Methods

Bandages as substrate are also coated to enhance the amount of

compression and also to widen their functionality. Zinc-Paste bandages,

cohesive and adhesive bandages are examples for such bandages. Besides the

coated compression bandages, there exist also medicated wound dressings.

The coating could either be the synthetic chemicals, latex /rubber or medicinal

products. Shear spreading, dip-dry, pad-dry-cure and spray drying are the

common methods used for coating the additives on the bandage surface.

Microcapsules can be coated on textile surfaces in various ways

and this section discusses them in detail. Conventional coating methods such

13

as blade-on air, blade-on-roll, screen coating and dosing roller have been

discussed by Ghosh (2006). Printing and digitial coating can also be used for

coating microcapsules on textiles. Dip-dry, pad-dry-cure, spray coating, printing,

Textiles coated with silver are used in the treatment of atopic

dermatitis (Haug et al 2006). Antiseptic, antimicrobial and anti-inflammatory

effects have been observed in the silver coated textiles.

2.4 PLANT RESOURCES

Plants are a sustainable source of medicinal products especially in

traditional medical practices. Plants contain active substances such as

alkaloids, tannins etc., produced during their secondary metabolism which

serve as a potential reservoir of medicinal products (Bourgaud et al 2001; Parr

1989; Croteau et al 2000). There are number of methods such as solvent

extraction and steam distillation to extract the active substances from the plant

parts (Ong Eng Shi 2004; Mukherjee 2002). The traditional method of

extracting oils (medicial tars) from the woody parts such roots, stem bark and

branches has been reported by Kargioğlu et al (2010), Julin (2008), Lindborg

(2009). The traditional practitioners of Indian medicine extract the stem part

of medicinal plants by a crude pyrolysis method and use the extracted oily

substance in the treatment of pain, inflammation and other musculoskeletal

disorders. There are numerous medicinal plants available for the treatment of

diseases ranging from headache to cancer.

2.4.1 Secondary Metabolites (Tolonen 2003)

Secondary metabolites of plants are found only in certain species

and family. The presence of a particular metabolite is specific to that plant

species. The production of such metabolites depends on the environment of

the plant or the available nutrition. They may provide protection against pests,

14

animals or UV radiation. Some of the secondary metabolites may be

pharmacologically active in humans and useful as medicines or food

additives. Some well known examples for such secondary plant metabolites

are the analgestic and antipyretic compound salicin which is used in the

synthesis of acetylsalicylic acid (aspirin), the anticancer drug taxol and a

strong addictive and narcotic compound morphine isolated from morphine.

Major classifications of secondary metabolites are phenoloics (eg.

Flavonoids), alkaloids and terpenoids.

2.4.2 Flavonoids

Flavonoids are the most extensively distributed phenolic

compounds of the plant kingdom. They are found in all parts of the plant as a

complex mixture with different chemical compounds. They have a three

carbon link in their backbone. The C6-C3-C6 structure renders them hydrogen

and electron donors. Flavonoids are free radical scavengers and they can

effectively retard cell aging process and can protect humans against cancer

and cardiovascular diseases (Shahidi 1997).

Figure 2.1 Basic structure of flavonoids

15

Flavonoids have three rings in their structure (Figure 2.1) and the

antioxidant property of the flavonoids is due the hydroxyl substitution of the

A- and B- rings and the substitution pattern of the C-ring (Tsimogiannis et al

2007; Dangles et al 1999). According to the structure of the C-ring,

flavonoids can be categorized into five major subgroups: flavanols, flavones,

flavanonols, flavanones and flavanols (Hermann 1988).

2.4.3 Terpenes and Terpenoids

Terpenes contribute to about 55% of the total secondary

metabolites (Croteau 2000). The term terpene refers to a hydrocarbon

molecule while the term terpenoid refers to a terpene that has been modified

such as addition of oxygen. Isoprene is the building block of plant secondary

metabolites. The isoprene unit can build upon itself in different ways in a

five-carbon molecule. The single isoprene unit represents hemiterpenes (C5).

Terpenes with two isoprene units are called as monoterpenes (C10).

Sesquiterpenes (C15) have three isoprene units and diterpenes (C20) and

triterpenes (C30) have two and three terpene units respectively. Distribution

of terpenes in the heartwood of trees has been extensively studied (Thompson

et al 2006; Martin et al 2003; Semiz et al 2007). Terpenes have been used in

various fields. Terpenes are found to have antimicrobial property (Islam et al

2003). Plant oils containing terpenes have shown inhibitory effects against

various species of bacteria (Prabu Seenivasan et al 2006). Terpenes have

been incorporated into antibacterial soaps, cosmetics and household products.

Absorption and penetration of terpenes into human skin has been analysed by

Cal et al (2000).

2.4.4 Alkaloids

Alkaloids are secondary plant metabolites with nitrogen group.

Many of these metabolic by-products are derived from amino acids and

16

include an enormous number of nitrogenous products. There are more than

10,000 different alkaloids identified from over 300 different families (Raffauf

1996). Some alkaloids have structural similarities with neurotransmitters in

the central nervous system of humans, including dopamine, serotonin and

acetylcholine. The effect of these alkaloids led to the development of pain-

killer medications. Alkaloids are broadly classified into two categories viz.,

pseudo and true alkaloids. True alkaloids have nitrogen in a heterocyclic ring

and they are again subdivided into indole alkaloids, steroidal alkaloids,

quinoline alkaloids, pyridine alkaloids, pyrrolidine alkaloids, tropane

alkaloids, iso-quinoline alkaloids, cyclopeptide alkaloids, phenanthrene

alkaloids, phenethylamine alkaloids and purine group etc (Cordell 2008). The

classification is based on the amino acid from which they rise. The

heterocyclic ring structures are given in Figure 2.2.

Figure 2.2 Heterocyclic ring structures of alkaloids

17

2.4.5 Dodonaea viscosa (L) Jacq

Dodonaea viscosa (L.) Jacq.is an evergreen shrub widely found in

tropical and subtropical regions, and it has been used in traditional medicines

in various countries (Anilreddy 2009; Chopra et al 1985; Sandhya Rani et al

2009). Medicinal use of Dodonaea viscosa in tribal and traditional medicine

in various regions of India and other countries has been reported, especially

for curing pain and swelling due to rheumatism, waist pain and gout (Ali

et al 2004; Bharath Kumar and Surya Naryana 2010; Ibrar et al 2007; Meena

et al 2009; Parkash and Aggarwal 2010; Ram et al 2007; Reddy et al 2009;

Venkataswamy et al 2010).Bark extracts have been used in astringent baths

and fomentations to relieve problems, including rheumatism and gout

(Amabeoku et al 2001). The tribes in the Maruthamalai area of Tamilnadu

(the location of this present study) crush the stem and tie it to fractured bones

to speed up bone setting (Senthilkumar et al 2006). Australian aborigines

fumigate a person by burning the stems, bark and leaves of Dodonaea viscosa

to alleviate pain (Wagner 2005).

Although the plant is rich in phyto-chemicals, most of the research

on Dodonaea viscosa has focused on its flavonoids (Pengelly, 2008). In

addition to flavanoids (Ghilselberti 1998; Sachdev and Kulshreshtha 1983,

1986), coumarins and lignocoumarins (Hemlata and Kalidhar 1994) as well as

saponins (Wagner et al 1987) and tannins (Sastry and Nayudamma 1966)

have been isolated from Dodonaea viscosa. Rojas et al (1996) isolated anti-

spasmodics, sakuranetin and kaempferyl from the stem of Dodonaea viscosa.

Antidiarrhoeal (Rajamanickam et al 2010), anti-diabetic, hypolipidaemic and

antioxidant properties (Veerapur et al 2010) have also been reported in

Dodonaea viscosa.

18

2.4.6 Ziziphus jujuba

Ziziphus jujuba belongs to the family Rhamnaceae. They are semi

deciduous and much branched medium sized trees. The bark of the tree has

deep longitudinal furrows and is grayish brown or reddish in color (Mahajan

and Chopda 2010). Ziziphus jujuba is rich in phytochemicals and thus has

various traditional medicinal uses. The fruit of the plant is rich in Vitamin C,

B1 (thiamine), B2 (riboflavin) (Kuliev and Guseinova 1974) and Pectin A

(Tomoda et al 1985) and possesses anti inflammatory, antioxidant and

antibacterial properties. Stem bark of the plant contains alkaloids (Pareek

2001). Cyclopeptide alkaloids, mauritine-A, mucronine-D, amphibine-H,

nummularine-A and –B, jujabine-A and –B were isolated from the stem bark

of Z. jujuba by Tschesche et al (1976), Tripathi et al (2001) isolated a new

cyclopeptide alkaloid jubanine – C along with the known cycloalkaloids

scutianine – C and zizyphine – A from the stem barks of Z. jujuba. Z. jujuba

contains also sativanines of various classes (Tan and Zhou 2006).

Frangufoline, another cyclopeptide alkaloid was isolated from the stem bark

of Z. jujuba by Devi et al (1987). Besides alkaloids, a pentacyclic triterpenoid,

zizyberanalic acid has also been isolated from the stem barks of Z. jujuba

(Kundu et al 1989). Lee et al (1996) isolated three more triterpene esters,

2-O-protocatechuoylaliphitolic acid, 2g-hydroxypyracrenic acid and 3-O-

protocatechuoylceanothic acid from the root part of the plant. Due to the

presence of such a wide range of phytochemicals, Z. jujuba has been used in

the traditional medicine for a long time. The Cyclopeptide and peptide

alkaloids from Z. jujuba were found to show sedative effects (Han et al 1989).

The traditional use of the stem barks of the plant for healing wounds is

reported by Ullah et al (2010). A traditional formulation of barks of Z. jujuba

with milk and honey is used to cure diarrhea, dysentery, cough and cold (Jan

et al 2008). The leaves of Z. jujuba are used in the treatment of diabetes

(Ahmad et al 2009; Inanç et al 2007).

19

2.4.7 Cedrus deodara

Cedrus deodara is an evergreen tree prevalent in north of India.

Traditionally the heart wood of C.deodara was used to strengthen cerebral

functions and nervous systems (Shivanand et al 2009). The anticonvulsant

and anxiolytic properties of the extract from the heartwood have been

reported. The heart wood is reported to have phytochemicals such as

alkaloids, glycosides, tannins and terpenoids (Agarwal and Rastogi 1989).

2.4.8 Moringa oleifera

Moringa oleifera is a soft perennial wood native of India, Pakistan,

Bangaladesh and Afghanistan. All parts of the tree are edible and used in the

traditional medicine for centuries as anti-tumour, anti-pyretic, anti-spasmodic

and anti-cardiac agent (Fuglie 2001). Phytochemicals such as tannins,

saponins, flavonoids, glycosides, terpenoids are present in leaf extracts of

M.oleifera (Nepolean et al 2009).

2.4.9 Celastrus paniculatus

Celastrus paniculatus is a climbing shrub used in the traditional

medicine. The seed contains saponins and sterols and used as anti-

inflammatory agents (Sudha Parimala et al 2009). The seed oil is used

externally for massaging for treating diseases like arthritis, paralysis, lumbago

and facial palsy (Lekha et al 2010).

2.5 MUSCULOSKELETAL DISORDERS

Musculoskeletal disorders can be defined as the disorders of the

muscles and their associated ligaments and other connective tissue and of the

bones and cartilage viewed collectively. Muscle is a tissue made up of

20

contractile cells which are capable of producing movement or tension.

Human body contains three types of muscles namely skeletal, cardiac and

smooths (Knight and Biswas 2003).

2.5.1 Categories

Bone diseases, cartilage diseases, fasciitis, foot deformities, foot

diseases, hand deformities, jaw diseases, joint diseases, muscular diseases,

musculoskeletal abnormalities, rheumatic diseases and tennis elbow are some

of the categories of musculoskeletal disorders. In musculoskeletal system,

disorders of soft tissues (muscles, tendons, ligaments, fascia, capsules etc.,)

are in most cases considered separately from those of the hard tissues such as

bones and cartilage (Sambrook 2001).

2.5.2 Arthritis (Clough 2006)

Arthritis is a condition of inflammation in one or more joints.

Arthritis may also result in swelling, redness, tenderness, stiffness or unusual

warmth only in joints. At advanced stages, arthritis is severely painful may

cause joint destruction and permanent disability. Arthritis is different from the

joint pain which is called as arthralgia. Arthritis is a disease and not a

symptom for other diseases except rheumatid arthritis where arthritis is

considered to be a symptom for rheumatism involving pain in the other tissues

along with joints. Rheumatid arthritis, osteoarthritis, gout and

spondyloarthropathies are some of the form of arthritis. Treatment methods

for arthritis include occupational therapy, chemotherapy and surgery. Anti-

inflammatory agents, antibiotics, immunosuppressive medicines (medicines

that inhibit the immune system), uric acid-lowering agents and corticosteroids

are used in the chemotherapy.

21

Various herbs have been used in the treatment of arthritis.

Hochberg (2008) has discussed some nonconventional methods including

Chinese acupuncture and herbal products to treat osteoarthritis. Venkatesha

et al (2011) have tried various herbal medicinal products which have anti-

arthritic property in the treatment of rheumatoid arthritis (RA). Herbal

ointments were applied on hands and knees of patients suffering from

osteoarthritis and the treatment has shown improvement in pain and stiffness

(Gemmel et al 2003).

2.5.3 Rheumatism

Dorland's Medical Dictionary for Health Consumers (2007) defines

rheumatism as any of a variety of disorders marked by inflammation,

degeneration, or metabolic derangement of the connective tissue structures,

especially the joints and related structures, and attended by pain, stiffness, or

limitation of motion. Rheumatism may include back pain, shoulder pain,

neck pain, arthritis, inflammation, swelling, rheumatic heart disease,

rheumatic fever, tendinitis and spondylitis.

Treatment methods for rheumatism include non-steroidal and anti-

inflammatory drugs (NSAIDs) and analgestics. Medicinal herbs have been

used in the treatment of rheumatism (Adams et al 2009; Chou and Chang

1998, Setti and Sigal 2005)

2.5.4 Oedema

Oedema is the accumulation of fluid in extra-vascular tissue as a

result of complex interactions involving the permeability of capillary walls

and the hydrostatic and oncotic pressure gradients that exist between the

blood vessels and surrounding tissue. Starling’s equation suggests that the

application of external compression will counteract the loss of capillary fluid

22

by increasing local tissue pressure and reinforce reabsorption by squeezing

fluid into the veins and lymph vessels. This in turn will help to resolve

oedema. Depending upon the amount of pressure applied, a compression

bandage may influence the internal volume of veins, arteries and lymph

vessels. Structures near the surface of the skin are compressed more than the

deep vessels. This is because the compressive force is partly dissipated by

compression of the surrounding tissues. Nuclear medical investigations have

shown that compression removes more water than protein from the tissue,

increasing oncotic tissue pressure. This results in a rapid reaccumulation of

oedematous fluid if compression is not sustained.

2.5.5 Venous Disorders

Varicose veins are dilated, tortuous, elongated superficial veins that

are usually seen in the legs. They appear as lumpy, winding vessels just

below the surface of the skin. There are three types of veins, superficial veins

that are just beneath the skin, deep veins that are large blood vessel found

deep inside muscles, and perforator veins that connect the superficial veins to

the deep veins. The superficial veins are the blood vessels most often affected

by varicose veins and are veins seen by eye when the varicose condition has

developed (Alexander et al 1998).

The inside wall of veins have valves that open and close in

response to the blood flow. When the left ventricle of the heart pushes blood

out into the aorta, it produces the high pressure pulse of the heartbeat and

pushes blood throughout the body. Between heartbeats, there is a period of

low blood pressure. During the low pressure period, blood in the veins is

affected by gravity and wants to flow downward (Figure 2.3).

23

(Source: www.varicose-vein-treatment.net)

Figure 2.3 Illustration of varicose veins

The valves in the veins prevent this from happening. Varicose veins

start when one or more valves fail to close. The blood pressure in that section

of vein increases, causing additional valves to fail. This allows blood to pool

and stretch the veins, further weakening the walls of the veins. The walls of

the affected veins lose their elasticity in response to increased blood pressure.

As the vessels weaken, more and more valves are unable to close properly.

The veins become larger and wider over time and begin to appear as lumpy,

winding chains underneath the skin. Varicose veins can develop in the deep

veins also. Varicose veins in the superficial veins are called primary

varicosities, while varicose veins in the deep veins are called secondary

varicosities (Berkow and Robert 1997)

24

There is no cure for varicose veins. Treatment falls into two classes

namely relief of symptoms and removal of the affected veins. Symptom relief

includes such measures as wearing support stockings and compression

bandages (Figure 2.4), which compress the veins and hold them in place. This

keeps the veins from stretching and limits pain. Surgery is used to remove

varicose veins from the body. It is recommended for varicose veins that are

causing pain or are very unsightly, and when haemorrhaging or recurrent

thrombosis appear. Injection therapy is an alternate therapy used to seal

varicose veins. This prevents blood from entering the sealed sections of the

vein. The veins remain in the body, but no longer carry blood.

(Source: www.londonvascularclinic.com)

Figure 2.4 Application of compression bandage in the treatment of

venous disorders

2.5.6 Transdermal Delivery System

Skin is the human body’s largest organ. It is a powerful system that

has inherent capacity to renew and heal itself. Skin is a permeable membrane

25

allowing transdermal migration of substances. The migration allows delivery

of active ingredients by means of the skin. Skin acts as the effective medium

from which absorption of the active material takes place. Topically applied

creams and ointments with formulations that get delivered by the absorption

through the skin are commonly applied transdermal system. The absorption

of the active ingredients varies with the psychological factors like stratum

corneum layer of the skin, site of application on the body, skin condition and

disease, age of the patient, skin metabolism, peeling of the surface skin,

sensitivity of the skin and human race. Formulations and carriers also

influence the transdermal bio availability (Kumar and Philip 2007). Suruse

et al (2009) have attempted to develop herbal extracts based anti-

inflammatory transdermal system.

2.6 EXTRACTION METHODS

Depending on the plant part to be extracted and the plant secondary

metabolite, there exist a variety of extraction methods (Mukherjee 2002).

Marceration, digestion, solvent extraction, soxhleation, ultrasonic extraction,

extraction using electrical energy, percolation, decoction, steam distillation

and super critical fluid extraction are some of the methods available for

extraction. A few important extraction methods have been discussed in this

section.

2.6.1 Hot Continuous Extraction – Soxhletion

Soxhletion is the process mainly used with pure solvents to prepare

crude plant crude extracts. Soxhlet extractor (Figure 2.5) is used in this

method. The material to be extracted is placed in a thimble made of cellulose

or cloth in a central compartment with a siphoning device and a side-arm both

connected to a lower compartment. The solvent is placed in a lower

26

compartment and a reflux condenser is attached above the central sample

compartment. The solvent in the lower container is heated to boiling and the

vapour passes through the side arm up to the reflux condenser. The vapour

liquefies in the reflux condenser and drips into the thimble containing the

material to be extracted. The solvent percolates through the material and the

wall of the thimble and the extract gradually collects in the central

compartment. Once the height of the extract reaches the top of the siphon, the

extract flows down to the lower container and the process repeats and the

extract in the lower container gets more and more concentrated.

Nikhal et al (2010) have extracted phytochemicals from the leaves

of Mangifera indica using soxhletion. Soxhletion was used to extract active

substances from the bulbs of Allium sativum (Shakya et al 2010).

(Source: J. Wood chem. & Tech,30/1,2010,Pg:31-47)

Figure 2.5 Soxhlet extractor

27

2.6.2 Steam Distillation

Steam distillation is the most widely used extraction method for

essential oils or volatile oils. Steam distillation can be carried out in a number

of ways. One of the methods is to mix the plant material with water and to

take the solution to boiling temperature. The vapours are collected and

condensed and later the oil is separated from the water. Steam distillation

relies on the physical principle that when two immiscible liquids are mixed

each liquid behaves as if it were on its own, and exerts a vapour pressure.

The total vapour pressure of the boiling mixture is the sum of the partial

pressures exerted by the individual components of the mixture. Since boiling

commences when the total vapour pressure equals the atmospheric pressure,

boiling point is reached at a lower temperature than if each liquid were in its

pure state. Steam distillation cannot be used if the mixture contains

hydrolysable compounds such as esters or those that are easily oxidized or

decomposed by heat. Figure 2.6 shows the schematic diagram of steam

distillation process.

(Source: www.fashion-writings.com)

Figure 2.6 Steam distillation to extract herbal contents

28

Hili et al (1997) have used steam distillation to extract essential oils

from various plants for medicinal purposes. Ripe fruits of Coriander

sativum L have been extracted using steam distillation method and later the

components present in the essential oil were identified using GC-MS method

(Anitescu 1999).

2.6.3 Pyrolysis

Pyrolysis is the subjection of organic compounds to very high

temperature to study its resulting decomposition. Biomass pyrolysis is defined

as the process during which the biomass undergoes thermal degradation and

gets converted into water vapor, gaseous volatiles, tarry volatiles and char

(Srikanth and Kolar 2009). Based on the heating rate and vapor residence

time of the process, pyrolysis is classified into slow, fast, flash and ultra

pyrolysis. Slow pyrolysis is with a heating rate < 50oC/min during which

primary wood degradations starts at about 230oC, fast devolatilisation rates

are attained at about 300oC, and the process is practically terminated at 430

oC

(Gómez, 2006). The biomass conversion has been analyzed in detail by

Bridgwater (2004). The mechanism of conversion of cellulose has been

studied by Mamleev et al (2009). Hosoya et al (2009) gives detailed

information about the formation of char during the biomass pyrolysis process.

Srikanth and Kolar (2009) have studied the kinetics involved in the thermal

degradation of various wood components such as lignin and hemi cellulose

during pyrolysis. White and Dietenberger (2001) have summarized various

kinetic parameters involved in wood pyrolysis.

Pyrolysis can be utilized to convert biomass to a product that is

used both as an energy source and a feedstock for chemical production

(Dinesh Mohan et al 2006). Pyrolysis has been widely employed for

converting biomass into fuels. There are extensive studies involving the

29

pyrolysis of plant material for the production of bio-diesel (Khor et al 2009;

Seng et al 2006)

2.7 EXTRACT CHARACTERIZATION METHODS

The plant extracts can be characterized using many qualitative and

quantitative methods. Few of the advanced characterization techniques are

discussed in this section.

2.7.1 Gas Chromatography-Mass Spectrometer (GC-MS) Analysis

Gas chromatography/Mass spectrometry is the synergestic

combination of two powerful analytic techniques. The gas chromatography

separates the components of a mixture. The mass spectrometer provides

information that helps in the structural identification of each component. The

two instruments are connected using an interface.

2.7.1.1 Gas Chromatogram (GC)

A mixture of compounds to be analysed is initially injected into the

GC where the mixture is vaporized in a heated chamber. The gas mixture

travels through a GC column, where the compounds become separated as they

interact with the column. Those separated compounds then immediately enter

the mass spectrometer.

2.7.1.2 Mass Spectrometer (MS)

All mass spectrometers consist of three distinct regions Figure 2.7.

1) Ionizer 2) Ion Analyzer 3) Detector

30

(Source: www.analytical-equipment.com)

Figure 2.7 Schematic representation of a GC-MS system

2.7.1.3 Ionizer

In the GC-MS discussed in this introduction, the charged particles

(ions) required for mass analysis are formed by Electron Impact (EI)

Ionization. The gas molecules exiting the GC are bombarded by a high-

energy electron beam (70 eV). An electron which strikes a molecule may

impart enough energy to remove another electron from that molecule.

Methanol, for example, would undergo the following reaction in the ionizing

region:

CH3OH + 1 electron CH3OH+.

+2 electrons

EI Ionization usually produces singly charged ions containing one

unpaired electron. A charged molecule which remains intact is called the

molecular ion. Energy imparted by the electron impact and, more

importantly, instability in a molecular ion can cause that ion to break into

smaller pieces (fragments). The methanol ion may fragment in various ways,

with one fragment carrying the charge and one fragment remaining

uncharged. For example:

CH3OH+.

(molecular ion) CH2OH+(fragment ion) + H

.

(or) CH3OH+.

(molecular ion) CH3+(fragment ion) +

.OH

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2.7.1.4 Ion Analyzer

Molecular ions and fragment ions are accelerated by manipulation

of the charged particles through the mass spectrometer. Uncharged

molecules and fragments are pumped away. The quadrupole mass analyzer in

this example uses positive (+) and negative (-) voltages to control the path of

the ions. Ions travel down the path based on their mass to charge ratio (m/z).

EI ionization produces singly charged particles, so the charge (z) is one.

Therefore an ion's path will depend on its mass. If the (+) and (-) rods shown

in the mass spectrometer schematic were ‘fixed' at a particular rf/dc voltage

ratio, then one particular m/z would travel the successful path shown by the

solid line to the detector. However, voltages are not fixed, but are scanned so

that ever increasing masses can find a successful path through the rods to the

detector.

2.7.1.5 Detector

There are many types of detectors, but most work by producing an

electronic signal when struck by an ion. Timing mechanisms which integrate

those signals with the scanning voltages allow the instrument to report which

m/z strikes the detector. The mass analyzer sorts the ions according to m/z

and the detector records the abundance of each m/z. Regular calibration of

the m/z scale is necessary to maintain accuracy in the instrument. Calibration

is performed by introducing a well known compound into the instrument and

"tweaking" the circuits so that the compound's molecular ion and fragment

ions are reported accurately.

2.7.2 Fourier Transform Infrared Spectroscopy (FTIR)

Fourier Transform Infrared Spectroscopy (FTIR) is the preferred

method of infrared spectroscopy. In infrared spectroscopy, IR radiation is

32

passed through a sample. Some of the infrared radiation is absorbed by the

sample and some of it is passed through (transmitted). The resulting spectrum

represents the molecular absorption and transmission, creating a molecular

fingerprint of the sample. Like a fingerprint no two unique molecular

structures produce the same infrared spectrum. This makes infrared

spectroscopy useful for several types of analysis.

2.7.2.1 Total Internal Reflection

When a ray of light passes from a denser medium to a rarer

medium, the ray bends away from the normal into the rarer medium and this

phenomenon is called refraction. Above a certain angle of incidence called

―critical angle‖, the light is completely reflected back into the denser medium

and this phenomenon is called total internal reflection.

2.7.2.2 Attenuated Total Reflection

Attenuated total reflection is a sampling technique used in

conjunction with infrared spectroscopy which enables the samples to be

examined directly in the solid or liquid state without any further preparation.

2.7.2.3 Applications in Textiles

FTIR-ATR has been used extensively in textiles for the analysis of

the coated surfaces of functional textiles. Surface chemistry of the

photocatalytic self-cleaning cotton by coation TiO2 was studied using ATR-IR

(Attenuated total reflection-infrared spectroscopy) (Meilert et al 2005). The

surface of polyester grafted with acrylic acid has been characterized using

ATR-IR (Kawase et al 1991). There were also reports of the use of

attenuated-total-reflectance (ATR) FTIR spectroscopy for the identification of

cellulosic fibres and characterisation of their state of degradation (Garside and

Wyeth 2004).

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2.7.3 Antimicrobial Assessment

Various test procedures have been used to evaluate the antibacterial

activity. Some of the tests used are (Ramachandran et al 2003)

Agar diffusion test.

Challenge test (Quantitative).

Soil burial test.

Humidity chamber test.

Fouling tests.

Agar diffusion test is a preliminary test used to assess the

qualitatively by measuring the zone of inhibition. It is not suitable for non

diffusive finishes and textile materials other than fabrics. Objective evaluation

of the antimicrobial activity is arrived at by making use of the challenge test

where in which the difference between the actual bacterial count of the treated

and are available from AATCC (USA), DIN(International), JIS (Japan ) and

SN(Switzerland). The degree of antimicrobial activity of the active substance

is expressed by the terms specific antimicrobial activity and general

antimicrobial activity. Antibacterial activity for herbal extracts has been

studied in various research works. Mohanasundari et al (2007) have examined

the antibacterial properties of ethanalic extracts of herbs using Agar diffusion

method.

2.8 MICROENCAPSULATION

The theory of microencapsulation, the methods and the applications

are discussed in this section.

34

Microencapsulation is defined as the application of a thin coating to

individual core materials that have an arbitrary particle size range between 5

and 5000 たm (Bakan 1986; Hawladar et al 2003). Microencapsulation is

widely used in the pharmaceutical and other sciences to mask tastes or odors,

prolong release, impart stability to drug molecules, improve bioavailability,

and as multi-particulate dosage forms to produce controlled or targeted drug

delivery (Wieland-Berghausen et al 2002; Yamuda et al 2001; Bolourtchian

et al 2005).

2.8.1 Types

Methods of microencapsulation include spray drying, sol-gel

process, spray cooling, spinning disk and centrifugal coextrusion, extrusion,

fluidized bed, coaervation. Gouin (2004) has done an industrial appraisal of

these existing technologies. Freital et al (2005) have reviewed the state of the

art in solvent extraction/evaporation-based microencapsulation technologies

for microencapsulating drugs and vaccines in order to utilize their therapeutic

benefits effectively. Various factors influencing the capsule retention in spray

drying process of volatile materials in food and pharma industry were

discussed by Rosenberg et al (1990).

2.8.2 Application in Textiles

In textiles, major interest of microcapsulation is in the application

of durable fragrances, skin softeners, insect repellents, dyes, vitamins,

antimicrobial agents, phase-change materials, medical applications, antibiotics,

hormones and other drugs (Nelson 2001). The combination of microcapsules

and coatings on textiles allow the introduction of new smart functionalities

that often are not possible with any other existing technologies (Ghosh 2006).

Ghosh (2006) also discusses about various commercially available

microencapsulation technologies for the applications in textile technology.

35

Few of the medical textile applications of microencapsulation include drug

delivery systems using drug loaded hollow fibre, ion-exchange fibres, fibres

with bio-active side-chains and textiles finished with cyclodextrins. Flame

retardant cotton has been developed by coating the microcapsules of

phosphate as the intumescent formulation of polyurethane-phosphate could

not be permanent because of the water solubility of the phosphate (Giraud

et al 2002).

2.9 FIELD TRIAL

Field trials are important for any product to validate the

performance of the product. Field trials for bandages have done on patients to

ascertain the therapeutic effect. Bauer bandage study gives insight on the

methodologies to conduct field trials for curative bandages. Parameters like

hospital, study period, patient group, average age, average time of illness,

working protocol, laboratory examinations, replacement of bandages,

assessment critical are all important criteria in designing a field trial.