Introduction
1. Wound A wound is defined as an injury or tear on the skin, which is caused by physical, chemical, mechanical, and thermal factors (Knight, 1996). The scientific definition of wound is a disruption of normal anatomic structure and function of the skin. On the basis of wound sites is classified into two types, such as open wound and closed wound. In other hand, on the basis of wound healing processes, there are divided into two types of wounds, such as acute and chronic wounds (Bryant and Nix, ).
Acute wounds are caused by traumas. However, these wounds are usually healable within 8 to 12 weeks. Acute wounds can also be caused by exposure to extreme heat, irradiation and irritated with corrosive chemicals. Chronic wounds are …show more content…
Wound healing
Wound healing is an orchestrated biological process, which is a complex and dynamic biological process that involves cells, mediators, growth factors and cytokines (Yates et al., 2007). Wound healing is initiated by tissue injury and culminating in restoration of tissue integrity. There are five consecutive cascades of events in wound healing process. They are hemostasis, inflammation, migration, proliferation and maturation. The first stage includes hemostasis and inflammation, which occurs soon after the damage of skin. Fibrinogen is one of the major components of the skin connective tissues, leads to the coagulation of exudates, and together with the formation of a fibrin network, produces a clot in the wound which stops. Therefore, both hemostasis and inflammatory stages play an important role in the healing process of a wound. The inflammatory phase occurring simultaneously with the hemostasis phase usually takes more than 24 h. At this stage, blood neutrophils followed by phagocytes enter the wound medium and penetrate inside the dead cells. In the migratory phase, the new and live cells called epithelial move towards skin injury to replace dead cells. The proliferation stage consists of the complete coverage of wound by epithelium. At this stage, new stomas usually known as granulating tissues are formed after about 4 days. Microphages, fibroblasts, and blood vessels move toward the wound environment and form a single unit. The completion of this stage …show more content…
Wound dressing Selection of a suitable wound dressing material for a specific type of wound requires comprehensive knowledge of the wound healing process. In earlier, man has used different materials such as linen, honey, animal fats and vegetables fibers for wound dressing. The continuous developments have led to extensive use of new bandages with improved performance. Nowadays, wound dressing materials are usually based on biopolymers such chitosan, alginate, collagen and starch. Chitosan sponges are mainly used as wound healing materials, as they can soak up the wound exudates, while helping the tissue regeneration.
The chemically modified derivative of chitosan that is derived from partially deacetylated chitin (Roberts, 1992). Chitin is a second most abundant natural polysaccharide after cellulose (Austin et al., 1981). It is found commercially in the waste product of the marine food processing industry (Limam et al., 2011). The α-chitins were isolated from the exoskeletons of crabs, lobsters and shrimps, endoskeletons of mollusks, β- chitin from squids, and γ-chitin also found in cell wall of fungi and algae (Peniche, Arguelles-Monal, & Goycoolea, 2008; Kumar, 2000; Kurita, 2006). However, the fungal cell wall chitin is associated with other polysaccharides such as cellulose, glucan, mannan and polygalactosamine, when this isolation is difficult (Peniche, Arguelles-Monal, & Goycoolea, 2008). But crabs, lobsters, shrimps, mollusks and squids chitin is associated with