47 Polysaccharides are abundant natural materials that are promising as substitutes for synthetic polymers in various applications Pakravan, Heuzey, & Ajji, 2011; Wu, Lin, & Meredith, 2016; Kumar, Lakshmanan, Raj, Biswas, Hiroshi, Nair, & Jayakumar, 2013. Chitin in particular is a linear polysaccharide that consists of ?(1?4)-linked 2-acetoamido-2-deoxy-?-D-glucose, and it is the second most abundant polysaccharide next to cellulose Min, Lee, Lim, You, Lee, Kang, & Park, 2004; Dutta, Dutta, & Tripathi, 2014; Liu, Zhu, Li, Tian, Chen,& Chen, 2013; Rolandi, & Rolandi, 2014. It has excellent properties including biocompatibility, biodegradability, non-toxicity, wound healing activity, anti-inflammatory action, mechanically robustness, and adsorption, even though it has a very limited solubility and low chemical reactivity Kumar, 2000. Chitin exists in the exoskeleton of various arthropods such as crabs, shrimps and other insects, and it is also in the cell wall of fungi. Depending on its source, chitin exists in a hierarchical structure associated with mainly calcium carbonates Lavall, Assis, & Campana-Filho, 2007. Chitin is known to have three types of crystalline forms: ?-, ?-, and ?-form. The most abundant and easily accessible form is ?-chitin, for which molecular chains are aligned in an antiparallel arrangement. This molecular arrangement is favorable to form strong intermolecular hydrogen bonding, indicating its most stable form. On the other hand, molecular chains in ?-chitin are packed in a paralleled arrangement, leading to weaker intermolecular forces. Therefore, ?-chitin is less stable than ?-chitin. ?-chitin has both parallel and antiparallel arrangements, indicating a mixture of the ?- and ?-forms Kumar, Lakshmanan, Raj, Biswas, Hiroshi, Nair, & Jayakumar, 2013; Lavall, Assis, & Campana-Filho, 2007.
48 Electrospinning has been studied as an efficient technique to fabricate fine nano-scale fibers. Various polymers have been successfully electrospun into nanofibers, and these have amazing characteristics, including a very large surface area-to-volume ratio and high porosity with very small pore sizes Anitha, Sowmya, Kumar, Deepthi, Chennazhi, Ehrlich, Tsurkan, & Jayakumar, 2014; Huang, Zhang, Kotaki,& Ramakrishna, 2003; Homayoni, Ravandi, & Valizadeh, 2009. Therefore, nanofibers can also be recognized as promising materials for many biomedical applications including tissue engineering, wound dressings, drug delivery, pharmaceuticals Elsabee, Naguib, & Morsi, 2012; Kriegel, Kit, McClements, & Weiss, 2009. There is more interest in nanofiber fabrication from polysaccharides due to their superior biocompatibility, biodegradability and general non-toxicity. However, electrospinning nanofibers from polysaccharides has proven to be challenging because they have a limited solubility in most organic solvents, poor molecular flexibility, and insufficient entanglement of the ionic polysaccharides to be electrospun Huang, Zhang, Kotaki, & Ramakrishna, 2003; Kriegel, Kit, McClements, & Weiss, 2009; Bhattarai, & Zhang, 2007; Bonino, Krebs, Saquing, Jeong, Shearer, Alsberg, & Khan, 2011. The most abundant ?-chitin is not soluble in most organic solvents, resulting in limited applicability to use its nanofibers. ?-chitin is soluble only in specific toxic solvents such as N,N-dimethylacetamide (DMAc)-LiCl, hexafluoroacetone (HFA), 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) Rolandi,& Rolandi, 2014; Kurita, 2001; Jayakumar, Prabaharan, Nair, & Tamura, 2010; Cho, Jang, Park, & Ko, 2000; Jayakumar, & Tamura, 2008; Jin, Lee, Im, Han, Jeong, Rolandi, Choi, & Bae, 2016; Noh, Lee, Kim, Oh, Kim, Chung, Choi, Park, & Min, 2006. On the other hand, ?-chitin is soluble in a mild acid, such as formic acid. ?-chitin has normally been isolated from the squid pen that is composed almost entirely of chitin and proteins, with small amounts of metal salts Pakravan, Heuzey, & Ajji, 2011; Wu, Lin, & Meredith, 2016; Kumar, Lakshmanan, Raj, Biswas, Hiroshi, Nair, & Jayakumar, 2013.
49 Cuttlefish is caught in the southern sea of Korea, and cuttlefish bone is usually destroyed as a waste product. In this study, cuttlefish bone was chosen as a new ?-chitin source for electrospinning Shushizadeh, Pour, Zare, & Lashkari, 2015. Wound dressing materials made from ?-chitin nanofibers are attractive because chitin has a superior wound healing activity. ?-chitin was extracted from cuttlefish bone and electrospun using a formic acid solvent. In the animal study, the electrospun ?-chitin nanofibrous web showed great potential as wound healing nanomaterial.