Stability Improvement of Electrospun Chitosan Nanofibrous Membranes in Neutral or Weak Basic Aqueous Solutions

Technological Center for Electrospun Fibers and the Petroleum and Petrochemical College, Chulalongkorn University, Soi Chula 12, Phyathai Road, Pathumwan, Bangkok 10300, Thailand.
Biomacromolecules (Impact Factor: 5.75). 11/2006; 7(10):2710-4. DOI: 10.1021/bm060286l
Source: PubMed


Further utilization of chitosan nanofibrous membranes that are electrospun from chitosan solutions in trifluoroacetic acid (TFA) with or without dichloromethane (DCM) as the modifying cosolvent is limited by the loss of the fibrous structure as soon as the membranes are in contact with neutral or weak basic aqueous solutions due to complete dissolution of the membranes. Dissolution occurs as a result of the high solubility in these aqueous media of -NH(3)(+)CF(3)COO(-) salt residues that are formed when chitosan is dissolved in TFA. Traditional neutralization with a NaOH aqueous solution only maintained partial fibrous structure. Much improvement in the neutralization method was achieved with the saturated Na(2)CO(3) aqueous solution with an excess amount of Na(2)CO(3)(s) in the solution. We showed that electrospun chitosan nanofibrous membranes, after neutralization in the Na(2)CO(3) aqueous solution, could maintain its fibrous structure even after continuous submersion in phosphate buffer saline (pH = 7.4) or distilled water for 12 weeks.

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    • "Chitosan is extremely difficult to be electrospun mainly due to its polyelectrolyte nature (Zhang, Su, Ramakrishna, & Lim, 2007). A few reports are found on fabrication of chitosan nanofibers, where a highly corrosive and toxic solvent, namely trifluoroacetic acid (TFA) is employed for spinning (Ohkawa, Cha, Kim, Nishida, & Yamamoto, 2004; Sangsanoh & Supaphol, 2006; Schiffman & Schauer, 2007). Geng et al. have reported fabrication of chitosan nanofibers using concentrated acetic acid (Geng, Kwon, & Jang, 2005). "
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    • "succeeded. Among those successful cases, most of them used toxic and expensive solvents such as 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) (Min et al., 2004), trifluoroacetic acid (TFA) (Haider et al., 2013; Kiechel & Schauer, 2013; Sangsanoh & Supaphol, 2006; Schiffman & Schauer, 2007), HFIP/TFA (Chen, Wang, Wei, Mo, & Cui, 2010), and TFA/dichloromethane (DCM) (Jacobs, Patanaik, Anandjiwala, & Maaza, 2011). This is a troubling problem especially when the scale of nanofiber production is to be enlarged. "
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