title: Role of solvent-mediated carbodiimide cross-linking in fabrication of electrospun gelatin nanofibrous membranes as ophthalmic biomaterials.
abstract: Due to their ability to mimic the structure of extracellular matrix, electrospun gelatin nanofibers are promising cell scaffolding materials for tissue engineering applications. However, the hydrophilic gelatin molecules usually need stabilization before use in aqueous physiological environment. Considering that biomaterials cross-linked via film immersion technique may have a more homogeneous cross-linked structure than vapor phase cross-linking, this work aims to investigate the chemical modification of electrospun gelatin nanofibrous membranes by liquid phase carbodiimide in the presence of ethanol/water co-solvents with varying ethanol concentrations ranging from 80 to 99.5vol%. The results of characterization showed that increasing water content in the binary reaction solvent system increases the extent of cross-linking of gelatin nanofibers, but simultaneously promotes the effect of biopolymer swelling and distortion in fiber mat structure. As compared to non-cross-linked counterparts, carbodiimide treated gelatin nanofibrous mats exhibited better thermal and biological stability where the shrinkage temperature and resistance to enzymatic degradation varied in response to ethanol/water solvent composition-mediated generation of cross-links. Irrespective of their cross-linking density, all studied membrane samples did not induce any responses in ocular epithelial cell cultures derived from cornea, lens, and retina. Unlike many other cross-linking agents and/or methods (e.g., excessive vapor phase cross-linking) that may pose a risk of toxicity, our study demonstrated that these nanofibrous materials are well tolerated by anterior segment tissues. These findings also indicate the safety of using ethanol/water co-solvents for chemical cross-linking of gelatin to engineer nanofibrous materials with negligible biological effects. In summary, the present results suggest the importance of solvent-mediated carbodiimide cross-linking in modulating structure-property relationship without compromising in vitro and in vivo biocompatibility of electrospun gelatin nanofibers for future ophthalmic applications.
authors.affiliation: Department of Mechanical Engineering, University of Texas at Tyler, Tyler, TX 75799, USA.
authors.forename: Shih-Feng
authors.initials: SF
authors.lastname: Chou
authors.affiliation: Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 33302, Taiwan, ROC.
authors.forename: Li-Jyuan
authors.initials: LJ
authors.lastname: Luo
authors.affiliation: Institute of Biochemical and Biomedical Engineering, Chang Gung University, Taoyuan 33302, Taiwan, ROC; Biomedical Engineering Research Center, Chang Gung University, Taoyuan 33302, Taiwan, ROC; Center for Tissue Engineering, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan, ROC; Department of Ophthalmology, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan, ROC; Department of Materials Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan, ROC. Electronic address: jylai@mail.cgu.edu.tw.
authors.forename: Jui-Yang
authors.initials: JY
authors.lastname: Lai
authors.affiliation: Center for Tissue Engineering, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan, ROC; Department of Ophthalmology, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan, ROC; Department of Chinese Medicine, Chang Gung University, Taoyuan 33302, Taiwan, ROC.
authors.forename: David Hui-Kang
authors.initials: DH
authors.lastname: Ma
mesh_terms: D002234:Carbodiimides / Q000737:chemistry*; D002460:Cell Line; D003315:Cornea / Q000166:cytology / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005780:Gelatin / Q000737:chemistry*; D006801:Humans; D007908:Lens, Crystalline / Q000166:cytology / Q000378:metabolism; D008422:Materials Testing; D008567:Membranes, Artificial; D057139:Nanofibers / Q000737:chemistry*; D012160:Retina / Q000166:cytology / Q000378:metabolism; D012997:Solvents / Q000737:chemistry
chemical_list: D002234:Carbodiimides; D003432:Cross-Linking Reagents; D008567:Membranes, Artificial; D012997:Solvents; D005780:Gelatin
keywords: Carbodiimide cross-linking; Electrospun nanofibrous membrane; Gelatin; Ophthalmic biomaterial; Solvent composition