title: Into the groove: instructive silk-polypyrrole films with topographical guidance cues direct DRG neurite outgrowth.
abstract: Instructive biomaterials capable of controlling the behaviour of the cells are particularly interesting scaffolds for tissue engineering and regenerative medicine. Novel biomaterials are particularly important in societies with rapidly aging populations, where demand for organ/tissue donations is greater than their supply. Herein we describe the preparation of electrically conductive silk film-based nerve tissue scaffolds that are manufactured using all aqueous processing. Aqueous solutions of Bombyx mori silk were cast on flexible polydimethylsiloxane substrates with micrometer-scale grooves on their surfaces, allowed to dry, and annealed to impart β-sheets to the silk which assures that the materials are stable for further processing in water. The silk films were rendered conductive by generating an interpenetrating network of polypyrrole and polystyrenesulfonate in the silk matrix. Films were incubated in an aqueous solution of pyrrole (monomer), polystyrenesulfonate (dopant) and iron chloride (initiator), after which they were thoroughly washed to remove low molecular weight components (monomers, initiators, and oligomers) and dried, yielding conductive films with sheet resistances of 124 ± 23 kΩ square(-1). The micrometer-scale grooves that are present on the surface of the films are analogous to the natural topography in the extracellular matrix of various tissues (bone, muscle, nerve, skin) to which cells respond. Dorsal root ganglions (DRG) adhere to the films and the grooves in the surface of the films instruct the aligned growth of processes extending from the DRG. Such materials potentially enable the electrical stimulation (ES) of cells cultured on them, and future in vitro studies will focus on understanding the interplay between electrical and topographical cues on the behaviour of cells cultured on them.
authors.affiliation: a J. Crayton Pruitt Family Department of Biomedical Engineering , University of Florida , Gainesville , FL 32611 , USA.|b Department of Biomedical Engineering , The University of Texas at Austin , Austin , TX 78712 , USA.|c Department of Biomedical Engineering , Tufts University , Medford , MA 02155 , USA.
authors.forename: John G
authors.initials: JG
authors.lastname: Hardy
authors.affiliation: a J. Crayton Pruitt Family Department of Biomedical Engineering , University of Florida , Gainesville , FL 32611 , USA.|b Department of Biomedical Engineering , The University of Texas at Austin , Austin , TX 78712 , USA.
authors.forename: Zin Z
authors.initials: ZZ
authors.lastname: Khaing
authors.affiliation: a J. Crayton Pruitt Family Department of Biomedical Engineering , University of Florida , Gainesville , FL 32611 , USA.
authors.forename: Shangjing
authors.initials: S
authors.lastname: Xin
authors.affiliation: c Department of Biomedical Engineering , Tufts University , Medford , MA 02155 , USA.
authors.forename: Lee W
authors.initials: LW
authors.lastname: Tien
authors.affiliation: c Department of Biomedical Engineering , Tufts University , Medford , MA 02155 , USA.
authors.forename: Chiara E
authors.initials: CE
authors.lastname: Ghezzi
authors.affiliation: b Department of Biomedical Engineering , The University of Texas at Austin , Austin , TX 78712 , USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Mouser
authors.affiliation: b Department of Biomedical Engineering , The University of Texas at Austin , Austin , TX 78712 , USA.
authors.forename: Rushi C
authors.initials: RC
authors.lastname: Sukhavasi
authors.affiliation: c Department of Biomedical Engineering , Tufts University , Medford , MA 02155 , USA.
authors.forename: Rucsanda C
authors.initials: RC
authors.lastname: Preda
authors.affiliation: c Department of Biomedical Engineering , Tufts University , Medford , MA 02155 , USA.
authors.forename: Eun S
authors.initials: ES
authors.lastname: Gil
authors.affiliation: c Department of Biomedical Engineering , Tufts University , Medford , MA 02155 , USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Kaplan
authors.affiliation: a J. Crayton Pruitt Family Department of Biomedical Engineering , University of Florida , Gainesville , FL 32611 , USA.|b Department of Biomedical Engineering , The University of Texas at Austin , Austin , TX 78712 , USA.
authors.forename: Christine E
authors.initials: CE
authors.lastname: Schmidt
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology*; D004553:Electric Conductivity; D004558:Electric Stimulation; D005727:Ganglia, Spinal / Q000166:cytology* / Q000187:drug effects; D048091:Guided Tissue Regeneration / Q000379:methods*; D051379:Mice; D016501:Neurites / Q000187:drug effects*; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry*; D047011:Silk / Q000737:chemistry*; D054457:Tissue Scaffolds / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D011108:Polymers; D011137:Polystyrenes; D011758:Pyrroles; D047011:Silk; C067635:polypyrrole
keywords: biomaterials; neural; silk; tissue engineering; topography