Electrospun fibroin/polyurethane hybrid meshes: Manufacturing, characterization, and potentialities as substrates for haemodialysis arteriovenous grafts

Abstract

Several attempts made so far to combine silk fibroin and polyurethane, in order to prepare scaffolds encompassing the bioactivity of the former with the elasticity of the latter, suffer from critical drawbacks concerning industrial and clinical applicability (e.g., separation of phases upon processing, use of solvents unaddressed by the European Pharmacopoeia, and use of degradable polyurethanes). Overcoming these limitations, in this study, we report the successful blending of regenerated silk fibroin with a medical-grade, non-degradable polyurethane using formic acid and dichloromethane, and the manufacturing of hybrid, semi-degradable electrospun tubular meshes with different ratios of the two materials. Physicochemical analyses demonstrated the maintenance of the characteristic features of fibroin and polyurethane upon solubilization, blending, electrospinning, and postprocessing with ethanol or methanol. Envisioning their possible application as semidegradable substrates for haemodialysis arteriovenous grafts, tubular meshes were further characterized, showing submicrometric fibrous morphologies, tunable mechanical properties, permeability before and after puncture in the same order of magnitude as commercial grafts currently used in the clinics. Results demonstrate the potential of this material for the development of hybrid, new-generation vascular grafts with disruptive potential in the field of in situ tissue engineering. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part B, 2018.

Structural investigations of polyurethane and silk‐polyurethane composite fiber studied by 13C solid‐state NMR spectroscopy

“…So far, there are many papers about SF-PU composite materials to use them as biomaterials. 13,25,[28][29][30][31][32][33][34][35][36][37]57,58 commercially available biomedical grade segmented PU by wet spinning method, which has potential as a fiber for artificial vascular graft. 28 The small-diameter tubular artificial vascular graft was prepared from the HFIP solutions of SF-biomedical grade segmented PU mixture by electrospinning method by us.…”

“…The electrospinning methods have been used widely for the application of the SF-PU composite materials in biomedical field. 13,[29][30][31][32] The SF-PU composite films were also prepared by physical blending method. 25,[34][35][36][37]58 The characterization of the SF-PU composite materials by FT-IR and X-ray diffraction analyses suggested that there are no specific interactions between SF and PU, implying molecular immiscibility and phase separation in these materials.…”

“…However, there are no reports to clarify the origin from viewpoint of the structure and dynamics of the composite fibers in molecular level experimentally although many papers have been reported about SF-PU composite fibers and films. [25][26][27][28][29][30][31][32][33][34][35][36][37] We studied the origin using solid-state NMR. As the newly synthesized PU to prepare SF-PU composite material, we synthesized PU samples by direct mixing of isophorone diisocyanate (IPDI) as diisocyanate and poly (butylene adipate) (PBA) as dialcohol by two-step polyaddition process [18][19][20] because the IPDI and PBA units are considered to be nontoxic and biosafe, and therefore suitable to the use for biomaterials.…”

A Novel Hybrid Silk Fibroin/Polyurethane Arteriovenous Graft for Hemodialysis: Proof‐of‐Concept Animal Study in an Ovine Model

“…[3] In situ tissue engineering strategies, using acellular, totally or partially degradable, scaffolds that are gradually replaced/remodeled by the host, might represent a viable alternative, joining the main advantage of synthetic grafts (i.e., early puncturability) and the ones of biological substitutes (higher compatibility, remodeling capability, higher patency rates). [4][5][6] In this context, we have previously developed an electrospun hybrid vascular graft based on the combination of natural silk fibroin and synthetic poly-carbonate urethane (a blend named Silkothane), [7] which proved to be a potential candidate for an in situ engineering approach to arteriovenous shunting, due to its favorable mechanical properties, suitable permeability, nonhemolytic character, long clotting time, capability of sustaining adhesion of human umbilical vein endothelial cells in vitro, and early cannulation potential. [8] Indeed, the validation of any in situ tissue engineering products, being their performances so much dependent on the host reaction, needs to face in vivo testing early in the product development pipeline, to assess safety and feasibility of implantation, as well as to preliminarily evaluate the outcomes of grafting in a clinically relevant setting.…”

Vascular Pedicle and Microchannels: Simple Methods Toward Effective In Vivo Vascularization of 3D Scaffolds

“…Scaffolds derived from Bombyx mori silk fibroin (referred to as “silk” throughout) have been used to engineer a number of tissues including heart, bone, cartilage, arteriovenous grafts, esophagous, nerve, urethra, and liver . Silk‐based biomaterials show great promise in regenerative medicine applications, but rapid vascularization of large, 3D silk constructs remains challenging.…”