Abstract
To enhance the hemocompatibility of silk fibroin fabric as biomedical material, polyelectrolytes architectures have been assembled through the layer-by-layer (LbL) technique on silk fibroin fabric (SFF). In particular, 1.5 and 2.5 bilayer of oppositely charged polyelectrolytes were assembled onto SFF using poly(allylamine hydrochloride) (PAH) as polycationic polymer and poly(acrylic acid) (PAA) as polyanionic polymer with PAH topmost. Low molecular weight heparin (LMWH) activated with 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) was then immobilized on its surface. Alcian Blue staining, toluidine blue assay and X-ray photoelectron spectroscopy (XPS) confirmed the presence of heparin on modified SFF surfaces. The surface morphology of the modified silk fibroin fabric surfaces was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and obtained increased roughness. Negligible hemolytic effect and a higher concentration of free hemoglobin by a kinetic clotting time test ensured the improved biological performance of the modified fibroin fabric. Overall, the deposition of 2.5 bilayer was found effective in terms of biological and surface properties of the modified fibroin fabric compared to 1.5 bilayer self-assembly technique. Therefore, this novel approach to surface modification may demonstrate long term patency in future in vivo animal trials of small diameter silk fibroin vascular grafts.
Highlights
Any biomaterial that is designed and manufactured to be used in direct contact with blood, cannot be expected its application without its surface modification
These results agree with the findings reported previously on the FTIR analysis of silk scaffolds and vascular grafts containing heparin [34,35]
ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride (EDC)/NHS activated low molecular weight heparin was immobilized onto polyelectrolytes assembled silk fibroin fabric in order to investigate its surface characteristics and to enhance its hemocompatibility
Summary
Any biomaterial that is designed and manufactured to be used in direct contact with blood, cannot be expected its application without its surface modification. Recent reports from our own laboratory and others have demonstrated that woven silk fibroin tubular fabrics provide a promising biomaterial for use as a small diameter arterial prosthesis [6,9,10]. In this study low molecular weight heparin (LMWH) was selected as an antithrombogenic bioactive material which is a glycosaminoglycan (GAG) and is extracted primarily from porcine intestinal tissues It is currently used for the prevention and treatment of venous thrombosis and pulmonary embolism, management of arterial thrombosis in patients presenting with acute myocardial infarction and in the prevention of rethrombosis after thrombolysis [13]. To the best of our knowledge, this is the first study which employs EDC/NHS activated heparin immobilization on polyelectrolytes assembled silk fibroin fabric to improve its hemocompatibility
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