Design of graphene-like boron nitride/gelatin electro spun nanofibers as new bio nanocomposite material for tissue engineering

摘要

Introduction: Improving the mechanical properties of biopolymers is very essential towards the fabrication of efficient nontoxic material for biomedical applications. To this aim, a novel mechanically stable graphene -like boron nitride (GBN) inorganic filler is introduced. Boron nitride (h-BN) is isoelectric analogue of graphite and exfoliated h-BN (GBN), exhibits very high mechanical properties. Hence the h-BN is exfoliated using the lewis acid base interaction of h-BN and gelatin. GBN/gelatin is used for the fabrication of electrospun mats (ESM) through electrospinning technique. The effect of biomineralization and the toxicity of the ESM with GBN concentration are analyzed. Materials and Methods: Various concentration of h-BN (0.1,1,5% (w/v)) were prepared using 20% of gelatin solution and sonicated for one hour. The solution is centrifuged at 500 rpm for 30 minutes to obtain the stable dispersion of gelatin/GBN in the supernatant. The ESM were fabricated using the stable dispersion of GBN/gelatin using an electrospinning system. Fibers prepared using 20% gelatin were denoted as G and using various h-BN weight fraction, such as 0.1,1 and 5% were referred as 0.1G, 1G 5G respectively. The electrospun mats were further cross-linked with 1% glutaradehyde, neutralized with 10% glycine solution and denoted as GC, 0.1GC, 1GC, 5GC. Results and Discussion: The X-ray diffraction patterns of ESM (figure 1 c) shows 2 peaks at 28= 26.6° and 55° corresponds to (002) and (004) planes of h-BN respectively. The peaks observed at 2G= 41.49°, 43.72° and 50° that corresponds to (100), (101) and (102) planes of h-BN respectively, disappears evidences of the efficient exfoliation of h-BN in ESMR The Fourier transform infrared of ESM are showed in (figure (1 (a,b)). Characteristic peaks of amide Ⅰ, Ⅱ and Ⅲ demonstrates the presence of gelatin chains. The shift in the symmetric stretching of carboxylates from 1406 to 1385cm-1 in 1G, 5G and broadening of carboxylate symmetry stretching in 0.1 G, 1G, and 5G respectively, depicts that carboxylates have strong interaction with the graphene like boron nitride nano-sheets and this interaction facilitates the exfoliation of BN. The tensile strength studies of cross linked ESM shows, the uniform reinforcement of Gelatin by the exfoliated GBN and hence the improvement of the young's modulus from 612 MPa to 1305 MPa. Beyond the optimal concentration of h-BN, GBN causes imperfect reinforcement and leads to sudden decrease to 218 MPa of young's modulus. The biomineralization in simulated body fluids evidences the formation of bone like apatite with the increasing of the GBN concentration. The ceil viability and alkaline phosphatase activity to Human HOS osteosarcoma cell lines evidences that addition of h-BN and the exfoliation into GBN does not affect the biocompatibility of gelatin. Conclusion: The h-BN is exfoliated into GBN using gelatin. GBN reinforced ESM were fabricated by electrospinning technique. The optimal concentration of GBN in ESM enhanced the mechanical properties and bone like apatite forming ability of the bionanocomposites. The ESM is nontoxic to osteoblast cell lines and possess alkaline phosphatase activity. Hence the ESM are highly suitable new class of bionanomaterial for orthopaedic application.