Effect of engineered PLGA-gelatin-chitosan/PLGA-gelatin/PLGA-gelatin-graphene three-layer scaffold on adhesion/proliferation of HUVECs

A three-layered fibrous scaffold composed of fibers of different diameters in each layer was fabricated in correspondence with the structure of the blood vessels. Effect of solution and electrospinning parameters on morphology and diameters of the fibers were investigated by scanning electron microscopy (SEM), for each layer. The SEM images showed that 18% poly (lactic-co-glycolic acid) (PLGA)-gelatin-chitosan in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)/acid acetic solution resulted in bead-free fibers for the outer layer. For the middle layer, 18% PLGA-gelatin in HFIP at 13 kV with 13 cm needle to collector distance was chosen as the optimum condition. SEM imaging demonstrated that by increasing graphene content from 0.5 to 2 wt% in the inner layer (as an electrically conductive/platelet anti-adhesion material), the fiber diameter decreased from 324.01 +/- 58.90 to 288.59 +/- 70.77 nm. The effect of gelatin crosslinking on the microstructure of the fibers was also examined. Shrinkage ratio decreased from 57 to below 21% upon crosslinking of the three-layered scaffold in exposure to vapor of 50% glutaraldehyde solution for 2 hours. Mechanical test showed that tensile strength of the crosslinked three-layer scaffold in the longitudinal direction was 2.90 MPa which is comparable to that of the vein and artery. The MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay displayed cell viability of above 96% for the PLGA-gelatin containing 2 wt% graphene. SEM analysis revealed that the addition of graphene to PLGA-gelatin (up to 2%) causes a remarkable improvement in cell adhesion.