Nanofiber-Desenli Polimerik Membranlar: Yüzey Kimyası, Topografisi ve Hücresel Etkileşimler

Abstract

In the presented study, two main aims were purposed. The first aim was to pattern polymeric membranes which have different chemistry by chemically and physically different nanofibers produced via electrospining technique and to investigate cellular behaviour on patterned membranes for cell-nanotopography interactions. The second aim was to investigate animal cell/bacterial attachment on implant surfaces coated by electrospun nanofibers. For the first part, chitosan and polycaprolactone (PCL) membranes were prepared by solvent casting method. Electrospinning conditions were optimized for patterning of membranes by PCL and PCL/collagen nanofibers in different physically form. Chitosan membranes were patterned by random PCL fibers with diameters of 205±65 nm or 550±190 nm and random PCL/collagen fibers with diameter of 480±20 nm. They were also patterned by aligned PCL and PCL/collagen fibers with diameter of 385±62 and 276±105 nm, respectively. Patterning of PCL membranes was realised by random and aligned PCL fibers with diameters of 211±70 nm and 228±43 nm, respectively. Cell-culture studies were performed under static conditions by using preosteoblastic MC3T3-E1 and epithelial MDBK (Madine Darby Bovine Kidney) cell lines to investigate nanotopography-cell interactions on patterned surfaces. Cell viability and proliferation were analyzed by MTT assay and morphological examination was done with SEM and confocal microscope. Results showed both cells were affected significantly by aligned fiber orientation. The fibers of the actin filament tend to align along the fiber direction forming long and highly organized actin bundles in the cytoplasm. Randomly oriented patterns also affected the cell morphology owing to an increase in fiber diameter. In the presence of PCL/collagen patterns, the spreading area of cells was increased. In the second part, polyethlene oxide (PEO) nanofibers were prepared by electrospinning for coating titanium (Ti) implants with nanofibers. Characterization of fibers was done by SEM. Crosslinking procedures were carried out to obtain insoluble PEO fibers under in-vitro conditions. Optimum crosslinking condition were determined by swelling experiments and ATR-FTIR analysis. As a result, Ti surfaces were coated by fibers including 10% (w/w) crosslinker PETA (pentaerythritol triacrylate). After drying for 8 days in 37ºC, coated surfaces were placed under UV light to crosslink fibers. Roughned (Ti-p) and smooth (Ti-y) Ti surfaces were used for coating. Characterization of Ti surfaces before/after coating was done by SEM, atomic force microscopy, perthometer and water contact angle measurements. Hydrophilicity of both surfaces was improved after coating. SEM results revealed that fiber diameters on coated Ti-y and Ti-p were 184±48 nm and 175±50 nm, respectively. Fibers on Ti-p exibited more stable attachment than the ones on Ti-y. To investigate the effect of PEO coated surfaces on adhesion of MC3T3-E1 cells and S. epidermidis bacteria, cell-culture studies were performed under static conditions. Cell viability and proliferation were analyzed by MTT assay and examination of attachment of the cells/bacteria was done by SEM. In conclusion, coated surfaces inhibited cellular attachment significantly, whereas proliferation of cells/bacteria was supported by uncoated surfaces. In conclusion, electrospinning technique can be used as ''an effective coating method'' for creating patterns on polymeric biomaterials and minimizing infection risk of metalic implant.