In the present work, a systematic study of the release kinetics of two embedded model drugs (one completely water soluble and one partially water soluble) from hydrophilic and hydrophobic nanofiber mats was conducted. Fluorescent dye Rhodamine B was used as a model hydrophilic drug in controlled release experiments after it was encapsulated in solution-blown soy-protein-containing hydrophilic nanofibers as well as in electrospun hydrophobic poly(ethylene terephthalate) (PET)-containing nanofibers. Vitamin B2 (riboflavin), a partially water-soluble model drug, was also encapsulated in hydrophobic PET-containing nanofiber mats, and its release kinetics was studied. The nanofiber mats were submerged in water, and the amount of drug released was tracked by fluorescence intensity. It was found that the release process saturates well below 100% release of the embedded compound. This is attributed to the fact that desorption is the limiting process in the release from biopolymer-containing nanofibers similar to the previously reported release from petroleum-derived polymer nanofibers. Release from monolithic as well as core-shell nanofibers was studied in the present work. Moreover, to facilitate the release and ultimately to approach 100% release, we also incorporated porogens, for example, poly(ethylene glycol), PEG. It was also found that the release rate can be controlled by the porogen choice in nanofibers. The effect of nanocracks created by leaching porogens on drug release was studied experimentally and evaluated theoretically, and the physical parameters characterizing the release process were established. The objective of the present work is a detailed experimental and theoretical investigation of controlled drug release from nanofibers facilitated by the presence of porogens. The novelty of this work is in forming nanofibers containing biodegradable and biocompatible soy proteins to facilitate controlled drug release as well as in measuring detailed quantitative characteristics of the desorption processes responsible for release of the model substance (fluorescent dye) and the vitamin (riboflavin) in the presence of porogens.

Changes in two important mechanical properties, tensile strength and knot strength, and tissue reactions are investigated for four different nonabsorbable sutures, silk, polyester, polyamide 6, and polypropylene, in vivo. Three different sizes (0, 2/0, 3/0) are also used for each suture type. In the experimental in vivo conditions, rats ( Rattus norvegicus) obtained from University of Uludag Medical Faculty Experimental Animals Breeding and Research Center are used. The experiments are carried out on the Instron 4301 tensile tester before and after implantation. In the tests, maximum tenacity values are obtained. After all suture materials are broken, a scanning electron microscope and optical light microscope are used to take their pictures. For braided sutures, the encapsulation rate around the suture plays a very important role in the strength and breaking mechanism and axial splits, but controls these parameters for polypropylene sutures. Encapsulation increases the strength and has a greater effect on smaller sizes. A granulomatous inflammation is observed around all sutures in varying degrees of severity.

This study has analyzed fracture morphology of four nonabsorbable commercially available sutures before and after implantation in rats. Also, tensile and knot strength retention have been evaluated after 3 and 8 weeks in vivo. Scanning electron and optical light microscopes were used for analysis of fracture morphologies and surface changes of the sutures. A clear effect of in vivo on the tensile and knot strength changes, and the fracture mechanism was seen for braided sutures. The suture size was also important for braided sutures, as fibrous tissue formation plays an important role in terms of the size. The fiber's surface properties were also important for the fracture morphology. A smooth and even surface was not suitable for the fibrous tissue formation as seen in monofilament sutures. Therefore, the polymer type was very important for the monofilament sutures, as it was the most important parameter to determine the fracture morphology and was not affected by the implantation and the implantation time. The size of the suture was also important for the polypropylene in terms of axial splitting before and after implantation. This, however, was not the case for knot strength tests. The knot was undone regardless of the size. Surface characteristics were very important for braided sutures, as they have a rough surface that supports tissue formation on the fracture mechanism, tensile and knot strength. Silk suture has single filaments with no regular diameter and smooth surface. Therefore, silk suture has more tissue formation postimplantation compared to polyester suture.

The aim of this study was to examine the properties of polyester nanofibers produced by the electrospinning method. Solvent-spun nanofibers with different concentrations of poly(ethylene terephthalate) (13, 16, and 20 wt %) were produced. The morphology and surface energy of the fibers were analyzed by scanning electron microscopy and contact angle measurements. Tensile testing, dynamic mechanical analysis, and differential scanning calorimetry were carried out to characterize the thermal and mechanical properties. X-ray diffraction and attenuated total reflection

The knot performance of four different nonabsorbable sutures—silk, polyester, polyamide, and polypropylene—is investigated by using square knots with two and three throws. All sutures are USP 2/0 in size. An instrument that can be mounted on the Instron tensile tester measures the knot performance of the sutures. The results are given as stress-elongation graphic, knot slippage, and knot break values. The effects of the number of throws and the structure of the sutures on knot performance are studied. For the knot performance tests, the effect of the physical structure (braided or monofilament) is clearly seen. For monofilament polyamide and polypropylene sutures, the knot with two throws unties before it breaks. For silk and polyester braided sutures, which have reasonably good two-throw square knot strength, the added throw does not remarkably increase strength and at the same time places more suture material in the tissue, which increases the risk of infection. Three-throw knot results reveal that the suture material plays an important role in knot strength.