In the field of tissue engineering there is always a need for new engineered polymeric biomaterials which have ideal properties and functional customization. Unfortunately the demands for many biomedical applications need a set of properties that no polymers can fulfill. One method to satisfy these demands and providing desirable new biomaterials is by mixing two or more polymers. In this work, random nanofibrous blends of poly (e-caprolactone) (PCL) and polyglycolic acid (PGA) with various PCL/PGA compositions (100/0, 80/20, 65/35, 50/50, and 0/100) were fabricated by electrospinning method and characterized for soft-tissue engineering applications. Physical, chemical, thermal, and mechanical properties of PCL/PGA blend nanofibers were measured by scanning electron microscopy (SEM), porosimetry, contact angle measurement, water uptake, attenuated total reflectance Fourier transform-infrared spectroscopy (ATR-FT-IR), Xray diffraction (XRD), differential scanning calorimetric (DSC), dynamic mechanical thermal analysis (DMTA), and tensile measurements. Morphological characterization showed that the addition of PGA to PCL results in an increase in the average diameter of the nanofibers. According to these results, when the amount of PGA in the blend solution increased, the hydrophilicity and water uptake of the nanofibrous scaffolds increased concurrently, approaching those of PGA nanofibers. Differential scanning calorimetric studies showed that the PCL and PGA were miscible in the nanofibrous structure and the mechanical characterization under dry conditions showed that increasing PGA content results in a tremendous increase in the mechanical properties. In conclusion, the random nanofibrous PCL/PGA scaffold used in this study constitutes a promising material for soft-tissue engineering.

Recently, Injectable Conducting Hydrogel (ICH) systems have gained much attention for tissue engineering and regenerative medicine. These systems can promote the regeneration of tissues responding to electrical responses. In this study, a novel ICH system was introduced. To achieve this system, firstly, a soluble non-toxic polypyrrole (PPy) synthesized by grafting pyrrole on alginate (Alg) backbone (Alg-graft-PPy), and then, ICH systems were prepared by the given ratios of Alg-graft-PPy, Alg, and collagen (Col). Three different amounts of Col (0.5, 1, and 1.5 mg/ml) were added to the system including Alg-graft-PPy: Alg wt. % with the ratios of 20:80 and 30:70. FTIR spectroscopy, electrical conductivity, viscosity, syringeability, gelation time, and MTT assay were performed in order to characterize the produced hydrogels. Due to the rheological behavior of 20:80 (Alg-graft-PPy: Alg wt. %), it was recognized more suitable to inject. Also this system associated with 0.5 mg/ml Col introduced as the best sample with respect to its viscosity and injectability. This ICH system has shown high conductivity in addition to a good level of cell viability and syringeability. With respect to properties of the produced ICH system, it can be applied for bone, nerve, muscle and cardiac cells, which respond to electrical impulses.

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