Farzaneh Ghasemkhah - Nanotechnology Institute, Amirkabir University of Technology, Tehran, Iran.
Masoud Latifi - Department of Textile Engineering, Textile Excellence and Research Centers, Amirkabir University of Technology, Tehran, Iran.
Afra Hadjizadeh - Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran.
Mohammad Ali Shokrgozard - National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran.

Threads or yarns are key building blocks in constructing complicated fibrous structures for many biomedical applications such as scaffolds to direct cells in tissue engineering applications. In this study, protein-loaded aligned fibers with core-shell structures were successfully fabricated by combining coaxial electrospinning with a rotating disk collector. A model protein, bovine serum albumin (BSA) as a core was incorporated into shell material, including PCL/gelatin (۵۰:۵۰) hybrid and then electrospun aligned core-shell fibers on the rotating disk. After manually twisting the aligned fiber bundle, the prepared threads were crosslinked with genipin. The fibers and thread morphologies were characterized by scanning electron microscopy (SEM), fluorescent microscopy (FM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR), and the threads tensile properties were then evaluated. The well-aligned fibers (with a mean diameter of ۱.۴۷۲±۰.۴۴۴ µm) with uniform core-shell structures without any bead formation and homogeneous protein incorporation into them were obtained using a rotating wheel at ۱۳۰۰ rpm. BSA-loaded threads with a diameter of ۱۵۰-۲۵۰ μm were finally prepared from aligned fiber bundle by keeping their well-aligned structure. The tensile tests revealed that fibrous thread with the modulus of ۳۴.۲ cN/tex had proper tensile properties for tissue engineering approaches. FTIR thus proved that the crosslinking was successful between thread and genipin. After crosslinking, threads retained their fibrous structure and demonstrated the improvement in the tensile properties (modulus increased to ۴۰.۶۴ cN/tex). These findings are promising to promote biomedical agents-loaded fibrous threads for tissue suturing and tissue regeneration applications.

coaxial electrospinning, core-shell fiber, aligned fibers, fibrous thread