Seminar Series:
Darya AsheghaliUniversity of Georgia, Department of Chemistry
Wednesday, November 15, 2017 - 11:15am
Chemistry Building, Room 400

The fibers and nanofibers are playing a growing role in various applications ranging from the design of new composite materials to the fabrication of tissue engineering scaffolds for artificial bones and organs. Here, a novel method called “touch-spinning” is introduced as an inexpensive and controllable setup for drawing micro- and nanofibers from polymer solutions or melts using a rotating rod.1 The touch-spinning setup can be used to wind a single filament into unidirectional, orthogonal or randomly oriented 2D and 3D scaffolds with controlled density, porosity, and thickness. The resulting fiber diameter is controlled precisely in the range of 40 nm to 5 μm by adjusting the rotational speed and polymer concentration. This method eliminates the effects of dielectric properties of the polymer solutions associated with electrospinning. One of the main advantages of touch-spinning over other common fiber spinning techniques is the fabrication of micro- and nanofibers from very fast and diffusion-limited chemical reactions.2-3

In this study, the aligned touchspun polycaprolactone (PCL) nanofibers were fabricated at different spinning rates and the proliferation potential of the neural stem cells (NSCs) was analyzed on these nanofibrous scaffolds. The aligned electrospun PCL nanofibers were fabricated at spinning rates similar to the touchspun nanofibers and they were served as a control group. The degree of crystallinity and the Young’s modulus values of the touchspun fibers were much higher than those of electrospun fibers at various spinning rates. The NSC cells exhibited an elongated neurite growth along the touchspun PCL nanofibers with varying spinning rates. Whereas, the NSC cells tend to aggregate on the entangled electrospun PCL nanofibers and they did not spread along the fibers. As the spinning rate of the touchspun nanofibers increased, the percentage of TUJ1 positive cells and the percentage of GFAP positive neurons increased. These results have shown the feasibility of using the touchspinning technique to fabricate fibrous scaffolds for neural tissue engineering applications. Based on the previous reports, the polymers with higher crystallinity result in a stiffer substrate which influences the cytoskeletal organization and consequently cell phenotype. No previous studies have successfully demonstrated the influence of the crystallinity of polymer on the alignment of NSCs.4-5

References

1. Tokarev, A.; Asheghali, D.; Griffiths, I. M.; Trotsenko, O.; Gruzd, A.; Lin, X.; Stone, H. A.; Minko, S., Touch‐and Brush‐Spinning of Nanofibers. Advanced Materials 2015, 27 (41), 6526-6532.

2. Tokarev, A.; Trotsenko, O.; Asheghali, D.; Griffiths, I. M.; Stone, H. A.; Minko, S., Reactive Magnetospinning of Nano‐and Microfibers. Angewandte Chemie 2015, 127 (46), 13817-13820.

3. Asheghali, D.; Griffiths, I. M.; Tokarev, A.; Stone, H. A.; Minko, S., Gravitation-Spinning of the Nano- and Microfibers. Manuscript submitted 2017.

4. Asheghali, D.; Lee, S.-J.; Larson, S.; Gruzd, A.; Furchner, A.; Hinrichs, K.; Zhang, L.; Minko, S., Enhanced Alignment of the Neural Stem Cells on the Touch-spun Nanofibrous Scaffolds. Manuscript submitted 2017.

5. Lee, S.-J.; Asheghali, D.; Minko, S., Zhang, L., Touch-spinning of the PCL Nanofibers for Nerve Regeneration. Manuscript submitted 2017.