FFT analysis was carried out systematically in the following steps. First, an original data image containing cell shape is used to generate an output image of

pixels distributed in a symmetrical, circular shape. Theoretically, this frequency distribution at specific pixel intensities in the data image should be identical in any direction. Therefore, the distribution of the angles at which cells were arranged in the analyzed images can be obtained by selleck chemical summation of Oval Profile similar to [20]. selleck compound It is reported that the sharper and higher the peak, the more precisely the CNFs were aligned along a specific axis of orientation [40]. Experimentally, no overt peak can be observed for the cells on randomly oriented CNF, and the random distribution of cells is confirmed in Figure  7a. Similar observation can be found in Figure  7b, in which the cells were seeded on CNF-free PPy

substrates, and no overt peak was produced in the FFT data, which was obviously related to the random distribution of cells. Figure  7c,d shows the grid patterns with 20- and 100-μm spacing, respectively. As anticipated, there was no overt peak produced in the FFT data, which was experimentally observed for the well-aligned grid patterns of cells. Presumably the grid patterns are thought to be able to limit the spreading of cells, which were not consistently obtained in Epigenetics inhibitor our experiments, especially for the sparse grid with approximately 37 fibers/mm2. In contrast, parallel CNF indicates that

the FFT alignment values sequentially increased as a function of positioning density (Figure  7e,f). Incrementally more aligned cells were closely related to the increasing of CNF positioning densities. Finally, Figure  7f indicates the highest degree of cell alignment and, most of the cells are nearly parallel. Figure 7 FFT analysis of HEK 293T alignment as a function of CNF positioning density. (a) On the substrate covered with randomly distributed nanofibers, (b) on the nanofiber-free solid substrate, oxyclozanide (c, d) on PPy substrate covered with aligned grid patterns of CNF at different positioning densities, and (e, f) on PPy substrate covered with aligned CNF at different positioning densities for parallel patterns. Conclusions In this study, we utilized NFES to prepare CNF in a direct-write manner and deposit prescribed patterns of different positioning densities. The cell ordering and alignment of HEK 293T was grown on PPy substrate with CNF of different orientations and positioning densities. Our experiments showed that the presence of parallel-aligned CNF greatly influenced cell shape. Acknowledgments This work was supported in part by the Taiwan National Science Council under contract no. NSC 101-2221-E-008-014. References 1. Ma PX: Biomimetic materials for tissue engineering. Adv Drug Del Rev 2008, 60:184–198.CrossRef 2.