# Electrospun Nanofibrous Membranes for Tissue Engineering and Cell Growth
## 9 Poly(acrylonitrile)  
Poly(acrylonitrile) (PAN) belongs to the polymers that can be electrospun from dimethyl sulfoxide (DMSO), is a low-toxic solvent, and should thus be highly attractive for biomedical and biotechnological applications [9; 12; 41]. Nevertheless, it is less often used for tissue engineering than other polymers.  
[PERSON] et al. blended PAN with Fe(III)-metal-organic framework (MOF), with different amounts of Fe-MOF, and investigated cell viability on this electrospun nanocomposite [126]. They found that for lower percentages of Fe-MOF, the electrospun nanofiber mats showed high porosity, with a suitable average fiber diameter, as well as chemical stability. The cell attachment, proliferation, and spreading were better than in pure PAN nanofiber mats or scaffolds with higher amounts of Fe-MOF, as shown for human umbilical vein endothelial cells (HUVEC) in Figure 7. For low amounts of Fe-MOF, cytotoxic effects could be excluded; in vivo implantation showed no inflammatory response for the lower amounts of Fe-MOF. The optimum concentration of Fe-MOF was explained by finding a balance between scaffold degradation and increasing cytotoxicity upon high concentrations of Fe-MOF; i.e., negative impact of this material, and modulation of the pH value at the biointerface towards optimum values for cell activity, i.e., the positive influence of the Fe-MOF.  
Combining PAN with ZnO as a negative reference and with a maltodextrin/protein blend, as well as with casein/gelatin, [PERSON] et al. showed significantly increased cell growth and viability on electrospun PAN/chitosan/gelatin nanofiber mats, as compared to pure PAN; which was attributed to the positive influence of the chemical modification on cell attachment [127]. The same group showed in a previous study the suitability of PAN/gelatin nanofiber mats for the growth of CHO (Chinese hamster ovary) cells [9].  
[PERSON] et al. studied PAN combined with the aforementioned hydroxyapatite as a possible scaffold for bone tissue engineering [128]. They prepared a highly three-dimensional scaffold by electrospinning and biomineralization. Seeding bone marrow mesenchymal stem cells onto the scaffolds, they found significantly higher cell growth, osteogenic differentiation, and mineralization than on two-dimensional scaffolds of the same material composition; underlining the importance of a 3D structure.  
Figure 7: Scanning electron micrographs showing the morphology of plated HUVEC on various scaffolds 24 h after seeding. (**a**) Plated HUVEC on PAN scaffold, (**b**) Plated HUVEC on PAN/5%FeO-MOF, (**c**) Plated HUVEC on PAN/10%Fe-MOF scaffold, and (**d**) Plated HUVEC on PAN/20%Fe-MOF. Reprinted from [126], with permission from Elsevier.  
Similarly working with PAN and hydroxyapatite, [PERSON] et al. carbonized the PAN nanofibers after electrospinningning [129]. They determined the bioactivity of these scaffolds by assessing crystalline apatite formation on the nanofiber mat upon immersion in simulated body fluid. In comparison with carbonized nanofiber mats without hydroxyapatite, a significant increase of mineralization activity was measured.  
[PERSON] et al. added MoS2 to PAN nanofibers by electrospinningning and doping and found good biocompatibility, as well as increased growth of bone marrow mesenchymal stem cells, high cellular activity, increased contact between cells, and improved cell proliferation [130]. These positive properties of PAN/MoS2 nanofiber mats were attributed to the good biocompatibility and the structure mimicking the extracellular matrix, as well as the support of the alkaline phosphatase expression by MoS2.  
Besides these examples, only a few reports about pure PAN or PAN blends being applied for tissue engineering can be found in the literature.