3.2.2. Fabrication of Micropatterned Nanofibrous GelMA Scaffolds

Once molds were fabricated, micropatterned nanofibrous scaffolds were obtained. The electrospun mats were collected over micropatterned molds and then they were peeled out carefully. GelMA nanofibrous mats were obtained using five different types of surface topographies: concentric-circles, dot, parallel-lines, random-lines (maze), and squares. After crosslinking, samples were examined by SEM. The electrospun mats successfully reproduced the micropatterned design of the molds, keeping the nanofibrous structure when the size of structures are 200 μm or more. Two of the micropatterned designs are shown in Figure 5.

Surface roughness is among the key parameters for biomaterials, which affect the cell attachment and proliferation. Roughness measurements were carried out on the patterned GelMA electrospun mats (Table 2). Fibers produced with 400 μm of thickness (NG-P400) were rougher than the sample produced with 200 μm of thickness (NG-P200). The depth of the patterns on the mats can be estimated from the roughness values recorded at Z-axis. The depth of the step on the mat NG-P400 was around 4 μm, whereas the depth of the step on the NG-P200 was estimated to be 2.5 μm. For all GelMA fiber mats with different topographies, the measured values of roughness showed an increase of surface patterning.

**Table 2.** Roughness values <sup>1</sup> of patterned GelMA electrospun mats.


<sup>1</sup> Ra: arithmetical mean deviation of the assessed profile, Rz: arithmetical mean deviation of the assessed profile, and Rmax: maximum peak-to-valley height.

**Figure 5.** Optic images of 200 μm row and maze patterned molds (**a** and **d**, respectively) and SEM images of 200 μm patterned GelMA electrospun mats (**b** and **c**: row patterns; **e** and **f**: maze patterns).
