# Lithographically-Fabricated HA-Incorporated PCL Nanopatterned Patch for Tissue Engineering
## 3 Results  
### Preparation of NG-PCL-C  
The lithographically fabricated NG-PCL and F-PCL were coated with the equine bone powders with submicron-size (EBPs). The detailed characteristics of EBPs are shown in Figure S1. The cumulative diameters (d0.1, d0.5, d0.9) of EBPs are 0.779 \(\pm\) 0.099, 4.13 \(\pm\) 1.71 and 19.40 \(\pm\) 0.2.47 \(\upmu\)m, respectively. Figure 1a shows a schematic diagram of the nanogrooved PCL patch (NG-PCL) fabrication process and EBPs coated NG-PCL with dip-coating method. Figures S2 and S3 show the optimization of coating conditions. In our previous study, we observed the surface morphologies of native ECM of the human body, which was well aligned of the bunch of the ECM fibers [9]. And the lithography technique was used for manipulating the naonogroove/ridge of NG-PCL. As shown in Figure 1b, the fabricated NG-PCL was confirmed to contain well-defined nonogrooves/ridges regularly. In addition, the EBPs were well coated on the NG-PCL (Figure 1b) without damaging the nanogroove/ridge structure of NG-PCL (e.g., designed nanostructures) during the dip-coating process, and were well dispersed on the surfaces of NG-PCL. Even though the surface of the patch was covered with EBPs, the nanopatterns were still observed (Figure S4).  
The water contact angle was measured to prove the effectiveness of the EBP coating for enhancing hydrophilicity (Figure 2). Interestingly, the water droplet forms an ellipse shape along with the direction of the nanogroove patterns. In addition, the water contact angle at the frontal and lateral direction of the droplet showed a different value (Figure 2a,b). The water contact angle of the nanopattern patch was measured in the major axis direction of the elliptical droplet and in perpendicular directions. On the other hand, the water droplet shape was an almost circular shape on the F-PCL and F-PCL-C (Figure 2a). Furthermore, it is noted that the water droplet elongation factor of NG-PCL-C was smaller than the value of NG-PCL. However, the elongation factor of NG-PCL-C was 1.20 and it was higher than those of F-PCL and F-PCL-C. This means that the droplets in NG-PCL-C forms an elliptical shape. In addition, the water contact angles of the NG-PCL and NG-PCL-C were higher than those on the F-PCL and F-PCL-C respectively, due to the nanogrooved surface topography. The EBPs coating enhanced the  
Figure 1: Preparation of PCL flat/nano-patterned patches coated with equine bone powders. (**a**) The schematic diagram of PCL nano-patterned patches and equine bone powder-coated PCL nano-patterned patches. (**b**) Surface observation of PCL flat and nano-patterned patches with or without equine bone powders.  
hydrophilicity; thus it led to decreasing the water contact angles of each sample. The elliptical water droplet on the NG-PCL and NG-PCL-C had different water contact angles along with their direction. Interestingly, the angles at the minor axis direction did not show a significant difference with the value of F-PCL and F-PCL-C. Furthermore, it was found that the contact angles at the major axis direction were more decreased than that of the minor axis.