# Micro-Structured Patches for Dermal Regeneration Obtained via Electrophoretic Replica Deposition
## 4 Discussion  
In the last decade, the study of so-called bioactive dressings has been actively promoted [22]. Such devices are based on the use of naturally occurring proteins and polysaccharides that possess a notable biocompatibility and allow the dressing to achieve the highest level of biomimery, recapitulating the native extracellular matrix (ECM) biological and physico-chemical features [23; 24; 25]. In this work, we have shown the use of the electrophoretic replica deposition technique as an innovative technology to simply manufacture bioactive dressings that can promote wound healing via the fine-tuning of their microstructure and an appropriate choice of material. This new family of structures was shown to support skin wound healing in large defects via an in vivo rat model. Figure 7 schematically illustrates the EPrD technology process diagram and the possible achievable material properties. EPD is a conventional electrophoretic process originally designed for surface modifications and largely exploited in several industrial applications to impart specific properties to material surfaces [11]. EPrD is an EPD process characterized by the subsequent mechanical or chemical removal of the deposited material from the working electrode. Through a machining technology (e.g., drilling, laser-cut), it is possible to impart a microstructure to the working electrode: such patterns will be hence replicated on the surface of the deposit by controlling EPD processing parameters. Moreover, complex three-dimensional shapes (such as tubes) can be replicated, allowing to obtain the manufacturing of objects at different scales, from fine-tuned compositions at nano-scale up to cm-scale devices (right box in Figure 7). Almost all the potentials offered by this technology have been exploited here in order to obtain structures suitable for skin wound management. Namely, through the correct selection of the composition of the deposition bath, the micro-structuring of the deposition substrate, and the process parameters, it was possible to manufacture in a consistent way a family of hierarchical patches (Figure 1). EPrD allowed the easy and consistent processing of chitosan: this biopolymer has been selected as material to design  
Figure 6: Immunohistochemistryidechemical analysis against keratin 10 (CK10) at day 14 on (**a**) CPR, (**b**) CP500, and (**c**) CP1000. (Scale bar 50 \(\upmu\)m.)  
bioactive dressings based on both the wide literature related to its processing via EPD [10] and its ability to promote hemostasis, accelerate tissue regeneration, and stimulate the fibroblast synthesis of collagen [26; 27; 28; 29]. Previous studies demonstrated that chitosan accelerates wound healing due to the infiltration of polymorphonuclear (PMN) cells at the wound site [30], which is a crucial event in rapid wound healing. The EPrD process also enabled the obtainment of hierarchical structures with controlled morphology and thickness: porous polymer structures are of increasing interest due to their wide application as scaffolds for tissue regeneration as well as immune-isolating membrane [24; 25; 31]. The microstructure of the porous patches, such as the pore shape, pore size, and pore distribution, has been easily tailored by combining the micro-structuring of the cathode substrate and exploiting the intrinsic effect of hydrogen gas development due to the water electrolysis [32; 33], the latter resulting in this work in a secondary random porosity in the range of 10-100 \(\upmu\)m (Figure 1). EPrD allowed us to obtain CS porous patches with a thickness of around 230 \(\upmu\)m, suitable for dermal regeneration [34]. In contrast to autografts, dermal substitutes suffer from a lack of normal vascular networks: a suitable thickness is then needed for oxygen and nutrient diffusion. Impaired diffusion processes due to thick scaffolds result in tissue necrosis, extensive inflammatory reaction, marked foreign-body reaction (FBR), and rapid scaffold degradation [34].