## 4 Chitosan/Graphene Oxide Films for Biomedical Applications
### Chitosan/Graphene Oxide Nanofibers  
Due to the similarity of their structure to the extracellular matrix, electrospun chitosan/graphene oxide nanofiber webs can promote cell adhesion, proliferation, and migration and, as a result, they can be considered as an attractive candidate for wound dressing applications. They can act as a barrier to the contamination of open wounds from exogenous microorganisms, and they can maintain the moisture of a wound's surface to promote the wound healing process. Electrospun nanofibers have a high surface area, which makes them ideal for use in drug delivery systems [52].  
[PERSON] et al. [52] prepared chitosan/polyvinyl alcohol/graphene oxide (CS/PVA/GO) nanofibers loaded with antibiotic drugs, such as ciprofloxacin and ciprofloxacin hydrochloride, by using an electrospinning technique. The drug release results showed a controlled release without an initial burst. Adding GO moderately improved the drug release ratio. The drug-loaded nanofibers had significant antibacterial activity against both Gram-negative and Gram-positive bacteria, as well as cytocompatibility with melanoma cells. In another study, by increasing the GO content in the electrospun antibacterial CS/PVA/GO, nanofibers were found to decrease the thermal stability of hybrid composite nanofibers [53]. The nanofiber web had effective antibacterial activity against both Gram-negative and Gram-positive bacteria, suggesting that the electrospun nanofiber web could be used as a wound dressing. The natural garlic extract, alicin, with its strong antibacterial activity, was loaded into the electrospun chitosan/polyvinyl alcohol/GO nanofibers, and the release study showed that the amount of alicin released could be controlled by GO content. The drug-loaded nanofibers had effective antibacterial activity against _Staphylococcus aureus_, and the nanofibers containing GO had superior antibacterial activity compared to those without GO. The drug-loaded nanofibers also had a significant moisture-retention capacity and hygroscopicity and, as a result, these nanofibers were considered to be potential candidates for wound dressing and tissue-engineering applications.  
In another study, multi-component nanofiber webs loaded with various antibacterial agents, such as silver nanoparticles (Ag), graphene oxide (GO), curcumin (CUR), and chitosan (CS), were prepared [2]. First, PEGylated GO was used as the template to synthesize a series of PEGylated GO/Ag/CUR nanocomposites by incorporating them into CS/polyvinyl alcohol nanofibers (Figure 6). The results from an antibacterial test indicated improved effectiveness compared to other formulations. The GO increased the mechanical properties of the nanofibers, with a tensile strength of 25 MPa compared to 7.2 MPa, and a Young's modulus of 364 MPa compared to 73 MPa. A cell viability assay also confirmed the biocompatibility of the nanofiber web, indicating that the prepared nanocomposites had potential for use as wound dressing materials.  
Figure 6: Schematic of synthesis of PEGylated GO and PEGylated-GO-based nanocomposites [2].  
Some other preparations are also listed in Table 2.