# Carbon Nanotubes-Based Hydrogels for Bacterial Eradiation and Wound-Healing Applications
## 5 CNT-Based Nanocomposites for Wound Healing
Decreased pore size and increased electrical conductivity were observed with 3 wt% of CNT compared to 0 and 1% CNT added samples. The hydrogel demonstrated remarkable antimicrobial and wound-healing performance on a murine dorsal skin model. The conductivity graph and in vivo wound treatment of MNH/CNT0 and MNH/CNT3 samples is shown in Figure 5c. The presence of CNT promoted the stability of emulsion and enhanced the conductivity and mechanical property of hydrogel. [PERSON] et al., developed injectable antibacterial and conductive nanocomposite cryogel with similar components (CNT and GelMA) with the addition of functionalized quaternerized chitosan [30]. Their results showed that 4 mg/mL CNT composition was outstanding for hemostatic application compared to gauze. The wound-healing performance was also compared with TegadermTM film, and the fabricated cryogels showed better results in the mouse-liver injury model. In another work, CNT was incorporated with chitosan and poly(acrylamide) to synthesize a multifunctional hydrogel. The film was prepared to deliver vascular endothelial growth factor (VEGF) and check the release pattern in the presence and absence of fluorescein isothiocyanate-tagged bovine serum albumin (FITC-BSA). The presence of CNT enhanced the interaction among cells and promoted cell proliferation. Figure 5d represents the hematoxylin and eosin (H&E) staining of regenerated granulation tissues from wound sites in different groups and their statistical analysis of tissue thickness [139]. [PERSON] et al., developed a nitrogen-doped CNT encapsulating cobalt (N-CNTs@Co) nanoparticles for antibacterial wound-healing application [140]. The nanocomposite showed oxidase-mimicking activity, which could produce a large number of ROS in an acidic environment. The generation of ROS exhibited good antibacterial activity against Gram-positive _Staphylococcus_ and Gram-negative _Escherichia coli_. To kill the bacteria, the ROS damaged the bacterial membrane and degraded its DNA. After the treatment of the N-CNTs@Co nanocomposite, the bacteria-infected wound shrank faster than the control group. The H&E analysis confirmed the healing process by showing the high speed of hair follicle recovery, and finally, the skin surface was smooth. Figure 5: **(a)** Schematic representation of wound-healing phases in cutaneous wound—hemostasis, inflammation, proliferation, and remodeling [2], **(b)** (i) Scheme representation of mouse-tail amputation model, (ii) bloodstain photograph of mouse tail in blank and hydrogel group, (iii) quantitative data of blood loss (\(n=5\)), **\(p<0.01\)[137], **(c)** In vivo wound-healing model evaluation of MNH hydrogels and observation of treatment in presence of \(S\). _aureus_ infection for 12 days [138], **(d)** (i) H&E staining of different groups showing the progress in thickness of skin, (ii) respective statistical analysis of average connective tissue thickness in different groups [139], **(e)** Schematic of chemoattractant-induced cell migration assay using a modified Boyden Chamber experiment. The addition of CNT increased the porosity of the hydrogel and cell migration (left). The average cell migration index for the samples with varying concentration of CNT with (solid pattern) and without (diagonal pattern) chemoattractant. *\(p<0.05\) corresponds to a significant difference (right) [35]. Similarly, [PERSON] et al., investigated and compared the effect of chitosan complexed SWCNT and MWCNT hydrogels for the wound-healing process [141]. Fibroblasts were viable in the presence of the complexes. The fabricated complexes showed effective organization and contraction of the extracellular matrix. The in vivo data demonstrated the re-epithelialization of the cells in wounded areas and an increase in fibrosis by both the complexes. The MWCNT-chitosan complex showed an enhanced effect in fibrosis formation and collagen deposition compared to the SWCNT-chitosan hybrid material. The inflammatory signs confirmed the wound-healing associated impact.