# Carbon Nanotubes-Based Hydrogels for Bacterial Eradiation and Wound-Healing Applications
## 5 CNT-Based Nanocomposites for Wound Healing
Inflammation plays an essential role in the primary process of wound healing. Here, the activated neutrophils secrete more lysosomal enzymes that facilitate the cleavage and eliminate damaged structural proteins of the extracellular matrix [142]. In addition, the inflammatory process enhances the number of macrophages at the wound site, which secretes more inflammatory mediators and cleanses out the wound area. Furthermore, it allows the migration of activated fibroblasts to the wound site [143]. Moreover, the activated fibroblasts gain greater capacity to contract the wound tissue and deposit more significant amounts of glycosaminoglycans and collagen, which are essential for tissue repair [144]. In the secondary stage, activated fibroblasts compensate for the damaged extracellular matrix by depositing large amounts of collagen (fibrosis), forming a scar. The next step includes healing, where the bulk of collagen in the scar is subjected to a long-lasting remodeling process over a year or more, which is facilitated by metalloproteinases secreted by fibroblasts and other cells to strengthen the repaired tissue. However, the fibrosis is never entirely resolved [145]. Hence, an increase in the inflammatory signs and collagen deposition can be indicated as an improvement in the wound-healing process, which is also associated with the improved re-epithelialization [141]. The application of CNT composites for cell proliferation and angiogenesis is included in Table 4. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**CNT Composite** & **Treatment** & **Cell Line** & **Effect** & **Reference** \\ \hline \multirow{4}{*}{rBC/PPy/CNT} & \multirow{4}{*}{Wound healing} & The mouse embryo fibroblast (NIH3T3) cell line & Good biocompatibility, enhanced cell proliferation, excellent thermal stability, mechanical properties, recoverability, and good water-absorbing capability. & [146] \\  & & & & \\ \hline PCL/CNT & neuron differentiation and regeneration & human bone-derived mesenchymal stem cells & Improved cell adhesion and differentiation. & [147] \\ \hline \multirow{4}{*}{Ch-PCL/CNT} & Antibacterial activity and other biomedical applications & \multirow{4}{*}{L92 fibroblast cells} & Improved cell attachment and proliferation, antibacterial activity against Gram-positive and Gram-negative bacteria. & [148] \\  & & & & \\ \hline CNT: gel-CT & \multirow{4}{*}{Cancer treatments} & WM266-4 human melanoma cell line & Induce cell growth inhibition and cell death. & [149] \\ \hline (OH)- CNTs & Stem cell-based regenerative medicines. & Carine bone marrow-derived mesenchymal stem cells & Positive influence on osteogenic and chondrogenic differentiation as well as neuronal differentiation. & [150] \\  & & & & \\ \hline PVA-Ch-CNT & \multirow{4}{*}{Cardiac differentiation stem cells (MSCs)} & Undifferentiated mesenchymal stem cells (MSCs) & Upregulation of cardiomyocytes differentiation. Increased conductivity, chemical stability, and enhanced adherence. & [151] \\ \hline \multirow{4}{*}{HA/CNT} & \multirow{4}{*}{Dental application} & \multirow{4}{*}{BALB/c-derived 4T1 metastatic processes.} & Induce angiogenesis and nebulited biocompatibility. Improved metastatic processes. & [152] \\  & & & & \\ \hline \multirow{4}{*}{CNT/PU} & Improved cytocompatibility for cardiomyocytesbats. & H9c2 cells and human umbilical vein endothelial cells (HUVECs) & Appropriate attachment, high viability, and proliferation of cardiomyoblasts. & [154] \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Application and aspect of CNT hybrids for cell proliferation and angiogenesis. Cell migration is usually determined based on the distance traveled by the cells or the number of migrated cells [155]. [PERSON] et al., studied the cell migration of fibroblasts in the presence of carboxylated MWCNT [35]. To analyze the chemoattractant-induced cell migration of CNT-glycol chitosan hydrogels, a modified Boyden chamber was used.