**3.1. Material characterization and water absorbability of wound‐dressing composites**

SEM images in **Figures 1** and **2** show distinct surface and cross‐section morphologies of PAQ composites prepared at different mass ratios of components. Overall, the PAQ composites display a porous morphology and the cross‐section images reveal a three‐dimensional (3D) porous network inside PAQ composites. It is noticed that the difference lies in the pore size in each composite. Due to the addition of different amounts of AE and QCS, the PVA fibers inside the 3D structural network are covered by AE and QCS. The pore size of 20–30 μm in PAQ2 appears to be more homogeneous on the surface and cross‐section areas than PAQ1 and PAQ2. The PAQ1 exhibits smaller pore size of 5–20 μm and the PAQ3 exhibits larger pore size of 20– 60 μm. Too smaller pore may inhibit the air exchange and too larger pores may not effectively prevent the adverse microorganism from infection to wound [36]. In order to prepare a satisfactory wound‐dressing material, the porous profile of PAQ2 with a mass ratio of PVA:AE:QCS (7:2:1) seems more qualified.

**Figure 1.** SEM images of surface of PAQ composites with different mass ratios of components: (a, b) PVA:AE:QCS = 6:3:1; (c, d) PVA:AE:QCS = 7:2:1; (e, f) PVA:AE:QCS = 8:1:1. Images b, d, and f indicate higher magnifications of images a, c, and e, respectively.

Multifunctional Wound‐Dressing Composites Consisting of Polyvinyl Alcohol, Aloe Extracts and Quaternary... http://dx.doi.org/10.5772/65476 261

CO2. At the assigned day, the culture medium was removed and the attached cells on the samples were rinsed by PBS. The samples were subsequently fixed with 2.5% glutaraldehyde PBS solution at room temperature for 2 h and stained by a small drop of fluorescent isothio‐ cyanate dye (FITC) at 4°C for 1 h. Laser scanning confocal microscope (LSCM, Leica SD AF) with an excitation wavelength of 488 nm was used to examine the cell attachment and

**3.1. Material characterization and water absorbability of wound‐dressing composites**

SEM images in **Figures 1** and **2** show distinct surface and cross‐section morphologies of PAQ composites prepared at different mass ratios of components. Overall, the PAQ composites display a porous morphology and the cross‐section images reveal a three‐dimensional (3D) porous network inside PAQ composites. It is noticed that the difference lies in the pore size in each composite. Due to the addition of different amounts of AE and QCS, the PVA fibers inside the 3D structural network are covered by AE and QCS. The pore size of 20–30 μm in PAQ2 appears to be more homogeneous on the surface and cross‐section areas than PAQ1 and PAQ2. The PAQ1 exhibits smaller pore size of 5–20 μm and the PAQ3 exhibits larger pore size of 20– 60 μm. Too smaller pore may inhibit the air exchange and too larger pores may not effectively prevent the adverse microorganism from infection to wound [36]. In order to prepare a satisfactory wound‐dressing material, the porous profile of PAQ2 with a mass ratio of

**Figure 1.** SEM images of surface of PAQ composites with different mass ratios of components: (a, b) PVA:AE:QCS = 6:3:1; (c, d) PVA:AE:QCS = 7:2:1; (e, f) PVA:AE:QCS = 8:1:1. Images b, d, and f indicate higher magnifications of images

morphology.

**3. Results and discussion**

260 Composites from Renewable and Sustainable Materials

PVA:AE:QCS (7:2:1) seems more qualified.

a, c, and e, respectively.

**Figure 2.** SEM images of cross‐section of PAQ composites with different mass ratios of components: (a, b) PVA:AE:QCS = 6:3:1; (c, d) PVA:AE:QCS = 7:2:1; (e, f) PVA:AE:QCS = 8:1:1. Images b, d, and f indicate higher magnifications of im‐ ages a, c, and e, respectively.

The FTIR spectra of pure PVA, AE, QCS, and PAQ composite samples are illustrated in **Figure 3**. Vertically numerical peaks at 3433 and 2908 cm‐1 on the pure PVA spectrum may be typical characters of hydroxyl groups and alkyl long chain of PVA, respectively [37]. The strong peak at 3433 cm‐1 indicates the proof of numerous existing interchain and intrachain hydrogen bonds in the samples of AE and QCS [38]. This peak in three PAQ composite samples shows a limited enhancement as compared to PVA and a remarkable reduction as compared to AE and QCS, suggesting that AE and QCS have been physically bound to PVA and possible hydrogen bonding may have been formed among them. PAQ1 shows a stronger peak at 3433 cm‐1 than PAQ2 and PAQ3 because of the highest AE component in its composition. The peaks at 1485 and 1230 cm‐1 are associated with amino groups and they slightly shift to 1400 and 1200 cm‐1 with the reduction of peak intensity in PAQ composite samples, which is the proof of the presence of QCS in the composites [39, 40]. The strong peaks at 1722 and 1624 cm‐1 are associated with carbonyl groups existing in AE and they are both present in PAQ composites with the reduction of peak intensity, which is another proof of the incorporation of AE into PVA [40]. The peak at 1120 cm‐1 is associated with ether groups representing the presence of sugar rings in the PAQ composites, suggesting the successful binding of AE and QCS onto the PVA substrate [40]. The above FTIR analysis chemically demonstrates that AE and QCS have been bound to PVA matrix, although the ratio of AE and QCS in the composites is far below PVA, and as‐prepared PAQ composites exhibit all characteristic peaks regarding specific functions that AE and QCS possess.

**Figure 3.** FTIR spectra of pure PVA, pure Aloe, pure QCS, and PAQ composites with different mass ratios of compo‐ nents: PAQ1, PVA:AE:QCS = 6:3:1; PAQ2, PVA:AE:QCS = 7:2:1; PAQ3, PVA:AE:QCS = 8:1:1.

The TGA thermograms of pure PVA and PAQ composites are shown in **Figure 4a** and DTG curves regarding the maximum decomposition temperature and decomposition rate of material components are shown in **Figure 4b**. All the samples show four stages of weight loss in **Figure 4a**. The first stage between 36 and 100°C is associated with the weight loss of absorbed water of samples [19]. Pure PVA exhibits around 8% weight loss in this stage as compared to 9.82% for PAQ3, 15.42% for PAQ2, and 18.51% for PAQ1, suggesting that the competency of moisture maintenance of PAQ composites increases according to the increasing content of AE and QCS in the composition. The second stage between 150 and 300°C is associated with the disintegration of intermolecular breaking of molecular structure which is believed to be the disassociation of physical binding among material components [41]. In this stage, the weight losses of composites are around 25% for pure PVA, 27.25% for PAQ3, 30.36% for PAQ2, and 29.91% for PAQ1, which suggests that AE and QCS bound to PVA start the disassociation from PVA matrix. Although the weight loss does not have a big difference among PAQ composites, due to the addition of AE and QCS, the maximum decomposition temperature of PAQ composites as shown in **Figure 4b** increases as compared with pure PVA, which results in the increase of thermal stability of PAQ composites. The third stage between 300 and 380°C shows the highest weight loss of materials which are associated with the decomposition of molecular structure of PVA, AE, and QCS [38]. As shown in **Figure 4b**, in this stage, the maximum decomposition temperature is increased from 328.7°C for pure PVA to 335.5°C for PAQ3, 341.7°C for PAQ2, and 342.4°C for PAQ1. This means that the addition of AE and QCS increases the thermal stability of PAQ composites. Meanwhile, the decomposition rate of PAQ3 com‐ posites is greatly reduced as the increasing content of AE in the composite. The fourth stage between 380 and 450°C is associated with the decomposition of material proportion with higher crystalline structure in AE or QCS [42]. PAQ2 and PAQ3 containing higher amount of AE and QCS exhibit higher weight losses than pure PVA and PAQ. The above TGA analysis indicates that the addition of AE and QCS in PAQ composites is conducive to the enhancement of thermal stability of materials and beneficial to the moisture maintenance of PAQ composites.

**Figure 3.** FTIR spectra of pure PVA, pure Aloe, pure QCS, and PAQ composites with different mass ratios of compo‐

The TGA thermograms of pure PVA and PAQ composites are shown in **Figure 4a** and DTG curves regarding the maximum decomposition temperature and decomposition rate of material components are shown in **Figure 4b**. All the samples show four stages of weight loss in **Figure 4a**. The first stage between 36 and 100°C is associated with the weight loss of absorbed water of samples [19]. Pure PVA exhibits around 8% weight loss in this stage as compared to 9.82% for PAQ3, 15.42% for PAQ2, and 18.51% for PAQ1, suggesting that the competency of moisture maintenance of PAQ composites increases according to the increasing content of AE and QCS in the composition. The second stage between 150 and 300°C is associated with the disintegration of intermolecular breaking of molecular structure which is believed to be the disassociation of physical binding among material components [41]. In this stage, the weight losses of composites are around 25% for pure PVA, 27.25% for PAQ3, 30.36% for PAQ2, and 29.91% for PAQ1, which suggests that AE and QCS bound to PVA start the disassociation from PVA matrix. Although the weight loss does not have a big difference among PAQ composites, due to the addition of AE and QCS, the maximum decomposition temperature of PAQ composites as shown in **Figure 4b** increases as compared with pure PVA, which results in the increase of thermal stability of PAQ composites. The third stage between 300 and 380°C shows the highest weight loss of materials which are associated with the decomposition of molecular structure of PVA, AE, and QCS [38]. As shown in **Figure 4b**, in this stage, the maximum decomposition temperature is increased from 328.7°C for pure PVA to 335.5°C for PAQ3, 341.7°C for PAQ2, and 342.4°C for PAQ1. This means that the addition of AE and QCS increases the thermal stability of PAQ composites. Meanwhile, the decomposition rate of PAQ3 com‐ posites is greatly reduced as the increasing content of AE in the composite. The fourth stage between 380 and 450°C is associated with the decomposition of material proportion with higher crystalline structure in AE or QCS [42]. PAQ2 and PAQ3 containing higher amount of AE and QCS exhibit higher weight losses than pure PVA and PAQ. The above TGA analysis indicates that the addition of AE and QCS in PAQ composites is conducive to the enhancement of thermal stability of materials and beneficial to the moisture maintenance of PAQ composites.

nents: PAQ1, PVA:AE:QCS = 6:3:1; PAQ2, PVA:AE:QCS = 7:2:1; PAQ3, PVA:AE:QCS = 8:1:1.

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**Figure 4.** TGA (a) and DTG (b) curves of pure PVA and PAQ composites with different mass ratios of components: PAQ1, PVA:AE:QCS = 6:3:1; PAQ2, PVA:AE:QCS = 7:2:1; PAQ3, PVA:AE:QCS = 8:1:1.

The water absorbability of PAQ composites was investigated using two physiological solu‐ tions, PBS (pH 7.4) and HAc‐NaAc (pH 5.0), at 37°C, to evaluate their potential to be used for fluid exchange and moisture maintenance because a real wound‐healing process generally involves a variation of pH values from pH 5.0 for wound occurrence to pH 7.4 for wound closure [15, 16]. As shown in **Figure 5**, all the PAQ composites exhibit strong water absorba‐ bility over 10 times higher than their dry weight, as well as higher than pure PVA. This suggests that the incorporation of AE and QCS could significantly enhance the water absorbability of pure PVA. Owing to the maximum content of AE in PAQ1 composite, the maximum water absorption is 23.85 ± 0.76 for PAQ1 soaked in PBS, which means that this composite material could absorb 23.85 times its dry weight. As compared to PBS (pH 7.4), the PAQ composites exhibited a slight decline of water absorbability in HAc‐NaAc (pH 5.0), partly because of the presence of QCS with a competency of proton donor neutralizing the acidic effect in HAc‐ NaAc buffer. Overall, the water absorption tends to be stable after soaking the composites for over 240 min and can be maintained until 720 min, which suggests that the optimal time to exchange new PAQ composites is somewhere between 240 and 720 min because old composites may lose persistent competency to absorb exudates from wound, whereas it can maintain the high moisture for wound. In consideration of both high water absorbability and relatively low cost resulted from less addition of AE and QCS, the composition of PAQ2 (PVA:AE:QCS, 7:2:1) may be the best choice.

**Figure 5.** Water absorbability of pure PVA and PAQ composites with different mass ratios of components: PAQ1, PVA:AE:QCS = 6:3:1; PAQ2, PVA:AE:QCS = 7:2:1; PAQ3, PVA:AE:QCS = 8:1:1.

#### **3.2. Antibacterial property and biocompatibility of wound‐dressing composites**

As shown in **Figure 6**, PAQ composites exhibit significant antibacterial property as compared to pure PVA because of the presence of QCS which is generally documented as a strong and bio‐safe antibacterial agent. PAQ1 in **Figures 6e** and **f** exhibits a slightly better antibacterial property against both *E. coli* and *S. aureus* than PAQ2 and PAQ3, although their antibacterial effects are quite similar. This may be a reason of a higher amount of AE present in PAQ1 composite. All the PAQ composites show the excellent antibacterial outcomes over 99% after cell counting and calculation, which are 99.85% for PAQ1, 99.58% for both PAQ2 and PAQ3 against *E. coli*, and 99.80% for PAQ1, 99.69 for PAQ2, and 99.52% for PAQ3 against *S. aureus.* The proliferation of L929 mouse fibroblasts in the presence of pure PVA and PAQ composites over time is shown in **Figure 7**. No significant difference is present in the proliferation of L929 fibroblasts for PAQ composites, which suggests that the addition of QCS and AE to PVA matrix did not significantly influence the proliferation of L929 cells.

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**Figure 6.** Antibacterial assays using *E. coli* (a, c, e, g, h) and *S. aureus* (b, d, f, h, j) for (c, d) pure PVA and PAQ compo‐ sites with different mass ratios of components: (e, f) PAQ1, PVA:AE:QCS = 6:3:1; (g, h) PAQ2, PVA:AE:QCS = 7:2:1; (i, j) PAQ3, PVA:AE:QCS = 8:1:1. Images a and b are blank samples.

**Figure 5.** Water absorbability of pure PVA and PAQ composites with different mass ratios of components: PAQ1,

As shown in **Figure 6**, PAQ composites exhibit significant antibacterial property as compared to pure PVA because of the presence of QCS which is generally documented as a strong and bio‐safe antibacterial agent. PAQ1 in **Figures 6e** and **f** exhibits a slightly better antibacterial property against both *E. coli* and *S. aureus* than PAQ2 and PAQ3, although their antibacterial effects are quite similar. This may be a reason of a higher amount of AE present in PAQ1 composite. All the PAQ composites show the excellent antibacterial outcomes over 99% after cell counting and calculation, which are 99.85% for PAQ1, 99.58% for both PAQ2 and PAQ3 against *E. coli*, and 99.80% for PAQ1, 99.69 for PAQ2, and 99.52% for PAQ3 against *S. aureus.* The proliferation of L929 mouse fibroblasts in the presence of pure PVA and PAQ composites over time is shown in **Figure 7**. No significant difference is present in the proliferation of L929 fibroblasts for PAQ composites, which suggests that the addition of QCS and AE to PVA matrix

**3.2. Antibacterial property and biocompatibility of wound‐dressing composites**

PVA:AE:QCS = 6:3:1; PAQ2, PVA:AE:QCS = 7:2:1; PAQ3, PVA:AE:QCS = 8:1:1.

264 Composites from Renewable and Sustainable Materials

did not significantly influence the proliferation of L929 cells.

**Figure 7.** The effect of pure PVA and PAQ composites with different mass ratios of components on the proliferation of L929 mouse fibroblasts: PAQ1, PVA:AE:QCS = 6:3:1; PAQ2, PVA:AE:QCS = 7:2:1; PAQ3, PVA:AE:QCS = 8:1:1.

The attachment and morphology observation in the 3‐day cultivation of HFCs on pure PVA and PAQ composites were analyzed as shown in **Figure 8**. All the samples show good attachment of HFCs on their substrates. A slightly preferable viability of HFCs is found in PAQ composites as compared to pure PVA, although no significant viability is present, suggesting that the impact of QCS against cell growth has been offset by AE which shows a potential of facilitating the growth of fibroblasts. L929 fibroblasts show a good morphology of extended shape on all the substrates, which suggests that either pure PVA or PAQ composites are satisfied substrates for the attachment and growth of L929 fibroblasts. In the light of the results from antibacterial assays and biocompatibility plus the analyses from SEM, FTIR, TGA, and water absorbability, considering the cost, the PAQ2 with a mass ratio of PVA:AE:QCS (7:2:1) exhibits relatively satisfactory properties and thereby it should become the optimal material composition.

**Figure 8.** The attachment and morphology of HFCs on (a) pure PVA and PAQ composites with different mass ratios of components on the proliferation of L929 mouse fibroblasts on day 3: (b) PAQ1, PVA:AE:QCS = 6:3:1; (c) PAQ2, PVA:AE:QCS = 7:2:1; (d) PAQ3, PVA:AE:QCS = 8:1:1.
