4.1. FTIR Analysis
The polymerization of the samples analyzed was used using FTIR spectroscopy. The infrared spectra of MSN and MSN-PVTri nanoparticles are shown in Fig. 1. At 1064 cm− 1 and 800 cm− 1, it indicates asymmetric and symmetric stretching vibrations of Si–O–Si bonds. The stretching vibrations of the Si-OH and O–H groups are assigned to the peaks at 977 cm− 1 and 3300 cm− 1, respectively. Peaks at 2900 and 3300 cm− 1 are caused by stretching vibrations of the C–H and OH bonds, respectively, and are most likely caused by residual CTAB that was not removed by acid etching. By polymerizing VTri to the surface, triazole rings form several moderately strong peaks in the 1430–1650 cm− 1 range due to ring stretch (C–N, C = N) vibrations. The peak at 1274 cm− 1 is due to stretching the N–N ring. The broad peak centered at 3430 cm− 1 is assigned to the O-H vibration of molecular water interacting with pristine PVTri [23, 30]. The HSS spectra show a strong absorption peak of the Si–O–Si asymmetric stretch at 1090 cm− 1. The peaks at 782 cm− 1 can be attributed to the symmetrical stretching vibration of Si–O, while the peak at 936 cm− 1 could be attributed to the bending vibration of Si-OH. At around 3600 cm− 1, a weak but distinct Si-OH stretching vibration can be seen. The peak at 3073 cm− 1 is attributed to the asymmetric stretching vibration of aromatic phenyl C-H groups bound to HSS. By polymerizing VTri on the surface, triazole rings form several moderately strong peaks in the 1430–1650 cm− 1 range due to ring stretch (C–N, C = N) vibrations [24]. The wide band e-SiO2 of the FTIR figure at 1073 cm− 1 originates from the epoxy ring. After the surface was modified with VTri, a peak from the triazole structure was formed at 1655 cm− 1. In addition, the peaks at the mountains and 750 cm− 1 are specific to VTri. The peaks that occur in cm− 1 are due to N-N ring stresses [31, 32].
4.2. SEM-EDS Analysis
SEM examined nanoparticles and nanocomposites of the surface morphologies. Figure 2 depicts the structural change caused by grafting on the MSN surface. When comparing natural and polymer-modified particles, a clear difference can be seen. The polymer covers the particle surface, but growth occurs as well in forming some irregularly shaped particles. It is seen in Fig. 2 that grafting takes place in the HSS pores and the number of porosity increases. Moreover, by coating the surface of HSS nanoparticles with a VTri monomer, the spherical particles became trapped in the bulk polymer. e-SiO2 of the SEM image revealed a high degree of accumulation due to the nanostructure. However, individual nanoparticles were observed in the 40–50 nm range, agreeing with the crystallite size informed by the X-ray line profile insertion. There was no significant increase in size with the modification of the surface. Figure 3 and Table 1 represent the outcomes of the EDS analysis of the nanocomposites. As seen in the EDS shapes of the nanocomposites, the presence of C, O, N, and Si atoms in their contents has been confirmed. MSN-PVTri (41.08%) and e-SiO2-PVTri (43.42%) nanocomposites have the highest percentage of Si atoms by mass, while the percentage of C atoms by mass is the highest in HSS-PVTri (37.22%) nanocomposites. As can be seen from the EDS results, MSN-PVTri, the nanocomposite with the highest nitrogen content, is the material that contains the most azole groups on its surface.
4.3. XRD Analysis
XRD did a phase investigation of MSN with MSN-PVTri, HSS with HSS-PVTri, and e-SiO2 with e-SiO2-PVTri the diffraction pattern is presented in Fig. 4. The MSN nanoparticle peaks around 2θ at 21.6°; it is seen in amorphous form. The decrease in density at 21.6° with the surface modification proves that the change has occurred. The HSS nanoparticle has a peak visible at 18.2° around 2θ, and it is seen that it is in amorphous form. The decrease in density at 19.4° with the surface modification proves that the change has occurred. And also, e-SiO2 and e-SiO2-PVTri are amorphous forms at 22.5° around 2θ.
4.4. TGA Analysis
Weight loss graphs of TGA prove the existence of polymer grown from nanoparticles. Thermally stable compounds that remain in the residue (polymer-bound silica), and degradable polymer structures and initiators contribute to weight loss in the coated particles. The thermal stability of the PVTri polymer is 300–350°C [33]. The thermal degradation curves show that the thermal stability of the MSN-PVTri nanocomposite, formed after the vinyltriazole monomer is grown on the surface of the MSN nanoparticle, has increased to 400°C. After VTri polymerization on the surface of the HSS nanoparticle, TGA, a total weight loss of 40% is seen in Fig. 5. Moreover, it was sighted that the thermal stability of e-SiO2 nanoparticles increased after polymerization and preserved its structure by 85% above 800°C.
4.5. Minimum Inhibitor Concentration (MIC)
All three nanoparticles are more impressive against Gram-negative bacteria than Gram-positive ones and yeast strains. MSN-PVTri has smaller MIC values (0–1 mg/mL for S. cerevisiae and E. Coli and 5–10 mg/mL for S. aureus) because of its higher antifungal and antibacterial activities. The larger porous surface area of the MSN nanoparticle compared to HSS and e-SiO2 provide more vinyltriazole monomer binding to the surface and high antimicrobial activity. The HSS and e-SiO2 nanoparticles have similar effects on the S. cerevisiae and S. aureus cells (MIC: >10 mg/mL). On the other hand, e-SiO2 is more effective (MIC: 1–5 mg/mL) compared to HSS nanoparticles (MIC: 5–10 mg/mL) in the E. coli cells. The e-SiO2 nanoparticle has more vinyltriazole monomer binding side on its surface because of the epoxy ring compared to the HSS nanoparticle. For this reason, it is more effective than HSS nanoparticles on Gram-negative bacteria.
4.6. Effect of Silica Nanoparticles on HaCaT KeratinocytesIn this study, we have shown that the all concentrations of PVTri increased cell proliferation when applied alone for 24h, 48h and 72h on HaCaT cells. Although 1 mg concentration of e-SiO2 treatment significantly decreased the cell proliferation for 24 h and 72 h on HaCat cells, all the concentrations of e-SiO2-PVTri (1 mg, 0,5 mg, and 0,25 mg) increased the cell proliferation for 24h, 48h, and 72h on HaCat cells. HaCaT cells were treated at varios concentrations of HSS nanoparticles (1 mg, 0,5 mg, and 0,25 mg). Our results indicated that the 1 mg concentration of HSS- PVTri nanocomposite more increased cell proliferation than the treatment of HSS (1 mg) nanoparticle on HaCaT cells for 24 h, 48 h, and 72 h. HaCaT cells were also treated with MSN-PVTri (1 mg, 0,5 mg and 0,25 mg) nanoparticle for the 24 h, 48 h, and 72 h. According to these results, unlike the other two nanocomposites, all concentrations of MSN-PVTri treatment significantly reduced cell growth on HaCaT cells. In this study, we demonstrated that all nanocomposites which contain with PVTri increased the cell proliferation on HaCaT keratinocytes cells, except MSN nanoparticle.