The properties of nano-materials that used in making packaging films such as silver (AgNPs) and titanium oxide (TiO2NPs) were studied. The properties of the films such as tensile strength (TS), elongation (E), Young`s elastic modulus (EM), water vapor permeability (WVP), transparency and antibacterial properties of bio-composite film were studied for the edible films reinforced with AgNPs and TiO2 -NPs.
Figure 3 shows that the spherical particles sizes were of 10 ± 2 nm diameter. TEM analysis was carried out on 100 times dilution of colloidal suspension only few particles were observed in the small section of high-resolution image. Utilization of microwave irradiation treatment showing good results not only due to faster heating but it gives uniformly distributed monodispersed particles. Colour of the solution was changed by the formation of silver nanoparticles. The characteristic surface plasmon band at 416 nm that is slightly higher was shown the visible spectrum of silver nanoparticles (Fig. 4). These results agreed with those obtained by Pal et al23,27. Silver nanoparticles had refractive index of the surrounding medium because of its slightly red shift on surface plasmon.
Figure 3Shows the TEM of AgNPs a different scales (A) 100 nm, (B) 20 nm.
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Figure 4UV–vis and fluorescence spectroscopy of silver nanopartic.
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TiO2-NPs were measured by XRD to determine the crystallite size and the purity of nanoparticles. The crystallinity size of nanoparticles was confirmed by XRD analysis as shown in Fig. 5. The XRD spectrum of dry nanoparticles were high purity, clear and broad peaks. The XRD pattern fits well with a wurtzite structure and the average crystal (diameter). Therefore, the results XRD characterization allow to conclude the nanoparticles size have a radius of around 50 ± 5 nm. These results are accordance with obtained by Aboud et al32.
Figure 5XRD pattern of titanium oxide nanoparticles (TiO2-NPs).
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Table 2 shows the antibacterial activities of inorganic nanoparticles i.e. Silver nanoparticles (AgNPs) and Titanium oxide nanoparticles (TiO2-NPs) against four food-borne pathogens: Bacillus cereus, Salmonella Typhimurium, E.coli and Staphylococcus aureus were evaluated results conducted that Ag-Nps (~ 10 nm) and TiO2-NPs (~ 50 nm) at 80 ppm were effective against food-borne pathogens i.e. B. cereus, S. Typhimurium, E. coli 0157:H7 and S. aureus, than 20 and 40 ppm respectively. These result with partially agreement those result indicated by Khezerlou et al33 and Ejaz et al34. Moreover, AgNPs at 80 ppm were more effective against B.Cereus and E. Coli these results agreement with data those reported by Nanda and Saravanan35. As well, TiO2-NPs at 80 ppm were more active against B.cereus and S. Typhimurium these results were similar to the results those obtained by Martinez-Gutierrez et al36. AgNPs and TiO2- NPs incorporated composite films demonstrated strong antibacterial activity against both the Gram-positive and Gram-negative food borne pathogenic bacteria.
Table 2 Antibacterial activities of nanoparticles at different concentration against food-borne pathogens bacteria.Full size table
Figure 6 shows the antibacterial activities of silver nanoparticles (Ag-NPs) and titanium oxide nanoparticles (TiO2-NPs) at different concentrations 20, 40 and 80 ppm against S.Typhimurium. The results were at a concentration of 80 ppm for (Ag-NPs) and (Tio2-NPs) more value than 20 and 40 ppm, the inhibition zone diameter was 8 and 10 mm, respectively, in Fig. 7 shows that the antibacterial activities of silver nanoparticles (Ag-NPs) and titanium oxide nanoparticles (TiO2 -NPs) at different concentration 20, 40 and 80 ppm against E. coli. The results were at a concentration of 80 ppm for (Ag-NPs) and (Tio2 -NPs) more value than 20 and 40 ppm, the inhibition zone diameter was 10 and 9 mm, respectively, in Fig. 8 shows the antibacterial activities of silver nanoparticles (Ag-NPs) and titanium oxide nanoparticles (TiO2-NPs) at different concentrations 20, 40 and 80 ppm against S.aureus. The results were at a concentration of 80 ppm for (Ag-NPs) and (TiO2 -NPs) more value than 20 and 40 ppm, the inhibition zone diameter was 8 and 8 mm, respectively, and in Fig. 9 shows the antibacterial activities of silver nanoparticles (Ag-NPs) and titanium oxide nanoparticles (TiO2-NPs) agent at concentrations 20, 40 and 80 ppm against B.cereus. The results were at a concentration of 80 ppm for (Ag-NPs) and (TiO2-NPs) more value than 20 and 40 ppm, the inhibition zone diameter was 9 and 11 mm, respectively.
Figure 6Antibacterial activities of nanoparticles at different concentrations against S. Typhimurium.
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Figure 7Antibacterial activities of nanoparticles at different concentrations against E. coli.
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Figure 8Antibacterial activities of nanoparticles at different concentrations against S. aureus.
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Figure 9Antibacterial activities of nanoparticles at different concentrations against B. cereus.
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The average of bio-composite films thickness was tested (HMPC, HMPC reinforced with AgNPs, and HMPC reinforced with TiO2NPs). As shown in Table 3, the results values of control film (HMPC), HMPC-AgNPs, and HMPC-TiO2NPs were 0.30, 0.19, and 0.12 µm, respectively.
Table 3 Thickness of bio-composite films reinforced with nanoparticles.Full size table
The mechanical properties such as tensile strength, elongation, and Young`s elastic modulus were evaluated. As shown in Table 4 the tensile values of HPMC film reinforced with Ag NPs and TiO2-NPs were higher than that of tensile strength of HPMC films without nanoparticle (control), the results values were 39.24, 143.87and 157.92 MPa, respectively, for HMPC, HMPC reinforced with AgNPs, and HMPC reinforced with TiO2NPs. On the other hands, elongation was tested, the results obtained that, the HPMC film reinforced with Ag NPs and TiO2-NPs have higher value of elongation compared to than HPMC films without nanoparticle (control), the results values were 2, 35 and 42%, respectively, for HMPC, HMPC reinforced with AgNPs, and HMPC reinforced with TiO2NPs. In addition to, Young`s elastic modulus was evaluated, the results show that, HPMC film reinforced with Ag NPs and TiO2-NPs have lower values compared to than HPMC films without nanoparticle (control). The elongation values were 19.62, 4.11 and 3.76 MPa, respectively. That is due to (a) the nanoparticles’ ability to filling pore between HPMC film structures. (b) The water evaporates permeability during film formation (c) Hence, the increased surface area reinforces the (d) film thickness and biodegradable. These results are in agreement with those obtained by Martinez-Gutierrez et al36, Jiménez et al37, Silva-Weiss et al38, Ahmadi et al39, Osorio et al40 and Sievens-Figueroa et al41.
Table 4 tensile strength, elongation, and Young`s elastic modulus of bio-composite films reinforced with nanoparticles.Full size table
The mechanical properties such as tensile, elongation, and Young`s elastic modulus were evaluated by Using a texture analyze. In Fig. 10 shows Texture Curve of HPMC film (Control), Fig. 11 a texture analyze shows Texture Curve of HPMC- AgNPs, and Fig. 12 a texture analyze shows Texture Curve of HPMC- TiO2 NPs.
Figure 10Texture Curve of HPMC film (Control).
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Figure 11Texture Curve of HPMC film reinforced with AgNPs.
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Figure 12Texture Curve of HPMC film reinforced with TiO2-NPs.
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Figures 13, 14 and 15 show the relationship between the weight gain and time to calculate the slope (C) by linear regression (Y) and correlation coefficient (r2) which is used to determine of WVP transferred through the film was determined by measuring the weight gain. As shown in Table 5, the slope of bio-composite films which is used to determine of water permeability of bio-composite films reinforced with nanoparticles.
Figure 13Graph of HMPC film.
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Figure 14Graph of HMPC film reinforced with Ag NPs.
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Figure 15Graph of HMPC film reinforced with TiO2 NPs.
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Table 5 The slope of bio-composite films which is used to determine of water permeability of bio-composite films reinforced with nanoparticles.Full size table
Table 6 shows the average of weight gain with time to determine of WVP of bio-composite films. The WVP results showed that, HPMC film reinforced with Ag NPs and TiO2-NPs were less value than that of HPMC films without nanoparticle (control), the results values were 0.5076 × 10–3 and 0.4596 × 10–3, and 0.4504 × 10–3 (g/msPa), respectively. These data revert to (a) film thickness. (b) The ability of nanoparticles to fill the pores between the HPMC films structure. (c) HPMC diffusion with different nanoparticles and form homogenized structure37. The value of the film thickness (x) of HMPC control was 0.164 µm. The values of thickness of edible films reinforced with AgNPs and TiO2NPs were 0. 1855 and 0.1455 µm, respectively. These results are in agreement with those obtained by Jiménez et al37, Silva-Weiss et al38, Ahmadi et al39, Osorio et al40 and Sievens-Figueroa et al41.
Table 6 Water vapor permeability of bio-composite film reinforced with nano-particles after 24 h.Full size table
Table 7 shows the transparency of the bio-composite film based on HPMC film reinforced with nanoparticle of Ag NPs and TiO2-NPs compared to HPMC only. It could be seen that the visible light peak (VL) at different wavelengths 395, 430 and 550 nm ranged from 45 to 63% for HPMC film reinforced with Ag NPs and TiO2-NPs nanoparticle films, which it ranged from 58 to 73% for HPMC control. That is due to the difference in films reinforced with nanoparticles color42.
Table 7 Transparency of bio-composite film based on HPMC reinforced with nanoparticles (Ag- NPs and TiO2-NPs).Full size table
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