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Article

Antibacterial Activity of TiO2- and ZnO-Decorated with Silver Nanoparticles

1
Faculty of Chemical Technology, Hanoi University of Industry, BacTu Liem, Hanoi 100000, Vietnam
2
Institute for Tropical Technology, Vietnam Academy of Science and Technology, Hanoi 122100, Vietnam
3
Hanvet Pharmaceutical and Veterinary Materials JSC, Hungyen17000, Vietnam
4
Department of Chemistry, University of Montreal, Montreal, QC H3T 1J4, Canada
*
Author to whom correspondence should be addressed.
Département de chimie, biochimie et physique, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 4M3, Canada.
J. Compos. Sci. 2019, 3(2), 61; https://doi.org/10.3390/jcs3020061
Received: 23 May 2019 / Revised: 7 June 2019 / Accepted: 9 June 2019 / Published: 17 June 2019

Abstract

:
This work emphasizes the use of the silver decorative method to enhance the antibacterial activity of TiO2 and ZnO nanoparticles. These silver-decorated nanoparticles (hybrid nanoparticles) were synthesized using sodium borohydride as a reducing agent, with the weight ratio of Ag precursors/oxide nanoparticles = 1:30. The morphology and optical properties of these hybrid nanoparticles were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD) patterns, and UV-Vis spectroscopy. The agar-well diffusion method was used to evaluate their antibacterial activity against both Staphylococcus aureus and Escherichia coli bacteria, with or without light irradiation. The TEM images indicated clearly that silver nanoparticles (AgNPs, 5–10 nm) were well deposited on the surface of nano-TiO2 particles (30–60 nm). In addition to this, bigger AgNPs (<20 nm) were dispersed on the surface of nano-ZnO particles (30–50 nm). XRD patterns confirmed the presence of AgNPs in both Ag-decorated TiO2 and Ag-decorated ZnO nanoparticles. UV-Vis spectra confirmed that the hybridization of Ag and oxide nanoparticles led to a shift in the absorption edge of oxide nanoparticles to the lower energy region (visible region). The antibacterial tests indicated that both oxide pure nanoparticles did not exhibit inhibitory effects against bacteria, with or without light irradiation. However, the presence of AgNPs in their hybrids, even at low content (<40 mg/mL), leads to a good antibacterial activity, and higher inhibition zones under light irradiation as compared to those in dark were observed.

1. Introduction

It was reported in literature that nanoparticles can attack bacteria through six main mechanisms [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]: (i) destruction of the cell wall and peptidoglycan layer; (ii) release of toxic ions; (iii) destruction of protons efflux bombs and modification of membrane charges; (iv) formation of reactive oxygen species (ROS) degrading cell wall; (v) reactive oxygen species (ROS) degrading DNA, RNA, and proteins; and (vi) low adenosine triphosphate (ATP) production. In the case of metallic oxide nanoparticles (such as NiO, Co3O4, ZnO, Fe2O3, Fe3O4, MgO, CuO, TiO2, and SiO2), ROS is the predominant antibacterial mechanism, especially for nano-ZnO and nano-TiO2. For noble metal nanoparticles, such as silver nanoparticles (AgNPs), they can attack effectively against both Gram-negative and Gram-positive bacteria [16,17,18,19] via all six abovementioned antimicrobial mechanisms [20,21,22]. Therefore, in this application, AgNPs can be used as the sole antimicrobial agent. AgNPs could also react with bacteria through the photocatalytic production of ROS in solution [23]. However, Ag+-free ions released from AgNPs are considered toxic not only to human cells but also to the environment. Loading (embedding/immobilizing) AgNPs into oxide matrices is a new approach due to its ability to control solubility and toxicity of AgNPs. Various metallic oxide matrices have been used for loading/hybridizing AgNPs, such SiO2, ZrO2, Al2O3, Fe3O4, and CuO [24].
In the case of ZnO and TiO2 nanoparticles, they can kill bacteria mainly through the ROS mechanism in the presence of UV light. The practical applications of these semiconducting oxide nanoparticles are limited due to the following two reasons: (i) wide band gap ~3.2 eV for nano-TiO2 [25] and 3.37 eV for nano-ZnO [26] and (ii) high recombination of photogenerated electron–hole pairs [27,28,29]. Thus, two main approaches have been tried to improve the photocatalytic properties of these nanoparticles: (1) diminution of the recombination for photogenerated electron–hole pairs and (2) enhancement of the visible light sensitivity [25]. The first pathway focused on the design of heterostructures (heterojunctions) for these semiconducting oxide nanoparticles [30,31,32,33,34]. The formation of the Schottky barriers at the interface of noble metals/semiconducting oxide nanoparticles could significantly enhance the segregation of charges and helps to reduce the charge recombination [35,36]. For this reason, under UV irradiation, Ag-doped TiO2 layers exhibited higher antibacterial activity against Pseudomonas aeruginosa bacteria compared to pure TiO2 layers [37]. It is reported that the sensibility of TiO2 with visible light could be significantly enhanced by doping with various elements [38,39].
Recently, the hybridization of noble metals (Au, Ag, Pd) and semiconducting oxides has become the most promising strategy to defeat the large band gap of semiconducting oxides [40,41,42,43,44]. The energy level alignment is combined by the heterojunction at the nanoscale in these nanoparticles. We have also recently published several books and articles on related topics [21,40,45,46].
In this study, the hybridization of AgNPs and ZnO/TiO2 nanoparticles is expected not only to simply combine properties of single components, but also to significantly enhance their antibacterial properties [46]. Thus, this work aimed to investigate the role of silver decoration in enhancing the antibacterial activity of ZnO and TiO2 nanoparticles against Staphylococcus aureus (ATCC 25923, Gram-positive) and Escherichia coli (Gram-negative, ATCC 25922).

2. Materials and Methods

2.1. Materials

TiO2 (rutile) and ZnO nanoparticles were purchased from Sigma Aldrich (Singapore), having a mean diameter of <100 nm and a specific surface area of 18 and 15–25 m2/g, respectively. AgNO3 and NaBH4 were provided by Sigma Aldrich (Pathumwan, Bangkok, Thailand).

2.2. Synthesis of Silver-Decorated Nanoparticles

Firstly, 0.2 g of TiO2 (or ZnO) nanoparticles was dispersed in 200 mL of distilled water under ultrasonication. AgNO3 solution (0.01 g in 20 mL water) was then slowly added into the prepared nano-TiO2 (or ZnO) solution under ultrasonication for 30 min. The mixing solution was then poured into the 500 mL three-necked pot. Then, NaBH4 solution (0.01 g in 30 mL water) was added dropwise (1 drop/s) to the 500 mL three-necked pot. The reaction temperature was kept at 4 °C, and reaction mixture was stirred mechanically for 60 min. The nanohybrids were then collected by centrifugation at high speed (10,000 rpm) for 5 min. The residual precursors and agents were then fully removed after several rounds of centrifugation by adding fresh distilled water.

2.3. Characterization

The morphology of the hybrid nanoparticles was investigated using a transmission electron microscopy (JEM1010, JEOL, Tokyo, Japan), operating at 80 kV. UV–Vis spectra were obtained using a CINTRA 40 spectrophotometer (Cintra, Austin, TX, USA) in absorbance mode with 2 nm slip width. To verify the possible phases that were present in the Ag-decorated oxide nanoparticles, the X-ray diffraction method was used a Siemens D5000 diffractor (Siemens/Bruker, Aubrey, TX, USA) with CuKα radiation at the scan rate of 0.015°·s−1).

2.4. Antibacterial Tests

The agar-well diffusion method was used to evaluate antibacterial activity against Gram-positive (Staphylococcus aureus—ATCC 25923) and Gram-negative (Escherichia coli—ATCC 25922) bacteria. Nutrient agar plates were inoculated in brain heart infusion (BHI) broth using 100 µL of 106 CFU bacterial suspensions. Wells (8 mm diameter) were then punched in the inoculated plates using a sterile plastic rod. These wells were then filled with 50 µL of solution containing nanoparticles, at various concentrations, such as 8, 16, and 40 mg/mL. Control wells were filled with 50 µL of distilled water. These plates were the incubated at 37 °C for 18 h (with or without light irradiation). After this period, the antibacterial activities of these nanoparticles were evaluated by measuring the inhibition zone diameter around the wells (100 µm resolution; Model: Haloes Caliper—Zone Reader, IUL, Barcelone, Spain).
For the light irradiation test, LED (cold white, 1500 mcd, 3V DC) bulbs (two bulbs) were used with an illumination intensity of 300 lux. These cold white LEDs were designed by mixing blue (450–470 nm) and yellow (560–590 nm) lights that could be perceived by the naked eye as white color [46].

3. Results and Discussions

3.1. Characterization of Prepared Ag/TiO2 and Ag/ZnO Nanoparticles

Figure 1 shows the electron microscopy images of AgNP-decorated nano-TiO2 particles. As can be seen in this figure, AgNPs (black particles, 5–10 nm) were well dispersed on the surface of nano-TiO2 particles (30–60 nm). The bigger nanoparticles are assigned to nano-TiO2 and the smaller ones are AgNPs, as described in the literature [21]. It is worth noting that the synthesis process of hybrid nanoparticles was optimized to obtain the reported sizes of the hybrid nanoparticles.
TEM images of AgNP-decorated nano-ZnO particles are shown in Figure 2. As shown in this figure, AgNPs (black spots <20 nm) were alternatively deposited and linked to nano-ZnO nanoparticles (30–50 nm). The presence of AgNPs is proven by a sharp peak, located at 410 nm in the UV-vis spectra for these Ag/ZnO nanohybrids. For a comparative study, the size of AgNPs deposited on the surface of TiO2 nanoparticles was smaller than that on the surface of ZnO nanoparticles.
Figure 3 presents the XRD patterns of TiO2 and Ag/TiO2 nanoparticles. Figure 3a shows that the rutile phases of TiO2 exhibit several diffraction peaks, and the reflections at at (110), (101), (111), and (211) appear as the most intense, which is in line with the literature [47]. In the case of Ag/TiO2 in Figure 3b, the intense peak at 38° refers to a (111) reflection of metallic Ag [48]. Due to low concentration (as compared to TiO2 nanoparticles), other peaks of Ag are dominated by TiO2 phases.
Figure 4 shows the XRD patterns of ZnO and Ag/ZnO nanoparticles. For the pure ZnO nanoparticles, all characteristics of the X-rau diffraction for ZnO are observed, especially the 100, 103, and 202 plans. In the case of ZnO-decorated with metallic Ag, some new peaks assigned to the (111), (200), (220), and (311) reflections are observed at high intensity [48,49]. This helps to confirm the presence of successful synthesis of these nanomaterials.
Figure 5 shows the UV-visible spectra of aqueous solutions containing AgNPs, TiO2, and Ag/TiO2 nanoparticles. In the case of AgNPs (~10 nm of diameter), a broad band around 398 nm is believed to be present due to the surface plasmon resonance (SPR peak) of AgNPs [50]. The absorption band for pure TiO2 nanoparticles was observed in the UV region (at 360 nm), whereas it was shifted to the visible region for Ag-decorated TiO2 nanoparticles. These results are in line with those reported in the literature for Ag-doped TiO2 nanomaterials [51,52]. Figure 6 shows the UV-visible spectra for nano-ZnO- and nano-TiO2-decorated with AgNPs (dispersed in water). This figure shows a broad band at the 410 nm band, indicating the presence of AgNPs on the surface of the nano-ZnO particles.

3.2. Antibaterial Tests

3.2.1. TiO2 and Ag/TiO2 Nanoparticles

Figure 7 and Figure 8 present the photographs of antibacterial tests for nano-TiO2 and Ag/TiO2 NPs against S. aureus and E. coli bacteria, with and without light irradiation, respectively. Table 1 and Table 2 show their corresponding inhibition zones. Figure 7a,b indicates that in the dark, TiO2 NPs do not exhibit inhibitory effects to S. aureus bacteria (at concentrations of 10–40 mg/mL), whereas Ag-loaded TiO2 NPs show a significant antibacterial activity at a concentration of 40 mg/mL. It was reported that TiO2 nanoparticles are easy to attach to the cell membranes and accumulate [53,54,55]. In general, TiO2 nanoparticles can destroy the pathogenic bacteria by the ROS mechanism under UV light radiation. Since the emitted wavelengths of the white LED lights include peaks in the blue (450–470 nm) and yellow (560–590nm) areas, the inhibition zone of Ag-loaded TiO2 NPs (40 mg/mL) could be attributed to the content of AgNPs in the nanohybrids (e.g., ~1.3 mg/mL). It is worth noting that the concentration of TiO2 in nanohybrids is 30 times higher than that of AgNPs (from synthesis: the weight ratio of Ag precursors:TiO2 = 1:30). These nanoparticles exhibited an inhibition zone of 2 mm (in diameter) at the lower concentration of 16 mg/mL, indicating the contribution of TiO2 nanoparticles in these nanohybrids to their antibacterial activity (Table 1). At a concentration of 40 mg/mL, their inhibition zone is similar to that observed in the dark (4 mm in diameter), indicating the dominated contribution of AgNPs to the antibacterial activity.
Figure 7c,d shows that TiO2 NPs did not exhibit inhibitory effects to bacteria under light irradiation (at concentration of 8–40 mg/mL). It was reported that the doping TiO2 with noble metals shifted its absorption band to the visible region [40]. Without UV irradiation, pure TiO2 nanoparticles did not inhibit bacterial growth. However, Ag–TiO2 core–shell nanoparticles exhibited a good antibacterial activity against both E. coli and S. aureus bacteria without UV light [56,57]. Other authors have also reported that TiO2 nanoparticles with highly dispersed Ag clusters are entirely restricted the growth of the E. coli bacterial [58]. Barudin et al. [59] indicated that Ag–TiO2 nanoparticles exhibited superior antibacterial activity, as compared to pure TiO2 nanoparticles, even under visible light irradiation [59].
In this work, for E. coli bacteria, under light irradiation, Ag/TiO2 nanohybrids show a higher antibacterial activity than that in the dark. Table 2 shows that, in the dark, the inhibition zones of Ag/TiO2 nanohybrids increase with their concentration, due to the increase of AgNP concentration in the nanohybrids.

3.2.2. ZnO and Ag/ZnO Nanoparticles

It was reported in literature that ZnO has the inherent gain of broad antibacterial activities against virus, bacteria, fungus, and spores [60,61,62]. Stoimenov et al. [63] defined that ZnO nanoparticles attach on the bacterial surface due to electrostatic force of attraction. We expect that the hybridization of AgNPs with ZnO NPs may exhibit a superior antibacterial activity compared to their counterparts [45].
Figure 9 and Figure 10 show the photographs of an antibacterial test for nano-ZnO and Ag/ZnO NPs against S. aureus and E. coli bacteria, without and with light irradiation, respectively. Table 3 and Table 4 show their corresponding inhibition zones. Figure 9 and Figure 10 indicate that ZnO NPs did not exhibit inhibitory effects for both bacteria, with or without light irradiation (at concentrations of 10–40 mg/mL).
For Ag/ZnO nanohybrids, as shown in Table 3 and Table 4, light irradiation leads to an increase of the diameter of the inhibition zone for both S. aureus (at 8 mg/mL) and E. coli (at 8, 16, and 40 mg/mL) bacteria. Similarity, Ibanescu et al. [64] reported the antimicrobial property of Ag/ZnO nanocomposites against both E. coli and M. luteus bacteria. Their finding indicates that small amounts of silver could significantly enhance antimicrobial activity. The photocatalytic activity of Ag/ZnO nanocomposites could also contribute to enhancing antimicrobial activity. Nagaraju et al. [65] indicated an improvement of antimicrobial activity of Ag–ZnO NPs against both E. coli and S. aureus bacteria compared to pure materials. The inhibition zone could be observed at a concentration of 500 µg Ag–ZnO NPs. Wei et al. [66] also described the high antibacterial activity of Ag–ZnO hybrid nanofibers against E. coli and P. aeruginosa bacteria.
For the comparative study, under light irradiation at a low concentration (8 mg/mL), Ag/ZnO nanohybrids exhibit higher antibacterial activity against both two bacteria than Ag–Ag/TiO2 nanohybrids. One possible explanation is the better hybridization between Ag and ZnO nanoparticles, through the presence of the SPR peak in Ag/ZnO nanoparticles (Figure 6), whereas the SPR peak seems to disappear in the Ag/TiO2 nanoparticles (Figure 5).

4. Conclusions

This research is a continuous works focused on polymers and multifunctional composites [67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86]. The main findings of this work were as follows:
  • Silver-decorated oxide nanoparticles were successfully prepared using sodium borohydride as a reducing agent, with the weight ratio of Ag precursors:oxide nanoparticles = 1:30.
  • The TEM images indicated that AgNPs (5–10 nm) were deposited on the surface of nano-TiO2 particles (30–60 nm), whereas the bigger AgNPs (<20 nm) were dispersed on the surface of nano-ZnO particles (30–50 nm). XRD patterns confirmed the presence of AgNPs in both Ag-decorated TiO2 and Ag-decorated ZnO nanoparticles.
  • UV-vis spectra indicated that the hybridization of Ag and oxide nanoparticles led to a shift in the absorption edge of oxide nanoparticles to the lower energy region (visible region).
  • The antibacterial tests indicated that both oxide nanoparticles did not exhibit inhibitory against bacteria, with or without light irradiation. However, the presence of AgNPs in their hybrids (at a concentration <40 mg/mL) exhibited higher inhibition zones under light irradiation, as compared to that in dark. At a high concentration of 40 mg/mL, the antibacterial behavior of these nanohybrids under light irradiation is similar to that in dark, indicating the dominated contribution of AgNPs to the antibacterial activity of these nanohybrids (at this high concentration).
  • In the comparative study, under light irradiation at a low concentration (8 mg/mL), Ag/ZnO nanohybrids exhibited higher antibacterial activity against both bacteria than the Ag–Ag/TiO2 nanohybrids.

Author Contributions

Conceptualization and methodology, P.N.-T., T.A.N. and V.T.N.; synthesis of ZnO–AgNPs, V.T.V., V.K.T. and V.T.N.; Synthesis of TiO2–AgNPs, T.H.N. and V.K.T.; writing—original draft preparation, T.A.N.; writing—review and editing P.N.-T.; supervision, P.N.-T.

Funding

This work was financial supported by Natural Sciences and Engineering Research Council of Canada (NSERC).

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Rai, V.R.; Bai, A.J. Nanoparticles and their potential application as antimicrobials. In Science against microbial pathogens: Communicating current research and technological advances, Formatex, Microbiology Series No.3; Méndez-Vilas, A., Ed.; Elsevier: Badajoz, Spain, 2011; Volume 1, pp. 97–209. [Google Scholar]
  2. BECON. Nanoscience and Nanotechnology Symposium Report; National Institutes of Health Bioengineering Consortium: Bethesda, MD, USA, June 2000. Available online: http://www.uta.edu/rfmems/060515-NSF-NUE/Info/biomed/nanotechsympreport.pdf (accessed on 10 June 2019).
  3. Rtimi, S.; Nadtochenko, V.; Khmel, I.; Konstantinidis, S.; Britun, N.; Kiwi, J. Monitoring the energy of the metal ion-content plasma-assisted deposition and its implication for bacterial inactivation. Appl. Sur. Sci. 2019, 467, 749–752. [Google Scholar] [CrossRef]
  4. Oesterling, E.; Chopra, N.; Gavalas, V.; Arzuaga, X.; Lim, E.J.; Sultana, R.; Butterfield, D.A.; Bachas, L.; Hennig, B. Alumina nanoparticles induce expression of endothelial cell adhesion molecules. Toxicol. Lett. 2008, 178, 160–166. [Google Scholar] [CrossRef] [PubMed]
  5. Dey, S.; Bakthavatchalu, V.; Tseng, M.T.; Wu, P.; Florence, R.L.; Grulke, E.A.; Yokel, R.A.; Dhar, S.K.; Yang, H.-S.; Chen, Y.; et al. Interactions between SIRT1 and AP-1 reveal a mechanistic insight into the growth promoting properties of alumina (Al2O3) nanoparticles in mouse skin epithelial cells. Carcinogenesis 2008, 29, 1920–1929. [Google Scholar] [CrossRef] [PubMed][Green Version]
  6. Chang, Y.-N.; Zhang, M.; Xia, L.; Zhang, J.; Xing, G. The Toxic Effects and Mechanisms of CuO and ZnO Nanoparticles. Materials 2012, 5, 2850–2871. [Google Scholar] [CrossRef][Green Version]
  7. Karlsson, H.L.; Cronholm, P.; Gustafsson, J.; Möller, L. Copper Oxide Nanoparticles Are Highly Toxic: A Comparison between Metal Oxide Nanoparticles and Carbon Nanotubes. Chem. Res. Toxicol. 2008, 21, 1726–1732. [Google Scholar] [CrossRef] [PubMed]
  8. Xia, T.; Kovochich, M.; Liong, M.; Mädler, L.; Gilbert, B.; Shi, H.; Yeh, J.I.; Zink, J.I.; Nel, A.E. Comparison of the Mechanism of Toxicity of Zinc Oxide and Cerium Oxide Nanoparticles Based on Dissolution and Oxidative Stress Properties. ACS Nano 2008, 2, 2121–2134. [Google Scholar] [CrossRef] [PubMed][Green Version]
  9. Rtimi, S.; Dionysiou, D.; Pillai, S.C.; Kiwi, J. Advances in catalytic/photocatalytic bacterial inactivation by nano Ag and Cu coated surfaces and medical devices. Appl. Catal. B Environ. 2019, 240, 291–318. [Google Scholar] [CrossRef]
  10. Ren, G.; Hu, D.; Cheng, E.W.; Vargas-Reus, M.A.; Reip, P.; Allaker, R.P. Characterisation of copper oxide nanoparticles for antimicrobial applications. Int. J. Antimicrob. Agents 2009, 33, 587–590. [Google Scholar] [CrossRef] [PubMed]
  11. Niskanen, J.; Shan, J.; Tenhu, H.; Jiang, H.; Kauppinen, E.; Barranco, V.; Picó, F.; Yliniemi, K.; Kontturi, K. Synthesis of copolymer-stabilized silver nanoparticles for coating materials. Colloid Polym. Sci. 2010, 288, 543–553. [Google Scholar] [CrossRef]
  12. Guggenbichler, J.-P.; Böswald, M.; Lugauer, S.; Krall, T. A new technology of microdispersed silver in polyurethane induces antimicrobial activity in central venous catheters. Infect 1999, 27, S16–S23. [Google Scholar] [CrossRef]
  13. Azam, A.; Ahmed, A.S.; Oves, M.; Khan, M.; Memic, A. Size-dependent antimicrobial properties of CuO nanoparticles against Gram-positive and -negative bacterial strains. Int. J. Nanomed. 2012, 7, 3527–3535. [Google Scholar] [CrossRef] [PubMed][Green Version]
  14. Allaker, R.P. The use of nanoparticles to control oral biofilm formation. J. Dent. Res. 2010, 89, 1175–1185. [Google Scholar] [CrossRef] [PubMed]
  15. Santos, C.L.; Albuquerque, A.J.R.; Sampaio, F.C.; Keyson, D. Nanomaterials with Antimicrobial Properties: Applications in Health Sciences. In Microbial Pathogens and Strategies for Combating Them: Science, Technology and Education; Méndez-Vilas, A., Ed.; Formatex: Badajoz, Spain, 2013. [Google Scholar]
  16. Huang, H.H.; Ni, X.P.; Loy, G.L.; Chew, C.H.; Tan, K.L.; Loh, F.C.; Deng, J.F.; Xu, G.Q. Photochemical Formation of Silver Nanoparticles in Poly(N-vinylpyrrolidone). Langmuir 1996, 12, 909–912. [Google Scholar] [CrossRef]
  17. Weir, E.; Lawlor, A.; Whelan, A.; Regan, F. The use of nanoparticles in anti-microbial materials and their characterization. Analyst 2008, 133, 835–845. [Google Scholar] [CrossRef] [PubMed]
  18. Marambio-Jones, C.; Hoek, E.M.V. A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment. J. Nanopart. Res. 2010, 12, 1531–1551. [Google Scholar] [CrossRef]
  19. Shenashen, M.A.; El-Safty, S.A.; Elshehy, E.A. Synthesis, morphological control, and properties of silver nanoparticles in potential applications. Part. Part. Syst. Charact. 2014, 31, 293–316. [Google Scholar] [CrossRef]
  20. Li, Q.; Mahendra, S.; Lyon, D.Y.; Brunet, L.; Liga, M.V.; Li, D.; Alvarez, P.J. Antimicrobial nanomaterials for water disinfection and microbial control: Potential applications and implications. Water Res. 2008, 42, 4591–4602. [Google Scholar] [CrossRef]
  21. Nguyen-Tri, P.; Nguyen, V.T.; Nguyen, T.A. Biological activity and nanostructuration of Fe3O4-Ag/polyethyelene nanocomposites. J. Compos. Sci. 2019, 3. [Google Scholar] [CrossRef]
  22. Hussain, S.M.; Hess, K.L.; Gearhart, J.M.; Geiss, K.T.; Schlager, J.J. In vitro toxicity of nanoparticles in BRL 3A rat liver cells. Toxicol. Vitr. 2005, 19, 975–983. [Google Scholar] [CrossRef]
  23. Le Ouay, B.; Stellacci, F. Antibacterial activity of silver nanoparticles: A surface science insight. Nano Today 2015, 10, 339–354. [Google Scholar] [CrossRef][Green Version]
  24. Dhanalekshmi, K.; Van Thang Nguyen, I.; Magesan, P. Chapter 26: Nanosilver loaded oxide nanoparticles for antibacterial application. In Smart Nanocontainers: Fundamentals and Emerging Applications; Nguyen-Tri, P., Do, T.-O., Nguyen, T.A., Eds.; Elsevier: Amsterdam, The Netherlands, 2019; ISBN 9780128167700. [Google Scholar]
  25. Akhavan, O. Lasting antibacterial activities of Ag–TiO2/Ag/a-TiO2 nanocomposite thin film photocatalysts under solar light irradiation. J. Colloid Interface Sci. 2009, 336, 117–124. [Google Scholar] [CrossRef] [PubMed]
  26. Gholap, H.; Warule, S.; Sangshetti, J.; Kulkarni, G.; Banpurkar, A.; Satpute, S.; Patil, R. Hierarchical nanostructures of [email protected]: Antibacterial and antibiofilm agent. Appl. Microbiol. Biotechnol. 2016, 100, 5849–5858. [Google Scholar] [CrossRef] [PubMed]
  27. Tamaki, Y.; Hara, K.; Katoh, R.; Tachiya, M. A Furub Femtosecond visible-to-IR spectroscopy of TiO2 nanocrystalline films: Elucidation of the electron mobility before deep trapping. J. Phys. Chem. C 2009, 113, 11741–11746. [Google Scholar] [CrossRef]
  28. Chen, X.; Mao, S.S. Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications. Chem. Rev. 2007, 107, 2891–2959. [Google Scholar] [CrossRef] [PubMed]
  29. Kudo, A.; Miseki, Y. Heterogeneous photocatalyst materials for water splitting. Chem. Soc. Rev. 2009, 38, 253–278. [Google Scholar] [CrossRef] [PubMed]
  30. Sun, L.; Li, J.; Wang, C.; Li, S.; Lai, Y.-K.; Chen, H.; Lin, C. Ultrasound aided photochemical synthesis of Ag loaded TiO2 nanotube arrays to enhance photocatalytic activity. J. Hazard. Mater. 2009, 171, 1045–1050. [Google Scholar] [CrossRef] [PubMed]
  31. Abdulla-Al-Mamun, M.; Kusumoto, Y.; Zannat, T.; Islam, M.S. Synergistic enhanced photocatalytic and photothermal activity of [email protected]2 nanopellets against human epithelial carcinoma cells. Phys. Chem. Chem. Phys. 2011, 13, 21026. [Google Scholar] [CrossRef] [PubMed]
  32. Jang, J.S.; Choi, S.H.; Kim, H.G.; Lee, J.S. Location and State of Pt in Platinized CdS/TiO2 Photocatalysts for Hydrogen Production from Water under Visible Light. J. Phys. Chem. C 2008, 112, 17200–17205. [Google Scholar] [CrossRef]
  33. Sarkart, D.; Ghosh, C.K.; Mukherjee, S.; Chattopadhyay, K.K. Three dimensional Ag2O/TiO2 type-II (p-n) nanoheterojunctions for superior photocatalytic activity. ACS Appl. Mater. Interfaces 2013, 5, 331–337. [Google Scholar] [CrossRef]
  34. Ji, Y.F.; Guo, W.; Chen, H.H.; Zhang, L.S.; Chen, S.; Hua, M.T.; Long, Y.H.; Chen, Z. Surface Ti3+/Ti4+ redox shuttle enhancing photocatalytic H2 production in ultrathin TiO2 nanosheets/CdSe quantum dots. J. Phys. Chem. C 2015, 119, 27053–27059. [Google Scholar] [CrossRef]
  35. Deng, Q.; Tang, H.; Liu, G.; Song, X.; Xu, G.; Li, Q.; Ng, D.H.; Wang, G. The fabrication and photocatalytic performances of flower-like Ag nanoparticles/ZnO nanosheets-assembled microspheres. Appl. Surf. Sci. 2015, 331, 50–57. [Google Scholar] [CrossRef]
  36. Liang, Y.M.; Guo, N.; Li, L.L.; Li, R.Q.; Ji, G.J.; Gan, S.C. Fabrication of porous 3D flower-like Ag/ZnO heterostructure composites with enhanced photocatalytic performance. Appl. Surf. Sci. 2015, 332, 32–39. [Google Scholar] [CrossRef]
  37. Ubonchonlakate, K.; Sikong, L.; Saito, F.P. aeruginosa inactivation with silver and nickel doped TiO2 films coated on glass fiber roving. Adv. Mater. Res. 2011, 150–151, 1726–1731. [Google Scholar]
  38. Umebayashi, T.; Yamaki, T.; Tanaka, S.; Asai, K. Visible light-induced degradation of methylene blue on S-doped TiO2. Chem. Lett. 2003, 32, 330–331. [Google Scholar] [CrossRef]
  39. Pelaez, M.; Nolan, N.T.; Pillai, S.C.; Seery, M.K.; Falaras, P.; Kontos, A.G.; Dunlop, P.S.M.; Hamilton, J.W.J.; Byrne, J.A.; O’Shea, K.; et al. A Review on the Visible Light Active Titanium Dioxide Photocatalysts for Environmental Applications. Appl. Catal. B Environ. 2012, 125, 331–349. [Google Scholar] [CrossRef]
  40. Mohapatra, S.; Nguyen, T.A.; Nguyen-Tri, P. Noble Metal-Metal Oxide Hybrid Nanoparticles: Fundamentals and Applications; Elsevier: Amsterdam, The Netherlands, 2018; Volume 1. [Google Scholar]
  41. Fageria, P.; Gangopadhyay, S.; Pande, S. Synthesis of ZnO/Au and ZnO/Ag nanoparticles and their photocatalytic application using UV and visible light. RSC Adv. 2014, 4, 24962–24972. [Google Scholar] [CrossRef]
  42. Xu, C.; Chen, P.; Liu, J.; Yin, H.; Gao, X.; Mei, X. Fabrication of visible-light-driven Ag/TiO2 heterojunction composites induced by shock wave. J. Alloy. Compd. 2016, 679, 463–469. [Google Scholar] [CrossRef]
  43. Xu, F.; Mei, J.; Zheng, M.; Bai, D.; Wu, D.; Gao, Z.; Jiang, K. Au nanoparticles modified branched TiO2 nanorod array arranged with ultrathin nanorods for enhanced photoelectrochemical water splitting. J. Alloy. Compd. 2017, 693, 1124–1132. [Google Scholar] [CrossRef]
  44. Chang, Y.; Xu, J.; Zhang, Y.; Ma, S.; Xin, L.; Zhu, L.; Xu, C. Optical Properties and Photocatalytic Performances of Pd Modified ZnO Samples. J. Phys. Chem. C 2009, 113, 18761–18767. [Google Scholar] [CrossRef]
  45. Tri, P.N.; Nguyen, T.A.; Nguyen, T.H.; Carriere, P. Antibacterial Behavior of Hybrid Nanoparticles (Chapter 7). In Noble Metal-Metal Oxide Hybrid Nanoparticles: Fundamentals and Applications; Mohapatra, S., Nguyen, T.H., Nguyen-Tri, P., Eds.; Elsevier: Amsterdam, The Netherlands, 2019; pp. 141–155. [Google Scholar] [CrossRef]
  46. Standard and White LED Basics and Operation. Available online: https://www.maximintegrated.com/en/app-notes/index.mvp/id/3070 (accessed on 10 June 2019).
  47. Reyes-Coronado, D.; Gattorno, G.R.; E Espinosa-Pesqueira, M.; Cab, C.; De Coss, R.; Oskam, G. Phase-pure TiO2 nanoparticles: Anatase, brookite and rutile. Nanotechnology 2008, 19. [Google Scholar] [CrossRef]
  48. Alshamsi, H.A.H.; Hussein, B.S. Hydrothermal Preparation of Silver Doping Zinc Oxide Nanoparticles: Studys, Characterization and Photocatalytic Activity. Orient. J. Chem. 2018, 34, 1898–1907. [Google Scholar] [CrossRef]
  49. Anandalakshmi, K.; Venugobal, J.; Ramasamy, V. Characterization of silver nanoparticles by green synthesis method using Pedalium murex leaf extract and their antibacterial activity. Appl. Nanosci. 2016, 6, 399–408. [Google Scholar] [CrossRef]
  50. Kuriakose, S.; Choudhary, V.; Satpati, B.; Mohapatra, S.; Xu, R. Enhanced photocatalytic activity of Ag–ZnO hybrid plasmonic nanostructures prepared by a facile wet chemical method. Beilstein J. Nanotechnol. 2014, 5, 639–650. [Google Scholar] [CrossRef]
  51. Kuriakose, S.; Choudhary, V.; Satpati, B.; Mohapatra, S. Facile synthesis of Ag-ZnO hybrid nanospindles for highly efficient photocatalytic degradation of methyl orange. Phys. Chem. Chem Phys. 2014, 16, 17560–17568. [Google Scholar] [CrossRef] [PubMed]
  52. Tian, Y.; Tatsuma, T. Plasmon-induced photoelectrochemistry at metal nanoparticles supported on nanoporous TiO2. Chem. Commun. 2004, 16, 1810. [Google Scholar] [CrossRef] [PubMed]
  53. Cai, R.; Hashimoto, K.; Itoh, K.; Kubota, Y.; Fujishima, A. Photokilling of malignant cells with ultrafine TiO2 powder. Bull. Chem. Soc. Jpn. 1991, 64, 1268–1273. [Google Scholar] [CrossRef]
  54. Ubonchonlakate, K.; Sikong, L.; Saito, F. Photocatalytic disinfection of P. aeruginosa bacterial Ag-doped TiO2 film. Procedia Eng. 2012, 32, 656–662. [Google Scholar] [CrossRef]
  55. Sakthivel, S.; Shankar, M.; Palanichamy, M.; Arabindoo, B.; Bahnemann, D.; Murugesan, V. Enhancement of photocatalytic activity by metal deposition: Characterisation and photonic efficiency of Pt, Au and Pd deposited on TiO2 catalyst. Water Res. 2004, 38, 3001–3008. [Google Scholar] [CrossRef] [PubMed]
  56. Yue, L.; Wang, Q.; Zhang, X.; Wang, Z.; Xia, W.; Dong, Y. Synthesis of Ag/TiO2 Core/Shell Nanoparticles with Antibacterial Properties. Bull. Korean Chem. Soc. 2011, 32, 2607–2610. [Google Scholar] [CrossRef]
  57. Dhanalekshmi, K.I.; Meen, K.S.; Ramesh, I. Synthesis and Characterization of [email protected]2 Core-shell nanoparticles and study of its antibacterial activity. Int. J. Nanotechnol. Appl. 2013, 3, 5–14. [Google Scholar]
  58. Zhang, H.; Chen, G. Potent Antibacterial Activities of Ag/TiO2 Nanocomposite Powders Synthesized by a One-Pot Sol−Gel Method. Environ. Sci. Technol. 2009, 43, 2905–2910. [Google Scholar] [CrossRef]
  59. Hidayati, N.; Barudin, A.; Sreekantan, S.; Thong, O.M.; Sahgal, G. Antibacterial Activity of Ag-TiO2 Nanoparticles with Various Silver Contents. Mater. Sci. Forum 2013, 756, 238–245. [Google Scholar]
  60. Jin, T.; Sun, D.; Su, J.Y.; Zhang, H.; Sue, H.J. Antimicrobial Efficacy of Zinc Oxide Quantum Dots against Listeria monocytogenes, Salmonella Enteritidis, and Escherichia coli O157:H7. J. Food Sci. 2009, 74, M46–M52. [Google Scholar] [CrossRef]
  61. Kumar, K.M.; Mandal, B.K.; Naidu, E.A.; Sinha, M.; Kumar, K.S.; Reddy, P.S. Synthesis and Characterization of Flower Shaped Zinc Oxide Nanostructures and Its Antimicrobial Activity. Spectrochim. Actapart A 2013, 104, 171–174. [Google Scholar] [CrossRef]
  62. Lipovsky, A.; Nitzan, Y.; Gedanken, A.; Lubart, R. Antifungal activity of ZnO nanoparticles—The role of ROS mediated cell injury. Nanotechnology 2011, 22, 105101. [Google Scholar] [CrossRef]
  63. Stoimenov, P.K.; Klinger, R.L.; Marchin, G.L.; Klabunde, K.J. Metal Oxide Nanoparticles as Bactericidal Agents. Langmuir 2002, 18, 6679–6686. [Google Scholar] [CrossRef]
  64. Ibănescu, M.; Muşat, V.; Textor, T.; Badilita, V.; Mahltig, B. Photocatalytic and antimicrobial Ag/ZnO nanocomposites for functionalization of textile fabrics. J. Alloy. Compd. 2014, 610, 244–249. [Google Scholar] [CrossRef]
  65. Nagaraju, G.; Udayabhanu; Shivaraj; Prashanth, S.A.; Shastri, M.; Yathish, K.V.; Anupama, C.; Rangappa, D. Electrochemical heavy metal detection, photocatalytic, photoluminescence, biodiesel production and antibacterial activities of Ag–ZnO nanomaterial. Mater. Res. Bull. 2017, 94, 54–63. [Google Scholar] [CrossRef]
  66. Wei, Y.; Chong, Y.B.; Du, H.; Kong, J.; He, C. Loose Yarn of Ag-ZnO-PAN/ITO Hybrid Nanofibres: Preparation, Characterization and Antibacterial Evaluation. Mater. Des. 2018, 139, 153–161. [Google Scholar] [CrossRef]
  67. Phuong, N.-T.; Rtimi, S. Claudiane Ouellet Plamondon. In Nanomaterials Based Coatings: Fundamentals and Applications; Elsevier: Amsterdam, The Netherlands, 2019; ISBN 9780128158845. [Google Scholar]
  68. Tri, P.N.; Guinault, A.; Sollogoub, C. Élaboration et propriétés des composites polypropylène recyclé/fibres de bambou. Matériaux Tech. 2012, 100, 413–423. [Google Scholar]
  69. Azizi, S.; David, E.; Fréchette, M.F.; Nguyen-Tri, P.; Ouellet-Plamondon, C.M. Electrical and thermal conductivity of ethylene vinyl acetate composite with graphene and carbon black filler. Polym. Test. 2018, 72, 24–31. [Google Scholar] [CrossRef]
  70. Azizi, S.; David, E.; Fréchette, M.F.; Nguyen-Tri, P.; Ouellet-Plamondon, C.M. Electrical and thermal phenomena in low-density polyethylene/carbon black composites near the percolation threshold. J. Appl. Polym. Sci. 2018, 136, 47043. [Google Scholar] [CrossRef]
  71. Boukehili, H.; Tri, P.N. Helium gas barrier and water absorption behavior of bamboo fiber reinforced recycled polypropylene. J. Reinf. Plast. Compos. 2012, 31, 1638–1651. [Google Scholar] [CrossRef]
  72. Phuong, N.T.; Gilbert, V. Non-isothermal Crystallization Kinetics of Short Bamboo Fiber-reinforced Recycled Polypropylene Composites. J. Reinf. Plast. Compos. 2010, 29, 2576–2591. [Google Scholar] [CrossRef]
  73. Phuong, N.T.; Sollogoub, C.; Guinault, A. Relationship between fiber chemical treatment and properties of recycled pp/bamboo fiber composites. J. Reinf. Plast. Compos. 2010, 29, 3244–3256. [Google Scholar] [CrossRef]
  74. Tri, P.N.; Rtimi, S.; Nguyen, T.A.; Vu, M.T. Physics, Electrochemistry, Photochemistry, and Photoelectrochemistry of Hybrid Nanoparticles. In Noble Metal-Metal Oxide Hybrid Nanoparticles; Woodhead Publishing: Sawston, UK, 2019; pp. 95–123. [Google Scholar]
  75. Tri, P.N.; Ouellet-Plamondon, C.; Rtimi, S.; Assadi, A.A.; Nguyen, T.A. Methods for Synthesis of Hybrid Nanoparticles. In Noble Metal-Metal Oxide Hybrid Nanoparticles; Woodhead Publishing: Sawston, UK, 2019; pp. 51–63. [Google Scholar]
  76. Nguyen, T.V.; Tri, P.N.; Nguyen, T.D.; El Aidani, R.; Trinh, V.T.; Decker, C. Accelerated degradation of water borne acrylic nanocomposites used in outdoor protective coatings. Polym. Degrad. Stab. 2016, 128, 65–76. [Google Scholar] [CrossRef]
  77. Tri, P.N.; Prud’Homme, R.E. Crystallization and Segregation Behavior at the Submicrometer Scale of PCL/PEG Blends. Macromolecules 2018, 51, 7266–7727. [Google Scholar]
  78. Nguyen, T.P. Nanoscale analysis of the photodegradation of Polyester fibers by AFM-IR. J. Photochem. Photobiol. A Chem. 2018, 371, 196–204. [Google Scholar] [CrossRef]
  79. Tri, P.N.; Prud’homme, R.E. Nanoscale Lamellar Assembly and Segregation Mechanism of Poly(3-hydroxybutyrate)/Poly(ethylene glycol) Blends. Macromolecules 2018, 51, 181–188. [Google Scholar] [CrossRef]
  80. El Aidani, R.; Nguyen-Tri, P.; Malajati, Y.; Lara, J.; Vu-Khanh, T. Photochemical aging of an e-PTFE/NOMEX® membrane used in firefighter protective clothing. Polym. Degrad. Stab. 2013, 98, 1300–1310. [Google Scholar] [CrossRef]
  81. Zeb, G.; Tri, P.N.; Le, X.T.; Palacin, S. Pulse potential deposition of thick polyvinylpyridine-like film on the surface of titanium nitride. RSC Adv. 2016, 6, 80825–80829. [Google Scholar] [CrossRef]
  82. Nguyen, T.V.; Le, X.H.; Dao, P.H.; Decker, C.; Nguyen-Tri, P. Stability of acrylic polyurethane coatings under accelerated aging tests and natural outdoor exposure: The critical role of the used photo-stabilizers. Prog. Org. Coat. 2018, 124, 137–146. [Google Scholar] [CrossRef]
  83. Nguyen-Tri, P.; Nguyen, T.H.; Ouellet Plamondon, C.; Vo Dai-Viet, N.; Nanda, S.; Mishra, A.; Chao, H.P.; Bajpai, A.K. Recent Progress in the Preparation, Properties and Applications of Superhydrophobic Nano-based Coatings and Surfaces: A review. Prog. Org. Coat. 2019, 132, 235–256. [Google Scholar] [CrossRef]
  84. Nguyen-Tri, P.; Altiparmak, F.; Nguyen, N.; Tuduri, L.; Ouellet-Plamondon, C.M.; Prud’Homme, R.E. Robust Superhydrophobic Cotton Fibers Prepared by Simple Dip-Coating Approach Using Chemical and Plasma-Etching Pretreatments. ACS Omega 2019, 4, 7829–7837. [Google Scholar] [CrossRef][Green Version]
  85. Nguyen-Tri, P.; Triki, E.; Nguyen, T.A. Butyl Rubber-Based Composite: Thermal Degradation and Prediction of Service Lifetime. J. Compos. Sci. 2019, 3, 48. [Google Scholar] [CrossRef]
  86. Nguyen-Tri, P.; Nguyen, T.A.; Carriere, P.; Xuan, C.N. Nanocomposite Coatings: Preparation, Characterization, Properties, and Applications. Int. J. Corros. 2018, 2018, 4749501. [Google Scholar] [CrossRef]
Figure 1. TEM images of Ag-loaded TiO2 nanoparticles at different magnifications showing the hybrid structure; (a) 40,000× and (b) 80,000×. Inserted images show the schematic illustration of hybrid nanoparticles. The red point represents Ag nanoparticles, and the blue support is nano-TiO2.
Figure 1. TEM images of Ag-loaded TiO2 nanoparticles at different magnifications showing the hybrid structure; (a) 40,000× and (b) 80,000×. Inserted images show the schematic illustration of hybrid nanoparticles. The red point represents Ag nanoparticles, and the blue support is nano-TiO2.
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Figure 2. TEM images of Ag-loaded ZnO nanoparticles at different magnifications: (a) 43,000× and (b) 195,000×.
Figure 2. TEM images of Ag-loaded ZnO nanoparticles at different magnifications: (a) 43,000× and (b) 195,000×.
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Figure 3. XRD patterns of (a) TiO2 nanoparticles and (b) Ag/TiO2 nanoparticles.
Figure 3. XRD patterns of (a) TiO2 nanoparticles and (b) Ag/TiO2 nanoparticles.
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Figure 4. XRD patterns of (a) ZnO nanoparticles and (b) Ag/ZnO nanoparticles.
Figure 4. XRD patterns of (a) ZnO nanoparticles and (b) Ag/ZnO nanoparticles.
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Figure 5. UV-Vis spectra of AgNPs, nano-TiO2, and AgNP-decorated nano-TiO2 particles (dispersed in water).
Figure 5. UV-Vis spectra of AgNPs, nano-TiO2, and AgNP-decorated nano-TiO2 particles (dispersed in water).
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Figure 6. UV-Vis spectra of AgNP-decorated nano-ZnO particles (dispersed in water).
Figure 6. UV-Vis spectra of AgNP-decorated nano-ZnO particles (dispersed in water).
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Figure 7. Photographs of antibacterial test against Staphylococcus aureus bacteria (agar-well diffusion method) for pure TiO2 and Ag-loaded TiO2 nanoparticles: (a) and (b): without light irradiation; (c) and (d): under light irradiation. Concentrations of AgNPs used are 8, 16, and 40 mg/mL.
Figure 7. Photographs of antibacterial test against Staphylococcus aureus bacteria (agar-well diffusion method) for pure TiO2 and Ag-loaded TiO2 nanoparticles: (a) and (b): without light irradiation; (c) and (d): under light irradiation. Concentrations of AgNPs used are 8, 16, and 40 mg/mL.
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Figure 8. Photographs of antibacterial test against Escherichia coli bacteria (agar-well diffusion method) for Ag-loaded TiO2 nanoparticles: (a) without light irradiation; (b) under light irradiation). Concentration of 8, 16, and 40 mg/mL.
Figure 8. Photographs of antibacterial test against Escherichia coli bacteria (agar-well diffusion method) for Ag-loaded TiO2 nanoparticles: (a) without light irradiation; (b) under light irradiation). Concentration of 8, 16, and 40 mg/mL.
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Figure 9. Photographs of antibacterial test against S. aureus bacteria (agar-well diffusion method) for pure ZnO nanoparticles ((a): without light irradiation; (b): under light irradiation) and Ag-loaded ZnO nanoparticles ((c): without light irradiation; (d): under light irradiation).
Figure 9. Photographs of antibacterial test against S. aureus bacteria (agar-well diffusion method) for pure ZnO nanoparticles ((a): without light irradiation; (b): under light irradiation) and Ag-loaded ZnO nanoparticles ((c): without light irradiation; (d): under light irradiation).
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Figure 10. Photographs of antibacterial test against E. coli bacteria (agar-well diffusion method) for ZnO nanoparticles ((a): without light irradiation; (b): under light irradiation) and Ag-loaded ZnO nanoparticles ((c): without light irradiation; (d): under light irradiation).
Figure 10. Photographs of antibacterial test against E. coli bacteria (agar-well diffusion method) for ZnO nanoparticles ((a): without light irradiation; (b): under light irradiation) and Ag-loaded ZnO nanoparticles ((c): without light irradiation; (d): under light irradiation).
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Table 1. Antibacterial activity against S. aureus bacteria of TiO2 nanoparticles and Ag-loaded TiO2 nanoparticles.
Table 1. Antibacterial activity against S. aureus bacteria of TiO2 nanoparticles and Ag-loaded TiO2 nanoparticles.
Concentrations (mg/mL)Inhibition Zone (mm)
Without Light IrradiationUnder Light Irradiation
TiO2 NanoparticlesAg-Decorated TiO2 NanoparticlesTiO2 NanoparticlesAg-Decorated TiO2 Nanoparticles
80000
160002
400404
Table 2. Antibacterial activity against E. coli bacteria of TiO2 nanoparticles and Ag-loaded TiO2 nanoparticles.
Table 2. Antibacterial activity against E. coli bacteria of TiO2 nanoparticles and Ag-loaded TiO2 nanoparticles.
Concentrations (mg/mL)Inhibition Zone (mm)
Without Light IrradiationUnder Light Irradiation
TiO2 NanoparticlesAg-Decorated TiO2 NanoparticlesTiO2 NanoparticlesAg-Decorated TiO2 Nanoparticles
80206
160608
400808
Table 3. Antibacterial activity against S. aureus bacteria of ZnO nanoparticles and Ag-loaded ZnO nanoparticles.
Table 3. Antibacterial activity against S. aureus bacteria of ZnO nanoparticles and Ag-loaded ZnO nanoparticles.
Concentrations (mg/mL)Inhibition Zone (mm)
Without Light IrradiationWith Light Irradiation
ZnO NanoparticlesAg-Decorated ZnO NanoparticlesZnO nanoparticlesAg-Decorated ZnO Nanoparticles
80002
160202
400404
Table 4. Antibacterial activity against E. coli bacteria of ZnO nanoparticles and Ag-loaded ZnO nanoparticles.
Table 4. Antibacterial activity against E. coli bacteria of ZnO nanoparticles and Ag-loaded ZnO nanoparticles.
Concentrations (mg/mL)Inhibition Zone (mm)
Without Light IrradiationWith Light Irradiation
ZnO NanoparticlesAg-Decorated ZnO NanoparticlesZnO NanoparticlesAg-Decorated ZnO Nanoparticles
80207
160408
400608

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Nguyen, V.T.; Vu, V.T.; Nguyen, T.H.; Nguyen, T.A.; Tran, V.K.; Nguyen-Tri, P. Antibacterial Activity of TiO2- and ZnO-Decorated with Silver Nanoparticles. J. Compos. Sci. 2019, 3, 61. https://doi.org/10.3390/jcs3020061

AMA Style

Nguyen VT, Vu VT, Nguyen TH, Nguyen TA, Tran VK, Nguyen-Tri P. Antibacterial Activity of TiO2- and ZnO-Decorated with Silver Nanoparticles. Journal of Composites Science. 2019; 3(2):61. https://doi.org/10.3390/jcs3020061

Chicago/Turabian Style

Nguyen, Van Thang, Viet Tien Vu, The Huu Nguyen, Tuan Anh Nguyen, Van Khanh Tran, and Phuong Nguyen-Tri. 2019. "Antibacterial Activity of TiO2- and ZnO-Decorated with Silver Nanoparticles" Journal of Composites Science 3, no. 2: 61. https://doi.org/10.3390/jcs3020061

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