- Email: [email protected]
TiO2 nanocomposite prepared by green deposition method
Materials Letters 178 (2016) 56–59
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Preparation, characterization and an efficient photocatalytic activity of Au/TiO2 nanocomposite prepared by green deposition method Kamran Tahir a,b,1, Aftab Ahmad a,1, Baoshan Li a,n, Arif Ullah Khan a, Sadia Nazir b, Shafiullah Khan b, Zia Ul Haq Khan c, Shahab Ullah Khan a a
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China Institute of Chemical Sciences Gomal University D. I. Khan, KP, Pakistan c Department of Chemistry, University of Science and Technology Bannu, 28100 KP, Pakistan b
art ic l e i nf o
a b s t r a c t
Article history: Received 12 February 2016 Received in revised form 10 April 2016 Accepted 23 April 2016 Available online 27 April 2016
The gold decorated titanium dioxide (Au/TiO2) nanocomposite was synthesized by a novel and ecofriendly green deposition method using phytochemicals from the aqueous extract of Ranunculus muricatus. The prepared nanomaterials were characterized by XRD, HRTEM, SEM and FT-IR techniques. The resulted nanomaterials were tested for photo inhibition of S. aureus and E. coli. The light irradiated Au/TiO2 exhibited significant photo inhibition efficiency against S. aureus 22(7 0.6 mm) and E. coli 16 ( 70.4 mm) than in dark. The promising photocatalytic activity of the nanocomposite may be attributed to the highly decorated AuNPs over the surface of TiO2. & 2016 Elsevier B.V. All rights reserved.
Keywords: Ranunculus muricatus Green deposition method Nanocomposite Nanoparticles Photo inhibition activity
1. Introduction The nanomaterials have characteristic features that happen from their extremely small spherical sizes and large specific surface area [1]. Nanotechnology is widely applied to prepare catalysts which have high applications to control the various diseases and infections caused by microbes. There are two types of nanoparticles i.e. organic and inorganic nanoparticles [2]. Organic nanoparticles are highly unstable at severe conditions i.e. high pressure, temperature. Alternatively inorganic nanoparticles i.e. ZnO [3], TiO2 [4] etc are stable even at elevated temperature and pressure, and have high efficiency against microbial attack. The TiO2 has been extensively used in water purification and air by removing pathogen i.e. bacteria and toxic organic molecules [5–7]. Usually the photo inactivation of bacteria is obtained in the presence of noble metal nanoparticles (NMNPs), which can reduce the growth of pathogenic microbes by producing reactive oxygen species (ROS). However the agglomeration and instability of MNPs is to be expected. To overcome the problem of aggregation, stability and recovery of MNPs, several inorganic materials have been applied as a support for nanoparticles i.e. Zeolite, TiO2, Fe2O3, n
Corresponding author. E-mail address: [email protected] (B. Li). 1 Author first and second ¼ same contribution.
http://dx.doi.org/10.1016/j.matlet.2016.04.176 0167-577X/& 2016 Elsevier B.V. All rights reserved.
graphene oxide [8–12]. To obtain highly dispersed and small size nanoparticles, TiO2 was used as a support. TiO2 has been extensively used as proficient support in the majority of the organic reactions due to its high thermal and chemical stability, low cost, low toxicity, high photocatalytic activity, optical properties and reusability [8,13–15]. In recent years, green syntheses of MNPs have got too much importance over the chemical and physical methods as it is a simple and ecofriendly way which includes non-toxic reaction media and solvents. Based on our continuous examination on the biogenic synthesis of MNPs [16,17], we have synthesized Au/TiO2 nanocomposite by eco-friendly procedure. The Ranunculus muricatus plant extract was used as a reducing and capping agent without using any hazard surfactant. In addition, the photo inhibition efficiency of Au/TiO2 nanocomposite against two bacteria i.e. S. aureus and E. coli were also examined in this report. 1.1. Materials and methods Ranunculus muricatus plant were collected from irrigation land in Pakistan and washed several times with doubly distilled water. 200 g of Ranunculus muricatus plant were ground into fine powder and then mixed with de-ionized water, stirred at 60 °C for 1 h and filtered to get the extract.
K. Tahir et al. / Materials Letters 178 (2016) 56–59
Fig. 1. FTIR spectra of plant extract, AuNPs, TiO2 and Au/TiO2.
57
The Au/TiO2 nanocomposites were prepared by a new green deposition method. According to this procedure the AuNPs and TiO2 nanoparticles were prepared in two different beakers each having 10 mL of plant extract. 3 mM aqueous solution of HAuCl4 and 3 mM of TiO(OH)2 were poured separately in these beakers. Then the solution of AuNPs was transferred to the solution of TiO2 drop wise with continuous stirring. After constantly stirred for 4 h, the Au/TiO2 was filtered, washed with distilled water and dried at 70 °C for 4 h. The gold and TiO2 nanoparticles were also prepared by the same method. Agar well diffusion method was used to test the antibacterial activity [18]. The inocula of the S. aureus and E. coli were grown in nutrient broth at 37 °C for 24 h incubation. The inocula of both the bacteria was splashed on to the Muller Hinton agar (Oxoid) plates by a sterilized glass spreader in order to make sure a uniform layer
Fig. 2. (A) XRD pattern of AuNPs, (B) (a) XRD pattern of Au/TiO2 and (b) XRD pattern of TiO2.
Fig. 3. HRTEM images of green synthesized (A) AuNPs, (B) TiO2 and (C) Au/TiO2 and their corresponding particle size distribution (DLS). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
58
K. Tahir et al. / Materials Letters 178 (2016) 56–59
Fig. 4. SEM analysis of green synthesized (a) TiO2, (b) Au/TiO2 (c) EDX analysis of Au/TiO2. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 5. Photo inactivation of two bacteria (A) S. aureus, (B) E. coli in the presence of photo irradiated Au/TiO2 (1), TiO2 (3) and dark Au/TiO2 (2), TiO2 (4). The figure also represents the antibacterial activity of plant extract (5) and standard (6) against both of the bacteria.
of growth following incubation. Wells of 6 mm in diameter were formed with the help of sterilized cork borer on to nutrient agar plates. On the other hand 1 mg of Au/TiO2 nanocomposite were kept in 1 mL distilled water under the visible light (300 W halogen lamp) for 60 min 50 μL of 1 mg/mL of test samples were put into the wells and the plates were allowed to stay for 2 h at room temperature. After that, the plates were incubated at 37 °C for 24 h and the resulting diameters of zones of inhibition were measured. Streptomycin was used as a standard. 2. Results and discussion The
FTIR
analysis
was
used
to
confirm
the
possible
phytoconstituents present in the Ranunculus muricatus plant which are responsible for the reduction and capping of nanoparticles. (Fig. 1) shows the FTIR spectra of plant extract and plant mediated Au/TiO2 nanocomposite. The FTIR spectrum of plant extract shows four major bands at 3333, 2900, 1633 and 1033 cm 1 which are associated with stretching vibration of OH, C4O, C4C and C-N respectively. These spectral bands were also observed in the plant extract mediated metal nanomaterials suggesting the possible association of these groups in the synthesis of these nanostructures. However, comparative FTIR spectra of gold and TiO2 NPs reveal that the peaks intensities at 3400 and 1600 cm 1 are more prominent in case of TiO2 NPs, indicating a
K. Tahir et al. / Materials Letters 178 (2016) 56–59
more stable interaction with TiO2. On the basis of this analysis we can say that the synthesized Au/TiO2 nanocomposite is stabilized by various functional groups present in the aqueous extract of plant, such as proteins, flavonoids and seponins etc. Metal ions have the ability to coordinate with electron donating species. The amino groups in protein and OH groups in flavonoids in plant extract interact with metal ions through coordinate covalent bond. (Supplementary Fig. S1). The X-ray diffraction analysis was used to study the crystalline structure of metals nanoparticles and nanocomposite. XRD spectra of AuNPs (Fig. 2(A)) showed three well resolved peaks at 2-theta corresponding to (111), (200) and (220) planes, confirmed the face centered cubic crystal structure of AuNPs. Wide angle XRD patterns of both TiO2 and Au/TiO2 were also analyzed which are shown in (Fig. 2(B)). The six well resolved peaks around 25.2°, 37.6°, 48.0°, 54.2°, 55.2°and 62.6° in (Fig. 2(b)) indicate the existence of anatase form of TiO2 nanoparticles. It is clear from (Fig. 2 (a)) that the two new peaks appeared at 38.3° and 44.2° indicate the distribution of AuNPs over the surface of TiO2. HRTEM was used to examine the dispersion, size and shape of green synthesized gold, TiO2 and gold decorated TiO2 nanoparticles and nanocomposites. The corresponding HRTEM images of free Gold nanoparticles (A), TiO2 (B) and gold decorated TiO2 (C) and their corresponding (DLS) are shown in Fig. 3. Fig 3(C) clearly shows the incorporation of Gold nanoparticles into TiO2 support as Indicated by pointed arrows. The biogenic AuNPs have irregular shapes and sizes (50–90 nm) with slight aggregation. Alternatively in the case of biogenic Au/TiO2 nanocomposite, the AuNPs have small size (50–70 nm), and high dispersion as compared to bare AuNPs which confirms that the green synthesized TiO2 nanoparticles have the ability to keep the AuNPs highly disperse with small size. The morphology of TiO2 and Au/TiO2 were also analyzed by SEM (Fig. 4). The SEM analysis of biogenic TiO2 nanoparticles clearly illustrates that the TiO2 have slightly aggregated with each other. The SEM analysis of Au/TiO2 nanocomposite is shown in (Fig. 4(b)) where the AuNPs are highly dispersed with small size and uniform morphology over the surface of TiO2. The EDX analysis confirmed the presence of elemental Ti and Au in the prepared nanocomposite (Fig. 4(c)). The bacterial inactivation ability of photoactive TiO2 and Au/TiO2 was observed both in visible light and in dark. The antibacterial activity of irradiated TiO2 and Au/TiO2 against both of the bacteria was higher than in dark as evident from the zones of inhibition in agar plates (Fig. 5) (supplementary Table. S2). The zone of inhibition of irradiated TiO2 against S. aureus and E. coli was 14( 70.6) mm and 11( 7 0.4) mm, while that in dark was 9 (7 0.3) mm and 8( 7 0.4) mm respectively. The zone of inhibition of irradiated Au/TiO2 against S. aureus and E. coli was 22( 70.6) mm and 16 ( 70.4) mm, while the observed zone of inhibition in dark was 14( 70.3) mm and 12( 7 0.4) mm respectively. The antibacterial activity of the standard drug and plant extract against S. aureus was 15( 70.2) and 11( 70.3) and E. coli was 13( 70.4) and 8 (7 0.4) respectively.
59
3. Conclusion Here we presented the synthesis of Au/TiO2 nanocomposite by a new green deposition method using Ranunculus muricatus plant extract as a reducing and stabilizing agents. In case of Au/TiO2, the TiO2 work as a support and the AuNPs of small size and spherical shape are highly dispersed over the surface of TiO2. The Au/TiO2 nanocomposites were evaluated for photo inactivation of S. aureus and E. coli. It was found that the photo inhibition efficiency of Au/TiO2 was much better than in dark condition.
Acknowledgments The authors are thankful to China Scholarship Council (No: 2013GXZ031) National Natural Science of Foundation of China (Grant No. 21271017) and the Fundamental Research Funds for the Central Universities (No. YS1406).
Appendix A. Supplementary material Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.matlet.2016.04.176.
References [1] J. Sunita, G. Suresh, N. Madhav, R. Anjali, J. Clust. Sci. 22 (2011) 121–129. [2] G.M. Whitesides, Nat. Biotechnol. 21 (2003) 1161–1165. [3] P.K. Stoimenov, R.L. Klinger, G.L. Marchin, K.J. Klabunde, Langmuir 18 (2002) 6679–6686. [4] Z. Hui, Z. Hong, Appl. Surf. Sci. 258 (2012) 10034–10041. [5] A. Fujishima, K. Honda, Nature 238 (1972) 37–38. [6] H. Sun, Y. Bai, Y. Cheng, W. Jin, N. Xu, Ind. Eng. Chem. Res. 45 (2006) 4971–4976. [7] H. Kato, A.J. Kudo, Phys. B Chem. 106 (2002) 5029–5034. [8] M. Nasrollahzadeh, S.M. Sajadi, A. Rostami-Vartooni, M. Khalaj, J. Colloid Interface Sci. 453 (2014) 237. [9] M. Nasrollahzadeh, S.M. Sajadi, A. Rostami-Vartooni, M. Khalaj, J. Mol. Catal, A: Chem. 396 (2014) 31. [10] M. Nasrollahzadeh, M. Enayati, M. Khalaj, RSC Adv. 4 (2014) 26264. [11] P. Fakhri, M. Nasrollahzadeh, B. Jaleh, RSC Adv. 4 (2014) 48691. [12] M. Nasrollahzadeh, Ceram. Int. 41 (2015) 14435. [13] X. Chen, S.S. Mao, Chem. Rev. 107 (2007) 2891. [14] Y. Kai, L. Yunxing, H. Kun, C. Xun, F. Xianzhi, D. Wenxin, Int. J. Hydrog. Energy 39 (2014) 18312–18325. [15] D. Xiao-Qing, Z. Bin, L. Xiao-Song, L. Jing-Lin, Z. Xiaobing, Z. Ai-Min, Appl. Catal. B: Environ. 188 (2016) 48–55. [16] K. Tahir, S. Nazir, B. Li, A.U. Khan, Z.U.H. Khan, A. Ahmad, Q.U. Khan, Y. Zhao, J. Photochem. Photobiol. B: Biol. 153 (2015) 261–266. [17] K. Tahir, S. Nazir, B. Li, A.U. Khan, Z.U.H. Khan, P.Y. Gong, S.U. Khan, A. Ahmad, Mater. Lett. 156 (2015) 198–201. [18] F. Hadacek, H. Greger, Phytochem. Anal. 11 (2000) 137–147.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Preparation, characterization and an efficient photocatalytic activity of Au/TiO2 nanocomposite prepared by green deposition method Kamran Tahir a,b,1, Aftab Ahmad a,1, Baoshan Li a,n, Arif Ullah Khan a, Sadia Nazir b, Shafiullah Khan b, Zia Ul Haq Khan c, Shahab Ullah Khan a a
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China Institute of Chemical Sciences Gomal University D. I. Khan, KP, Pakistan c Department of Chemistry, University of Science and Technology Bannu, 28100 KP, Pakistan b
art ic l e i nf o
a b s t r a c t
Article history: Received 12 February 2016 Received in revised form 10 April 2016 Accepted 23 April 2016 Available online 27 April 2016
The gold decorated titanium dioxide (Au/TiO2) nanocomposite was synthesized by a novel and ecofriendly green deposition method using phytochemicals from the aqueous extract of Ranunculus muricatus. The prepared nanomaterials were characterized by XRD, HRTEM, SEM and FT-IR techniques. The resulted nanomaterials were tested for photo inhibition of S. aureus and E. coli. The light irradiated Au/TiO2 exhibited significant photo inhibition efficiency against S. aureus 22(7 0.6 mm) and E. coli 16 ( 70.4 mm) than in dark. The promising photocatalytic activity of the nanocomposite may be attributed to the highly decorated AuNPs over the surface of TiO2. & 2016 Elsevier B.V. All rights reserved.
Keywords: Ranunculus muricatus Green deposition method Nanocomposite Nanoparticles Photo inhibition activity
1. Introduction The nanomaterials have characteristic features that happen from their extremely small spherical sizes and large specific surface area [1]. Nanotechnology is widely applied to prepare catalysts which have high applications to control the various diseases and infections caused by microbes. There are two types of nanoparticles i.e. organic and inorganic nanoparticles [2]. Organic nanoparticles are highly unstable at severe conditions i.e. high pressure, temperature. Alternatively inorganic nanoparticles i.e. ZnO [3], TiO2 [4] etc are stable even at elevated temperature and pressure, and have high efficiency against microbial attack. The TiO2 has been extensively used in water purification and air by removing pathogen i.e. bacteria and toxic organic molecules [5–7]. Usually the photo inactivation of bacteria is obtained in the presence of noble metal nanoparticles (NMNPs), which can reduce the growth of pathogenic microbes by producing reactive oxygen species (ROS). However the agglomeration and instability of MNPs is to be expected. To overcome the problem of aggregation, stability and recovery of MNPs, several inorganic materials have been applied as a support for nanoparticles i.e. Zeolite, TiO2, Fe2O3, n
Corresponding author. E-mail address: [email protected] (B. Li). 1 Author first and second ¼ same contribution.
http://dx.doi.org/10.1016/j.matlet.2016.04.176 0167-577X/& 2016 Elsevier B.V. All rights reserved.
graphene oxide [8–12]. To obtain highly dispersed and small size nanoparticles, TiO2 was used as a support. TiO2 has been extensively used as proficient support in the majority of the organic reactions due to its high thermal and chemical stability, low cost, low toxicity, high photocatalytic activity, optical properties and reusability [8,13–15]. In recent years, green syntheses of MNPs have got too much importance over the chemical and physical methods as it is a simple and ecofriendly way which includes non-toxic reaction media and solvents. Based on our continuous examination on the biogenic synthesis of MNPs [16,17], we have synthesized Au/TiO2 nanocomposite by eco-friendly procedure. The Ranunculus muricatus plant extract was used as a reducing and capping agent without using any hazard surfactant. In addition, the photo inhibition efficiency of Au/TiO2 nanocomposite against two bacteria i.e. S. aureus and E. coli were also examined in this report. 1.1. Materials and methods Ranunculus muricatus plant were collected from irrigation land in Pakistan and washed several times with doubly distilled water. 200 g of Ranunculus muricatus plant were ground into fine powder and then mixed with de-ionized water, stirred at 60 °C for 1 h and filtered to get the extract.
K. Tahir et al. / Materials Letters 178 (2016) 56–59
Fig. 1. FTIR spectra of plant extract, AuNPs, TiO2 and Au/TiO2.
57
The Au/TiO2 nanocomposites were prepared by a new green deposition method. According to this procedure the AuNPs and TiO2 nanoparticles were prepared in two different beakers each having 10 mL of plant extract. 3 mM aqueous solution of HAuCl4 and 3 mM of TiO(OH)2 were poured separately in these beakers. Then the solution of AuNPs was transferred to the solution of TiO2 drop wise with continuous stirring. After constantly stirred for 4 h, the Au/TiO2 was filtered, washed with distilled water and dried at 70 °C for 4 h. The gold and TiO2 nanoparticles were also prepared by the same method. Agar well diffusion method was used to test the antibacterial activity [18]. The inocula of the S. aureus and E. coli were grown in nutrient broth at 37 °C for 24 h incubation. The inocula of both the bacteria was splashed on to the Muller Hinton agar (Oxoid) plates by a sterilized glass spreader in order to make sure a uniform layer
Fig. 2. (A) XRD pattern of AuNPs, (B) (a) XRD pattern of Au/TiO2 and (b) XRD pattern of TiO2.
Fig. 3. HRTEM images of green synthesized (A) AuNPs, (B) TiO2 and (C) Au/TiO2 and their corresponding particle size distribution (DLS). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
58
K. Tahir et al. / Materials Letters 178 (2016) 56–59
Fig. 4. SEM analysis of green synthesized (a) TiO2, (b) Au/TiO2 (c) EDX analysis of Au/TiO2. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 5. Photo inactivation of two bacteria (A) S. aureus, (B) E. coli in the presence of photo irradiated Au/TiO2 (1), TiO2 (3) and dark Au/TiO2 (2), TiO2 (4). The figure also represents the antibacterial activity of plant extract (5) and standard (6) against both of the bacteria.
of growth following incubation. Wells of 6 mm in diameter were formed with the help of sterilized cork borer on to nutrient agar plates. On the other hand 1 mg of Au/TiO2 nanocomposite were kept in 1 mL distilled water under the visible light (300 W halogen lamp) for 60 min 50 μL of 1 mg/mL of test samples were put into the wells and the plates were allowed to stay for 2 h at room temperature. After that, the plates were incubated at 37 °C for 24 h and the resulting diameters of zones of inhibition were measured. Streptomycin was used as a standard. 2. Results and discussion The
FTIR
analysis
was
used
to
confirm
the
possible
phytoconstituents present in the Ranunculus muricatus plant which are responsible for the reduction and capping of nanoparticles. (Fig. 1) shows the FTIR spectra of plant extract and plant mediated Au/TiO2 nanocomposite. The FTIR spectrum of plant extract shows four major bands at 3333, 2900, 1633 and 1033 cm 1 which are associated with stretching vibration of OH, C4O, C4C and C-N respectively. These spectral bands were also observed in the plant extract mediated metal nanomaterials suggesting the possible association of these groups in the synthesis of these nanostructures. However, comparative FTIR spectra of gold and TiO2 NPs reveal that the peaks intensities at 3400 and 1600 cm 1 are more prominent in case of TiO2 NPs, indicating a
K. Tahir et al. / Materials Letters 178 (2016) 56–59
more stable interaction with TiO2. On the basis of this analysis we can say that the synthesized Au/TiO2 nanocomposite is stabilized by various functional groups present in the aqueous extract of plant, such as proteins, flavonoids and seponins etc. Metal ions have the ability to coordinate with electron donating species. The amino groups in protein and OH groups in flavonoids in plant extract interact with metal ions through coordinate covalent bond. (Supplementary Fig. S1). The X-ray diffraction analysis was used to study the crystalline structure of metals nanoparticles and nanocomposite. XRD spectra of AuNPs (Fig. 2(A)) showed three well resolved peaks at 2-theta corresponding to (111), (200) and (220) planes, confirmed the face centered cubic crystal structure of AuNPs. Wide angle XRD patterns of both TiO2 and Au/TiO2 were also analyzed which are shown in (Fig. 2(B)). The six well resolved peaks around 25.2°, 37.6°, 48.0°, 54.2°, 55.2°and 62.6° in (Fig. 2(b)) indicate the existence of anatase form of TiO2 nanoparticles. It is clear from (Fig. 2 (a)) that the two new peaks appeared at 38.3° and 44.2° indicate the distribution of AuNPs over the surface of TiO2. HRTEM was used to examine the dispersion, size and shape of green synthesized gold, TiO2 and gold decorated TiO2 nanoparticles and nanocomposites. The corresponding HRTEM images of free Gold nanoparticles (A), TiO2 (B) and gold decorated TiO2 (C) and their corresponding (DLS) are shown in Fig. 3. Fig 3(C) clearly shows the incorporation of Gold nanoparticles into TiO2 support as Indicated by pointed arrows. The biogenic AuNPs have irregular shapes and sizes (50–90 nm) with slight aggregation. Alternatively in the case of biogenic Au/TiO2 nanocomposite, the AuNPs have small size (50–70 nm), and high dispersion as compared to bare AuNPs which confirms that the green synthesized TiO2 nanoparticles have the ability to keep the AuNPs highly disperse with small size. The morphology of TiO2 and Au/TiO2 were also analyzed by SEM (Fig. 4). The SEM analysis of biogenic TiO2 nanoparticles clearly illustrates that the TiO2 have slightly aggregated with each other. The SEM analysis of Au/TiO2 nanocomposite is shown in (Fig. 4(b)) where the AuNPs are highly dispersed with small size and uniform morphology over the surface of TiO2. The EDX analysis confirmed the presence of elemental Ti and Au in the prepared nanocomposite (Fig. 4(c)). The bacterial inactivation ability of photoactive TiO2 and Au/TiO2 was observed both in visible light and in dark. The antibacterial activity of irradiated TiO2 and Au/TiO2 against both of the bacteria was higher than in dark as evident from the zones of inhibition in agar plates (Fig. 5) (supplementary Table. S2). The zone of inhibition of irradiated TiO2 against S. aureus and E. coli was 14( 70.6) mm and 11( 7 0.4) mm, while that in dark was 9 (7 0.3) mm and 8( 7 0.4) mm respectively. The zone of inhibition of irradiated Au/TiO2 against S. aureus and E. coli was 22( 70.6) mm and 16 ( 70.4) mm, while the observed zone of inhibition in dark was 14( 70.3) mm and 12( 7 0.4) mm respectively. The antibacterial activity of the standard drug and plant extract against S. aureus was 15( 70.2) and 11( 70.3) and E. coli was 13( 70.4) and 8 (7 0.4) respectively.
59
3. Conclusion Here we presented the synthesis of Au/TiO2 nanocomposite by a new green deposition method using Ranunculus muricatus plant extract as a reducing and stabilizing agents. In case of Au/TiO2, the TiO2 work as a support and the AuNPs of small size and spherical shape are highly dispersed over the surface of TiO2. The Au/TiO2 nanocomposites were evaluated for photo inactivation of S. aureus and E. coli. It was found that the photo inhibition efficiency of Au/TiO2 was much better than in dark condition.
Acknowledgments The authors are thankful to China Scholarship Council (No: 2013GXZ031) National Natural Science of Foundation of China (Grant No. 21271017) and the Fundamental Research Funds for the Central Universities (No. YS1406).
Appendix A. Supplementary material Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.matlet.2016.04.176.
References [1] J. Sunita, G. Suresh, N. Madhav, R. Anjali, J. Clust. Sci. 22 (2011) 121–129. [2] G.M. Whitesides, Nat. Biotechnol. 21 (2003) 1161–1165. [3] P.K. Stoimenov, R.L. Klinger, G.L. Marchin, K.J. Klabunde, Langmuir 18 (2002) 6679–6686. [4] Z. Hui, Z. Hong, Appl. Surf. Sci. 258 (2012) 10034–10041. [5] A. Fujishima, K. Honda, Nature 238 (1972) 37–38. [6] H. Sun, Y. Bai, Y. Cheng, W. Jin, N. Xu, Ind. Eng. Chem. Res. 45 (2006) 4971–4976. [7] H. Kato, A.J. Kudo, Phys. B Chem. 106 (2002) 5029–5034. [8] M. Nasrollahzadeh, S.M. Sajadi, A. Rostami-Vartooni, M. Khalaj, J. Colloid Interface Sci. 453 (2014) 237. [9] M. Nasrollahzadeh, S.M. Sajadi, A. Rostami-Vartooni, M. Khalaj, J. Mol. Catal, A: Chem. 396 (2014) 31. [10] M. Nasrollahzadeh, M. Enayati, M. Khalaj, RSC Adv. 4 (2014) 26264. [11] P. Fakhri, M. Nasrollahzadeh, B. Jaleh, RSC Adv. 4 (2014) 48691. [12] M. Nasrollahzadeh, Ceram. Int. 41 (2015) 14435. [13] X. Chen, S.S. Mao, Chem. Rev. 107 (2007) 2891. [14] Y. Kai, L. Yunxing, H. Kun, C. Xun, F. Xianzhi, D. Wenxin, Int. J. Hydrog. Energy 39 (2014) 18312–18325. [15] D. Xiao-Qing, Z. Bin, L. Xiao-Song, L. Jing-Lin, Z. Xiaobing, Z. Ai-Min, Appl. Catal. B: Environ. 188 (2016) 48–55. [16] K. Tahir, S. Nazir, B. Li, A.U. Khan, Z.U.H. Khan, A. Ahmad, Q.U. Khan, Y. Zhao, J. Photochem. Photobiol. B: Biol. 153 (2015) 261–266. [17] K. Tahir, S. Nazir, B. Li, A.U. Khan, Z.U.H. Khan, P.Y. Gong, S.U. Khan, A. Ahmad, Mater. Lett. 156 (2015) 198–201. [18] F. Hadacek, H. Greger, Phytochem. Anal. 11 (2000) 137–147.