Elsevier

Materials Research Bulletin

Volume 97, January 2018, Pages 238-243
Materials Research Bulletin

Ambient light antimicrobial activity of reduced graphene oxide supported metal doped TiO2 nanoparticles and their PVA based polymer nanocomposite films

https://doi.org/10.1016/j.materresbull.2017.08.056Get rights and content

Highlights

  • Cu2O-TiO2/rGO nanocomposite as a new ambient light antimicrobial.

  • PVA-TiO2 and PVA-Cu2O-TiO2/rGO polymer composite films for antimicrobial packaging.

  • Improved antibacterial activity under visible light compared to the unmodified TiO2.

Abstract

Copper doped TiO2 nanoparticles with reduced graphene oxide as a solid support were introduced as new ambient light antimicrobial agents. The doping with copper extended the activity to the visible light and the reduced graphene oxide helped to enhance charge transport during photocatalytic degradation of microorganisms. The antimicrobial activity of the bare as well as the modified TiO2 particles was tested with four different microorganisms, namely two Gram positive and two Gram negative types. Zone of inhibition and minimum inhibitory concentration (MIC) tests were carried out under visible light conditions. The results suggest that Cu2O-TiO2/rGO exhibits better visible light antibacterial property with higher zone of inhibition area and lower value of minimum inhibitory concentration for both Gram positive and Gram negative microorganisms compared to the bare TiO2. Polymer nanocomposite films were prepared using these nanoparticles with PVA and the antimicrobial activity was tested again for possible packaging applications.

Introduction

Materials research with efforts to apply the unique properties of nanomaterials in micro-biology has a great potential of expanding future antimicrobial technologies [1], [2]. Antimicrobial activity refers to the destruction or inhibition of the growth of the microorganism such as bacteria, viruses and fungi on water surfaces or in the air surfaces [3], [4], [5]. Antimicrobial agents are highly relevant for a host of industrial applications in environmental, food, synthetic textiles, packaging, health care, and medical care products [6]. Contamination of food materials due to the spoilage and growth of microorganisms constitutes a major public health concern and economic burden on the food industry [7]. Nanotechnology can assist to attain improved antimicrobial covering for food products in the form of photocatalytic nanoparticles and polymer nanocomposite films used in packaging and storage applications.

Metal oxide nanoparticles exhibit excellent antimicrobial properties to inactivate a wide spectrum of pathogenic microorganisms including bacteria, viruses, fungi and algae [8]. Particularly, titanium dioxide (TiO2) has attracted significant attention due to their high stability, low cost, bio capability, reusability and effective applications particularly in photocatalysis, catalyst support, antibacterial, environmental remediation, air purification, water disinfection [9], [10], [11]. TiO2 has a strong oxidizing power to kill the microorganism under UV light illumination [12], [13]. The metal oxide photocatalysts such as TiO2, ZnO were modified with different plasmonic nanometals or with transition metal co-catalysts, so that their antimicrobial activity can be shifted from UV to visible region [14], [15], [16]. Ag doped nanocrystalline TiO2 [17], Ag-ZnO nanomaterial [18], Cu doped TiO2 nanoparticles [19], CuO-doped TiO2 nanofibers [20] etc. were studied as potential visible light driven photocatalysts and antimicrobial agents. In addition, many researchers have introduced graphene or reduced graphene oxide (rGO) as a support for the photocatalysts to enhance the charge transport and reported improved activity towards degradation of contaminants, hydrogen evolution reaction etc [21], [22]. Here, in this work, we have introduced such a visible light active catalyst, Cu2O-TiO2/rGO composite, for the antimicrobial application. Doping with copper extends the activity of TiO2 to the visible light and reduced graphene oxide acts as a solid support to improve the charge transport during photocatalytic degradation of microorganisms.

Recently, antimicrobial packaging technique combining antimicrobial agents with polymeric films to restrain the activities of targeted microorganisms is widely gaining interest among the scientific community [23]. This approach maintains the food quality and safety, and in turn, leads to an extended shelf life. All the components of the visible light active antimicrobial agent proposed in this work are potential biocompatible materials with proven bio related applications [24], [25], [26], [27], [28], [29], [30], [31]. Polyvinyl alcohol (PVA) is a water-processable polymer with high technological potential as a biocompatible and biodegradable material, which has been also explored for packaging applications [32], [33], [34], [35]. In this context, along with the study of antimicrobial activity of TiO2 as well as the modified TiO2 nanoparticles, we have also prepared PVA based nanocomposite films with them and tested the antimicrobial properties.

Section snippets

Materials

Titanium tetraisopropoxide (TTIP) and glycerol were purchased from Merck India Pvt Ltd. Graphite powder (synthetic, conducting grade, 325 mesh, 99.9995%) was procured from Alfa Aesar. Cu (NO3)2·3H2O from Loba Chemie Pvt. Ltd. All the other chemicals such as NaNO3, KMnO4, H2SO4 and solvents was received from Rankem, India without further purification. Mueller-Hinton broth, agar, Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 29213),

Results and discussion

Fig. 1 shows the representative FESEM and TEM images of Cu2O-TiO2/rGO nanocomposite, confirming the uniform distribution of Cu2O-TiO2 spherical nanoparticles on the layers of reduced graphene oxide. The particle size varied from 12 nm to 22 nm with an average value of 17 nm as shown in the inset of Fig. 1 (b). Further details on the characterization of the TiO2 and the modified TiO2 nanoparticles can be found in our previous report [22]. The TiO2 nanoparticles exhibited absorption of light in the

Conclusion

In conclusion, the results from zone of inhibition and MIC tests showed that, as compared to the unmodified TiO2 nanoparticles, the Cu2O-TiO2/rGO nanocomposite has improved antimicrobial activity against the four pathogens (S. aureus, S. oralis, E. coli and P. aeruginosa) under visible light conditions. The antimicrobial activity of PVA based polymer nanocomposite films containing the TiO2 nanoparticles and Cu2O-TiO2/rGO nanocomposite was also tested against the four microorganisms and was

Acknowledgements

The authors would like to acknowledge the financial support from the SRM Research Institute, SRM University, Kattankulathur, Tamilnadu, India. We also thank Nanotechnology Research Centre, SRM University, Kattankulathur, Tamilnadu, India for the help with FESEM characterization. We also acknowledge the help from Prof. Ick Soo Kim (Division of Frontier Fibers, Institute for Fiber Engineering, National Shinshu University, Ueda, Japan) regarding the TEM imaging.

References (46)

  • T.-F. Yeh et al.

    Roles of graphene oxide in photocatalytic water splitting

    Mater. Today

    (2013)
  • S.Y. Sung et al.

    Antimicrobial agents for food packaging applications

    Trends Food Sci. Technol.

    (2013)
  • J.A. Li et al.

    Preparation of SiO2/TiO2 and TiO2/TiO2 micropattern and their effects on platelet adhesion and endothelial cell regulation

    Nucl. Instrum. Methods Phys. Res. Sec. B

    (2013)
  • Z. Zhou et al.

    Fabrication of 3D TiO2 micromesh on silicon surface and its effects on platelet adhesion

    Mater. Lett.

    (2014)
  • P. Kanhed et al.

    In vitro antifungal efficiency of copper nanoparticles against selected crop phatogenic fungi

    Mater. Lett.

    (2014)
  • Dongying Hu et al.

    Fabrication of antibacterial blend film from poly (vinyl alcohol) and quaternized chitosan for packaging

    Mater. Res. Bull.

    (2016)
  • S. Rajeshkumar et al.

    In vitro antibacterial activity and mechanism of silver nanoparticles against food had borne pathogens

    Bioinorg. Chem. Appl.

    (2014)
  • A. Majdalawieh et al.

    Recent advances in gold and silver nanoparticles: synthesis and applications

    J. Nanosci. Nanotechnol.

    (2014)
  • G. Fu et al.

    Anatase TiO2 nanocomposites for antimicrobial coatings

    J. Phys. Chem. B

    (2005)
  • C.C. Peng et al.

    Composite nano-titanium oxide-chitosan artificial skin exhibits strong wound-healing effect-an approach with anti-inflammatory and bactericid alkinetics

    Macromol. Biosci.

    (2008)
  • L. Ye et al.

    Targeted disinfection of E. coli via bioconjugation to photoreactive TiO2

    Bioconjug. Chem.

    (2013)
  • S. Smita et al.

    Nanoparticles in the environment: assessment using the causal diagram approach

    Environ. Health

    (2012)
  • M. Sunil

    Antimicrobial food packaging to enhance food safety: current developments and future challenges

    Food Process. Technol.

    (2012)
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