(251l) Microwave Assisted Green Fabrication of Antibacterial Ag-Chitosan Films for Food Packaging Applications

Food contamination by microbes is one of the major problems associated in food packaging industry, causing food spoilage and bringing huge loss for the industry and the end user. Research has been intensified to put a check lock for the associated problem.  Contamination of food is possibly tackled by a suitable antimicrobial packaging. The antimicrobial packaging is of great importance because it could be a potential alternative solution to extend the shelf life and assure the innocuousness and preservation of food products specifically [1]. The antimicrobial packaging provided by silver nanoparticles is much significant, since silver nanoparticles devastate broad spectrum of micro-organisms covering not only the common food prone bacteria but also various gram positive and gram negative bacteria, fungi and multidrug resistant bacteria like Pseudomonas aeruginosa, ampicillin-resistant Escherichia coli, erythromycin-resistant Streptococcus pyogenes, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus(VRSA) [2, 3]. The additional advantage is that, these metal nanoparticles do not act via cell receptors to kill the microorganisms [4]. Hence, the chance of immune response in microbes to develop resistance against these nanoparticles is not possible. So, the problem of the disease transmission/contamination through various micro-organisms could be greatly eradicated without bringing any resistance in micro-organisms after disposal of the food packaging film [5, 6].

In the view of above, by taking into the considerations of the major problem associated in packaging industry and by considering the relevance of silver nanoparticles in killing the microbes, a series of Ag-chitosan films are intended to fabricate for food packaging applications. The necessary silver nanoparticles are going to be synthesized by adopting green methods, by using microwave radiation. To date, only a very few studies have been carried out in the following sector using microwave irradiation; however, a lot of crucial facts as a topic of scientific interest remained unexplored in optimizing the final desired conditions. The present investigation is one which synchronizes to develop various antibacterial films from chitosan and silver nanoparticles for food packaging applications, along with scientifically investigates the heterogeneity effects of the silver nanoparticles with respect to various food packaging properties.

In the present investigation, antibacterial Ag-chitosan films are going to be fabricated by following green methods. The possible silver nanoparticles are effectively synthesized by microwave irradiating the chitosan-silver ions’ solutions of varying concentration. The irradiation turns the chitosan-silver ions’ solutions to chitosan-silver nanoparticles’ solutions, which are technically utilized to cast Ag-chitosan films. The reduction of silver ions into silver nanoparticles can be visually identified by color change from colorless to ruby red and can be monitored simultaneously from UV-Vis spectrometer with a noticeable absorption peak in the UV-Vis range of 400-450 nm. The presence of silver nanoparticles in the films can be inferred from fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). Scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) images illustrate the presence of embedded silver nanoparticles throughout the films. Transmission electron microscopy (TEM) analyses confirm the nano dimension of the formed silver nanoparticles. The diffraction patterns from X-ray diffraction (XRD) studies reveal the crystallite nature of the synthesized silver nanoparticles. The functional properties of films for food packaging applications are going to be characterized from universal testing machine (UTM), water vapour transmission rate (WVTP) and oxygen transmission rate (OTR). Further, the effectiveness of the fabricated films towards curbing the microbes is tested by both E. Coli (G -) and S. Aureus (G +).

 The significance of the investigation is, as the adopted methodology offers the feasibility to synthesize the silver nanoparticles in a facile manner with an overall less energy consumptions by microwave treatment, the present process reduce the overall cost of the manufacture of the antibacterial food packaging chitosan films [7]. This signifies the cost benefit too for large scale industrial production.

References

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[2] M. K. Rai, S. D. Deshmukh, A. P. Ingle, A. K. Gade, Silver nanoparticles: the powerful nanoweapon against multidrug-resistant bacteria. Journal of Applied Microbiology 112 (2012) 841-52.

[3] G. M. Raghavendra, T. Jayaramudu, K. Varaprasad, R. Sadiku, S. S. Ray, K. M. Raju, Cellulose-polymer-Ag nanocomposite fibres for antibacterial fabrics/skin scaffolds. Carbohydrate Polymers 93 (2013) 553– 560.

[4] N. S. Z. Haider, U. Kiran, I. M. Ali, A. Hameed, S. Ahmed, N. Ali, Combined efficacy of biologically synthesized silver nanoparticles and different antibiotics against multidrug-resistant bacteria. International Journal of Nanomedicine 8 (2013) 3187–3195.

[5] T. Ristic, L. Z. Zemljic, M. Novak, M. K. Kuncic, S. Sonjak, N. G. Cimerman, S. Strnad, Science against microbial pathogens: communicating current research and technological advances, ed. A. M´endez-Vilas (2011) 36–51.

[6] G. M. Raghavendra, T. Jayaramudu, K. Varaprasad, G. S. M. Reddy, K. M. Raju. Antibacterial nanocomposite hydrogels for superior biomedical applications: a Facile ecofriendly approach. RSC Advances 5 (2015) 14351–14358.

[7] A. G. Kahrilas, W. Haggren, R. L. Read, L. M. Wally, S. J. Fredrick, M. Hiskey, A. L. Prieto, J. E. Owens, Investigation of antibacterial activity by silver nanoparticles prepared by microwave-assisted green syntheses with soluble starch, dextrose, and arabinose. ACS Sustainable Chemistry and Engineering 2 (2014) 590−598.