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The present project addresses the development of polymer-based nanocomposites with tunable and enhanced bactericidal capacity for food packaging and related environmental applications. Envisioned nanocomposites will consist of a matrix of films or porous beads made of biocompatible polymers (e.g., chitin, chitosan, alginate, cellulose) hosting size/shape- controlled nanosize inorganic particles. The determination of the mechanisms involved with the crystal size-dependence of the bactericidal capacity of inorganic materials at the nanoscale; the optimum processing conditions leading to suitable dispersion of nanocrystals within the polymeric matrix, and the corresponding thermo-mechanical properties are also under the scope of this work. The bactericidal capacity of isolated phases and the nanocomposites will be evaluated in presence of different types of bacterial populations as a function of the dipersoids size or shape at the nanoscale and their volumetric loading in the polymeric matrix. The commercialization potential of developed materials and protocols for agriculture-related applications, including food safety and water cleaning, among others, will also be considered.
Non-Technical Summary:<br/>
Food packaging is indispensable to preserve the quality and safety of the food from the time of manufacturing to its final use by the consumer. Although commercially available plastics (polymers) fulfill most of the technical and economical requirements for food packaging, they are finally discarded to landfills and minimally recycled. This poor recycling practice added to the no-biodegradability of these plastics, makes the search for alternative bio-compatible, non-toxic and bio-degradable materials an indispensable task. The incorporation of bactericidal compounds into food packaging materials can combine physical stability and barrier properties provided by the polymeric matrix with the antimicrobial properties of antimicrobial agents dispersed as solid tiny particles. In this regard, novel and more efficient composites for food packaging based on the control of particle size of specific bactericidal materials and their suitable distribution within a bio-degradable polymeric matrix will provide innovative and safe alternatives to increase the food protection efficiency. On this basis, the present research will be focused on the development of biocompatible polymer-inorganic particle mixtures, so-called nanocomposites, with tunable and enhanced antimicrobial activity for food packaging and related environmental protection applications.
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Approach:<br/>
The incorporation of antimicrobial compounds into food packaging materials can combine structural integrity and barrier properties provided by the polymeric matrix with the antimicrobial properties of antimicrobial agents added as solid dispersoids or impregnating compounds. In particular, the dispersion of functional nanoparticles in the polymer matrix will improve the packaging properties of the resulting nanocomposite while enhancing gas barrier properties, temperature/moisture stability and resistance to bacterium and other microorganisms. Nanometric bactericidal materials have a very large surface to volume ratio that enable them to attach more copies of biological molecules, and hence, enhanced antimicrobial efficiency. These features coupled with tunable bactericide activity of specific nanoparticles and polymeric matrices will enable the development of more efficient and effective materials for food preservation and protection against human health-compromising microorganisms. Accordingly, the present research will be focused on the development of bio-degradable polymer-based nanocomposites with tunable and enhanced antimicrobial activity for food packaging. Single and bi-layered films of chitin/chitosan or Ca-alginate hosting nanometric particles (e.g. MgO and others) will be synthesized in solution phase and characterized on a structural, morphological, and thermo-mechanical basis. The bactericidal particles will be synthesized at various diameters below100nm and homogeneously dispersed within the polymeric matrix. The bactericide character of isolated phases and the corresponding nanocomposites will be assessed in presence of pure cultures of selected microorganisms (e.g. E. coli O157:H7, Salmonella, Shiguella, among others) as a function of the nanoparticle size and volumetric loading in the polymeric matrix. The potential dissolution and release of the nanoparticles constituents will also be investigated.