Worldwide, almost one third of food produced is wasted and spoilage caused by microbial contamination has been recognized as one major contributor. In addition, food borne pathogens also result in significant illness and deaths. However, conventional food contact materials for food packaging are vulnerable to initial pathogen attachment and subsequent biofilm development. Herein, we propose to develop an antimicrobial food packaging material based on the visible-light-responsive graphitic carbon nitride (g-C3N4) and one earth-abundant biopolymer, chitosan. The antimicrobial potential of g-C3N4 against biofilms and planktonic bacteria under visible light irradiation has been well demonstrated in previous studies. After being incorporated into chitosan, a flexible polymeric composite film with promising antimicrobial effectiveness and robustness was achieved. Our study aims to understand the bactericidal mechanism of the composite material against biofilms and viruses under visible light irradiation and to seek opportunities to utilize the material for food packaging. g-C3N4 powder was first prepared via thermal polycondensation of melamine, cyanuric acid, and barbituric acid with an optimized ratio to achieve desired photocatalytic performance, and the powder was added to the chitosan matrix to fabricate the graphitic carbon nitride/chitosan composite material. The properties of the composite were characterized by Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The results of confocal laser scanning microscopy (CLSM), SEM, and optical coherence topography (OCT) demonstrated that the composite material inhibited Staphylococcus epidermidis and Pseudomonas aeruginosa biofilms formation under the irradiation of visible white light emitting diodes (LEDs). Moreover, mature biofilms were removed from the surface of composite films after exposure to visible light. The reactive oxygen species (ROS), i.e. singlet oxygen and superoxide anion radicals, identified during the photocatalytic process are believed to play an important role in biofilm inhibition and removal. In addition, the effectiveness of the composite material against two specific foodborne pathogens, Escherichia coli O157:H7 and norovirus, is being under investigation. Our study will have great impacts in food industry, by developing a new generation of antimicrobial food packaging to protect public health.

Visible-light-responsive graphitic carbon nitride/chitosan composite films for antimicrobial packaging

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.