Antibacterial Paper Could Extend Shelf Life

A new paper that inhibits the growth of bacteria in food products could extend product shelf life and protect consumers from bacteria-causing foodborne illnesses. Overcoming the concerns associated with earlier antibacterial materials, this paper is nontoxic, environmentally friendly, and low in cost. The relatively simple processing of this antibacterial material suggests it may be commercially viable for food packaging methods in the near future.

The paper, an antibacterial nanomaterial composed of graphene oxide (GO) and reduced graphene oxide (rGO), was developed using a one-step vacuum filtration method by Qing Huang, PhD, Chunhai Fan, PhD, and colleagues at the Laboratory of Physical Biology at the Shanghai Institute of Applied Physics of the Chinese Academy of Sciences.

A paper made of an antibacterial nanomaterial composed of graphene oxide and reduced graphene oxide was shown to attack the cell membrane of E. coli cells.

Their study, “Graphene-Based Antibacterial Paper,” which was published in American Chemical Society NANO this July, details their studies of both GO and rGO nanosheets interacting with E.coli cells and a line of mammalian cells. A 98.5% viability loss of E.coli cells and a relative biocompatibility for mammalian cells was determined through transmission electron microscopy (TEM) studies, flow cytometric analysis, and cell cycle analysis.

The nanosheets hinder the growth of E.coli cells by attacking the membrane first, explained Dr. Huang. “Our TEM studies clearly showed that E.coli largely lost cellular integrity, with the cell membrane being severely destroyed and the cytoplasm flowing out,” Dr. Huang told PFQ. The growth of the cell is completely stopped, and no further growth can occur, Dr. Huang and Dr. Fan said in an e-mail.

Although only the effects of GO and rGO nanosheets on E.coli cells were examined, any other bacteria would suffer the same results, they said. Thus, consumers would be protected not only from foods contaminated by E.coli but also from any foodborne illness caused by a bacterium in a food product.

Commercial Use

The integration of GO and rGO solutions in food packaging is not in the works just yet, but Dr. Huang, Dr. Fan, and their colleagues suggest their continued studies of GO’s antibacterial mechanisms will soon lead to its commercial use. “We guess it [could] only take two years, maybe even earlier,” Dr. Huang said.

The application could be as simple as spreading the GO and rGO solutions across the packaging of the food product, suggested Dr. Huang. Once the solution dries, the packaging will possess the same antibacterial properties as the GO and rGO nanosheets.

Mass producing graphene nanomaterials, however, may not be as simple as the filtration processing used in Dr. Huang and Dr. Fan’s research. “It is still a challenge to mass produce graphene nanomaterials, and particularly to fabricate large-scale graphene materials like graphene paper. [The filtering method] seemed unsuitable for mass producing [nanomaterials], but we believe we can find some ways to do it in the future.”

Dr. Huang and Dr. Fan have yet to test foods and packing materials to determine how long deterioration could be prevented or how long a food product’s shelf life could be extended. Such tests may be delayed as Dr. Huang and Dr. Fan explore other potential applications for GO and rGO solutions, including their use as an antibacterial material in bandages for better wound healing.