A US team has pioneered a technique which allows a nanoparticle to attract and hold nisin, which has strong antibacterial properties. Yuan Yao, an assistant professor of food science at Purdue University, altered the surface of phytoglycen, a carbohydrate found in sweet corn, which led to the creation of several forms of a nanoparticle.
The nanoparticle can then safeguard the food-based peptide nisin for up to three weeks, combating Listeria, a potentially fatal foodborne pathogen found in meats, dairy and vegetables.
"People have been using nisin for a number of years, but the problem has been that it is depleted quickly in a food system," said paper co-author Arun Bhunia. "This nanoparticle is an improved way to deliver the antimicrobial properties of nisin for extended use."
The research, funded by the US Department of Agriculture and the National Science Foundation, appears in the online version of the Journal of Controlled Release.
Methodology
The scientists employed two strategies to draw nisin to the phytoglycogen nanopoarticles. The first involved negatively charging the surface of the nanoparticle and using electrostatic activity to attract the positively charged nisin molecules. The other method saw the creation of a partially hydrophobic condition on the surface of the nanoparticle - which triggers a reaction with partially hydrophobic nisin molecules. When the particles are hydrophobic, or repel water, they become attracted to each other.
"Both strategies may work together to allow nanoparticles to attract and stabilize nisin," Yao said, "This could substantially reduce the depletion of nisin in various systems. to counteract the Listeria."
He added that a solution containing the required balance of nanoparticles and free nisin could be sprayed onto foods or included in packaging. Based on work carried out in the lab, he estimated that a sufficient amount of nisin to combat Listeria could be preserved for up to 21 days.
"When you reduce the amount of free nisin, it will trigger a release of more nisin from the nanoparticles to re-establish the equilibrium," said the assistant professor. "There will be a substantial amount of nisin preserved.”
The team is also working to develop other food-based antimicrobial peptides and nano-constructs to combat Listeria other foodborne pathogens such as E. coli O157:H7 and salmonella.